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STATE OF FLORIDA
STATE BOARD OF CONSERVATION



DIVISION OF GEOLOGY
Robert O. Vernon, Director





REPORT OF INVESTIGATIONS NO. 50







WATER RESOURCES
OF
ORANGE COUNTY, FLORIDA

By
W. F. Lichtler, Warren Anderson, and B. F. Joyner
.U. S. Geological Survey


Prepared by the
UNITED STATES GEOLOGICAL-SURVEY -
in cooperation with the
DIVISION OF GEOLOGY, FLORIDA BOARD OF CONSERVATION
and the
BOARD OF COUNTY COMMISSIONERS OF ORANGE COUNTY



Tallahassee
S1968




SCIENCE
LIBRAyft





FLORIDA STATE BOARD
OF
CONSERVATION




CLAUDE R. KIRK, JR.
Governor


TOM ADAMS
Secretary of State



BROWARD WILLIAMS
Treasurer



FLOYD T. CHRISTIAN
Superintendent of Public Instruction


EARL FAIRCLOTH
Attorney General



FRED O. DICKINSON, JR.
Comptroller



DOYLE CONNER
Commissioner of Agriculture
;4


W. RANDOLPH HODGES
Director


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LETTER OF TRANSMITTAL


STATE BOARD QF CONSERVATION
Division of Geology
Tallahassee
January 26, 1968

Governor Claude R. Kirk, Chairman
State Board of Conservation
Tallahassee, Florida

Dear Governor Kirk:

The Division of Geology of the Florida Board of Conservation
is publishing as our Report of Investigations No. 50, a study of
the water resources of Orange County, Florida, prepared by
Lichtler, Anderson and Joyner of the U. S. Geological Survey. This
report is a cooperative study between the Orange County Com-
mission, the Division of Geology, and the U. S. Geological Survey.
With the anticipated urban expansion of Orange County that
will be accompanied with the development of Disney World, the
water resources of the area must be adequate to meet the demands
of an expansion that will change a swamp to an urban area in a
space of five years. We feel that the water resources of Orange
County are adequate to meet these demands and we are proud
to be able to contribute in a substantial way to the development
of the area.
Respectfully yours,

Robert O. Vernon
Director and State Geologist
ROV :lam



















































Completed manuscript received
January 26, 1968
Printed for the Florida Board of Conservation
Division of Geology
By the E. 0. Painter Printing Company
DeLand, Florida

iv










CONTENTS

Page
Abstract .............--- .. ..........--- .--- ---- ----------------. .........-----------..... ---------- 1
Introduction ..------...----......---............---- ------..-----...--......... 2
Purpose and scope of investigation ...---..-..--. --.......... ..............--...............- 3
Acknowledgments -..--.......................----------------.......- .--- .---.... 3
Previous investigations ......-- ................ --....---..-- ---- ......--- 4
W ell-numbering system ...--....-.........--- .. --.-...--..... ....--- ......------.....--- -.... 5
Description of the area .....---..---......-- ......-------- ------ --------- 6
Location and extent ....................... ...... .......................-.......... ....-------- 6
Topography ---........ ----...---............................. ....... ........ .... 6
Climate ...---................------ .....------ --.. .... .. -- ------.. ... --- 10
Sinkholes --... ---.. ---...........- .............---...... ----- .......... ....... 10
Drainage -..-....-----... .... -----------------.....--- ...... ..... ................. 14
Geology --...---......--..-.......---------.-------- ---.....---..---... 14
Form nations ........ ......... .. ................................................ .................... .. 18
Structure .-- ------...........-.............. --- ..... --.. -- ---- -..- ....... .. 22
Hydrology .......--...----.......... ...---- -- -------------------......... .. ...... .--. ..-... 23
Chemical quality of water .-..................-........---------- .. --..............-- .... ----23
Relation of quality of water to use -..------... ..---...-..- .....------ .------.-- 24
Domestic use .........---..-------..-.......-------------- -------------- 29
Agricultural use --..-...- ------------.......---------.........--...-...-. 30
Industrial use -...........--....-.......-- ..........- -------------------... .....- ... 32
Surface water --.. --.........-....-..------.......-.....----..................-....--- 32
Occurrence and movement .......-----.........- --- ---------...--.... 32
Variation -....-............-------..... ...........--------- ..----..------- 33
Presentation of data ...........---..-...-...------- ----- ----........----... ... 35
Surface drainage ..---......--.. ---.------.---------.........-- 43
Kissimmee River basin -........................---------------...-- ..---.-- 45
Reedy Creek ---..--- .--------------- ...---.....-------.-----. 45
Bonnet Creek ...........-- .......-...-....----- ....-------- ----.-----.... ------ 47
Cypress Creek ..-..........................--------- -- --------.---------- 48
Shingle Creek -....-.......-................---------------- .. ........ .. 49
Boggy Creek -.....-- ............................-------..--.---- ..--- ------ 50
Jim Branch ---.......--..---------...-.......-..-...--- ......... -------------52
Ajay-East Tohopekaliga Canal .........-----..-..- __..--..-.----------..--- 52
St. Johns River basin -......--...----.........-----. ---------.----------------- 53
St. Johns River ..........- -..-........ .---------......--------- 53
Small tributaries draining east ....---.....-.....--......---......------- 59
Lake Pickett ..--...................-...---.-- --- ---------------------------------. 61
Econlockhatchee River ....-..--..-....- ...---------- --------------.. 61
Little Econlockhatchee River --. ------..-.........-.........---...--------.--- 65
Howell Creek .-----.......--......-...-------------..--------------------- 67
Wekiva River .....--------------.............---------.........................................-------------------- 68
Apopka-Beauclair canal ....--................----.------ ------------------- 71
Lakes ...-------........---.... ------................----.....----...---------- -. -- ---------- 71







Occurrence ...-.--- .........-... .....--- ... ............................... .........-............ 71
Surface area -....-.....-....--....--.......--..........--.... --. ..---.......-..--....-... 74
Depths .... ........ ...........--. -.-- ..-........ .------------............. 74
Altitudes ..-.--.-........-.......-........-...........----....--...-..-... ..-........--.....----.... 74
Seasonal patterns in lake-level fluctuations .......................--.---..-..-..--- 74
Range in lake-level fluctuations ....-..-..........--- ....----...-...-..-.......-- ...-- 77
Water quality in lakes --..-.....-......--...-- ..-- ..----- ....----- .------ 78
Control of lake stages .---..--..----....--......--. -----------...- ...--..-- 80
Problems ......------..-..........-...--...--.....---- ................--.-- .......------. -----.....................---..... 81
Ground water ...-............................................-............................. ....-..-.................. 82
Nonartesian aquifers ---.........---.......... .........-------------........ 82
Water levels ................-..-- ..--....-...-- ......- .....-------.....----- -----..-..-. 83
Recharge ..--.......--- ..- ----..........-.-------..---------- 86
Discharge ..-----....-.-----..-...-...--.----..--..-- ..............------ 86
Quality of water .---....---......-..-- ..-------... ...-..-- ..--..........----. 87
Secondary artesian aquifers .---...-.......-...--..--- .. ........ ------ 88
Water levels ...-...---........ ..----------- .......-- ....------- ...-- 88
Recharge ..---........-..---.---....------ ---------..-.. 90
Discharge .--...---....----......---------------..-- .-- -.....- -....... 90
Quality of water -....-.--..-......... .----------......--------------------..-...-... 90
Floridan aquifer ---......--.--... ...... ------.-------.. -......--..... 91
Aquifer properties ..---......-.... ...... ---....---- -- .......--..-... 91
Zones of the aquifer ...-...-..-------....--------- -----------...... 94
Interrelation of zones ...-.----........ --------------- -.......--.....-. 95
Piezometric surface .-------..._~.~. ..........- ....- ...-.-- .. --101
Fluctuations ...------...........-------------- -- ..-......--.. .. -- 106
Recharge areas --.......----.... ---------------- ----..------- 112
Discharge areas -..------............. ... ............. ...-..-....-......-.. ..116
Quality of water ...-......... .. .................................... .... ................ .. 117
Salt-water contamination ......_.......- ---- .------------......-....-...--. 124
Drainage wells .--..-..--...-..-----....................----------------------------...............--..-..--.. 128
History .....--...--... --........... ...-...-............... ...................-.. 128
Pollution --... ..... ----------------------.........-..... ............-- .-- 128
Other aspects of drainage wells .-----...----.-........--....------------ ... 133
Pum ping tests ....................................................... ....... ...... 134
Water use--- -------------- ............ -----------..................--....--- 139
Ground water .--......-- ..------.~... .........-- ... ........ 139
Surface water .---------. .......---------------.... ...- .................. ....---- -- ...- ....-...... 142
Summary ---...................................................................----------------------------------------------------.................. 143
Conclusions ..-----.------ -... -------.........--------- -------........................ 145
References ...--........................................----------..... -----------------------------. 148


ILLUSTRATIONS
Figure Page
Frontispiece. Aerial view of the Orlando business district looking north-
ward from Lake Lucerne ..---...........----------..........-......--..... Facing p. 1
1 Location of Orange County and illustrating well-numbering system 5
2 Location of inventoried wells other than drainage wells, Orange
County, Florida ...........................- ......... ....-................---- -.................... 7







3 Topographic regions of Orange County, Florida .......................... 8
4 Sinkhole two miles west of Orlando formed in summer of 1953 ....... 12
5 Location of drainage wells in Orange County, Florida, 1964 ........ 15
6 Geologic sections --...-......... ..... ............................... ....... ....... Facing p. 14
7 Configuration and altitude of top of the Avon Park Limestone,
Orange County, Florida ............... ........... ........ ................. ... .-- ........ 19
8 Configuration and altitude of top of the limestone of Eocene age,
Orange County, Florida ..... ........----.........- .................... ........---- ....--.. 21
9 Annual average discharge and average discharge for period of
record at three stations on streams draining from Orange County... 34
10 Annual rainfall at Orlando .-................ ...............- .. ......... ...-.. 35
11 Average, maximum, and minimum monthly mean discharges of
three streams draining parts of Orange County and rainfall at
Orlando ................................................ ............. .......... ..---- ........... 36
12 Monthly runoff from Econlockhatchee River basin 1949 and 1958 .. 37
13 Type and duration of surface-water stage and discharge records
and number of chemical analyses of surface water samples col-
lected at gaging sites in and near Orange County .-..... -...._.......- 38
14 Duration curves of daily flow for streams in and near Orange
County ..................................----- ..--- ....-.................. .......... ...... 40
15 Estimated flow-duration curves for streams and springs for which
periodic or miscellaneous discharge data are available ....--............ 41
16 Stage-duration curves for selected lakes ...........................-...--.. 42
17 Water-surface profiles for floods of selected recurrence intervals
on main stem of St. Johns River in Orange County -....-..-.... .... 44
18 Drainage basins and surface-water data collection points .... Facing p. 44
19 Streambed profile for selected streams in the upper Kissimmee
River basin ..-..-.....-- ..-.--. ....-....-...-..... ....---...------ ........... ....... .. 46
20 Streambed profiles of Boggy Creek and Jim Branch .............. ---..... 51
21 Flow-duration curve for Myrtle-Mary Jane canal near Narcoossee 53
22 Low-flow frequencies for St. Johns River near Christmas .............. 55
23 Chloride concentration in water in St. Johns River from U. S. High-
way 192 to State Highway 16, northeastern Florida.................-...- ..-... 56
24 Specific conductance of water in St. Johns River near Cocoa ..-....-..- 57
25 Cumulative frequency curve for specific conductance of the St.
Johns River near Cocoa, October 1953- September 1963 .............--.. 58
26 Streambed profiles of small streams draining east into St. Johns
River .-..-........--...---- ------..... .... ...........- -....... -. ----..--...----..... 60
27 Streambed profiles of Econlockhatchee River and selected tribu-
taries --- --------.... -.. -. .......--- ...... .........---------- -...........-..- ... .............. 62
28 Low-flow frequencies for Econlockhatchee River near Chuluota....... 64
29 Cumulative frequency curve of specific conductance of the Econ-
lockhatchee River near Bithlo, October, 1959 May, 1962 .-..--...-.......- 65
30 Relation of specific conductance to hardness and mineral content
for Econlockhatchee River near Bithlo -....-......-.......................---- ... --66
31 Estimated flow-duration curves for Howell Creek near Maitland ... 68
32 Streambed profiles for Wekiva River and tributaries....--....--..--........ 69
33 Low-flow frequencies for Wekiva River near Sanford --...-....-..---..-...-- 70
34 Estimated average monthly evaporation from lakes..............-------...---. 75
35 Comparison of average monthly change in stage of three lakes







with average monthly difference in rainfall and evaporation at
Orlando 76
36 Hydrographs for wells near Bithlo and Hiawassee Road showing
pattern of fluctuation of the water table 84
37 Relationship between water levels at Bithlo and rainfall at Orlando 89
38 Configuration and altitude of the top of the Floridan aquifer in
Orange County, Florida___- 92
39 Depth below land surface to the top of the Floridan aquifer in
Orange County, Florida __ 93
40 Distribution of reported cavities in Floridan aquifer in Orange
County, Florida _______- 96
41 Relationship between water levels in the upper and lower zones of
the Floridan aquifer at Orlando 97
42 Hydrograph of well 833-120-3 showing effects of pumpage in the
Orlando well fields __ 98
43 Configuration and altitude of the piezometric surface in the lower
zone of the Floridan aquifer in the Orlando area 99
44 Relation between dissolved solid and hardness of water depths of
wells in the Orlando area __ _-_ 100
45 Piezometric surface and areas of artesian flow of the Floridan
aquifer in Florida, July 6-17, 1961 __ 101
46 Contours of the piezometric surface at high-water conditions,
September 1960 __ 102
47 Contours of the piezometric surface at about normal conditions,
July 1961___ 103
48 Contours of the piezometric surface at about normal conditions,.
December 11-17, 1963 ___ ____ 104
49 Contours of the piezometric surface at extreme low water condi-
tions, May 1962 ____ 105
50 Piezometric surface relative to land surface datum, at high water
conditions, September 1960, Orange County Florida .______ 107
51 Piezometric surface relative to land surface datum, at low-water
conditions, May 1962, Orange County, Florida ___ --_ 108
52 Hydrographs of wells __-___ 109
53 Range of fluctuation of the piezometric surface from September
1960 to May 1962, Orange County, Florida 110
54 Recharge areas to the Floridan aquifer in Orange County, and
selected adjacent areas, Florida __ Facing p. 112
55 Dissolved solids in water from wells that penetrate the Floridan
aquifer, Orange County, Florida __ 114
56 Hardness of water from wells that penetrate the Floridan aquifer,
Orange County, Florida 119
57 Chloride concentration in water from wells that penetrate the
Floridan aquifer, Orange County, Florida -____ 120
58 Composition of mineral content of water from selected wells in the
Floridan aquifer _--- --_ 123
59 Temperature of ground water in Orange County, Florida 125
60 General areas where bacterially polluted water has been reported
from some wells. (After unpublished map prepared by Charles W.
Sheffield, Orange County Health Department)___--- 130







61 Location of wells used in salt test in Lake Pleasant area____ 131
62 Changes in population and water use_._ ___ 140

TABLE
Table Page
1 Temperature and rainfall at Orlando, Florida __. 11
2 Summary of the properties of the Geologic formations penetrated
by water wells in Orange County _-----_ --_________.-------- 16
3 Altitudes of terraces in Florida _.__ 22
4 Water quality characteristics and their effects ____------------------ 25
5 Drinking water standards for fluoride concentration _.- ---_. 30
6 Water quality requirements for selected uses Facing p. 32
7 Sites where miscellaneous surface-water data have been collected 39
8 Ranges in quality of surface water in Orange County __ Facing p. 40
9 Chemical analysis of St. Johns River water, June 7, 1962_ __ 57
10 Minor elements in water from St. Johns River near Cocoa, May 11,
1962 -- --------- -------- 59
11 Discharge measurements of springs in Orange County, Florida.__- 72
12 Analysis of water from Lake Francis and Spring Lake 79
13 Analysis of water from selected wells in the Floridan aquifer in
Orange County, Florida ___ 122
14 Results of pumping tests in Orange County, Fla. --- 136



















































Aerial view of the Orlando business district looking northward from
Lake Lucerne.








WATER RESOURCES
OF
ORANGE COUNTY, FLORIDA

By
W. F. Lichtler, Warren Anderson, and B. F. Joyner

ABSTRACT

The population and industry of Orange County are expanding
rapidly but the demand for water is expanding even more rapidly.
This report provides information for use in the development and
management of the water resources of the area.
The county is divided into three topographic regions: (1) low-
lying areas below 35 feet (2) intermediate areas between 35 and
105 feet and (3) highlands above 105 feet. The highlands are
characterized by numerous sinkholes, lakes and depressions.
Surface runoff forms the principal drainage in the lowlying and
intermediate regions, whereas underground drainage prevails in
the highlands.
Lakes are the most reliable source of surface water as swamps
and most of the streams, except the St. Johns and Wekiva Rivers,
go dry or nearly dry during droughts.
Approximately 90 of the 1,003 square miles in Orange County
are covered by water. The southwestern 340 square miles of the
county drain to the south to the Kissimmee River. The remainder
drain to the north to the St. Johns River.
The water in the lakes and streams in Orange County generally
is soft, low in mineral content, and high in color. The quality of
the water in most of the lakes remains fairly constant except were
pollution enters the lakes.
Ground water is obtained from: (1) a nonartesian aquifer com-
posed of plastic materials of late Miocene to Recent age; (2) several
discontinuous shallow artesian aquifers in the Hawthorn Forma-
tion of middle Miocene age; and (3) the Floridan aquifer composed
of limestone of Eocene age.
The surficial nonartesian aquifer yields relatively small quan-
tities of soft water that is sometimes high in color. The shallow
artesian aquifers yield medium quantities of generally moderately
hard to hard water. The Floridan aquifer is the principal source






REPORT OF INVESTIGATIONS NO. 50


of ground water in Orange County. It comprises more than 1,300
feet of porous limestone and dolomite and underlies sand and clay
deposits that range in thickness from about 40 to more than 350
feet. Most large diameter wells in the Floridan aquifer will yield
more than 4,000 gpm (gallons per minute).
Water levels of the Floridan aquifer range from about 15 feet
above to more than 60 feet below the land surface. The quality of
the water ranges from moderately hard in the western and central
parts to saline in the extreme eastern part of the country.
The Floridan aquifer in Orange County is recharged by rain
mostly in the western part of the county. Drainage wells artificially
recharge the Floridan aquifer, but may pollute the aquifer unless
the quality of the water entering the wells is carefully controlled.
Urbanization in the recharge area and pollution can reduce the
amount of potable water available in the Floridan aquifer. Artificial
injection of good quality surplus surface water can increase the
amount of water available and improve its quality, especially in
the eastern part of the county where there is salty water in the
aquifer.
Use of ground water in 1963 was estimated to average about
60 mgd (million gallons per day) for municipal, industrial, domes-
tic and irrigational use. Use of surface water was estimated to
be about 5.5 mgd for irrigation. Surface water was also used for
cooling and recreation.


INTRODUCTION

The rapid increase of population and industry in Orange County
and nearby areas has created a more than commensurate increase
in the demand for water. Not only are there more people and
more uses for water, but the per capital use of water is increasing.
East-central Florida, as a growing center in missile development
and space exploration, is increasing in population and industry;
therefore, the increase in demand for water is expected to continue
and even to accelerate.
This report contains information on the quantity, chemical
quality, and availability of water in Orange County. The report
will be useful to people who have the responsibility of planning,
developing, and using the water resources of Orange County and
much of the East-central Florida region and to anyone interested
in water.






WATER RESOURCES OF ORANGE COUNTY


PURPOSE AND SCOPE OF INVESTIGATION

The purpose of this investigation is to furnish data that will
be useful in the conservation, development, and management of
the water resources of Orange County. Water is one of the most
important natural resources and Orange County, with more than
50 inches of annual rainfall, hundreds of lakes, and the Floridan
aquifer, is blessed with an abundant supply. However, the rainfall
is not evenly distributed throughout the year, or from year to
year, nor are there adequate storage reservoirs in all parts of the
county.
Knowledge of all factors affecting the water resources of an
area is necessary in planning for the protection, efficient develop-
ment, and management of water supplies. Recognizing this need,
the Board of County Commissioners of Orange County entered into
a cooperative agreement with the U. S. Geological Survey to
investigate the water resources of Orange County. The investiga-
tion is a joint effort by the three disciplines within the Water
Resources Division of the Survey under the direction of W. F.
Lichtler, project leader. The report was prepared under the
supervision of C. S. Conover, District Chief, Water Resources Divi-
sion, Tallahassee. It is the comprehensive report of the 5-year
investigation and also incorporates information contained in an
interim report (Lichtler, Anderson, and Joyner, 1964), a lake-level
control report (Anderson, Lichtler, and Joyner, 1965), a ground-
water availability map (Lichtler and Joyner, 1966), and a
surface-water availability map (Anderson and Joyner, 1966),
produced as byproduct reports of the investigation.
The report includes determinations of variation in lake levels,
stream flow, chemical quality of surface and ground waters and
ground-water levels, evaluation of stream-basin characteristics,
delineation of recharge and discharge areas, investigation of
characteristics of the water-bearing formations, assembly of
water-use information and interpretations of water data.


ACKNOWLEDGMENTS

The authors express their appreciation to the many residents
of Orange County who freely gave information about their wells
and to various public officials, particularly the Board of County
Commissioners, whose cooperation greatly aided the investigation.






REPORT OF INVESTIGATIONS NO. 50


Special appreciation is expressed to Fred Dewitt, County Engineer;
to Robert Simon and Jesse Burkett of the City of Orlando Water
and Sewer Department; and to L. L. Garrett and Gene Birdyshaw
of the Orlando Utilities Commission for their assistance.
Appreciation is given to the well drillers in and near Orange
County who furnished geologic and hydrologic data and permitted
collection of water samples and rock cuttings and measurements
of water levels during drilling operations, and to the grove owners,
managers and caretakers who furnished data on irrigational use
of water.
The Board of Supervisors of the Orange Soil Conservation Dis-
trict and Albert R. Swartz and other members of the technical
staff of the U. S. Soil Conservation Service gave much useful advice
and information and provided strong support and encouragement
during the course of the investigation.


PREVIOUS INVESTIGATIONS

Two previous investigations of the water resources of Orange
County have been made. A report by the U. S. Geological Survey
(1943) gives the results of a study of lakes as a source of
municipal water supply for Orlando. A detailed investigation by
Unklesbay (1944) deals primarily with drainage and sanitary wells
in Orlando and vicinity and their effect on the ground-water
resources of the area.
Other investigators have included Orange County in geologic
and hydrologic studies. Fenneman (1938), Cooke (1939), MacNeil
(1950), and White (1958) describe the topographic and geomorphic
features of Central Florida. Cole (1941, 1945), Cooke (1945), Ver-
non (1951), and Puri (1953) describe the general geology of Cen-
tral Florida and make many references to Orange County. Sellards
(1908), Sellards and Gunter (1913), Matson and Sanford (1913),
Gunter and Ponton (1931), Parker, Ferguson, Love, and others
(1955), D. W. Brown, Kenner, and Eugene Brown (1957), and
D. W. Brown and others (1962) discuss the geology and water
resources of Brevard County. Stringfield (1935, 1956) and
Stringfield and Cooper (1950) investigated the artesian water in
peninsular Florida, including Orange County. Collins and Howard
(1928), Black and Brown (1951), Wander and Reitz (1951), and
the Florida State Board of Health (1961) give information about
the chemical quality of water in Orange County.






WATER RESOURCES OF ORANGE COUNTY


WELL-NUMBERING SYSTEM

The well-numbering system used in this report is based on
latitude and longitude coordinates derived from a statewide grid
of 1-minute parallels of latitude and meridians of longitude. Wells
within these guadrangles have been assigned numbers consisting
of the last digit of the degree and the two digits of the minute
of the line of latitude on the southside of the quadrangle, the
last digit of the degree and the two digits of the minute of the line
of longitude on the east side of the quadrangle, and the numerical
order in which the well within the quadrangle was inventoried.
For example, well 827-131-3 is the third well that was inventoried
in the 1-minute quadrangle north of 28027' north latitude and west
of 81031' west longitude (See figure 1.).


Figure 1. Location of Orange County and illustration of well-numbering
system.





REPORT OF INVESTIGATIONS NO. 50


Wells referred to by number in the text can be located on
figure 2 by this system.

DESCRIPTION OF THE AREA

LOCATION AND EXTENT

Orange County is in the east-central part of the Florida
peninsula (fig. 1). It has an area of 1,003 square miles of which
about 916 square miles are land and about 87 square miles are
water. It is bounded on the east by Brevard County, on the north
by Seminole and Lake Counties, on the west by Lake County, and
on the south by Osceola County.
The estimated population of Orange County in 1963 was 290,000.
In that year, the estimated population of Orlando, the largest city
in the county, was 90,000 while Winter Park, the second largest
city, had an estimated population of 20,000. The growth rate of
Orange County's population has increased enormously since 1950
(See figure 63) and this trend is expected to continue. The
population of Orange County is expected to reach 530,000 by 1975.
The principal agricultural products in Orange County are citrus,
ornamental plants, vegetables, cattle, and poultry. In 1960 there
were about 67,000 acres of citrus groves, more than 600 nurseries
and stock dealers, about 6,000 acres of vegetables-mostly in the
Zellwood muck lands northeast of Lake Apopka-about 23,000 head
of cattle and about 180,000 laying hens in the county. )J

TOPOGRAPHY

Orange County is in the Atlantic Coastal Plain physiographic
province described by Meinzer (1923, pi. 28). The county is sub-
divided into three topographic regions: (1) the lowlying regions
where altitudes are generally less than 35 feet; (2) -intermediate
regions where altitudes are generally between 35 and 105 feet; and
(3) highland regions where altitudes are generally above 105 feet.
(fig. 3).
The lowland regions include the St. Johns River marsh, the
northern part of the Econlockhatchee River basin and the north-
eastern part of the county east of Rock Springs. Altitudes range
from about 5 feet above msl (mean sea level) near the St. Johns
River to about 35 feet above msl where there is a relatively steep
scarp in many places in Orange County. The St. Johns River marsh






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A .,ln cPI I. W4 11M 1 0 10f 1<44 ,l1 WO
Ioalm If, o.9 oll 44 calps CIn
4.04 44 0 g006
.l4l 4 ol 6041 0 11f W

t Wlal wla 01t 1 0 lO, ehf WI r1
Cbil4 14: ll '4 11 I4cyp1 gdCmIiW l


10 too coiloi, Pinv-1 "fgnow ICKlO, 19411


C 0 U N T Y


0 I 2 3 4 5 6 7 8 9 Om.es


Figure 3. Topographic regions of Orange County, Florida.






WATER RESOURCES OF ORANGE COUNTY


in the eastern part of the county is a part of Puri and Vernon's
(1964, figure 6) Eastern Valley. The low area east of Rock
Springs is a part of the Wekiva Plain and the Econlockhatchee
Valley is a small part of the Osceola Plain.
The intermediate region occupies most of the middle part of the
county between the lowlands and the highlands. Altitudes range
from 35 to 105 feet above msl but are mostly between 50 and 85
feet above msl. A characteristic area of ridges and intervening
lower areas parallel the Atlantic coast is best developed in the
area between Orlando and the Econlockhatchee River. These ridges
are believed to be fossil beach ridges from higher stands of the sea.
The intermediate region coincides, in general, with Puri and
Vernon's (1964, figure 6) Osceola Plain except for the area in the
northwestern part of the county which is a part of Puri and
Vernon's Central Valley.
The highlands occupy the western part of Orange County with
an island outlier in Orlando and vicinity. Altitudes are generally
above 105 feet but range from about 50 feet in low spots, such as
the Wekiva River basin, to about 225 feet above msl near Lake
Avalon on the western border of the county. The highlands contain
many lakes and depressions, most of which do not have surface
outlets.
The highland regions in Orange County include parts of Puri
and Vernon's Orlando Ridge, Mount Dora Ridge, and Lake Wales
Ridge.
The three topographic regions described above are approximately
equivalent to the Pleistocene terraces postulated by MacNeil (1950)
as the Pamlico terrace from about 8 feet to about 30 feet above
msl, the Wicomico terrace from about 30 feet to about 100 feet
above msl, and the Okefenokee terrace from about 100 to 150 feet
above msl.
Cooke (1939, 1945) has called the surface defined by the 42-
and 70-foot shorelines the Penholoway terrace and the surface
defined by the 70- and 100-foot shorelines the Wicomico terrace.
The areas in Orange County that are above 150 feet probably are
sandhills or altered remnants of higher terraces.
The water resources of Orange County are directly related to
the topography of the area. In general, the highlands are the
most effective natural ground-water recharge areas. They have
few surface streams but have many lakes and depressions. The
intermediate region ranges from good to very poor as a ground-
water recharge area. There are many lakes in some areas and none






REPORT OF INVESTIGATIONS NO. 50


in others. Surface streams in this region either go dry or recede
to very low flow after relatively short periods of drought. The
lowlands are ground-water discharge areas and contain few
lakes except in the mainstem of the St. Johns River. Streamflow
is more sustained than in the other regions because of water stored
in the lakes along the mainstem of the St. Johns River, spring
flow, and seepage of ground water from both the water-table and
artesian aquifers.

CLIMATE

Orange County has a subtropical climate with only two
pronounced seasons-winter and summer. The average annual
temperature at Orlando is 71.50F and the average annual rainfall
is 51.4 inches. (See table 1.) Summer thunderstorms account for_
most of the rainfall. Thunderstorms occur on an average of 83
days per year, one of the highest incidences of thunderstorms in
the United States (U. S. Weather Bureau, Annual Report 1960).


SINKHOLES

Sinkholes are common in areas such as Orange County that are
underlain by limestone formations. Rainfall combines with carbon
dioxide from the atmosphere and from decaying vegetation to
form weak carbonic acid. As the water percolates through the
limestone, solution takes place and cavities of irregular shape are
gradually formed. When solution weakens the roof of a cavern
to the extent that part of it can no longer support the sandy
overburden, sand falls into the cavity and a sinkhole forms on the
surface. (See figure 4.) Most of Orange County's natural lakes,
ponds, and closed depressions probably were formed in this manner.
Sinkholes range in size from small pits a few feet in diameter to
large depressions several square miles in area. Large depressions
are usually formed by the coalescence of several sinkholes.
Sinkholes may form either by sudden collapse of a large part
of the roof of a large cavern or by gradual infiltration of sand
through small openings in the roof of the cavity. The latter
condition is illustrated by the formation of a sinkhole in Canton
Street in Winter Park in April 1961. The sink was first noted as
a depression in the graded road. By the following day a hole about
6 feet in diameter had formed. In the next 2 days the hole gradually








TABLE 1. TEMPERATURE AND RAINFALL AT ORLANDO, FLORIDA

Normal Normal Maximum Minimum
daily daily Normal Normal rainfall3 rainfalls
maximum minimum average rainfall
temperature13a temperature2 temperature12 inches1'2 Inches Year Inches Year

January 70.7 50.0 60.4 2.00 6.44 1948 0.15 1950
February 72.0 50.7 61.4 2.42 5.64 1960 0.10 1944
March 75.7 54.0 64.9 3.41 10.54 1960 0.16 1956
April 80.5 59.8 70.2 3.42 6.18 1953 0.28 1961
May 85.9 66.2 76.1 3.57 8.58 1957 0.43 1961
June 89.1 71.4 80.3 6.96 13.70 1945 1.97 1948
July 89.9 73.0 81.5 8.00 19.57 1960 3.83 1963
August 90.0 73.5 81.8 6.94 15.19 1953 3.20 1960
September 87.6 72.4 80.0 7.23 15.87 1945 1.65 1958
October 82.6 65.3 74.0 3.96 14.51 1950 0.46 1963
November 75.6 56.2 65.9 1.57 6.39 1963 0.09 1950
December 71.6 51.2 61.4 1.89 4.30 1950 Trace 1944
Yearly 80.9 62.0 71.5 51.37 68.74 1960 39.61 1943

SAverage for 10 or more years.
"U. S. Weather Bureau records, 1931-60.
3U. S. Weather Bureau records, 1943-60.







































~ :$f; ~..


Figure 4. Sinkhole 2 miles west of Orlando formed in summer 1953. It was
:uhibscquently filled in and no further sinking has occurred.
W., n .u'. .... ...* ^. .- .. M ..,* . i !* *>**. *-


1 'I





h s
o


00 1


"i ?-
^..i


~,"F~~c:'IF' t

c,
s! ',,p E ;,g IF~
~P~crl1rilf~ 7
~F
',.
f ir r
,~i fi~ i:
'' ~5~
"







WATER RESOURCES OF ORANGE COUNTY


increased in size to about 60 feet in diameter and to about 15 feet
in depth. The hole was filled and no further development has been
noted.
Another sinkhole formed in 1961 in Pine Hills, west of Orlando.
A depression about 1-foot deep and 50 feet in diameter that formed
on April 23 and 24 was marked only by a faint line in the sand
except where the outer edge intersected two houses. The floor of
one room, the carport, and the concrete driveway of one house were
badly cracked. The corner of the other house dropped about 6
inches. The slow rate of settlement was probably caused by a
gradual funneling of the overlying sand and clay into relatively
small solution channels in the limestone. The channels eventually
became filled and the subsidence ceased.
A sinkhole formed rather rapidly in Lake Sherwood on May 22,
1962. This spectacular sinkhole removed a section of the west-
bound lane of Highway 50 and about 3,000 cubic yards of fill were
required to repair the damage. According to eye witnesses, the
sinkhole formed over a period of about 2 hours.
Sinkholes are most likely to form in areas of active ground-
water recharge because the dissolving action of the water is
greatest when it first enters the limestone aquifer. As the slightly
acid water moves through the aquifer, it gradually reacts with
the limestone and is neutralized. The prevalence of sinkholes is
usually a good indication that the area is, or was in the past, an
area of active recharge.
Sinkholes can either improve or impede the recharge efficiency
of an area. In some instances, sinkholes breach the semipervious
layers that separate the surface sand from the aquifer and permit
water to enter the aquifer more readily than before. In other
instances, lakes that form in sinkholes become floored with
relatively impermeable silt, clay and organic material which retards
the downward movement of water.
Much remains to be learned about the solution of limestone by
water. Caverns have been discovered several thousand feet below
the surface, and evidence indicates that active solution is going on
at these depths. Present and future research by the U. S. Geo-
logical Survey and other agencies should provide much useful
information about this important subject and its relation to
ground-water movement and availability.






REPORT OF INVESTIGATIONS No. 50


DRAINAGE

The eastern and southern parts of Orange County aredra ained
principally_by..urface streams. The St. Johns River and its,
tributaries drain the eastern and nr e odh-f the county while
Sb ngle reek R reek, Boggy Creek and canals in the upper
Kissimmee River-basin drain mostof the south-central and south-
westernpartsofthecounty. Many swa dsouhocur in
the eastern and-southernpartsof tthe-county because.of the poorly
developed-drainage.
Surface drainage in the western and northwestern parts- of
the county is mostl~lyitocloTiied depre-sionis whe-re it--itler seeps
into the ground or evaporates. A few sinliholes iilthis area have
open connections with solution channels in the underlyinglime-
stonfe-Wa-ter ~fat collects in these sinkholes drains directly into
t esiolution channels. Most of the sinkholes, however, are floored
with relatively impermeable sediments and the rate of seepage
through these lake-filled sinkholes may be less than in areas
ad'jcent to the lakes.
kMore than 300 drainage wellswere-drilledhetween 1906_nnd
1961 in the upland area of the _Qunty,_especially in Orlando and
cidiity, to i dray surface water directly into the arteiSinquife;)
-(fig. 5). The greatest activity was during 1960 when about 35
drainage wells were drilled. Considerable quantities of water-are
drained underground in this manner, but the total amount is not
kn-I6Wn. e after that entersls-e-aquifer through drainage _ells
ranges from purr water used to fush--o Farns.


GEOLOGY

The occurrence, movement, availability,'quality, and quantity
of the ground water in Orange County are closely related to the
geology of the area. Therefore, knowledge of the structure,
stratigraphy, and lithology of the geologic formations is essential
to an evaluation of the ground-water resources.
O--- range County is underlain mostly by marine limestone,
dolomite, shale, sand, and anhydrite to about 6,500 feet at which
depth granite and other crystalline rock of the basement complex
occur. Only the top 1,500 feet of sediments that have been
penetrated by water wells will be discussed in this report. A
summary of the properties of the formations is given in table 2.











_M cu.j c.j- lb CD 0
... T iT

\ r O Jrorr \ 3cJ o\j
ro Cro rl ror) S4) 0"3 cc Co o
oo oo aooooaooo co co a,
o lb





..... MOO


- C\J -1

TI I I T T
C'J r0 N c0
cNi oj C j cNi C~j
co CC co co

-,
c(z lt
A l^ -.1


A'

I A I
0 0
ro ro




CIZ
tr


00
I I
ro C\j
C.. c\J
a, a
Co Co


0 10


t0
ro


C:)


co


B


0
co
g


Note: See figure 2 for location of sections.
Vertical exaggerotion x 264


OJ -
I I

toto
roo
00 00


C\1

CJ C\1
* I)
col
LC3


100


200


300


400


200


100


SEA
LEVEL

100


200


300


400


200


100

SEA
LEVEL


Figure 6. Geologic sections.


200rn


EXPLANATION


LITHOLOGY



Shell



Marl


L I
Sand



Clay



Limestone



Dolomite



Cavity zone


GEOLOGY



Undifferentiated
Sediments


Hawthorn
Formation


Ocala Group



Avon Park
Limestone


00 -


_ _A


5 0J .i
500


_20
3: '


400
4QO --


I~ -_ _


aYhan
o
p\\\`
O
o n \a nTp~b`


40 miles














EXPLANATION

Drainage 0ll


NOLE


C 0 U N T Y


CRLANDO


C 0 U NTY


Bose loken from U.S Geological
Survey lopogrophic quodrangles


Figure 5. Location of drainage wells in Orange County, Fla., 1964.







TABLE 2. SUMMARY OF TIE PROPERTIES OF THE GEOLOGIC FORMATIONS PENETRATED BY
WATER WELLS IN ORANGE COUNTY, FLORIDA


Description of
material


Thick-
ness,
in
feet




0-200


Gray-green, clayey,
quartz sand and silt;
phosphatic s a n d;
and bu.T, impure,
phosphatic limestone,
mostly in lower part.


Cream to tan, fine,
soft to medium hard,
granular, porous,
sometimes dolomitic
limestone.


Water-bearing
properties



Varies widely in
quantity and qual-
ity of water pro-
duced.


Generally imper-
meable except for
limestone, shell,
or gravel beds.


Moderately high
transmissibility,
most wells also
penetrate under-
lying formations.


Aquifer


Non-artesian


Shallow arte-
sian, lower
limestone beds
may be part of
Floridan aqui-
fer.


Formation
name

Undiffer-
entiated,
may in-
clude
Caloosa-
hatchee
Marl


Series


Recent and
Pleistocene


Pliocene (?)


Miocene


Mostly quartz sand
with varying
amounts of clay and
shell.


0-200


0-125


Water level



0 to 20 feet below
the land surface
but generally less
than 10 feet.


Piezometric sur-
face not defined,
water level gen-
erally is lower
than nonartesian
aquifer and higher
than Floridan
aquifer.


Hawthorn


Ocala
Group


iI-




TABLE 2 CONTINUED

Upper section most- Overall transmis-
ly cream to tan, sibility very high,
granular, porous contains many in-
limestone. Often con- terconnected so- Piezometric sur-
Avon 400- tains abundant cone- lution cavities. Floridan face shown in fig-
Eocene Park 600 shaped Foraminifers. Many large capa- ures 10 and 11.
Limestone Lower section mostly city wells draw
dense, hard, brown, water from this
crystalline dolomite, formation.

Lake Over Dark brown crystal- Similar to Avon
City 700 line layers of dolo- Park Limestone.
Limestone Total mite alternating with Municipal supply
un- chalky fossiliferous of City of Or-
known layers of limestone. lando obtained
from this forma-
tion.


z
'.4





I-A






REPORT OF INVESTIGATIONS NO. 50


Geologic sections showing the formations and types of material
are shown in figure 6.


FORMATIONS

The oldest formation penetrated by water wells in Orange
County is the Lake City Limestone of middle Eocene age (about
50 million years old). The Lake City Limestone consists of
alternating layers of hard, brown, porous to dense, crystalline
dolomite and soft to hard, cream to tan, chalky, fossiliferous
limestone and dolomitic limestone.
The Lake City Limestone is distinguished from the overlying
Avon Park Limestone by the presence of the fossil Dictyoconus
americanus; however, in Orange County, the rock in the depth
interval (about 600-900 feet) where the top of the Lake City would
normally be has been partly crystallized and the fossils have been
badly damaged. Therefore, the exact location of the top of the
formation is unknown. No water wells penetrate the total thickness
of the Lake City, but the formation is probably more than 700 feet
thick.
The Avon Park Limestone conformably overlies the Lake City
Limestone and is composed of similar materials. The formation
is distinguished from overlying formations by the occurrence of
many sand-sized cone-shaped foraminifera. In many areas, the
Avon Park is composed mostly of the shells of these tiny single-
celled animals.
Contours on the top of the Avon Park Limestone are shown in
figure 7. The thickness of the Avon Park is not accurately known
because only a few wells penetrate the formation and the contact
with the underlying Lake City Limestone is indistinct, but the
Avon Park is probably 400 to 600 feet thick.
The Ocala Group' of the Florida Geological Survey overlies the
Avon Park Limestone and contains the Crystal River, Williston,
and Inglis Formations of late Eocene age. The limestone of the
Ocala Group in Orange County was deeply eroded and in some
areas entirely removed before the overlying formations were


'The term "Ocala Group" has not been adopted by the U. S. Geological
Survey. The Florida Geological Survey uses Ocala as a group name as
proposed by Puri (1953) and divided into three formations-Crystal River,
Williston and Inglis Formations.








o^wl
llvirtr' w w' 'fc Imir C ew ifcsc'"-
IScn 05 Llm4 9 crl 5 i I soldier 5tB



SIM OM4 0 Me W dct re 40-r fl1r -r.
C~oV s'Vnf SO i rr 5 00 'S rS V IMn/ .
U

rtrM'r 9itf~ Us455'tcm sn''5' vI'


INOLE


-------------

.." i -
I I P
:/0 .. ..~ *14 r-


," '\ ".




.I ORUDO

Ifisc. A


C O U N T
- - - - -


0 1 2 3 4 5 6 7 B 9 K1 miles


Figure 7. Configuration and altitude of top of the Avon Park Limestone,

Orange County, Florida.






20 REPORT OF INVESTIGATIONS No. 50

deposited. In south-central Orange County, formations of the
Ocala Group are missing, but in the northeast part of the county
near Bithlo the Ocala is about 125 feet thick. The contours on
the top of the Eocene limestones in figure 8 show the eroded surface
of the Ocala Group except where the Ocala is absent. In these
areas the contours represent the top of the Avon Park.
The Hawthorn Formation of Miocene age (about 25 million
years old) unconformably overlies the Ocala Group and, where the
Ocala is missing, the Avon Park Limestone. The clayey sand of the
Hawthorn Formation retards the vertical movement of water
between the water-table aquifer and the underlying limestone of
the Floridan aquifer. In most parts of the county the Hawthorn
retards, to varying degrees, the downward seepage of the water
from the water-table aquifer. In low lying parts of the county
where the artesian head is above land surface the Hawthorn
Formation retards the upward movement of water.
The lower part of the Hawthorn Formation usually contains
more limestone than the upper part. The limestone sections usually
contain much phosphorite and quartz sand and may grade into
sandstone known locally as "salt and pepper rock." In the
northwestern part of the county, the Hawthorn Formation has a
higher percentage of limestone than in the southeastern part.
Orange County lies in the intermediate/zone between the
limestone-clay type of Hawthorn in north-central Florida and the
clay-sand type of Hawthorn in south-central and southern Florida.
In Orange County the contact between the Hawthorn Formation
and the underlying Eocene limestone is usually quite distinct; but
the contact with the overlying deposits is gradational. The top
of the Hawthorn is usually placed at the first occurrence of appre-
ciable quantities of phosphorite or where a distinct and persistent
greenish color appears. The Hawthorn is thickest (about 300 feet)
in the southeastern part of Orange County and thinnest (about 50
feet) in the northwestern part of the county.
Undifferentiated sediments above the Hawthorn Formation
may include the Caloosahatchee Marl (which has been designated
Upper Miocene, Pliocene or Pleistocene by various workers)2;
thick deposits of red clayey sand which occur near the surface in
some areas in western Orange County; and marine terrace
deposits. The red clayey sand is used extensively in road building.


2The U. S. Geological Survey gives its age as Pliocene.









"" EXPLANATION

ORArSE COUNTY c^ '' 1 --.
Sm w -'. -re ,c cn o fe I .v e .
a, o o ~ ~ &cb c n I --- r eS--





so 1w or
~ t-v9 tos v w r Z I i Po te ren
Or "an e C ou t, a&.V L







Lake I' N

S| C U N T Y





C OUnI





Orange County, Florida
0 5AN

I.-A
Fu 8CniMI/If ration an atotfe snf n




OrangeCounty, Flor





Orange County, Florida.






REPORT OF INVESTIGATIONS NO. 50


The marine terrace deposits consist mostly of loose unsorted
quartz sand with varying amounts of organic matter and occasional
seams of clay. These sediments are generally thought to have been
deposited during interglacial times of the Pleistocene ice age when
sea level was higher than it is at present. Table 3 gives the
altitude of the more prominent terraces as defined by Cooke. Only
the Pamlico terrace with a shoreline at about 30 feet and the
Wicomico terrace with a shoreline at about 100 feet are well
developed in Orange County. The altitudes in Orange County
above 100 feet represent eroded remnants of the higher
Okefenokee and Coharie terraces or sand dunes formed during
higher stands of the sea.

TABLE 3. ALTITUDES OF TERRACES IN FLORIDA.

Brandywine 270 feet
Coharie 215 feet
Sunderlahd 170 feet
Wicomico 100 feet
Penholoway 70 feet
Talbot 42 feet
Pamlico 25 feet
Silver Bluff 5- feet


STRUCTURE

The surface-of the limestones of Eocene age is shown in figure
8. This represents approximately the land surface as it was in
post-Eocene/pre-Miocene time after a long period during which
the limestone was above sea level and exposed to erosion. Figure 8
is one interpretation of limited data, and future studies based on
more complete information and regional interpretation may result
in drastic revision. For example, a steep-walled trough is shown
in the southeastern part of the county, whereas actually there may
be a fault in the St. Johns River valley as indicated on the geologic
section in figure 6.
Figure 7 shows contours on the top of the Avon Park Limestone.
The top of the Avon Park Limestone appears smoother than the
top of the overlying Ocala Group and was probably not eroded
except where the Ocala is missing. Therefore, the Avon Park
Limestone probably more nearly represents the regional dip of
shallow limestone formations underlying Orange County.






WATER RESOURCES OF ORANGE COUNTY


The irregularities in the surface of the Eocene limestone may
have been caused by deep erosion, but the contours on the top of
the Avon Park Limestone strongly suggest a fault in the St. Johns
River valley. Movement along this fault probably started in
post-Eocene time and continued into Miocene time.


HYDROLOGY

CHEMICAL QUALITY OF WATER

All waters except distilled water contain dissolved materials
in varying amounts. The type and amount of dissolved materials
is influenced by many factors such as source, movement, geology,
topography, climate, biological action, and cultural changes.
Rain falling through the atmosphere picks up small quantities
of dust particles, atmospheric gases, and windblown salts. In
areas near the ocean, the amount of salts picked up by rain may
be appreciable especially if it is blown inland from the ocean. In
industrialized areas the atmosphere generally contains exhaust
gases and particles that are readily picked up by rain. The type
and amount varies with the industry. Rain may also pick up
radioactive fallout from nuclear explosions. To date, however, the
amount of radioactive materials in water has remained far below
tolerable limits.
When rain reaches the earth, it begins to dissolve or pick up
in suspension varying amounts of the materials contacted. The
carbon dioxide dissolved from the atmosphere and from decaying
organic matter- on the earth's surface react with the water to
form a weak carbonic acid. Carbonic acid greatly increases the
ability of water to dissolve inorganic materials especially limestone
such as underlies Orange County.
Surface water moves more rapidly than ground water,
consequently, its time of contact with soils and rocks is shorter.
This is one reason for lower mineralization in surface water than
in ground water. Surface water is usually higher in color than
ground water because surface water dissolves living and decaying
organic materials that it contacts. Decaying organic matter
consumes dissolved oxygen from the water and releases. carbon
dioxide.
When water percolates into the ground, the rate of movement
is greatly reduced. When water percolates very far through soils






REPORT OF INVESTIGATIONS NO. 50


and rocks, any bacteria or color present will usually be removed.
The fluctuations in the quality and temperature of ground water
are smaller than in most surface-water bodies because of the long
period of time required for ground water to percolate downward
to the aquifer and then laterally through the aquifer to the point
of discharge.
Dissolved mineral constituents in water are usually reported
in parts per million (ppm) (one unit weight of a constituent in a
million unit weights of water). Hardness of water is caused by
the presence of alkaline earth metals, mostly calcium and
magnesium, and is expressed as an equivalent quantity of calcium
carbonate. Specific conductance is a measure of the ability of water
to conduct an electric current and may be used in estimating the
dissolved mineral content. The most important dissolved con-
stituents can usually be related to specific conductance (fig. 25).
Color is expressed in units of the platinum-cobalt scale. The
symbol pH is a measure of the acidity or alkalinity of a solution,
and is expressed as the negative logarithm of the hydrogen-ion
concentration.

RELATION OF QUALITY OF WATER TO USE

The amount and type of dissolved and suspended materials in
water determines its value for a particular use. Water suitable
for one use may be entirely unsatisfactory for another. For
example, sea water is used for cooling purposes, whereas it is
unsatisfactory for most other industrial use. Water used in the
manufacturing of products such as high-grade paper and textiles
must be very low in dissolved solids.
Table 4 shows the more common characteristics of water
quality. Some constituents in water can be removed inexpensively
whereas other constituents can be removed only by expensive
distillation. Hardness of water may be removed by the relatively
simple and inexpensive ion-exchange method which replaces the
calcium and magnesium with sodium from common table salt.
Iron, color, and turbidity may be economically removed by
flocculation, settling, and filtration. The removal of sodium,
chloride, and sulfate is difficult and expensive.





TABLE 4. WATER-QUALITY CHARACTERISTICS AND THEIR EFFECTS.

Constituent
or property Source or cause Effects


Silica (SiO)


Dissolved from practically all
rocks and soils, commonly less
than 30 ppm. High concen-
trations, as much as 100 ppm,
generally occur in highly al-
kaline waters.
Dissolved from practically all
rocks and soils. May also be
derived from iron pipes,
pumps and other equipment.
More than 1 or 2 ppm of iron
in surface waters generally
indicate acid wastes from
mine drainage or other
sources.
Dissolved from practically all
soils and rocks, but especially
from limestone, dolomite, and
gypsum. Calcium and magne-
sium are found in large quan-
tities in some brines. Magne-
sium is present in large quan-
tities in sea water.


Forms hard scale in pipes and boilers. Carried over in steam of
high pressure boilers to form deposits on blades of turbines. In-
hibits deterioration of zeolite-type water softeners.




On exposure to air, iron in ground water oxides to reddish-brown
precipitate. More than about 0.3 ppm stains laundry and utensils
reddish-brown. Objectionable for food processing, textile processing,
beverages, ice manufacture, brewing and other processes. U. S.
Public Health Service (1962) drinking-water standards state that
iron should not exceed 0.3 ppm. Larger quantities cause unpleasant
taste and favor growth of iron bacteria.



Causes most of the hardness and scale-forming properties of water;
soap consuming (see hardness). Waters low in calcium and magne-
sium desired in electroplating, tanning, dyeing, and in textile manu-
facturing.


Iron (Fe)


Calcium (Ca) and
Magnesium (Mg)










TABLE 1 CONTINUED

Constituent
or property Source or cause Effects


Sodium (Na) and
Potassium (K)


Bicarbonate (HCO,)
and Carbonate (CO,)



Sulfate (SO4)





Chloride (Cl)


Dissolved from practically all
rocks and soils. Found also
in ancient brines, sea water,
industrial brines, and sewage.
Action of carbon dioxide in
water on carbonate rocks such
as limestone and dolomite.


Dissolved from rocks and soils
containing gypsum, iron sul-
fides, and other sulfur com-
pounds. Commonly present in
mine waters and in some in-
dustrial wastes.
Dissolved from rocks and
soils. Present in sewage and
found in large amounts in an-
cient brines, sea water, and
industrial brines.


Large amounts, in combination with chloride, give a salty taste.
Moderate quantities have little effect on the usefulness of water for
most purposes. Sodium salts may cause foaming in steam boilers
and a high sodium content may limit the use of water for irrigation.
Bicarbonate and carbonate produce alkalinity. Bicarbonates of cal-
cium and magnesium decompose in steam boilers and hot water
facilities to form scale and release corrosive carbon-dioxide gas.
In combination with calcium and magnesium, cause carbonate
hardness.
Sulfate in water containing calcium forms hard scale in steam
boilers. In large amounts, sulfate in combination with other ions
gives bitter taste to water. Some calcium sulfate is considered bene-
ficial in the brewing process. USPHS (1962) drinking water stand-
ards recommend that the sulfate content should not exceed 250 ppm.

In large amounts in combination with sodium, gives salty taste to
drinking water. In large quantities, increases the corrosiveness of
water. USPHS (1962) drinking-water standards recommend that
the chloride content should not exceed 250 ppm.




TABLE 4 CONTINUED
Constituent
or property Source or cause Effects


Fluoride (F)


Dissolved in small to minute
quantities from most rocks
and soils. Added to many
waters by fluoridation of mu-
nicipal supplies.


Decaying organic matter, sew-
age, fertilizers, and nitrates
in soil.





Chiefly mineral constituents
dissolved from rocks and soils.
Includes some water of crys-
tallization.
In most waters nearly all the
hardness is due to calcium and
magnesium. All of the metal-
lications other than the alkali
metals also cause hardness.


Nitrate (NO,)







Dissolved solids



Hardness as CaCO,


Fluoride in drinking water reduces the incidence of tooth decay
when the water is consumed during the period of enamel calcifica-
tion. However, it may cause mottling of the teeth, depending on the
concentration of fluoride, the age of the child, amount of drinking
water consumed, and susceptibility of the individual. (Maier, F. J.,
1950, Fluoridation of public water supplies, Jour. Am. Water Works
Assoc., vol. 42, pt. 1, p. 1120-1132).
Concentration much greater than the local average may suggest
pollution, USPHS (1962) drinking-water standards suggest a limit
of 45 ppm. Waters of high nitrate content have been reported to
be the cause of methemoglobinemia (an often fatal disease in in-
fants) and therefore should not be used in infant feeding. Nitrate
has been shown to be helpful in reducing inter-crystalline cracking
of boiler steel. It encourages growth of algae and other organisms
which produce undesirable tastes and odors.
USPHS (1962) drinking-water standards recommend that waters
containing more than 500 ppm dissolved solids not be used if other
less mineralized supplies are available. Waters containing more
than 1,000 ppm dissolved solids are unsuitable for many purposes.
Consumes soap before a lather will form. Deposits soap curd on
bathtubs. Hard water forms scale in boilers, water heaters, and
pipes. Hardness equivalent to the bicarbonate and carbonate is
called carbonate hardness. Any hardness in excess of this is
called non-carbonate hardness. Waters of hardness up to 60 ppm
are considered soft; 61 to 120 ppm, moderately hard; 121 to 180
ppm, hard; more than 180 ppm, very hard.








TA11LE 1 CONTINUED


Constituent
or property

Specific conductance
(micromhos at 250C)


Hydrogen ion
concentration (pH)


Color


Hydrogen sulfide
(H.S)


Source or cause


Mineral content of the water.



Acids, acid-generating salts,
and free carbon dioxide lower
the pH. Carbonates, bicarbon-
ates, hydroxides, and phos-
phates, silicates, and borates
raise the pH.
Yellow to brown color of some
waters is usually caused by
organic matter extracted from
leaves, roots, and other or-
ganic substances. Objection-
able color in water also results
from industrial waste and
sewage.
Probably the reduction of sul-
fates to sulfides by organic
material under anaerobic con-
ditions in deep wells. In
some cases, it may be derived
from the anaerobic reduction
of organic matter with which
the water comes in contact.


Effects


Indicates degree of mineralization. Specific conductance is a meas-
ure of the capacity of the water to conduct an electric current.
'Varies with concentration and degree of ionization of the con-
stituents.
A pH of 7.0 indicates neutrality of a solution. Values higher than
7.0 denote increasing alkalinity; values lower than 7.0 indicate
increasing acidity. pH is a measure of the activity of the hydrogen
ions. Corrosiveness of water generally increases with decreasing
pH. However, excessively alkaline waters may also attack metals.

Water for domestic and some industrial uses should be free from
perceptible color. Color in water is objectionable in food and
beverage processing and many manufacturing processes. The
USPHS (1962) states that color should not exceed 15 units in
drinking water.



Causes "rotten-egg" odor and causes corrosion. Limits of tolerance
are generally less than 0.5 ppm. Since hydrogen sulfide is a gas
it is easily removed from water by aeration.


1






WATER RESOURCES OF ORANGE COUNTY


DOMESTIC USE

Water used for human consumption should be pathologically
safe, low in turbidity and color, and free from taste and odor.
Federal drinking water standards were first established in 1914 to
control the quality of water used on interstate carriers and for
culinary purposes. These standards have been revised several
times, most recently in 1962 by the U. S. Public Health Service.
They have been endorsed by the American Water Works
Association as minimum standards for all public water supplies.
Some of the U. S. Public Health Service's recommended limits
for the various dissolved constituents and physical properties are
given under the column of effects in table 4. Following are
additional U. S. Public Health Service's recommended limits for
dissolved chemical substances in drinking water.

Substance Concentration (ppm)
Alkyl Benzene Sulfonate (ABS) 0.5
Arsenic (As) 0.01
Copper (Cu) 1
Carbon Chloroform Extract (CCE) 0.2
Cyanide (Cn) 0.01
Fluoride (F) See table 5
Manganese (Mn) 0.05
Phenols (CGH,OH) 0.001
Zinc (Zn) 5

The U. S. Public Health Service states that the presence of the
following toxic substances, in excess of concentrations listed shall
constitute grounds for rejection of the supply for drinking water:

Substance Concentration (ppm)
Arsenic (As) 0.05
Barium (Ba) 1.0
Cadmium (Cd) 0.01
Chromium (Hexavalent) (Cr+G) 0.05
Cyanide (CN) 0.2
Lead (Pb) 0.05
Selenium (Se) 0.01
Silver (Ag) .05






REPORT OF INVESTIGATIONS NO. 50


Unpolluted water rarely contains excessive concentrations of the
above toxic substances. In highly industrialized areas, objectionable
amounts of toxic substances are sometimes found in water. Two
samples, one from the St. Johns River at low flow and the other
from a typical Orlando supply well, were analyzed for minor ele-
ments. The cadmium, chromium and lead concentrations were less
than .0014 ppm.
The U. S. Public Health Service's standards for fluoride in
drinking water are based on climatic conditions, because children
drink more water in warmer climates and, consequently, consume
more fluoride. Table 5 lists the drinking water standards for
fluoride concentration. Where fluoride occurs naturally in water,
it should not exceed the upper limit in table 5. Where fluoridation
is practiced by water treatment plants, the concentration should be
held between the lower and upper limits. The U. S. Public Health
Service states that the presence of fluoride concentrations more
than twice the optimum values in table 5 constitutes grounds for
rejection of the supply. The yearly normal maximum daily
temperature in Orange County is 80.90 F; therefore, the optimum
amount of fluoride in drinking water is 0.7 ppm and the
concentration should not be below 0.6 ppm or above 0.8 ppm.
Fluoride concentrations in Orange County water are usually less
than 0.8 ppm and often less than 0.4 ppm.


AGRICULTURAL USE

The primary non-domestic uses of water on the farm are for
livestock consumption and for irrigation. The quality standards of

TABLE 5. DRINKING WATER STANDARDS FOR FLUORIDE
CONCENTRATION.

Yearly normal maximum Recommended fluoride control
daily temperatures oF limits in ppm
Lower Optimum Upper

50.0- 53.7 0.9 1.2 1.7
53.8- 58.3 0.8 1.1 1.5
58.4- 63.8 0.8 1.0 1.3
63.9- 70.6 0.7 0.9 1.2
70.7- 79.2 0.7 0.8 1.0
79.3- 90.5 0.6 0.7 0.8






WATER RESOURCES OF ORANGE COUNTY


water for human consumption have already been discussed. Very
little information is available on quality of water standards for
livestock watering, but it is assumed that water safe for human
consumption is safe for animals. In general, animals can tolerate
higher mineralization than man.
The Department of Agriculture and Government chemical
laboratories of Western Australia list the following limits for
dissolved solids in ppm:

Poultry 2,860
Pigs 4,290
Horses 6,440
Cattle, dairy 7,150
Cattle, beef 10,000
Adult sheep 12,900
Investigators have found that water with a dissolved-solids
content of more than 15,000 ppm is dangerous if used continuously
for livestock watering. The water from the Floridan aquifer in
eastern Orange County is the most highly mineralized. The water
from a few wells exceeds 3,000 ppm in dissolved solids but none
exceed 4,000 ppm.
The chemical quality of water is important in evaluating its
usefulness for irrigation. The quality requirements for irrigation
varies with the nature and composition of the soil and subsoil,
topography, quantity of water used and method applied, climate,
and type of crops grown. Good soil drainage is important where
irrigation is practiced. Water of good quality for irrigation may
not produce good crops on poorly drained land, whereas highly
mineralized water may often be used successfully on open-textured
well-drained soils.
There is much published material on the quality requirements
of irrigation water for various crops grown under varying
conditions. U. S. Department of Agriculture Circular 969 entitled,
"Classification and Use of Irrigation Water" by L. V. Wilcox
(1955), classifies irrigation water based on electrical conductivity
in micromhos/centimeter. The dividing point between four classes
is 250, 750, and 2,250 micromhos. Wilcox points out that ". .. in
classifying an irrigation water, it is assumed that the water will
be used under average conditions with respect to soil texture,
infiltration rate, drainage, quantity of water used, climate, and
salt tolerance of the crop." All water in Orange County is suitable
for irrigation. The artesian water in the eastern part is high in






REPORT OF INVESTIGATIONS NO. 50


mineralization, but because of adequate flushing during-the rainy
season it is used successfully.

INDUSTRIAL USE

Water quality requirements for industry are so varied that it is
impossible to set standards to meet the demands of all users. For
some purposes, such as cooling, water of poor quality is often used
when better quality water is not available. Water for some
processes and for use in high-pressure steam boilers must approach
the quality of distilled water. In general, most industrial water
should be low in dissolved solids, soft, uniform in quality and
temperature, and noncorrosive. Table 6 gives the quality
requirements for several selected industries. The greatest
industrial use of water in Orange County is for citrus processing
and canning. (See section on use of water.) With a minimum of
treatment most of the water in the county is suitable for most
industrial uses.


SURFACE WATER

OCCURRENCE AND MOVEMENT

Most of the surface water in Orange County is from rain
within the county, but some flows into the county from adjacent
areas of higher elevation. Some of the streams that provide water,
such as the St. Johns River, also drain parts of Orange County.
The amount of water on the land surface is determined by
climate, geology, and topography. Only part of the rainfall remains
on the surface long enough to be useful. Losses by evaporation
and infiltration begin immediately and continue indefinitely unless
the supply becomes exhausted. Some of the water that infiltrates
into the soil and to the aquifers returns to the surface as seepage
or as spring flow into lakes and streams. The part of the rain that
doesn't evaporate or infiltrate collects in topographic depressions
to form lakes, swamps, and marshes, or enters a stream channel
and flows out of the county.
It is estimated that about 70 percent of the rain that falls on
Orange County returns to the atmosphere by evaporation and
transpiration, about 20 percent flows out of the county in streams
and about 10 percent flows out underground.






TABLE 6. WATER QUALITY REQUIREMENTS FOR SELECTED USES1

(Allowable limits in parts per million)




S- -

Use = O ""10 CS P Other requirements(

Air Conditioning 0.5 low 1 No corrosiveness, slime formation
Baking 10 10 .2 low .2 P

Boiler feed water
0-150 PSI 20 80 80 3000-500 5 40 50 200 8.0 -
150-250 PSI 10 40 40 2500-500 3 20 30 100 8.4 -
250-400 PSI 5 10 10 1500-100 0 5 5 40 9.0 -
Over 400 PSI 1 2 2 50 0 1 0 20 9.6 -
Brewing
Light beer 0-10 0-10 .1 500-1500 75-80 low .2 50 50-68 6.5-7.0 10 60-100 100-200 30 P NaC1 less than 275 ppm
Dark beer 0-10 0-10 .1 500-1500 80-150 low .2 50 50-68 6.5-7.0 10 60-100 200-500 30 P NaC1 less than 275 ppm
Carbonated Beverages 1- 2 5-10 200-250 0.1-0.2 850 50-128 low 0-0.2 250 250 0.2-1.0 P
Confectionary 0.2 50-100 low .02 7.9 P No corrosiveness, slime formation
Dairy industry 0 180 0.1-0.3 500 none 17 30 60 P
Food Canning and Freezing 1-10 __ 50-85 0.2 850 30-250 none 1.0 7.5 8.6 400-600 1.0 P
Food Equipment washing 1 5-20 10 .2 850 none 250 1.0 P

Food Processing, general 1-10 5-10 10-250 .2 850 30-250 low- 1.0 P
Ice 1- 5 5 .2 300 30-50 10 _- P
Laundering 50 .2 -
Plastics, clear, uncolored 2 2 53 .02 200 -

tAmerican Water Works Association 1950 and Water Quality Criteria, McKee and Wolf 1963
-P indicates that potable water, conforming to USPHS standards, is necessary
-Peas 200400, fruits and vegetables 100-200, legumes 25-75





WATER RESOURCES OF ORANGE COUNTY


VARIATION

Part of the difficulty in managing the water resources of an
area stems from variations in the amount of water stored on and
beneath the earth's surface in the area. These variations are
brought about because rainfall is extremely variable and
intermittent, while evaporation, transpiration, surface outflow, and
underground outflow though also variable are relatively continuous.
Figure 9 shows the average discharge in cfs (cubic feet per second)
per square mile for each year of record at three stations draining
parts of Orange County. Figure 10 shows the annual rainfall at
Orlando for this period. Comparison of these two figures reveals
that the pattern of variations in runoff and rainfall are similar but
not identical. The years of high flow agree well with the years of
high rainfall and except for a 1-year attenuation of Wekiva River
caused by depletion of ground-water storage, so do the years of low
flow and low rainfall. Streamflow may average above normal during
a year following a wet year because of the carry-over of storage
from the wet year even though rainfall is below normal. After a
severe drought, streamflow may average below normal and even
decrease during a year of above-normal rainfall because of the
large amounts of water required to replenish the depleted soil
moisture before an excess to provide runoff becomes available.
The flow of Wekiva River is much less variable than that of
Econlockhatchee River and St. Johns River because it is maintained
by the flow of large springs that discharge from a vast highly
permeable ground-water reservoir (Floridan aquifer). The base
flow of the Econlockhatchee and St. Johns Rivers is maintained
mostly by seepage of water from the relatively thin and low
yielding water-table aquifer. Their channels are very shallow so
that a small drop in the water table causes a sharp reduction or
cessation of ground-water inflow.
Figure 11 shows that the distribution of monthly runoff during
the year corresponds in a general way to the distribution of rainfall,
but there are some apparent discrepancies. Although average
rainfall for months March, April, May, and October is about equal,
runoffs for these months differ widely. Average runoff decreases
from March to May because evaporation and transpiration losses
increase during this period (See fig. 41.). Runoff for October is
higher than that for May because in October evaporation is less
and storage, which increased during July, August, and September,






REPORT OF INVESTIGATIONS No. 50


Figure 9. Annual average discharge and average discharge for period of
record at three stations on streams draining from Orange County.


WEKIVA RIVER NEAR SANFORD
Drainage area-200 sq. mi, approximately
Average-1.38 cfs per sq. mi.


01 ^:::s^?wi:i.: X.;





WATER RESOURCES OF ORANGE COUNTY


Figure 10. Annual rainfall at Orlando.


is released to the streams. There is some indication that this
storage effect carries over into November.
In a given year the distribution of flow for a particular station
may differ markedly from that representing average conditions.
Contrasting distributions of flow for Econlockhatchee River are
shown in figure 12 for 2 years in which total runoff was about the
same.


PRESENTATION OF DATA

The data used for this report were obtained during the period
October 1935 to September 1963. If the physical conditions in the
basin remain unaltered and no drastic changes in the climate take
place, values for the next 28 years should be very similar to those
for this period. The 28-year moving average of annual rainfall at
Orlando beginning in 1893 has varied from the 71-year average
by no more than 3.8 percent, indicating that conditions during







10
AXM.IMUM
*220





VMRAVERAGE Gi
AVERAGE ERAGE
U), _1.0

MM AVERAGE % 1.0





.10 MINIMUM MINIMUM z o



W RST. JOHNS RAINFALL
E A D RIVER HATA VEAT
:.. .: NEAR ..RVE OR LANDED

01 AMJAA JFMAMJAJASOND
0
Figure 11. Average, maximum, and minimum monthly mean discharges of
three streams draining parts of Orange County, and rainfall at Orlando.





WATER RESOURCES OF ORANGE COUNTY


ECONLOCKHATCHEE
RIVER NR. CHULUOTA
WI Total 13.13 in.
o 1958
Z2

U-
z 2 ----------


I


r 4
Total 13.85 in.

i- 1949
z





LLJ. |< M=" < .i.l-n Z
T >> I I iiiiiiiiiiiiiiii iiD



Figure 12. Monthly runoff from Econlockhatchee River basin-1949 and 1958.


the period October 1935 to September 1963 are representative of
the long-term average. The average for the 28-year period
1936-1963 differed from the 71-year average by only 0.01 of 1
percent. The value of this report is premised on the applicability
in the future of analyses based on past record.
Surface-water data have been collected at 62 sites in the county.
Data on the chemical quality of surface water have been collected
at 35 of these sites since 1953. Figure 13 lists the sites where data
have been collected systematically and shows the number of water
samples analyzed, the types of stage and flow record collected,
and the periods of record. Table 7 lists the sites where miscellaneous
records have been collected.







REPORT OF INVESTIGATIONS No. 50


Stalton N l


I AdaCr Lake, o Orlndo
;2 y-E'.lt Tahoo:kalgqo Cnr Norcoossee
3 Apopka-o eauclair Canal at control nr Asatula
4 AooPaedB-. uclar iLt at S.R. 448 nr Astatulo
A .Ipophk, Lake, at Winter Garden 5
T ia t' Laoke nr Orlando __ __
7 3Bellla, Lake. at Windermere
aB B Sand Lake at Doctor Phillips
19 #l9y Creek nr Kissimmee

II (lnter, Lake, O1 Wlndormetr




I .'.voirw Creek it Vineland
|In i uilan Canal nr Wewainotee
1cr, Lake, at Mount Datw
S Eonlacknttchlee River nr Btthlo 34
i c-tiackllatchee ~ver nr ChuluOta 3
Lik,- ta? Orlando
1 Hr!Hat', nr no, k J7



4 ;,t Creek nr Ctr'itmas
5 iJoans Lake at Oakland 4

SILittle Lake Fnirvew a Orlando
I Matland, Lake, ot Wlnler Park

29 Mary Jane, Lake, nr Norcoaee 2
(3 Mary Jane-CHart Canal nr Norcoossee
3, Myrtle-Mary Jane Canal rr NorCOOSSee
32 Park Lake ot Orlando
It Ponidetri, Lake, fn COCO0 730
-4 RAowe.na, Lake, at Orlando
j1 5t Jornn River nr Christmas 47
36 St Jaons River nr Cocoa 170
i' St jahns River Flood Profile
rk Sh n ile Creek t olrport, nr KisSimmee
'1 Sh~il'iln Creek nr Vineland 22
4 1 Silver Lake, at Orlando
- p I oheor. Lake, nr Orlando
-42 $LQinq Lake of Orlando
4,3 Sun, Lake, at Orlando
4-4 Susa5nnah, Lake, nr Orlando I
4 ake :ailO, Lake, at Orlando
46 Weikiv River nr Sanlord
4I Wnanonro (Franci, ) Lake nr Plymouth 2


EXPLANATION

I Tr"111TT' I I IITIll,11' wY LL 1111 1 111 117333I
. . . . . .


Daaly to weekly stage
Monthly :1aJe or annual flood crest

Periodic discharge measurements
Daily stage and discharge


Figure 13. Type and duration of surface-water stage and discharge records
and number of chemical analyses of surface water samples collected at gaging
sites in and near Orange County.





WATER RESOURCES OF ORANGE COUNTY


TABLE 7. SITES WHERE MISCELLANEOUS SURFACE-WATER DATA
HAVE BEEN COLLECTED.

No. of
chemical
Station no. Station analyses

48 Bonnet Creek near Vineland 3
49 Christmas Creek near Christmas 1
50 Howell Creek near Maitland 2
51 Jim Branch near Narcoossee 2
52 Little Wekiva River near Forest City 1
53 Mills Creek near Chuluota 1
54 Reedy Creek near Vineland 2
55 Roberts Branch near Bithlo
56 Rock Springs near Apopka 7
57 Second Creek near Christmas 1
58 Settlement Creek near Christmas
59 Taylor Creek near Cocoa 1
60 Tootoosahatchee Creek near Christmas
61 Wekiva Springs near Apopka 5
62 Witherington Spring near Apopka 1


Table 8 gives the ranges in quality of surface water at selected
sites in and near the county.
Many of the data on surface water are presented as flow-
duration curves, stage-duration curves, flood-frequency curves,
and low-flow frequency curves.
Flow-duration curves (figures 14 and 15) are cumulative
frequency curves that show the per cent of time specified discharges
were equaled or exceeded during a given period. In a strict sense
flow-duration curves apply only to the period in which the data
used to develop the curve were obtained. Flow-duration curves
are useful for predicting future flow distribution only if the data
used represent the long-term distribution and if the climate and
basin characteristics remain unaltered. Flow-duration curves
based on less than 5 years of record were adjusted on the basis of
concurrent records at a nearby site having a long-term record. The
curves were thus made more representative of the longer periods.
Flow-duration curves were estimated for the sites having only a
few periodic observations by correlating these observations with
concurrent data for nearby stations where data were complete.
The shape of a flow-duration curve indicates the physical
characteristics of the basin it represents. A curve that is steep









* wo-- -^--^a --

2 o--- --a ---S:_- -
3P:": -^^:


5. Boggy reek near Taft (October 1959 to September 1962)
adjusted to (October 1935 to September 1962).

6. Shingle creek at airport near Kissimmee (October1958 to September
1962) ad used to (October 935 to September 1962).

7.Little Eceaockhatchee Rivernear Union Park (October 1959 to5eptem'-
S ber 1962) adjusted to(October 1935 to September 1962).

8. Cypress Creek at Vinelond October 1945 to September 1962),


L S John RiverwnearChristmas (October 1934 to Sepltmber 1962).

S.St. Johns Rivw near Cocoa (Oclober 1953 to Septmber 1962),
adjusted to October 1934 to September 1962).

SEcrdoahotlchee River near Chuluoo (October 1935 to September 1962).

4.Wehiva Rivernear Sonford (October 1935 to September 19621.


2
o


- -- 05
---3


'\ lM2


40 50 60 70 80 90 95 .98. 99 995 99.89999.95
PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN


99.99


20 30


FiRure 14. Duration curves of daily flow for streams in and near


w:--- \ ^s.--"^ S --- -- --- ---- -- ------ - --~ ---





100
10 10-0-- -- ^^ ^ ^ -- -- -- -- -- --







.ol-- I I I -. 1 -- ----- %" -\ I -- --- --- I=- to-- 'a


4


IW i .- 1 IV I


10 20 50 40 50 60


001 005 0.2 0 5. 0 I










TABLE 8. RANGE IN QUALITY OF SURFACE WATER IN ORANGE COUNTY, FLORIDA

(Chemical Analyses in parts per million, except specific conductance, PH, and color)
II II II I M ,


So arce


I0 B3og Creek near Taft
13 Econloekharchee River nr. Bithlo
13 E-onlockhatchee River nr. Chuluota
1 Ear: Lake near Narcoossee
25 .oahns Lake at Oakland
3 Lake Apopka at Winter Garden
iJS Lake MairLand at Winter Park
25 Lir:e E-onlockhatchee River near
Union Park
a Rock Springs near Apopka
35 Sc. Johns River near Christmas
; t. Johns River near Cocoa
::D Shingle Creek near Vineland
51 V-akiva Springs near Apopka


Period
of
Record


11/59-7/63
10/59-7/63
5/53-7/58
10/54-7/63
10/59-7/63
10/59-7/63
10/59-7/63

1/60-7/63
4/56-7/63
9/52-7/63
10/53-9/63
11/59-7/63
4/56-6/62


21
34
36
17
4
5
5

25
7
47
170
22
5


0.8-10
.0- 8.9
1.7-12
.5- 4.1
.0- 1.6
5.1-15
.0- .9

.3-11
8.2-10
.2-11
.0-16
.0- 8.8
8.9-11


.01-.33
.02-.50
.01-.60
.00-.31
.01-.18
.01-.27
.00-.04

.01-.66
.00-.35
.00-.43
.00-.49
.03-.73
.00-.42


3.8-8.8
2.6-26
3.6-51
1.7-8.8
7.2-8.0
28-38
18-24

5.4-16
27-30
7.5-162
8.4-136
2.8-21
28-30


8
ao

E
.3
g

J
==
s


0.7-4.3
.2-27
1.0-14
.5-2.9
2.9-6.1
8.8-13
4.9-6.8

.6-4.8
7.1-9.7
2.2-77
2.1-56
.5-3.9
7.7-10


5.5-14
1.8-15


.7-112
.9-11
10-20
8.4-23
9.3-14

5.2-16
3.9-5.1
11-621
12-454
4.7-35
4.7-5.4


0.8-2.8
.2-1.5


6.0-8.0
3.3-13
3.7-5.2

.2-2.4
.3- .7

.0-14
.0-5.1
.4- .8


9- 34
8- 83
10-112
3- 13
7- 13
104-186
57- 72

9- 51
94-105
21-138
21-136
5- 62
103-123


1.2-6.4
.0-6.4
1.0-58
.2-16
26-42
15-20
24-31

1.2-6.8
16-18
2.0-364
2.5-156
.0-19
6.0-12


9-18
3.0-23
8.0-179
7.5-16
18-24
16-25
15-20

9.5-20
5.0-8.0
20-1150
21-900
8.0-37
7.0-8.5


a


0.1-0.7
.0- .8


.1- .3
.4- .6
.1- .5

.0- .4
.0- .3
.0- .5
.0- .7
.1- .5
.1- .3


0
z

a


Dissolved solids


Calculated


0.0- .9 29-73
.0-1.3 16-108
.0-14 32-468
.0-1.4 20-52
.0- .4 77-111
.9-3.7 149-229
.0-2.8 104-131

.0- .8 35-75
.0-2.7 121-129
.0-2.8 57-2350
.0-5.3 67-1760
.0-4.3 25-150
.0-2.7 123-134


Residue


59-134
32-163


114-146
206-285
128-154

69-146
123-140
-2830
103-2320
53-168
131-139


Hardness as CaCO,


Calcium Non-
Magnesiuml carbonate


13- 30 0-14
8- 74 0-19
13-162 5-71
9- 31 6-20
30- 44 20-38
106-150 0-25
65- 88 22-32

16- 48 4-20
102-110 19-25
28-720 11-672
30-570 9-494
12- 66 0-19
104-114 11-24


0
C4

4o


,a
0-


55-121
24-1971
55-873
38-110
150-202
333-385
195-230

58-146
212-223
110-4060
107-35002
48-268
215-240


a
0
"s
(_


4-210
35-400
40-600
30-170
25- 80
20- 45
5- 10

20-400
0- 10
45-220
45-280
45-200
0-5


6.2-8.0
5.7-7.8
6.2-7.6
5.4-6.3
5.8-6.5
7.0-7.9
6.6-7.6

5.6-8.0
6.8-7.8
6.3-7.5
6.4-7.7
5.7-7.8
7.3-7.6


I I %


i I


i


I


I


I


I


-


I I I i I I I






WATER RESOURCES OF ORANGE COUNTY


oeo i o g oQ i e to ie o 3o oeo
IQOO0 ==
-00 1 \ .. ...




w=oo ,. = ==
SJim GreCft ne hrists,

%oe, ===- == =^--^ == =^== 4, Reedy Gfeek ow Vinelond,
--- -= f=@=y o r

10^v- =-




^ -= --- r^ -^ ----- IB%
aN 1
\ ,'l ,


5 hingle Geek near Vinelond,

6, gennet l eeN@ ne@f Vineland,

?, WOkivo Spfinug neor Anepka,

8 Rock Spfino_ nwef AeeO t,


^ \\
==
___=
___ = -
_it~Z~ 'j=


PERCENT OF TIME DISCHARGE EQUALED OR EXCEED0E THAT SHOWN
Figure 16. Estimated flow-duration curves for streams and springs for
which periodic or miscellaneous discharge data are available.


throughout its range indicates a highly variable stream having
little or no surface storage or ground-water storage. A curve with
a flat slope throughout its range indicates the release of water
from surface- or ground-water storage which tends to equalize the
flow. A curve that flattens out at its lower end indicates the
release of ground-water storage at low flow. A curve that flattens
at its upper end indicates release of storage from lakes or swamps
at high flow.
Flow-duration curves are useful for water power, water supply,
and pollution studies.
Stage-duration curves (figure 16) present stage data in the
same way flow-duration curves present flow data. The limitations







42 REPORT OF INVESTIGATIONS NO. 50


'o02 -- ILake Butler at Windermere (1941-63),


S- -_ -. 2, Johns Lake at Oakland (1959-63) adjusted to
(1941-63),

94 -- -
3, Bass Lake near Orlando (1959-63) adjusted to
21 (1941-63),


e. 4 Lake Corrine near Orlando(1943-49) (1959-63)


84 5,Lake Sllvr at Orlando(1959-63) adjusted to
:: I (1941-63),


G 6. Lake Conway at Pine Castle (1952-63).


7,Lake Apopka at Winter Garden (1942-63),


S_8 Lake Moitland at Winter Pork(1945-52)(1959-63)


S' 9,Lake Francis near Plymouth (1959-63) adjusted
4 ...to (1941-63),


10 Lake Dora at Mount Dora (1942-63).






SO -12,Lake Hart near Norcoossee (1941-63),


f -13.Lake Poinsett near Cocoa (1941-63),


2- 14,Lake Cone near Christmas (1933-63) records for
0 10--= 00 St0. Johns River near Christmas,
O 1o 20 30 40 O 60 70 80 0 90 100
PuRCENT OF TIME ALTITUDE UALeD OR EXCLDEOD THAT SHOWN

Figure 16. Stage-duration curves for selected lakes.






WATER RESOURCES OF ORANGE COUNTY


in the use of flow-duration curves for predicting future flows are
applicable to the prediction of future stages by use of stage-
duration curves based on short records can be adjusted to longer
periods by correlation with records for a long-term station. This
has been done for the stage stations established for this
investigation.
Knowledge of the magnitude and probable frequency of floods
is essential to the proper design and location of water-related
structures such as dams, bridges, culverts, levees, etc., and any
other structures that may be located in areas subject to periodic
flooding. Such knowledge is also useful in solving problems
associated with flood insurance and flood zoning.
Because flood-frequency information is often needed for
locations where no flow data are available, methods have been
devised that permit determination of the probable magnitude and
frequency of floods at any point along a stream.
Methods of determining the probable magnitude and frequency
of floods of recurrence intervals from 1.1 to 50 years on streams in
Orange County are given in U. S. Geological Survey Water-Supply
Paper 1674 (Barnes and Golden, 1966).
Because of the importance of stage in floods on the main stem
of the St. Johns River, stage-frequency data are presented in
the form of water-surface profiles for floods of recurrence intervals
of 2.33, 5, 10 and 30 years (figure 17). These profiles are for the
reach between the southern Orange County line and State
Highway 46.
A low-flow frequency curve shows the average interval between
the recurrence of annual low flows less than the indicated values.
Curves for durations of 7, 30, 60, 120, and 183 days, 9 months, and
1 year are given. These curves are useful in determining whether
the natural flow of a stream is adequate for a particular
development and, if not, how much the natural flow must be
augmented from storage or some other source. In Orange County
only the St. Johns River, the Econlockhatchee River, and the
Wekiva River has sufficient low flow to warrant analysis.

SURFACE DRAINAGE

Surface water from the southwestern 341 square miles of
Orange County drains southward into the Kissimmee River.
Surface water from the eastern and northern 662 square miles of
the county drains northward into the St. Johns River. Figure 18













1 vr =,- ,,....




,,,-___ _..._ i ___,,_ __ ,
o14o a ,

A Ja






-II









i DISTANCE IN MILES ALONG MAIN STEM OF ST. JOHNS RIVER i,
,' Figure 17. Water-surface profiles for floods of selected recurrence intervals ", ".*. : ,,
"__________________^ on main stem of St. Jo1--- River in Orange County.
8, ~:

5. 1 15-2025 0 3
DITNEI IE LN AI TMO T ON IE
Fiue1.Wtrsraepoie o loso eetdrcrec nevl
stmo S.Jl -Rve nOrneCony








S 81000' 55'


ORANGE COUNTY
EXPLANATION
- Major Drainage Divide
-- Tributary Drainage Divide
-...... High-water Line from Profile Gages
_L_ Cities and Towns
Surface Water Data Collection Point
A Quality-of-water Data Collection Point,Surface Source
19 Station Number Refers to Figure 13 and Table 7,8,11 and 12


e'Cf-J71" R tf


0 1 2 3 4 5 6 7 8 9 10 miles
I ^ I I 1 1 I


Figure 18. Drainage basins and.surface-water collection points.


80050'
-I 28*50'


25'


_1


2 1 11






WATER RESOURCES OF ORANGE COUNTY


shows the drainage basins and the surface-water data-collection
points in Orange County.
Parts of some of the basins delineated on figure 18 are closed
basins that do not contribute direct surface runoff.
The efficiency of a stream in removing surface water from the
land is closely related to the average slope of its bed. During the
flood of March 1960, rainfall on Jim Creek basin above State
Highway 520 (drainage area 22.7 sq mi) and on Boggy Creek
basin above the station near Taft (drainage area 83.6 sq mi) was
about the same. Even though the contributing area of Boggy
Creek is more than three times that of Jim Creek, its peak flow
was only 3,680 cfs whereas that of Jim Creek was 3.750 cfs. This
anomaly can be explained in part by the reduction of the peak flow
on Boggy Creek by storage in lakes and swamps. It is due mostly,
however, to the fact that the slope of Boggy Creek (3 feet per
mile) is about half that of Jim Creek. Streambed profiles for most
of the streams in Orange County are included in this report.

KISSIMMEE RIVER BASIN

Reedy Creek

Reedy Creek drains 49 square miles in the southwest corner of
Orange County. The drainage from about 22 square miles of this
basin in Lake County flows into Orange County. The drainage
area above the gaging station near Vineland (station 54) is 75
square miles.
Land surface altitude in Reedy Creek basin in Orange County
ranges from 75 feet above msl at the southern county line to 210
feet at Avalon fire lookout tower. The eastern part of the basin
consists of relatively flat swampy terrain interspersed with islands
of low relief. The western part consists of rolling hills interspersed
with lakes and swamps. The divide between Reedy Creek basin
and Bonnet Creek basin to the east is rather indefinite, and there
is some interchange of water between basins. Figure 19 shows a
profile of the bed of Reedy Creek.
At Reedy Creek near Vineland (station 54, 1 mile south of the
county line, the minimum flow observed was less than 0.01 cfs in
May 1961. The maximum flow was 1,910 cfs at the peak of the flood
in September 1960.
The average flow of Reedy Creek near Vineland is estimated to
be 55 cfs or 0.73 cfs per square mile. Average yearly runoff from




































DISTANCE FROM COUNTY LINE, IN MILES

Figure 19. Streambed profiles for selected streams in the upper
Kissimmee River basin.






WATER RESOURCES OF ORANGE COUNTY


the entire basin is estimated to be 10 inches. Average yearly runoff
from the western part of the basin is probably less than 4 inches
and that from the eastern part 14 inches or more. Curve No. 4
(fig. 15) is the estimated flow-duration curve for Reedy Creek near
Vineland. Note that the variability in flow (the steeper the slope
of the duration curve the more variable the flow of a stream) is
less during the upper 10 per cent of flow than during the middle
80 percent. This is due to the storage effect of lakes and swamps
which tends to distribute high flow over a longer period of time.
The stream is dry about 10 percent of the time.
Analyses of water collected from Reedy Creek at station 54
at low flows on June 15, 1960 and May 23, 1961, show the water
to be very soft and low in mineral content. At almost zero flow on
May 23, 1961, the hardness was 11 ppm and the mineral content,
based on a conductivity measurement, was estimated to be 24 ppm.
The low mineral content in the water indicates Reedy Creek
probably does not receive very much ground-water inflow.

Bonnet Creek

Bonnet Creek and its tributary, Cypress Creek, drain 55 square
miles of Orange County, east of Reedy Creek basin. The part of
the Bonnet Creek basin that is drained by Cypress Creek differs
hydrologically from the rest of the basin.
Land surface altitude in Bonnet Creek basin ranges from abut
75 feet at the county line to 195 feet near Windermere. Altitudes
in the western part of the basin, the part excluding Cypress Creek
basin, range from about 75 to 130 feet. This area is mostly flat
and swampy but it contains several lakes of moderate size and
islands of low relief. Figure 19 shows profiles of stream beds in
Bonnet Creek basin.
The minimum flow observed at Bonnet Creek near Vineland
(station 48), 1 mile south of the county line, was 0.4 cfs in May
1961 and the maximum flow was 1,180 cfs at the peak of the flood
in September 1960.
The average flow at station 48 is estimated to be 33 cfs or
0.60 cfs per sq. mi. Average yearly flow from the entire basin is
estimated at 8.1 inches. Prorating this yield between the 30 square
miles of Cypress Creek basin, for which the gaged yield is 4.4
inches, and the remaining 25 square miles of the western part of
the basin gives an average yield of 12.6 inches from the western
part. Curve 6 (figure 15) is the estimated duration curve for






REPORT OF INVESTIGATIONS NO. 50


Bonnet Creek. The upper part of the curve reveals the similarity
between Bonnet Creek and Reedy Creek basins. The lower part,
however, reveals that a base flow is maintained in Bonnet Creek
by ground-water seepage. It is unlikely that Bonnet Creek dries up
during even the most severe droughts.
The water in Bonnet Creek has a slightly higher mineral content
and less color at low flow than the water in most other streams in
the county. On November 24, 1959 the mineral content was 107
ppm, the hardness was 66 ppm and the color was 10 units. The
higher mineral content and lower color are caused by ground-water
inflow.
At high flow the water in Bonnet Creek has a low mineral
content, is soft, high in color and low in pH. At high flow on
July 24, 1963, the mineral content was 35 ppm, hardness 17 ppm,
color 400 units, and the pH was 4.5. The low mineral content was
caused by dilution by rain water runoff. The high color was caused
by organic material being flushed from swamps. Some of the
organic material is slightly acidic which lowered the pH to 4.5.
Water with a pH of 4.5 is corrosive.

Cypress Creek

Cypress Creek basin is comprised of about 8 square miles of
lakes, 2 square miles of swamps, and 22 square miles of rolling
hills in the eastern part of Bonnet Creek basin. Altitudes range
from 90 feet at its junction with Bonnet Creek to 195 feet near
Windermere.
The flow from Cypress Creek has been gaged at Vineland
(station 15) since 1945. The annual runoff averaged 4.4 inches and
ranged from a minimum of 0.27 inch in 1962 to a maximum of 17.72
inches in 1960. During the 18 complete years of record, flow ceased
at least once in each of 13 years. The longest period of no flow
was 107 days in 1956. The maximum flow recorded was 354 cfs in
September 1960. Curve No. 8 (figure 14) is the duration curve for
Cypress Creek. The flattening of the slope at its upper end indicates
the stabilizing effect of the large lakes in this basin. Cypress Creek
is dry about 10 per cent of the time.
At high flow on July 24, 1963 the water in Cypress Creek was
similar in quality to the water in Bonnet Creek. The mineral
content was 32 ppm, hardness 18 ppm, color 450 units, and the pH
was 4.4. No analytical data is available on the water in Cypress
Creek at low flow.






WATER RESOURCES OF ORANGE COUNTY


Shingle Creek

Shingle Creek drains 83 square miles of Orange County west
of U. S. Highway 441 and south of State Highway 50.
Altitudes range from 70 feet at the county line to 175 feet near
Windermere. The basin is relatively flat and altitudes are generally
less than 105 feet except for rolling hills on the western fringe. A
closed depression occupies 3.3 square miles of the northern part of
the basin. Figure 19 shows a profile of the bed of Shingle Creek.
Continuous records of stage and discharge for Shingle Creek
near Kissimmee (station 38) have been obtained since October
1958. The average flow during the period October 1958 to
September 1963 was 62.9 cfs. The long-term average is estimated
to be 52 cfs, or 0.60 cfs per square mile, by comparison with records
for Econlockhatchee River near Chuluota. Periodic observations
of stage and discharge near Vineland (station 39) have been
obtained since September 1959. The average flow here is estimated
to be 27 cfs or 0.60 cfs per square mile. The unit values of runoff
at the two sites show the hydrologic characteristics of the basin
to be homogeneous. Average yearly runoff from the basin is about
8 inches. The maximum discharge during the period of record at
station 38 was 3,320 cfs and at station 39, 1.740 cfs, both in March
1960. In most years, there is no flow for many days at either site.
Curve No. 6 (figure 14) is the adjusted flow-duration curve for
station 38 and curve No. 5 (figure 15) is the estimated flow-
duration curve for station 39. The similarity in the shape of the
two curves is another indication of the homogeneity of basin
characteristics. The fact that Shingle Creek is dry about 20
percent of the time points up the poorly developed state of its
channel which is not incised deeply enough to intercept the water
table when ground-water levels are low.
The water in Shingle Creek near Vineland (station 39) generally
has a low mineral content and is soft. At low flow, however, the
mineral content is as high as 150 ppm and the water is moderately
hard, 66 ppm, which indicates that ground-water inflow occurs in
this stream. At high flow the pH was low (5.7) and the color was
high. The iron content was as high as 0.73 ppm. Some of the iron
probably combines with organic compounds in the color. The
relatively high sodium (35 ppm) and chloride (37 ppm) indicates
pollution as the ground water in the area is generally less than 10
ppm in chlorides and low in sodium. Table 7 shows the ranges in
quality for 22 water analyses from November 1959 to July 1963.






REPORT OF INVESTIGATIONS NO. 50


Boggy Creek

The Boggy Creek drainage basin includes 86 square miles of
the county in and south of Orlando. An area of about 11 square
miles in the upper part of the basin has no surface outlet and
drains underground.
Altitudes range from 60 feet at the county line to about 125
feet in the upper basin. The lower part of the basin is flat and
contains many swamps and marshes but relatively few lakes.
The upper part of the basin is rolling hills interspersed with many
lakes. Figure 20 shows a profile of the bed of Boggy Creek.
Periodic measurements of the discharge of Boggy Creek near
Kissimmee (station 9) were made from January 1955 to September
1959. Since September 1959, continuous records of the discharge
of Boggy Creek near Taft (station 10) have been collected. The
maximum discharge during the period of record was 3,680 cfs in
March 1960, and the minimum was 0.1 cfs in June 1961. Average
discharge for the period October 1959 to September 1963 was 54.2
cfs at station 10. Comparison of this record with records for
Econlockhatchee River indicates a long-term average of 48 cfs
or 0.57 cfs per square mile. Average yearly runoff is 7.7 inches.
The fact that this average yield, like that of Reedy, Bonnet, and
Shingle Creeks, is less than the average for the state as a whole
may be attributed to the relatively larger proportion of non-
contributing area in the basin. Curve No. 5 (figure 14) is the
adjusted flow-duration curve for station 10. Comparison of the
curve with that for station 38 shows the basins to have similar
characteristics except that base flow is higher at station 10. This
higher base flow may be attributed to a slightly better channel
development and extensive canalization in the basin.
The water in Boggy Creek is soft, low in mineral content and
high in color. At station 10 the water hardness ranged from 13 to
30 ppm, the mineral content from 29 to 73 ppm, and color from 40
to 210 units. The analytical data on water from this station
indicates that most of the water is direct surface runoff. Table 8
gives the ranges in water quality for 21 analyses from November
1959 to July 1963.























o
Ij
C)

0


Figure 20. Streambed profiles of Boggy Creek and Jim Branch.






REPORT OF INVESTIGATIONS NO. 50


Jim Branch

Jim Branch drains 5.8 square miles in the south-central part
of Orange County. Altitudes in the basin range from 75 to 85 feet.
Figure 20 shows a profile of the bed of Jim Branch.
The maximum flow of Jim Branch near Narcoossee (station
51) has not been determined. A dry stream channel has been
observed at station 51.
Water collected from Jim Branch on May 23, 1961, was very
soft (9 ppm) and low in mineral content (30 ppm, estimated from
its conductivity).

Ajay-East Tohopekaliga Canal

This canal drains approximately 171 square miles, of which
54.5 square miles are in Orange County and 116.5 square miles are
in Osceola County.
Altitudes of the drainage area in Orange County range from 60
to 90 feet. The topography is fairly flat and is characterized by
swamps in the northern part and by lakes in the southern part.
Periodic measurements of the flow in Ajay-East Tohopekaliga
Canal near Narcoossee (station 2) have been made since 1942. The
maximum measured discharge was 1,420 cfs in March 1960. A
reverse flow of 0.25 cfs was measured in February 1946. The
average discharge, based on the relation between drainage area
and average discharge at several points on the main stem of the
Kissimmee River, is estimated to be about 170 cfs or 1.0 cfs per
square mile.
The flow into Orange County from an area of 111 square miles
in Osceola County has been measured in Myrtle-Mary Jane Canal
near Narcoossee (station 31) since November 1949. The maximum
flow into the county via this canal was 990 cfs in September 1960.
In September 1956, the flow reversed for 2 days and flowed out
of the county at the rate of 17 cfs. The average discharge in this
canal for the period of 1950 to 1963 was 109 cfs or 0.98 cfs per
square miles. Average annual runoff is 13.6 inches at station 2
and 13.3 inches at station 31. This indicates fairly uniform yield
from all parts of the basin. Curve 2 (figure 15) is the estimated
flow-duration curve for station 2 and figure 21 is the flow-duration
curve for station 31. The flatness of the upper parts of these curves
indicates the large amount of storage in the lakes and swamps in
this basin.







WATER RESOURCES OF ORANGE COUNTY


S -I1 1 1 1 i
700
.__ _Period of record'
"500 October 1950 to September 1962
300 -- - ^ !t -- - -- -
200-


70 FLOW TO NORTH ____
50-

30\
20-
NOTE.--No flow 2.87 percent of time
10

5- \N





077 FLOW TO SOUTH
0.5
0.3-
0.2- --

0.1 -- -


0.050.1 02 0.5 1


20 30 40 50 60 70 80


95 98


PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN
Figure 21. Flow-duration curve for Myrtle-Mary Jane Canal near Narcoossee.



Water from Ajay-East Tohopekaliga Canal, collected at station
2 during low flow on May 23, 1961, was very soft (16 ppm), and
low in mineral content (39 ppm, estimated from its conductivity).


ST. JOHNS RIVER BASIN

St. Johns River

The St. Johns River is the eastern boundary of Orange County.
Small tributaries drain 174 square miles of Orange County directly
to the St. Johns River. An additional 490 square miles of the county
are drained to the St. Johns River by tributaries which flow across
the county line from the south before joining the main stem.






REPORT OF INVESTIGATIONS NO. 50


The average slope of the St. Johns River is less than 0.3 of a
foot per mile in its approximately 26-mile reach along the border
of Orange County. At flood stages, the river falls from an altitude
of about 17.5 feet at Lake Poinsett to about 10.5 feet at the
northern county line. At the minimum stages in 1945, the river
fell from 8.0 feet to minus 0.4 foot in this reach. Figure 17 shows
probable flood altitudes for the St. Johns River for selected
recurrence intervals.
Stage and discharge records have been collected at St. Johns
River near Christmas (station 35) since December 1933 and at
St. Johns River near Cocoa (station 36) since October 1953. The
average discharge for the period of record at station 35 was 1,379
cfs. For the 10-year period October 1953 to September 1963, the
average discharge at station 35 was 1,463 cfs; and at station 36,
1.237 cfs. The maximum flow during the period of record at station
35 was 11,700 cfs in October 1953. There was no flow at station
35 for periods during March, April, and June 1939. Average yearly
runoff is 13.2 inches at station 35 and 12.8 inches at station 36.
The slightly higher yield at station 35 may be due partly to the
absence of lakes, where evaporation losses are high, and partly
to upward seepage of artesian water in the area between the two
stations. Curves 1 and 2 (fig. 14) are flow-duration curves for
stations 35 and 36. As indicated by the curve, about 99 percent
of the time flow at station 35 exceeds that at station 36 but 1
percent of the time evaporation and transpiration demands on the
river exceed the seepage into the river causing a loss in flow
between the stations. Figure 22 shows the magnitude and
frequency of annual minimum flow for selected durations at
station 35.
Analyses of water collected daily from the St. Johns River near
Cocoa (station 36) from October 1953 to September 1960, and a
continuous record of its conductivity since June 1959 show that the
quality of the water varies greatly. Table 8 gives ranges for the
various dissolved constituents.
Except for color the quality of the water in the St. Johns River
near Cocoa is good during normal and high flows. During droughts
when low flows occur, the water in the St. Johns River becomes
highly mineralized. During extended droughts, as occurred in 1962,
very little water flows into the St. Johns River above the Wekiva
River. Most of the low flow comes from seepage of highly
mineralized artesian water from the Floridan aquifer. Along the
reach of the river adjacent to Brevard County, the Floridan aquifer







WATER RESOURCES OF ORANGE COUNTY


3000

2000
Drainage area: 1418 sq. mi.
Average flow: 1379 cfs
a 1000 --
Zo






2 200
m3 flows \ 41 ofs

10


5. 50 --- -- --- --- --- -- 10 1 3-- 0 -- -
R R LOW-FLOW FREQUENCY IN Y
Example: For a 10-year recurrence
interval the 7-day minimum flow o ,n
20 h is 22.5 cfs and the l-year mini-
mun flow is 415 cfs ss w e

I 10


1.05 1.1 1.2 1.5 2 3 4 5 7 10 15 20 30
RECURRENCE INTERVAL IN YEARS
Figure 22. Low-flow frequencies for St. Johns River near Christmas.


is overlain by a thin aquiclude (impervious formation) through
which there is considerable leakage. In addition, there are many
wells heavily pumped for irrigation, and the excess water flows
through drainage ditches to the St. Johns River. Many artesian
wells flow wild along the banks of the river. Consequently, during
extended droughts the mineral content of the water in the St. Johns
River above the Wekiva River approaches that of the highly
mineralized artesian water.
The water in the St. Johns River was very highly mineralized
during the drought in the spring and early summer of 1962. Figure
23 shows a chloride profile of the river from headwaters to Green
Cove Springs from May 29 to October 24, 1962. This extended
reach of the river is shown for comparative purposes. Figure 23







REPORT OF INVESTIGATIONS No. 50


Figure 23. Chloride concentration in St. Johns River, northeastern Florida.

shows that the quality of the water in the St. Johns River is highly
variable, especially from the headwaters to State Highway 46 and
in the lower reaches where salt-water encroachment occurs. At
low flow the most abundant constituent in the water is chloride,
but sodium, sulfate, calcium, and magnesium are also present in
high concentrations. Table 9 presents a comparison of the chemical
analyses of water in the St. Johns River on June 7, 1962 at State
Highways 520 (station 36), 50 (station 35), and 16.
The increase in concentration from State Highway 520 to State
Highway 50 was caused by more ground-water inflow. The high
concentrations of dissolved minerals at' State Highway 16 are
caused by sea-water encroachment. The lower concentrations at
low flow between the Wekiva River and U. S. Highway 17 are
caused by dilution from relatively fresh spring flow.
As the rainy season began in late June 1962, the flow in the
St. Johns River increased and the quality of the water improved.








WATER RESOURCES OF ORANGE COUNTY


TABLE 9. CHEMICAL ANALYSES OF ST. JOHNS RIVER WATER,
JUNE 7, 1962.

Analysis State Highway State Highway State Highway
(ppm) 520 50 16

Chloride 900 1,150 2,050
Sodium 454 606 1,270
Sulfate 150 248 315
Calcium 136 160 196
Magnesium 56 77 79
Hardness 570 716 814


As indicated by figure 23, the quality of the water in the headwaters
improves early with increased flow, but remains poor downstream
until the highly mineralized water stored in the lakes is flushed
out. The chloride concentrations in the water on October 24, 1962
indicate that most of the highly mineralized water was flushed
from the river.
Figure 24 shows a cumulative frequency curve of specific
conductance of the water-the percent of time the specific






I O


400

20


S40 ----------N6--------I9




| 10---- --- -- == -

05 1 2 5 10 20 3040 50 60 70 80 90 95 98 99995 999 99.99
PERCENT OF TIME SPECIFIC CONDUCTANCE WAS EQUALED OR EXCEEDED
Figure 24. Cumulative frequency curve for specific conductance of the
St. Johns River near Cocoa, October 1953 September 1963.








58 REPORT OF INVESTIGATIONS NO. 50

conductance equals or exceeds values shown-in the St. Johns
River near Cocoa from October 1953 to September 1963. For
example, the conductance was 3,000 or greater for 2 percent of the
time during the period of record. Figure 25 shows the relation of
specific conductance to sodium, hardness, chloride and mineral
content in water of the St. Johns River near Cocoa.
By using figure 24 in conjunction with figure 25 the percentage
of time that the various constituents would exceed a given value
can be estimated. For example, from figure 25, if the chloride
content was 250 ppm, the specific conductance would be about 1,020
micromhos. From figure 24 a conductance of 1,020 micromhos or
greater would occur about 18 percent of the time.
From October 1953 to September 1963, the mineral content and
chloride concentration in water in the St. Johns River near Cocoa
exceeded the U. S. Public Health Standards for drinking water
during the following periods: April 21 to September 10, 1956;
June 21 to July 31, 1961; October 13, 1961 to August 21, 1962;


4,000


3,5 0 /, --- --

3.00HARDNESS

00 SODIUM C-- / ORIDE MINERAL CONTENT
CHLORIDE







2000
2.000










500

0 --- -- -- -


800 1,000
PARTS PER MILLION


1200


1,400


1,600


Figure 25. Relation of specific conductance to hardness, chloride, sodium, and
mineral content for St. Johns River near Cocoa.


1,800


--







WATER RESOURCES OF ORANGE COUNTY


and June 20 to July 31, 1963. This would be about 15 percent of
the time in the 10-year period of record.
A spectrograph analysis for minor elements was made on water
collected from the St. Johns River near Cocoa at low flow on
May 11, 1962. The results in micrograms per liter are given in
Table 10. Micrograms per liter can be converted to ppm by dividing
by 1,000. The symbol > indicates that the concentrations are less
than the values shown which are the lower limits of detection.

Small Tributaries Draining To East

The eastern part of the county between the main stem of the
St. Johns River and the Econlockhatchee River, amounting to
about 180 square miles drains to the St. Johns River by numerous
small tributaries. Table 7 shows data pertinent to these tributaries.
Figure 26 shows profiles of the beds of several of the small
tributaries.
The hydrologic characteristics of all these small streams are
probably similar to those of Jim Creek. Curve 3 (fig. 15) is the
estimated flow-duration curve for Jim Creek near Christmas
(station 24). The relative straightness of this curve indicates the
small amount of storage both on the surface and in the ground in
this area. Its steepness is indicative of the extreme variability
associated with steep bed slope and absence of storage. As indicated
by the curve, streams in this area are dry about 20 percent of the
time. The average flow at station 24 is estimated to be 26 cfs or


TABLE 10. MINOR ELEMENTS IN WATER FROM ST. JOHNS RIVER
NEAR COCOA ON MAY 11, 1962.
(Quantitative results in micrograms per liter. The symbol < indicates
concentrations are less than the values shown which are the
lower limits of detection)

Aluminum 66 Germanium < 0.29
Beryllium < 0.57 Manganese < 1.4
Bismuth < 0.29 Molybdenum < 1.4
Cadmium < 1.4 Nickel 1.9
Cobalt < 1.4 Lead < 1.4
Chromium < 1.4 Titanium < 5.7
Copper < 1.4 Vanadium 0.54
Iron 5.1 Zinc < 5.7
Gallium < 5.7






































4 5 6 7 8 9 10 II 12 13 14
DISTANCE FROM ST, JOHNS RIVER, IN MILES

Figure 26. Streambed profiles of small streams draining east into
St. Johns River.







WATER RESOURCES OF ORANGE COUNTY


1.15 cfs per square mile. Average runoff from the area is estimated
at 15.6 inches.
During the low flow period from June 14 to 17, 1960, the
dissolved mineral content in the water in the small tributaries
draining eastward into the St. Johns River was estimated from
conductivity measurements to range from 33 ppm in Taylor Creek
to 86 ppm in Second Creek. The mineral content in the water in
Christmas Creek was estimated on basis of its conductivity, to be
52 ppm on May 24, 1961, when the other small tributaries were dry.

Lake Pickett

Lake Pickett and its contributary drainage area occupy 8.1
square miles. Mills Creek drains Lake Pickett to the Econlock-
hatchee River. Altitudes in the Lake Pickett drainage basin range
from 60 to 75 feet.
The hardness of the water in Mills Creek at Chuluota (station
53) on May 24, 1961, was 7 ppm and the mineral content, estimated
from its conductivity, was 21 ppm. The pH of the water was 5.9
indicating that it is slightly corrosive. The water quality of Lake
Pickett is similar to that of Mills Creek.

Econlockhatchee River

The Econlockhatchee River drains 117 square miles of Orange
County. The width of drainage basin ranges from 2.5 to 9.5 miles
with the average in Orange County being 6.2 miles. The basin is
about 14 miles east of Orlando and spans the county from south to
north. The drainage from 17 square miles of the basin in Osceola
County enters Orange County. Altitudes in the Econlockhatchee
River basin in Orange County range from 20 to 90 feet. Figure 27
shows profiles of the beds of Econlockhatchee River and several of
its tributaries.
The Econlockhatchee River basin and the area drained by small
tributaries to the St. Johns River are unusual for Orange County
in that they contain only three lakes of significant size. These
basins do, however, contain many swamps and marshes.
Continuous records of the flow of the Econlockhatchee River
near Chuluota (station 19) have been collected since 1936, and
periodic measurements of the flow of the Econlockhatchee River
near Bithlo (station 18) have been made since September 1959.
The maximum flow of record at station 19 was 11,000 cfs and at





































5 6 7 8 9 10 11 12 G 14 16 r7 s8 1 20 21 22 23 24 25 26 27 28
DISTANCE FROM COUNTY LINE, IN MILES

Figure 27. Streambed profiles of Econlockhatchee River and selected
tributaries.







WATER RESOURCES OF ORANGE COUNTY


station 18, it was 7,840 cfs, both in March 1960. The minimum
flow at station 19 was 6.7 cfs in June 1945. The river flow ceases at
station 18 in most dry years. The average flow at station 19 was
275 cfs or 1.06 cfs per square mile for the period 1936 to 1963.
The estimated average flow at station 18 is 88 cfs or 0.74 cfs
per square mile. Runoff from the part of the basin above this
station is estimated to be 10 inches per year. Average runoff from
the entire basin above station 19 is 14.4 inches per year. Runoff
from the area above station 26 on Little Econlockhatchee River is
estimated to be 10 inches per year. Prorating the 10 inches of
runoff from the 146 square miles above stations 18 and 26 with the
14.4 inches from the 260 square miles above station 19 gives an
average yearly runoff from the intervening 114 square miles of 20
inches. About 11/ inches (11 cfs) of the 10-inch increase in runoff
from the lower basin over runoff from the upper basin is accounted
for by the effluent from Orlando's sewage plant. The remaining 8.5
inches is accounted for by higher base flow resulting from
ground-water seepage into the more deeply incised channel in the
lower basin and possibly upward seepage of artesian water. Curve
3 (fig. 14) is the flow-duration curve for station 19 and curve 1
(fig. 15) is the estimated flow-duration curve for station 18. Note
the similarity in the shape of the curves up to 50 percent duration
when direct runoff is the main source of flow. Above 50 percent
the curve for station 18 falls off rapidly to no flow at 75 percent
reflecting the absence of base flow whereas the curve for station
19 continues on at about the same slope reflecting the base flow
supplied by the sewage effluent and ground-water seepage.
Low-flow characteristics of Econlockhatchee River at station 19
are shown by figure 28. The streamflow indicated by these curves
is somewhat more than occurs within Orange County.
A continuous record of conductivity from October 1959 to June
1962 and analyses of water collected periodically to July 1963 from
the Econlockhatchee River near Bithlo (station 18), show the water
to be high in color, soft, and low in mineral content. Table 8 gives
the ranges of mineral constituents from October 1959 to July 1963.
The color is always greatest during the early part of high-flow
periods. The pH of the water was as low as 5.7 during high-flow
periods which indicates that the water would be slightly corrosive.
The high percentage of calcium bicarbonate detected during
low-flow periods indicates that ground-water inflow may occur.
Figure 29 shows a cumulative frequency curve of specific
conductance of the water in the Econlockhatchee River near Bithlo








REPORT OF INVESTIGATIONS NO. 50


1000


LOW-FLOW FREQUENCY
700 Example: For a 10-year recurrence
interval the 7-day minimum flow ,
is 12.5 cfs and the I-year minimum
500 I flow is 112 cfs




300 -- -- -_---- -- -- --- -- --- -- --



z 200

\, \





S50--
LL 100- ----s----- ---
U 5




30






30---_--


:u-1---I--- ~ --- ~S-^ "'^-- --- -- --

-Drainage area 260 sq. mi.
Average flow: 277 cfs

10-


1.05 1.1 1.2


1.5 2 3 4 5 7
RECURRENCE INTERVAL, IN YEARS


Figure 28. Low-flow frequencies for Econlockhatchee River near Chuluota.


L01


15 20 30








WATER RESOURCES OF ORANGE COUNTY


ta 4,000


S2,000



V) 1,000 -- -- S - -- -- -- --
I _-- -- -^ -- -- __ -- --

uj--


6 ,00--




0z ?00



1001
0.5 2 5 10 20 30 40 50 60 70 80 90 95 98 99 995 999 9999
PERCENT OF TIME SPECIFIC CONDUCTANCE WAS EQUALED OR EXCEEDED
Figure 29. Cumulative frequency curve of specific conductance of the
Econlockhatchee River near Bithlo, October, 1959 May, 1962.

from October 1959 to May 1962. Figure 30 shows the relation of
specific conductance to hardness and mineral content for the
Econlockhatchee River near Bithlo. Hardness and mineral content
were the only properties of the water that could be related to the
specific conductance for the Econlockhatchee River. The sodium,
chloride, and sulfate content is usually very low. By using figure 29
in conjunction with figure 30, the percentage of time that hardness
and mineral content would exceed a given value can be estimated.

Little Econlockhatchee River

The Little Econlockhatchee River drains 71 square miles of
Orange County east of Orlando. Altitudes in this basin range from
about 35 feet near the county line to 127 feet at the eastern edge
of Orlando. Figure 27 shows a profile of the bed of the Little
Econlockhatchee River.
A few lakes exist along the western rim of the basin but none
exist elsewhere. Many swamps and marshes temporarily store
water and thereby reduce the magnitude of peak flows in the river.







REPORT OF INVESTIGATIONS NO. 50


V 'II / /






HARDNESS
1 20
I o ---- -/ -- ----- --- ---- -
MINERAL CONTENT

I


0 1



0 -- /f


20 10 20 30 40 50 60 70 80 90 I00 110
PARTS PER MILLION
Figure 30. Relation of specific conductance to hardness and mineral content
for Econlockhatchee River near Bithlo.

The flow from the upper 27 square miles of the basin has been
gaged since October 1959 at Little Econlockhatchee River near
Union Park (station 26). The maximum and minimum flows at this
station were 1,640 cfs in March 1960 and 0.1 cfs in June 1961. The
average flow of the period October 1959 to September 1963 was
24.5 cfs.
The long-term average is estimated to be 20 cfs or 0.74 cfs per
square mile. Average runoff from the area above station 26 is
estimated at 10 inches per year. Curve 7 (figure 14) is the
flow-duration curve for station 26. The steepness and straightness
of this curve indicate a highly variable stream in a basin having
little surface or ground-water storage.
Analyses of water collected from the Little Econlockhatchee
River at station 26 show that the quality is similar to that of the
Econlockhatchee River. Table 8 gives ranges of concentrations and
properties of water in Little Econlockhatchee River.







WATER RESOURCES OF ORANGE COUNTY


Howell Creek

Howell Creek drains about 20 square miles in Orange County,
mostly in the suburban areas of Maitland, Winter Park, and the
northern half of Orlando. Altitudes in the Howell Creek basin
range from about 55 to 125 feet.
This basin contains a chain of lakes connected by natural
channels, canals, and culverts, beginning at Spring Lake at Orlando
(station 42), at an altitude of about 88 feet and ending at Lake
Maitland at Winter Park (station 28), at an altitude of about 66
feet. Several other lakes are connected to the chain of lakes by
canals or culverts. Lake Underhill at Orlando (station 45), in the
Boggy Creek basin, is connected to Lake Highland in the Howell
Creek basin by a culvert.
The flow of Howell Creek near Maitland (station 50) has been
measured several times. The maximum discharge of record as
determined from the stage-discharge relation was about 160 cfs
in September 1960. Flow at this site ceases when the level of Lake
Maitland is below about 65.5 feet with the center board of the
control out or about 66.0 feet with the center board in. The levels
of many of the lakes in the basin are partly controlled by drainage
wells and the flow from the basin is accordingly modified.
The average flow at station 50 is estimated to be 40 cfs or 2
cfs per square mile. Runoff is estimated to average about 27 inches
per year; more than half of the average annual rainfall. This yield
is much greater than elsewhere in the county despite the high
percentage of area covered by lakes from which the loss by
evaporation probably approaches the total rainfall on the lakes and
water discharged to the aquifer through drainage wells. This high
yield is due to the large percentage of area covered with pavement
and roofs from which runoff is a high percentage of rainfall.
Figure 31 shows estimated flow-duration curves for station 50. The
percentages indicated are for the time the control was in one or
the other of the conditions indicated and not for the total period
of record. A record of board changes is not available, so a
consolidated flow-duration curve cannot be prepared.
The water in Howell Creek and Lake Maitland are similar and
are of good quality except for moderate hardness which indicates
ground-water inflow. Hardness at high and low lake levels was 65
and 88 ppm, respectively. Table 8 gives ranges for other dissolved
constituents and properties of the water in Lake Maitland.







REPORT OF INVESTIGATIONS NO. 50


160


140
0
z
0
La 120
01--

100





z
U.







< 40
'I,
0


2 5 10 20 30 40 50 60 70 80


90 95


PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN

Figure 31. Estimated flow-duration curves for Howell Creek near Maitland.

Wekiva River

The Wekiva River and its tributaries, the Little Wekiva River
and Rock Springs Run, drain about 130 square miles in Orange
County. Altitudes in this basin range from about 15 feet at the
northern county line to about 195 feet near Windermere. Figure 32
shows profiles along the beds of streams in the Wekiva basin.
The area near the stream channels is flat and swampy, and
ranges in altitude from about 15 to 30 feet. From the edges of
these flat swamps, rolling hills rise abruptly to altitudes ranging
between 60 and 100 feet. More than half of the Wekiva River
basin in Orange County consists of rolling hills interspersed with
lakes and sinks. There is no surface outflow from this area.
Records of the daily stage and discharge of the Wekiva River
near Sanford (station 46) have been collected since October 1935.
The topographic drainage area at this station is about 200 square
miles. The average discharge for the period 1935-63 was 276 cfs.


FOR PART OF TOTAL
TIME WHEN CENTERBOARD
WAS NOT IN PLACE



FOR PART OF TOTAL
TIME WHEN CENTERBOARD
WAS IN PLACE


0051I 02 05 I







WATER RESOURCES OF ORANGE COUNTY

ALTITUDE,IN FEET ABOVE MEAN SEA LEVEL


Figure 32. Streambed profiles for Wekiva River and tributaries.

The maximum discharge was 2,060 cfs in September 1945 and the
minimum, 105 cfs in June 1939.
Curve 4 (figure 14) is a flow-duration curve for station 46.
The flatness of this curve indicates the small amount of surface
inflow in relation to the very high base flow of this stream. The







REPORT OF INVESTIGATIONS NO. 50


average flow at this station is the same as that at Econlockhatchee
River near Chuluota (station 19), yet the peak flow is less than
one-fifth that at station 19 and the minimum flow about 16 times
that at station 19. At station 46, the maximum flow is only 20
times as great as the minimum flow while at station 19, the
maximum flow exceeds the minimum flow by more than 1,600 times.
This great difference in variability is due to the fact that about
one-third of the rain that falls on Wekiva River basin and nearby
areas seeps downward into the artesian aquifer where it is stored
until released slowly through many springs whereas little of the
rain that falls on Econlockhatchee seeps into the artesian aquifer
but instead remains on or near the surface from where about
one-fourth of it runs off very rapidly. Figure 33 gives low-flow
frequency curves for Wekiva River.

500 ----.



365 days Average flow: 275 cfs
/273 days
400-- 183 days
1 /120 days LOW-FLOW FREQUENCY
SK //60 days Example: For a 10-year recurrence
30 days interval the I-day minimum flow is
S / 139 cfs and the 365-days minimum
300 -- .... ..flow is 221 cfs __
U

y


S200


1.01 1.1 1.2 1.5 2 3 4 5 7
Recurrence interval in years
Figure 33. Low-flow frequencies for Wekiva River


near Sanford.







WATER RESOURCES OF ORANGE COUNTY


The flow of Rock Springs, Wekiva Springs, and Witherington
Spring (stations 56, 61, and 62) near Apopka in the Wekiva River
basin have been measured occasionally since 1931. Table 11 shows
the results of these measurements.
The average flow from Wekiva Springs is estimated to be 74 cfs
and from Rock Springs, 60 cfs. Curves 7 and 8 (figure 15) show
flow-duration for Wekiva Springs and Rock Springs, respectively.
The extremely flat slope of these curves is due to the small variation
in flow characteristic of ground-water sources.
The quality of water from Rock and Wekiva Springs is similar
to that of the ground water in the area, and it varies only slightly
with flow. Table 8 gives ranges of dissolved constituents and
properties of the water in Rock and Wekiva Springs.

Apopka-Beauclair Canal

This canal drains Lake Apopka and the surrounding areas. The
total area drained by the canal is about 180 square miles, of which
about 120 square miles is in Orange County. Altitudes in this basin
range from about 65 feet in the mucklands adjacent to Lake
Apopka to 225 feet near Lake Avalon.
The flow in Apopka-Beauclair canal near Astatula was measured
periodically at station 3 from 1942 to 1948. Since July 1958 the
daily flow has been determined at station 4. During the period
of record, the maximum flow at station 4 was 754 cfs in March
1960 and the minimum flow was estimated to be about 1 cfs during
periods when a control structure in the canal was closed. The
average flow at station 4 during the period 1958-63 was 118 cfs.
Flow-duration curves and flow-frequency curves have no signifi-
cance at this station because of the artificial regulation of the
flow; therefore none are given.
The quality of the water in Apopka-Beauclair canal is similar
to that in Lake Apopka. The water quality of Lake Apopka is
discussed under the following section on lakes, swamps, and
marshes:

LAKES

OCCURRENCE

Orange County has about 1,100 permanent bodies of open water
ranging from small water-filled sinks to widening of stream









TABLE 11. DISCHARGE MEASUREMENTS OF SPRINGS IN ORANGE COUNTY, FLORIDA.

Downstream location
Discharge of measuring section
Name of spring and Date of in relation to head
station number measurement (cfs) (mgd) of spring (feet)


Rock Springs (56)
















Wekiva Springs (61)


2- 5-31
3- 8-32
2-10-33
1-30-35
11- 7-35
12- 6-35
1- 4-36
1- 4-36
6- 7-45
5- 9-46
4-26-56
11-24-59
11-24-59
6-17-60
10-17-60
5-25-61

3- 8-32
2-10-33
11- 7-35
6- 7-45
5- 9-46
4-27-56


55.9
51.9
54.2
62.8
57.1
62.8
54.9
56.2
52.5
59.1
54.7
70.0
72.4
78.2
83.2
68.4

63.9
66.9
72.5
64.8
67.5
62.0


36.1
33.5
35.0
40.6
36.9
40.6
35.5
36.3
33.9
38.2
35.4
45.2
46.8
50.5
53.8
44.2

41.3
43.2
46.9
41.9
43.6
40.1


50
50
40
80
50
500
600
60
50
30
1,000
150
1,200
1,250
1,250
1,300

100
100
300
200
150
200




TABLE 11. CONTINUED


Witherington Spring (62)


11-25-59
6-17-60
10-17-60
5-25-61

8- 8-45
10-19-60


300
200
150
150

4,200
4,750






REPORT OF INVESTIGATIONS NO. 50


channels. Lakes occur in all parts of the county, but the vast
majority of them are in the western half.

SURFACE AREAS

The surface areas of lakes in Orange County range from less
than one acre for some sinkhole lakes to 31,000 acres for Lake
Apopka. The area of a lake continually changes. If the range in
stage of a lake is large and its shores slope gently, changes in its
area are large. If the range in stage is small or if the shore is
steep, changes in area are small.

DEPTHS

The shallowest of the permanent lakes in Orange County is
Lake Poinsett. This lake was only 2-feet deep when it was at its
lowest level in 1945. The deepest body of water in the county is
Emerald Spring, a sinkhole near Little Lake Fairview. Emerald
Spring was sounded to a depth of 334 feet.
Depth contours for 73 selected lakes in Florida were shown by
Kenner (1964). Six of these lakes are in Orange County.

ALTITUDES

At its lowest level, Lake Cone, a widening of the St. Johns
River, was only about 2 feet above msl. A small lake near Tangerine
is shown on the U. S. Geological Survey topographic map to be at
an altitude of 158 feet.
The altitude of a lake's surface seldom remains constant very
long. Figure 16 shows the percent of time that specific altitudes
were equalled or exceeded for selected lakes in Orange County.

SEASONAL PATTERNS IN LAKE-LEVEL FLUCTUATIONS

Lake levels fluctuate in response to the net differences between
rainfall and evaporation with modifications by surface- and
ground-water inflow and outflow. Table 1 shows the monthly
averages and extremes of rainfall at Orlando and figure 34 shows
the estimated monthly averages of evaporation from lakes in
Orange County. Average monthly evaporation from lakes in Orange
County was computed by multiplying average pan evaporation at
Orlando as determined by the Weather Bureau by monthly
coefficients determined from evaporation studies at Lake










WATER RESOURCES OF ORANGE COUNTY


8






7






6



V)
w

5
z


z



O
i-


0
w' 3

w


J F M A M


J A S 0 N D


Figure 34. Estimated average monthly evaporation from lakes.


Okeechobee between 1941 and 1946 (Kohler, 1954). Departures

of lake evaporation from average are small in comparison to
departures from average in rainfall. Figure 35 shows the monthly
average change in stage of three lakes in Orange County in

comparison with the monthly differences in the average rainfall
and average evaporation. In general, when the difference is


~y?)~:l,.'. Lj"

.:;..r;.ii ~"~


"* ~~PI." g~r
ri-.
r .
r .
.1.
-
-?r-1' :'
., *'r;L. '~
*- ,~
...,.,
-6 r: .
~~~
I*~ c-~ Jl
v-r-r I.xr*''

..I 'I i f







0.4


0.3

0,2

S0.1
c
J 0.0
w- oo
z
S--0.1

-0.2

-0.3

-0.4
w
| 0.3
w
W 0.2
U.
0z 0.1
I
(j o,o



S-0.I

D ,

w -0,1
uj -O


Figure 35. Comparison of average monthly change in stage of three lakes
with average monthly difference in rainfall and evaporation at Orlando.


B-LAKE BUTLER M-LAKE MAITLAND


JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.


A-LAKE APOPKA







WATER RESOURCES OF ORANGE COUNTY


negative (rainfall less than evaporation), the lake levels fall, and
when the difference is positive (rainfall more than evaporation),
the lake levels rise. The levels of lakes with surface outlets
normally decline in October despite a slight excess in rainfall over
evaporation because of large surface outflow when the lakes are
high. Other factors such as manipulation of control structures may
account for inconsistencies like the behavior of Lake Maitland in
December and January and Lake Apopka in June.

RANGE IN LAKE-LEVEL FLUCTUATIONS

All of the lakes in Orange County receive about the same
number of inches of rainfall on their surfaces and lose about the
same number of inches of water by evaporation from their surfaces;
yet the range in fluctuation of their levels varies widely from
lake to lake. Differences in the physiographic features of the
individual lakes and in some cases, control and use of the lake
water account for this wide variation in range of fluctuation. The
physiography of a lake determines how each of four processes
(surface inflow, surface outflow, underground inflow, and
underground outflow) will affect its level. The relationships of
these processes to lake levels is extremely complex. The degree of
imbalance between inflow and outflow determines the range in
fluctuation. A specific change in a lake's level can be brought about
either by a small imbalance occurring over a long period or by a
large imbalance occurring over a short period. To further
complicate matters, the same lake may be affected by different
combinations of factors at different times.
In Orange County the lakes having the greatest range in
fluctuation are those effectively connected to the artesian aquifer
in areas where the piezometric surface has a large range in
fluctuation. Lake Sherwood, whose range in stage is the greatest
observed in Orange County (22.4 feet) is an example. The surface
drainage from about 2,400 acres and ground-water seepage from
the water-table aquifer in the surrounding sand hills enter Lake
Sherwood from which the only escape is by evaporation and
downward seepage into the underlying artesian aquifer. The rate
at which the downward seepage occurs depends on how high the
lake level is above the piezometric surface. In September 1960, the
piezometric surface at Lake Sherwood rose to 85 feet and inflow
was so great that the lake level rose to above 88 feet before
equilibrium between gains and losses was achieved. By June 1963,






REPORT OF INVESTIGATIONS NO. 50


the piezometric surface had fallen to about 62 feet and a lake level
of only 64.7 feet produced equilibrium between gains and losses.
Generally lakes having the least range in fluctuation arc those
whose levels are mainly affected by the water table in areas of
relatively flat terrain. Lakes Silver and Corrine are examples.
These lakes have relatively impermeable bottoms. Their levels are
always high above the piezometric surface which has no effect
on them. Surface inflow is small in comparison to the size of the
lakes and they have surface outlets which readily remove excess
water. During droughts seepage into the lakes from the relatively
stable water-table aquifer tends to offset evaporation losses. These
characteristics tend to reduce the difference in the rates of gains
and losses so that ranges in fluctuation are small. In areas where
the range of fluctuation of the piezometric surface is small, the
range in fluctuation of a lake is small, no matter how effective its
connection to the artesian aquifer.

WATER QUALITY IN LAKES

In general, the water in lakes in Orange County is of suitable
chemical quality for most purposes, however, in some lakes
hardness, high color, low pH, and other factors limit the usefulness
of the water. An exception is the water in Lake Poinsett at the
southeastern corner of the county which becomes so highly
mineralized during extended droughts due to inflow of salty
artesian water that it is not useful for many purposes.
One or more water analyses were made from 12 lakes in the
county during the investigation (figure 13). Four lakes were
sampled several times during high and low stages; the results of
the analyses of these samples are summarized in table 8.
The water in Lake Francis near Plymouth has the lowest
mineralization and Spring Lake at Orlando has the highest
mineralization except for Lake Poinsett. Table 12 gives analyses
of Lake Francis and Spring Lake. The mineral content of the
water in Lake Francis is low because the surrounding hills are
composed of clean, practically insoluble sand which allows the rain
to seep rapidly to the lake without becoming very mineralized and
because downward leakage to the artesian aquifer prevents a build-
up of mineralization. The relatively high calcium, sodium sulfate,
and chloride concentrations in water from Spring Lake indicate
that some pollution occurs. The sodium, sulfate, and chloride
concentrations are all higher than they are in surface or ground










TABLE 12. ANALYSIS OF WATER FROM LAKE FRANCIS AND SPRING LAKE.


Chemical analyses, parts per million


except Specific


Conductance, pH and Color.


Hardness
U as CaCO



ci s, .0 i i en i ij i ii
S Source 0 0 3 CIOS

47 Lake Francis
near Plymouth 7-24-63 0.1 .06 2.8 4.1 5.7 1.2 2 12 11 .2 0.0 38 24 22 71 5.0 10
42 Spring Lake
at Orlando 6- 6-62 1.2 .00 32 6.8 18 4.5 96 34 22 .3 .4 166 108 30 300 7.0 10






REPORT OF INVESTIGATIONS NO. 50


water in the Orlando area. Runoff from fields that are fertilized
and drainage from septic tanks contribute to pollution in the lake.
Water from Lake Hart near Narcoosee (station 21), has been
analyzed semiannually since October 1954 (See table 8). This
water has high color, low pH values, and low dissolved mineral
content. Lake Hart is in a swampy area which contains much
decaying organic material which causes the high color in the water.
Decaying organic material usually contains weak organic acids
which cause low pH. The mineral content of the water is low
because the soil in the area is relatively insoluble. The color during
the period of record ranged from 30 to 170 units. The pH ranged
from 5.4 to 6.3, indicating that the water is slightly corrosive. The
dissolved mineral content ranged from 20 to 52 ppm.
The water in Lake Apopka at Winter Garden (station 5) is
hard and high in calcium bicarbonate, indicating inflow of water
from the Floridan aquifer. During low stage in February 1963,
the calcium content was 28 ppm, the bicarbonate was 156 ppm,
and the water hardness was 150 ppm. The range in quality of
water from Lake Apopka in table 8 shows other constituents in
concentration that are higher than those in water in the Floridan
aquifer near Lake Apopka. Possible sources of these constituents
are waste water from nearby citrus processing plants, sewage
plant and septic tank effluent, and leaching of fertilizer and
pesticides applied to lands within the lake basin.
Water collected from Johns Lake at Oakland (station 25) at
low stage in 1963, had a hardness of 44 ppm, a mineral content of
111 ppm, and a color of 25 units. This relatively high mineralization
is probably caused by some of the fertilizer that was applied to
the surrounding groves entering the lake through surface runoff
and seepage of ground water.

CONTROL OF LAKE STAGES
The logical approach to control of lake levels is through control
of the factors that affect them. These factors are: rainfall,
evaporation, surface inflow and outflow, and underground inflow
and outflow. However, rainfall and evaporation cannot be
effectively controlled.
Control of lake levels through control of surface inflow has
been practiced in Orange County for years. For example, water
that would normally drain from Colonial Plaza into the south
Orlando lakes is diverted to Lake Sue through a pipeline. Much
water that would otherwise enter lakes from street drainage is







WATER RESOURCES OF ORANGE COUNTY


diverted to the artesian aquifer through drainage wells. However,
during extremely wet years, such as 1960, flow into these wells
when added to the normal recharge raises the piezometric surface
so that the wells in some lakes refuse to take water and some wells
even discharge water into the lakes.
Surface outflow from a lake may be conveyed in open channels
and culverts or pumped out through pipes. Conceivably, open
channels can be used to drain any of Orange County's lakes.
However, gravity drainage of many of the landlocked lakes would
be expensive because of the depth and length of channel excavation
required. For instance, to drain Lake Sherwood through an open
channel would require a channel more than 10 miles long with cuts
up to 45 feet deep. The channel would, of course, provide drainage
for those intervening lakes through which it could be routed, but
it might drain some of them dry.
Open channels require considerable maintenance; they require
wide rights-of-way; they are often unsightly; and they break up
the continuity of the land; they interfere with land transportation;
and they may add to water-control problems elsewhere by in-
troducing water where there is already an excess. A combination
of open channels, culverts, and pumps can often be used to
advantage.
Artesian wells can be used to remove water from or to put
water into a lake. If the lake level is higher than the piezometric
surface, water from the lake will flow into the well; if the
piezometric surface is higher than the lake level, water will flow
out of the well. The natural direction of flow can, of course, be
reversed by using pumps; however, pumping of water down
drainage wells is prohibited by State Board of Health regulations.

PROBLEMS

Surface-water problems in Orange County stem from two main
causes-floods and water deficiency.
Types of flooding that occur in Orange County are: (1) floods
resulting from surface runoff which are short-lived, and (2) floods
resulting from high ground-water conditions which persist much
longer. Type 1 floods are far more frequent than type 2 floods.
Type 1 floods are confined to areas contiguous to streams and lake
depressions that have large surface inflows. Type 2 floods are
confined mostly to lake flood plains, "Bottoms" in closed basins and
reach a peak at about 6-year intervals. Because of the long duration






REPORT OF INVESTIGATIONS NO. 50


of type 2 flooding, the county often suffers soil moisture deficiencies
at high-ground locations while lakes remain flooded in other areas.
The bed slopes of the streams that drain Orange County are so
slight that velocities are not sufficient to cause appreciable erosion
of the vegetation-filled channels. Consequently, the channels have
not cut to depths that are below the water table when it is at even
moderately low levels. Because of this most of the streams either
cease flowing or recede to extremely low flow after only about 90
days of drought. To date, problems associated with low flow have
been minimal in the country; but as the population and industrial
complex expand, the need to dispose of wastes by way of streams
may become more pressing. Because streamflow is small or
nonexistent a large part of the time, streams cannot be used to
transport wastes without becoming excessively polluted unless their
base flows are improved or augmented. The base flow of a stream
can be increased by deepening its channel to intercept the water
table during droughts and cutting lateral ditches from the channel
to increase the length of channel exposed to seepage. This would,
of course, lower the water table adjacent to the channel and lateral
ditches, but it would also improve the conveyance of the channel
and the increased channel capacity would tend to reduce the height
of flood crests. The flow of the streams could be augmented with
water pumped from the artesian aquifer.

GROUND WATER

Ground water is the subsurface water in the zone of saturation
-the zone in which all the openings of the soil or rock are
completely filled with water. The source of all natural fresh ground
water is precipitation which in Florida is almost entirely rain.
Ground water in Orange County occurs under nonartesian and
artesian conditions. Nonartesian conditions occur when the upper
surface of the zone of saturation (the water table) is not confined
and, accordingly, is free to rise and fall directly in response to
variation in rainfall and discharge. Artesian conditions occur
where the water is confined and rises in wells above the point at
which it is first penetrated.

NONARTESIAN AQUIFER

The nonartesian aquifer extends over most of the county and
is composed mainly of quartz sand with varying amount of clay,







WATER RESOURCES OF ORANGE COUNTY


hardpan and shell. In most parts of Orange County, the base of
the aquifer is approximately 40 feet below the land surface.
However, in parts of the highlands region, the nonartesian aquifer
may extend to greater depths. Its permeability and thickness and,
consequently, its productivity vary; and there are local areas
where it does not yield much water. Most wells in the nonartesian
aquifer are small diameter, sand-point or screened wells 20- to
30-feet deep that yield sufficient water for domestic use (5 to 10
gpm). In some areas open-end wells can be constructed by seating
the casing in a hardpan or clay layer and then drilling through the
hard layer and pumping out stand until a small cavity or "pocket"
is formed below the hardpan or clay layer. The well is then pumped
at a rate higher than the planned normal rate until it is virtually
sand free so it will not yield sand when in normal use. Wells of
this type usually yield more water (up to 30 gpm) and require less
maintenance than sand-point or screen wells; but, in many areas
of the county, geologic conditions are not favorable for their
development.

WATER LEVELS
The water table in Orange County ranges from about 0 to 20
feet below the land surface except below some of the sand hills in
the western part of the county where it may be considerably
deeper. In the lowlands and flatwoods sections of the county, the
water table is usually within a few feet of the land surface. The
water table conforms in a general way to the configuration of the
land surface, but it is usually at greater depths under hills and
may be above the land surface in low swampy areas. The degree
to which the water table conforms to the configuration of the land
surface depends to a large extent on the permeability of the
nonartesian aquifer and the materials below it. Other factors being
equal, the water table follows the land surface closest where the
permeability is least.
The water table fluctuates in response to changes in recharge
and discharge in a manner similar to the fluctuation in the levels
of lakes and reservoirs. Fluctuations of the water table range from
a few feet in flat areas of the county to 15 feet or more in hilly
areas. Figure 36 shows the water table fluctuation in a well on
East Highway 50, about 1 mile east of Bithlo (well 832-105-3) and
in a well on Hiawassee Road about a mile south of West Highway
50 (well 832-128-4). The hydrographs show that the Bithlo well
fluctuated about 4.5 feet during the period of record while the










w
-u.






m

S25


-w






w
W
U
'15
< 20



-J 25





0.
30



aj 35


J FM A M J J A S O N D J FM A M J J AS 0 N D J F M A M J J A S 0 N D J F M A M J J A S O.N D
1960 1961 1962 1963

Figure 36. Hydrographs for wells near Bithlo and Hiawassee Road showing
patterns of fluctuations of the water table.







WATER RESOURCES OF ORANGE COUNTY


Hiawassee well fluctuated about 16 feet. The hydrograph of the
Hiawassee well is much smoother than the Bithlo well hydrograph,
partly because the Hiawassee well is measured only once a month,
whereas the Bithlo well has a continuous recorder and is plotted
six times a month; but mostly because the water table is close
to the land surface at the Bithlo well whereas it is 21 to 37 feet
below the surface at the Hiawassee well. At Bithlo the water table
reacts quickly to local showers and with prolonged rainfall quickly
rises to the land surface where surface runoff occurs. During
drought the water table quickly declines to a few feet below the
land surface because surface drainage and evaporation can rapidly
remove the water. However, once the water table is 3 or 4 feet
below the surface, further decline is very slow because the streams
have very shallow beds and cease to flow, evaporation practically
ceases, and transpiration diminishes because most vegetation is
shallow rooted. Also, lateral ground-water flow from the area is
very slow because of the flat terrain; and downward leakage into
the underlying artesian aquifer is slight because of the thick
section of relatively impermeable marl and clayey sand that
separates the nonartesian and the artesian aquifers.
At the Hiawassee well the water table is always 20 feet or more
below the land surface. Rain filters slowly through the overlying
sand, and the response of the water table to heavy rainfall or
drought usually lags about a month. The water table fluctuations
in this area reflect long periods of excessive and deficient rainfall.
Brief showers after a dry period have little or no effect on the water
table because the rain is held as soil moisture and returned to the
atmosphere by evaporation and transpiration. However, the
surface sands rapidly absorb even a heavy and prolonged rainfall
and no surface streams flow from the area. The water that
infiltrates below the root zone eventually seeps to the water table.
After the water reaches the water table, it either seeps into nearby
lowlying ponds (which occur to a considerable extent during
periods of excessive rainfall) or it seeps downward into the artesian
aquifer through the relatively thin and permeable clayey sand that
separates the nonartesian and artesian aquifers. During droughts
most of the ponds in the Hiawassee area go dry and the water table
is mostly below the root zone, so it is apparent that further decline
of the water table is due mostly to downward leakage into the arte-
sian aquifer. The fluctuations of the water table in the Bithlo and
Hiawassee wells reflect only natural changes as there is no
appreciable pumping or irrigation in their vicinities.







REPORT OF INVESTIGATIONS NO. 50


RECHARGE

Most natural recharge to the nonartesian aquifer in Orange
County comes from rain within or near the county. Some recharge
comes from upward leakage of water from the artesian aquifer in
areas where the piezometric surface is above the water table and
from seepage from streams in areas where the streams are higher
than the surrounding water table.
Artificial recharge to the nonartesian aquifer occurs by
infiltration of water applied for irrigation, discharge from septic
tanks, and by discharge from flowing wells.
Most of Orange County is blanketed with permeable sand which
allows rain to infiltrate rapidly. In much of the eastern and
southern parts of the county, where the land is flat and the water
table is near the surface, the overlying surfaces and is quickly
saturated during the rainy season; and the excess collects in
swamps and sloughs or runs off in streams and rivers. In much
of the western part of the county, the water table is far below
the surface except in depressions. The surface sand can absorb
rainfall at a rate of as much as 3.5 inches per hour with little
or no direct surface runoff (Powell and Lewis, open-file report),
and the large volume of sand above the water table holds large
S quantities of water which percolates slowly to the water table.

DISCHARGE

Discharge from the nonartesian aquifer in Orange County is
by evapotranspiration, seepage into surface-water bodies, down-
ward leakage to underlying aquifer, pumpage, and seepage into
neighboring counties.
Ground water is removed from the zone of saturation and from
the capillary fringe by the roots of plants and is given off to the
atmosphere by transpiration. The depth to which plant roots
penetrate depends on the type of plant and the soil, and ranges
from a few inches to 50 feet or more for certain types of desert
plants. In Orange County the maximum depth of tree roots is
about 15 feet whereas the water table in most of the county is less
than 15 feet below the surface; therefore, discharge of nonartesian
ground water to the atmosphere by transpiration is appreciable.
Where the water table is near the land surface, ground water
moves upward by capillary action through the small pores in the
soil to the surface and evaporates. The rate of evaporation varies






WATER RESOURCES OF ORANGE COUNTY


with the depth to the water table, the porosity of the soil, the
climate, the season and other factors.
The base flow of most streams in Orange County is maintained
by seepage from the nonartesian aquifer. Seepage from the
nonartesian aquifer also helps to maintain the levels of lakes and
ponds during droughts.
Practically all natural recharge to the -Floridan aquifer in
Orange County passes through the nonartesian aquifer. In the
western part of the county, downward leakage is probably the
principal form of discharge from the nonartesian aquifer. Seepage
of nonartesian water out of the county is probably small.
Water is pumped from the nonartesian aquifer for lawn
irrigation, stock watering, and domestic use. Most wells are small
11/4- to 2-inch sand-point wells which yield about 5 to 10 gpm.

QUALITY OF WATER
Several factors influence the quality of the nonartesian ground
water in Orange County. Rain recharging the aquifer dissolves
soluble material contacted such as fertilizer and insecticides.
Drainage from septic tanks percolates to the nonartesian aquifer.
Harmful bacteria and color are usually removed if the recharge
water percolates through sand. Some of the very shallow wells
located in swampy areas yield water with high color. Most of the
nonartesian ground water that is soft and low in mineral content
has low pH indicating that it is corrosive. In areas where the
piezometric surface is above the water table, upward leakage occurs
and the nonartesian water is more highly mineralized.
The dissolved mineral content of water from wells in the
nonartesian aquifer varies greatly depending on the composition
of the aquifer. The water from wells developed in clean quartz
sand is usually very soft (hardness generally less than 25 ppm)
and low in mineral content (about 25 to 50 ppm). The following
is a typical analysis of water from a well in western Orange County
(838-128-1) developed in clean quartz sand:

Silica (SiO2) 2.5 ppm Dissolved solids 21 ppm
Iron (Fe) .45 ppm Specific conductance 39 micromhos
Calcium (Ca) .8 ppm at 25C
Magnesium (Mg) .7 ppm Bicarbonate (HCO,) 5 ppm
Sodium (Na) Sulfate (SO,) 2.8 ppm
Potassium (K) .0 ppm Chloride (Cl) 5.5 ppm
Fluoride (F) 0.1 ppm pH 5.2 units







REPORT OF INVESTIGATIONS No. 50


Nitrate (NO3) .0 ppm Color 8 units
Hardness as
CaCO, 5 ppm

The relatively high iron content (.45 ppm) was probably due
to iron dissolved from the casing or pump by the water of low pH
(5.2). The water from a well (832-101-2) at Christmas in eastern
Orange County had an iron content of 4.5 ppm. This high iron
content probably came from the aquifer because the neutral pH
of the water, 7.0, indicates that it is not corrosive.
Total mineral content as high as about 500 ppm and- high
concentration of some constituents indicate that the water in some
wells in the nonartesian aquifer is polluted. The water from a well
(822-138-3) in the southwestern part of Orange County had a
dissolved mineral content of 530 ppm (estimated from a
conductivity measurement). Concentrations of other constituents
were potassium, 10 ppm, sulfate, 107 ppm, and nitrate, 173 ppm,
which definitely indicates a nearby source of pollution. Use of
water containing an excess of about 45 ppm of nitrate for feeding
formulas for infants results in metheglobinemia or cyanosis (blue
babies) in the infants. The water from some of the shallow wells
had as much as 90 units of color.

SECONDARY ARTESIAN AQUIFERS

Several secondary artesian aquifers occur locally within the
confining beds of the Hawthorn Formation and less extensively
within the formations above the Hawthorn. These aquifers are
usually found at depths ranging from about 60 to more than 150
feet below the land surface and are composed of discontinuous
shell beds, thin limestone lenses or permeable sand-and-gravel
zones. The secondary artesian aquifers are most productive in tthe
area east and south of Orlando where they generally yield sufficient
water for domestic use. Open-end cased wells can sometimes be
constructed in the secondary artesian aquifers, but screens are
often necessary to keep sand from the well and to obtain sufficient
water.

WATER LEVELS

A continuous record of the water levels of a secondary artesian
aquifer have been recorded in a well about 1 mile east of Bithlo








WATER RESOURCES OF ORANGE COUNTY


(832-105-2), figure 37. The casing of this well extends 75 feet
below land surface into a 12-foot shell bed. At this site there is
also a record of the fluctuations of the water table (well 832-105-3)
and the fluctuations of the piezometric surface of the Floridan
aquifer (well 832-105-1). The water level of the secondary artesian
aquifer is always below the water table and above the piezomtric
surface of the Floridan aquifer at this site. This relation probably
exists wherever the water table is continuously above the
piezometric surface. At this location the secondary artesian water
level is 6 to 12 feet below the water table and 6 to 14 feet above
the water level in the Floridan aquifer. The range of fluctuation
of the water level in the secondary artesian aquifer for the period
of record was about 31/ feet or from 7 to 101/2 feet below land
surface. The secondary aquifer water level does not respond
rapidly to rainfall. The recorder chart usually shows very little
daily fluctuation, however there is a gradual long-term decline or

0 .?, _o_ .,. J.

Well 832-105-23' --
Depth 75 feet


S screened 65 feet
Nonortecsion artesian aquifer


5--

2 0 - - - _ _ _
Well 832-105-1
Depth 75 feet
Cased 65 feet
S Secondary artesianaqaifer



Depth 492 feet
I Cosed 151 feet
5 Floridan aquifer I
L o






L 20I












1960 1961 1962 1963

Figure 37. Relationship between water levels at Bithlo and rainfall
at Orlando.






REPORT OF INVESTIGATIONS NO. 50


rise that corresponds to general wet or dry periods. This indicates
that water enters and leaves the aquifer at a slow rate, and the
hydraulic connections to the overlying and underlying aquifers are
probably rather poor.

RECHARGE
Recharge to the secondary artesian aquifers in Orange County
is by downward leakage from the nonartesian aquifer in most
parts of the county and by upward leakage from the Foridan
aquifer where the piezometric surface of the Floridan aquifer is
above the piezometric surface of the secondary artesian aquifers.
A small amount of water probably flows into the county from
secondary artesian aquifers in surrounding counties. The second-
ary artesian aquifers are the least likely to be polluted because the
overlying, low-permeability beds tend to protect them from sur-
face pollution, and drainage wells are usually cased through the
secondary artesian aquifer zone.

DISCHARGE
Water discharges from the secondary artesian aquifers by
downward leakage to the Floridan aquifer, upward leakage to the
nonartesian aquifer where the piezometric surface is above the
water table, underground flow out of the county, and pumpage.

QUALITY OF WATER
The quality of water in the secondary artesian aquifers in
Orange County varies with location, depth, and the local hydrology.
In areas where the piezometric surface of the secondary artesian
aquifer is below the water table, downward leakage from the
water table aquifer occurs and the water tends to be similar to the
nonartesian water except where additional solution has taken
place within the aquifer. In areas where the piezometric surface
of the Floridan aquifer is higher than the piezometric surface of
the secondary artesian aquifer, upward leakage occurs from the
Floridan aquifer and the water in the secondary aquifer tends to
be similar to the water in the Floridan aquifer.
Generally, the dissolved-solids content of the water in the
secondary artesian aquifers ranges from 100 to 400 ppm. The
predominating ions usually are calcium and bicarbonate. Water
from secondary artesian aquifers is sometimes more mineralized
than is water from the Floridan aquifer. For example: The water







WATER RESOURCES OF ORANGE COUNTY


from a 75-foot deep well at Bithlo (832-105-2) constructed in a
secondary artesian aquifer had a dissolved solids content of 380
ppm. The water from an adjacent 492-foot deep well in the Floridan
aquifer had a dissolved solids content of 290 ppm.

FLORIDAN AQUIFER

The principal artesian aquifer in Orange County is part of the
Floridan aquifer that underlies all of Florida and parts of Alabama,
Georgia, and South Carolina. The Floridan aquifer, as defined by
Parker (1955, p. 189) includes "parts or all of the middle Eocene
(Avon Park and Lake City limestones), upper Eocene (Ocala
limestone), Oligocene (Suwannee limestone), and Miocene (Tampa
limestone) and permeable parts of the Hawthorn formation that
are in hydrologic contact with the rest of the aquifer."

AQUIFER PROPERTIES

The Floridan aquifer is one of the most productive aquifers in
the country. In Orange County many large diameter wells (20
inches or more) yield more than 4,000 gpm. These wells can be
constructed in almost any area of the county. Wells that will yield
only small quantities of water are usually in the vicinity of
sinkholes where sand has filled solution channels in the aquifer.
Pumping rate-drawdown ratios range from less than 100 gpm
per foot of drawdown to over 500 gpm per foot of drawdown. The
aquifer consists of nearly 2,000 feet of porous limestone and
dolomite or dolomitic limestone covered by sand and clayey sand
ranging in thickness from a few feet to about 350 feet. The
altitude and configuration of the top of the Floridan aquifer is
shown in figure 38. The depth below land surface to the top of the
aquifer is shown in figure 39. The total thickness of the aquifer
is not accurately known because the deepest water well in the
county penetrates only the upper 1,400 feet. The log of an oil test
hole drilled southeast of Orlando shows dense anhydrite at about
2,000 feet, and this is assumed to be the base of the aquifer.
The lithologic and hydrologic character of the Floridan aquifer
is not uniform either horizontally or vertically. In general, there
are alternating layers of limestone and dolomite or dolomitic
limestone. The limestone layers are usually softer and of lighter
color than the dolomitic layers. The aquifer stores huge quantities
of water and also acts as a conduit. Water moves slowly through






I 5 40 35 30 I2 I IB I 0 ao' a*O I' cI I IN

S- a EXPLANATION
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Barn s.aken.from U.S.GSooe iical 3 4 X 7 0 3.10miles
Survey opographic quadrangles.

Figure 88. Configuration and altitude of the top of the Floridan aquifer in
range County, Florida.
10 0

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Orange County, Florida.





40' 35 30 25 20 15 10 s. 05 SI'00 SS ac40


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35' 10 05' lO' 5' 80'5 '
0 0 INS



























Survey topogrophic quadrongles .-- ,

Figure 39. Depth below land surface to the top of the Floridan aquifer
in Orange County, Fla.
0 r 0 0 C UU N N

Rd P o 2 o 0;? I'm
3se 00e 9o U. ." l4


I ,45'






REPORT OF INVESTTIGATIONS N. 50


the rock from areas of recharge to areas of discharge. The entire
aquifer has been affected to some degree by the dissolving action
of ground water and is somewhat analogous to an enormous sponge.
Some of the largest known caverns in Florida have been found
within the Floridan aquifer in Orange County. One of the largest
caverns with no opening to the surface ever discovered in Florida
was encountered in a city supply well drilled in the southwest part
of Orlando. This cavern was 90-feet high with the ceiling 578 feet
below the land surface. The cavern was filled with water and
there was 12 feet of black organic muck on its floor. The areal
extent of this cavern is unknown, but several deep wells 1,000 feet
to the north did not penetrate it. One of the deepest and largest
known caverns in Florida is a sinkhole near Little Lake Fairview,
northwest of Orlando, known as Emerald Springs. Emerald Springs
was measured in 1956 and found to extend 884 feet below the water
surface which is about 45 feet below the surrounding land surface.
According to divers who have explored the sinkhole, it has sloping
sand-covered sides for 45 feet below the water surface and then a
vertical neck, about 20 feet in diameter, through limestone for
about 45 feet. Below this depth, there is a large room with a
sloping ceiling. The wall of the room was found at a distance of 89
feet in one direction but had not been found at a distance of 100
feet in the opposite direction (when the divers were forced to
return to the surface).

Zones of the Aquifer

The Floridan aquifer in central Orange County has two major
producing zones that are separated by a relatively impermeable
zone. The upper producing zone extends from about 150 feet below
the land surface to about 600 feet. The lower producing zone
S extends from about 1,100 feet to 1,500 feet or more below the land
Surface. Both major producing zones are composed of hard brown
dolomitic limestone or dolomite and relatively soft cream limestone;
however, the top half of the upper zone is mostly soft limestone.
Some of the dolomite in both major producing zones is very dense,
but many interconnecting solution cavities make the overall
permeability of both zones very high.
The limestone in the top half of the upper zone is mostly white,
soft, granular. and fossiliferous. This limestone contains cavities,
but they are usually neither as large nor as numerous as the
cavities in the dolomitic parts of either major producing zone. At






WATER RESOURCES OF ORANGE COUNTY


some locations, very large (4,000 gpm or more) yields can be
obtained from the limestone, but most high yield wells also
penetrate the underlying dolomitic limestone. However, many
domestic wells and small public supply wells draw all their water
from the limestone section of the upper zone. The municipal supply
wells for the Cities of Orlando and Winter Park are developed
in the lower (1,100-1,500 feet) producing zone. These wells
generally yield 3,000 to 5,000 gpm with 10 to 25 feet of drawdown.
The relatively impermeable zone (600 to 1,100 feet below the
land surface) separating the two major producing zones is
composed of layers of relatively soft, mealy limestone and dolomitic
limestone. It contains some water-bearing layers, but generally
this separating zone yields much less water than the zones above
and below it. In many parts of the country the separating zone
would be considered a good aquifer; but because much larger
supplies can be obtained above and below this zone in Orange
County, very few wells are developed in it.
The occurrence of reported cavities is shown in figure 40. The
number of cavities shown for different depths actually does not
represent t the true distribution of the cavities because many more
wells penetrate the upper part of the aquifer than penetrate the
lower part. However, the illustration does show that although
cavities have widespread vertical distribution, they are more
prevalent in some zones than in others.

Interrelation of Zones

The interrelation of the upper and lower producing zones is of
vital importance to the people of Orlando and Winter Park because
excess surface water is disposed of in the upper zone while most of
the municipal water supplies are developed from the lower zone.
Contaminated water can enter the upper producing zone through
the numerous drainage wells (See section on drainage wells, page
83) and it is important to know if this contaminated water can
move into municipal supply wells.
It has been postulated that some dense dolomitic beds between
400 and 600 feet in the upper zone might be continuous and act as
an impervious layer to protect the lower zone. To test this idea, a
well was drilled at Lake Adair in Orlando into the upper zone of
the aquifer adjacent to an existing well in the lower zone. The
shallow well is cased to the top of the aquifer (105 feet) and
bottomed at the top of the hard dolomitic zone at 400 feet. The









REPORT OF INVESTIGATIONS NO. 50


Figure 40. Distribution


n of reported cavities in Floridan aquifer in
Orange County, Fla.


cuu










100
-m ,--- -n- Inn n*,











-200



-300



-400




-500



-600




-700


EXPLANATION
-00

Well Cavify

90L-- Cavity tone




.1000



-1100



-1200




-30oo -



-I l l -- _ _ _ ^ __ _








WATER RESOURCES OF ORANGE COUNTY


deep well is cased to 601 feet and bottomed at 1,281 feet. Automatic
water level recording gages were installed on each well to compare
the fluctuation of the water levels in the two zones in response to
hydrologic changes. If the two zones were effectively separated,
the water levels should respond differently to local hydrologic
changes such as pumping and rainfall. Figure 41 shows that the
water levels in the two zones are almost identical when the water
levels are stable or slowly declining. Both zones react rapidly to
local rainfall, but the rise in the upper zone is usually about twice
the rise in the lower zone. After the rain, the upper zone declines
more rapidly than the lower zone so the two levels again approach
each other. This indicates that the two zones are somewhat
separated; but given time and a difference in pressure head, water
will move from one zone to the other.
Further evidence of interconnection of the two zones is shown
by the hydrograph of an observation well at the Orlando Air Force
Base (well (833-120-3). This well is about 11/2 miles north of the
w
S12

U.

Well 833-123-10
Depth 400 feet
o Cased 105 feet
Upper Zone I
t! t
U ') Norcord' I
I ___ ___
327-- --
Well 833-123-9
SDepth 1245 feet
Cased to 601 feet
S32 Lower Zone





wMS
.s ,,-. | _-,"- -- -- -- -

-J
il l


0
J FM AM J J A S O N D J FM AM J 'J AS 0 N D J FMA M J J AS ON D


1962


1963


1964


Figure 41. Relationship between water levels in the upper and lower zones
of the Floridan aquifer at Orlando.







REPORT OF INVESTIGATIONS NO. 50


Orlando Utilities Commission well field (two wells) at Primrose
and Church and about the same distance east of the Commission's
Highland well field. The observation well is 655 feet deep and
cased to 383 feet, whereas the supply wells are about 1,200 to
1,500 feet deep and cased to about 1,000 feet. A comparison of
pumping times in the well fields with minor fluctuations in the
water levels in the observation well shows a direct and immediate
correlation (See figure 42.). Each time a pump in either well field
was turned on or off a sharp change occurred in the water level in
the observation well. This indicates a good connection between
the upper and lower zones.
The water level in the lower zone in the vicinity of Orlando
was always somewhat below the level in the upper zone in 1963-64
because an average of about 25 million gpd (gallons per day) was
withdrawn from the lower zone and was replaced by leakage
through the overlying beds. Also, several hundred drainage wells
discharged water directly into the upper part of the aquifer in

8125' 24' 23' 22' 21' 20' 8119'
28*35' -
N :- r

34' I I
Highland Observation
wgla 1 well .
well fild 833-120-3'
33, ---
59 Primrose
32' -..
IfI
So 28-31 I I 2 Mile


Observtion Well
833-120-3 V
u 0 60.5




8I

hm.U -: 1


2 3 4 5 6
MARCH,1964
rograph of well 833-120-3 showing effects of pumpag
Orlando well fields.


Figure 42. Hyd


5e in the






WATER RESOURCES OF ORANGE COUNTY


addition to the natural leakage that occurred through the overlying
confining beds.
Figure 43 shows the altitude and configuration of the
piezometric surface of the lower zone in June 1962. The altitude
and configuration do not differ materially from the altitude and
configuration of the piezometric surface of the upper zone in May
1962 (See figure 5.) indicating that both zones are connected and
are recharged in the same general area.
Chemical analyses of the waters from the two zones tend to
support the conclusion that the two zones are interconnected.
Figure 44 shows that there are no significant differences in the
chemical quality of the waters in the two dolomite zones.
All available evidence indicates that, given sufficient time and
pressure head differences, water will move from any part of the
aquifer to any other part carrying with it any soluble, long-enduring
pollutants it might contain. If heavy pumping creates a deep,
permanent cone of depression in the lower zone and pollutants such
as hard detergents are present in the upper zone, the pollutants
will tend to migrate to the lower zone.


81015'


Figure 43. Configuration and altitude of the piezometric surface in the lower
zone of the Floridan aquifer in the Orlando area.









REPORT OF INVESTIGATIONS NO. 50


0


I


*


200




300




400 _----__=


500




600




a 700




g 800




900


1000 1
*


- 1 =**-


1200
*



1300 *--




1400 -



*
1S00 0 100 200 300
HARDNESS, IN PARTS PER MILLION


Figure 44. Relation between dissolved solid and hardness of water and
depths of wells in the Orlando area.


100


S

S


**0 *
ee


---4
r
b o''


0 too 200 300 400
OISSOLVED SOUOS, IN PARTS PER MILLION


~ ~


-- ---L-~---~- L --is~


L -J--*-C


I 1=-------- i----


L _








WATER RESOURCES OF ORANGE COUNTY


101


PIEZOMETRIC SURFACE


The artesian pressure or piezometric surface is the height to
which water will rise in tightly eased wells that penetrate the
artesian aquifer. Where the water table is above the piezometric
surface, nonartesian water may infiltrate through the confining
layer and recharge the artesian aquifer. Conversely, where the
piezometric surface is above the water table, the artesian water
tends to discharge upward. The piezometric surface and flowing
well areas in Florida are shown in figure 45.
The piezometrie surface of the Floridan aquifer in Orange
County slopes to the northeast and east from its highest point in
the southwestern part of the county (figs. 46, 47, 48, and 49).


EXPLANATION
-10-
rliremeitrl Celnreur
Oh I elttllie t s 0hleh il er we old hrve rlsel
lin fl rll iiili wlrlll lhet Ientetate the
mel wtele etetllt toN e etlene in1 t0 Pletlien
ilitar, July l.I?, e1(1,
C trur Inlfvl 10 flit, Dih l iupplemenltal
slnrlet It |tO em t O, Detum Is moen i11e II l,
Amr f t f(l Illtr
Itnt Ili d l ll, itlrb lt of flow Grie 11 l v Ith
tlullulstvlone X the o lofeelrl lueltol pel.
*ulT ll IIrtoi rt ha llvl II rluMg, Ptlrlvel
omi IGe.II of Itrt'lio alow Ore "e f llididI
Immli(llll ef leoltnlt I* *# l etlIt llto the
"of! MI R oit ef the Miller rivers nd



L C O8 40 in il.

t1?* ~^ii' '-^-;---.-....^^,-


I


-- I I
m40 OFe


Figure 45. Piezometric surface and areas of artesian flow of the Floridan
aquifer in Florida, July 6-17, 1961.








I1
















0




rn
z









Cn
4=
8







en
3
0







CO


Figure 46. Contours of the piezometric surface at high-water conditions,
SSentrmber 1960.









*EKPL WAT ON
M ll

tumbew In iw rh In %9 l(
910b9n Interl fe lMev.
-4-7-4-
Sh0 11ll luN 11 111 "MW W1 i3 0131'".
Il n ftl t itiB m lr "Y.'RMel
cWan 9 n.01 19 1w, Dum 96 MM1 M eveMI.


COUNTY


Figure 47. Contours of the piezometric surface at about normal conditions,
July 1961.


CI








a







3.









icc









t$ fo oa bo _r'o ss a0 to

A EXPLANATION
N "
*I 'Jf.rf9,#,.v r.',
I, ..1 .' o ::. r w. w" 'I


Vi. ,9 I L jl .', 9 r if-I I '
L "'.> ir,:!' l" t 4i0'r:, rlLl>.r, U,,wII++.P kr

E VNGE I 02

dVT' l I. .... T224J :





4't '4 30'
... .. \ ,
C 0





+..+ L,1 to ;


Figure 48. Contours of the piezometric surface at about normal conditions,
December 11-17, 1963.













EXPLANATION


D.iuspw Ni;tI
zm ri */fmo ." 4,m'l1J w 1. MW Able,
p nnrrm m v,



SnvB iiiui i; ievsir4 me' *mrvsns Isnew
.1415 pel i toI l lt *Hf TlB]V .01at-tW '1f
110MVInrs rw ci091 opi~r. VAI VORti
"nVlr mruul r w' :iriom l; elr 196niu
A-ST nvruMs lut' *vJrV'l't vv $mte:-o
ltB.,


N OLE


C0 U N T Y


0 II 2 3 4 5 6 7 6 9 1omlln


Figure 49. Contours of the piezometric surface at extreme low-water

conditions, May 1962.






REPORT OF INVESTIGATIONS NO. 50


Water moves downgradient from areas of high piezometric level to
areas of low piezometric level. In general, the direction of
movement, shown by the arrows in the figures, is at right angles
to the contour lines, although locally the direction of flow may be
different because of differences in permeability such as caused by
cavern systems.
Figure 46 depicts the piezometric levels in September 1960, the
highest observed during the investigation. The high levels of
September 1960 equalled or exceeded the highest previous recorded
levels which occurred in the early 1930's. Figures 47 and 48 which
show the piezometric surface in July 1961 and December 1963
represent about normal conditions; figure 49 shows the piezometric
surface in May 1962 when artesian levels were at their lowest
for the period of record 1943 through 1963. The relation of the
piezometric surface to the land surface is shown in figures 50 and
51. Figure 50 shows the distance above and below land surface
of the static water level in tightly cased wells in the Floridan
aquifer during extremely high-water conditions (Sept. 1960).
Figure 51 shows the distance above and below land surface of the
static water level in tightly cased wells in the Floridan aquifer
during extremely low-water conditions (May 1962).

Fluctuations

Gages were installed on six wells in the Floridan aquifer to
record the fluctuations of the piezometric surface (figures 37, 41,
52, and 53). In addition, water levels were measured periodically
in about 70 wells. Most water-level fluctuations are caused by
changes in rates of recharge (mostly rainfall) and/or discharge.
However, variation in barometric pressure, temporary loading of
the land surface such as by-passing of trains and earthquakes also
cause fluctuations. For example, the Alaskan earthquake of March
27, 1964 created a brief surge of more than 10 feet in the water
levels of some wells in Orange County.
The sharp rises in the water levels in well 833-120-3 at the
Orlando Air Force Base (figure 52) and well 932-128-1 west-of
Orlando (figure 53) are caused by rapid recharge through the many
drainage wells in the area. The nearly equally sharp declines
following the rises show that the water mound created by the
drainage wells rapidly dissipated through the porous limestone.
Although the water probably moves slowly, the pressure is
transmitted relatively rapidly to other parts of the aquifer


106







40' 5' 30' 25' C 15' O5' 800' b5' 80-50'


I I I I I I I f I I I I I I I 1, i 1 I I I 1 I, I ; .- I i I I I 1 I 1 B '5 o
.. J..."" ..M D'JM D .. ... ., .
.. 0K E C O U N 1 Y


45- EXPLANATION
--o --l ----45
Sr. INh qPlormic Wi -onlo th
Flr 50. oootiooldor.ce u ote f I h

loand face, Sept 1960 Intervl 10


4 40
SEMINOLE

L a 7 A N GO U N






3rr5 'oK

30
0poPOo C o u N Y ,-20
.. ... ,-T; .














,)' i o-:o


2E f, ,I 1 t I I I, I oI


8145 40' 35' 30' 2W 20' W 1'0 O b oc' 5 90050"
(k 0u 25'











Survey topogroaphic quodrangles .

Figure 50. Piezometric surface relative to land surface datum, at high-water
conditions, September 1960, Orange County, Florida.


8r45


I





















EIPLAUITCO
-0-
pe*un C~
V" 1 I sor lou *0 S
Wt ier, C pf se i
- ltus. MAY 0U o** a
'w .. ssWO 5 IO IWas


POLE'


C O U N T Y


0 1 2 3 4 5 6 7 I 9 iO m 's


Figure 51. Piezometric surface relative to land surface datum, at low-water
conditions. Mayv I92. Ornnro County. Florida.










109


WATER RESOURCES OF ORANGE COUNTY


itW 11 Kt-3.1 OSERVITiON WELL. U.S. GEOLOGICAL SURVEY fldont oaulifr






10----------------- -- -- -- - -


W1 14. I TI I IC IT Y O F I IF-O.I- I oI I 1 0 I
DIph of well 310 ft.











Dopth ol cag.II- I.

















Wel ItO30.3l UNULSD SUPPLY WELL. ORLANDO AIR FORCE eASE FloAol AAVI,*l




Well atZ.i-1041 T GUEST W IRR CITY OF CO CALL. H. HNSCIrN l an quillfer
40-- ------- --- -
Gplh of Mil-SI ft.
at1Ih olf t *o"tiI0I,

Well 033-120.3 UNUOSED SUPPL Y WELL OLANDO AIR FORCC BASE 5o ,q.f



40-- ---- -I .I-- -.--- -----


































5IO 19 1 1961 193
Figure 52. ydrographs of wells.
Welle 833-3-2 UNUSED IRRIATION WI LL. H. HENSCHEN Fl on iin qulfer



30---------------------------




40-^---------^ -- -




IFMAM 4 JA 0N D IFMA M J 4AS O NDJ FMA M J JAS O ND J F MA MJ J ASO N 0
1960 1981 1962 1MI

Figure 52. Hydrographs of wells.











'^'* *T 'r i 1r ? r r T i 1 1


. ;: A \ I -

- kI O' Oi 47C (- Z. 4 I I I y i r
'Wf ?6 -"
'--e P ,4j "I 0 I*41 *4QY
tSOOa 48 ifet

r, T y ) ..... ... ,



,


0 0
J I,'
1 0*1


Figure 53. Range of fluctuation of the piezometric surface from September,
1960 to May 1962, Orange County, Plorida.






WATER RESOURCES OF ORANGE COUNTY


including nearby discharge points such as Rock and Wekiva
Springs. The flow of the springs increases during high-water
stages and decreases during droughts. (See table 11.)
The relatively small fluctuations of the water levels in well
822-138-1 in the southwest corner of Orange County; well 833-137-3.
in the western part of the county, and well 823-104-1 in the eastern
part of the county (figure 52) indicate that recharge and discharge
occur at a more uniform rate in these areas. Rain infiltrates
through the sand overlying the aquifer in the western areas and
/ recharges the Floridan aquifer and flows through the aquifer to the
eastern area. Discharge is largely by outflow through the aquifer.
The range of fluctuation of the piezometric surface from the
high level (September 1960) to the low level (May 1962) is shown
in figure 53. The piezometric surface does not rise and fall
uniformly. The range of fluctuation _is much greater in and
northwest of Orlando (20 to 25 feet) than it is in the outlying parts
of the countyi(5 t~1O0feet)7 The m-rain reasons for the greater
fluctuation in Orlando and vicinity are twofold: first, the area has
greater recharge especially through the more than 300 drainage
wells in the area; and second, there is much more pumping in
Orlando and vicinity than in other parts of the county.
Large natural recharge, augmented by the unusually large
quantity of water that entered the aquifer through drainage wells
during the period of exceptionally heavy rainfall in 1958-60, caused
record-high artesian levels in the Orlando area. Drainage wells in
Orlando and vicinity contributed recharge to the aquifer in
sufficient quantities during the time of heavy rainfall to create a
localized temporary mound or high on the piezometric surface.
From September 1960 through May 1962, severe drought conditions
caused water levels to decline markedly from their abnormal high.
The area of greatest decline, shown by the 20-foot line on figure 53,
encompasses most of the drainage wells in the county. Most of the
ground water used in Orange County is pumped within this area,
and during the drought pumping rates were far above normal.
The well fields of Orlando and Winter Park are within the
20-foot line (See fig. 2.), but the decline from 1960 and 1962 near
the well fields was about the same as it was in the area between
Lake Apopka and Orlando where there was relatively little pumping.
Most of the decline during this period was probably due to
abnormally high-water levels at the start caused by abnormal
recharge followed by abnormally low recharge during the drought.
This indicates that withdrawal in 1963 (See Water Use section.)


111






REPORT OF INVESTIGATIONS No. 50


caused only a relatively small decline in water levels. Most of the
- fluctuations shown by the hydrograph on figure 53 are caused by
variations in recharge; however, as pumpage increases in the
future, continuing decline of average water levels near the centers
of heavy pumping can be expected.
Before man began to withdraw and inject water, the artesian
aquifer was in hydrologic equilibrium; that is, over climatic cycles
the amount of discharge from the aquifer equalled the recharge.
The average slope of the piezometric surface adjusted to the
average discharge and the average recharge. Withdrawal of water
by wells is a new discharge from the system which must be
balanced by a reduction in natural discharge, an increased recharge
or a combination of the two if a new equilibrium is to be reached.
To reduce natural discharge, the slope of the piezometric surface
between the area of pumping and the area of natural discharge
must be reduced so that less water flows to the discharge points.
When piezometric levels are lowered in recharge areas, the head
difference between the water table and the artesian aquifer is
increased which tends to cause an increased rate of recharge,
thereby salvaging water that would normally flow off in streams
or be lost to evapotranspiration. Thus, it is obvious that some
lowering of the average piezometric levels is necessary if water
is used. '
If pumping rates are stabilized, the piezometric surface
eventually will stabilize at a new equilibrium slope-providing the
average pumpage does not exceed the reduction in natural discharge
and the increase in recharge. A continued increase in pumping will
will result in a continued lowering of average piezometris level.

RECHARGE AREAS

Most of the recharge to the Floridan aquifer in Orange County
is from infiltration of rain through the relatively thin,
semipermeable confining beds in the highlands section and through
the more than 300 drainage wells in the county. A lesser quantity
enters the county by underground flow from southern Lake County
and a small amount enters from Osceola County. A knowledge
of the areas where rainfall can recharge the Floridan aquifer
is necessary if development of Orange County is to be planned to
protect the future water supplies of the area. Several methods can
be used to delineate these areas. One method is by analysis of
hydrologic and geologic data. Figure 54 shows the limits of the


112

























































SOSCEOLA






L. .


.........


Posm) diode. Top ,o.iotm- ndaovles imri'0'05
WAY-ence of rtwiofp'1 i;nchos from Monsm
a= s LUtwpwed j to imvtf Aram Ale FmY1Cv~h holfhee
75 b. hos o flonom mnber indicavts oavvo
".Ofi f. naIw. 160-963
COUNTY
NT i


BOGGY


C) 4 2 5 4 5 1 a 9 9 0 IOnitrs


40 i.,_ i 0 __ 25' 2_ 10 05, L i00' 55' 80050'
-?4' -' -i^' 40 35 30 25 20 15' 10' 05' 8100' 55' 80050'


Fii.-uro 5-1. I:tvhargot ttrrowst to tht' Floricltn aquiftr in Orangc CouMty nld s c'cted nadjancnt. arons, Florida.


/
E7
F7


Apopko


ECCON


_ ---


EXPLANATION

Rechorfe ci riloted to soil lypos
IVet) ,f~Y ,eC/%hrg. Ares domNotd by poo),'
tcid ety podly dronand sois
ito' ,rcharve Areasos dvnnoad by pocvly
dfoned sods
Aodriole ,chorg. ,Areos Airmn,,kd t,) mode-
froody 1kolned SOds
Gdv, recharge. Aores dworimald by mICMsswe/y
well *aia'd sois

Cliali of aryvorph'ro/ly closed ryes


C
^-.... ~;
c p


I AKFI


TV


)l c


fQ






WATER RESOURCES OF ORANGE COUNTY


area-based on the configuration of the piezometric surface shown
in figure 45-that might contribute recharge to the Floridan
aquifer in Orange County.
Water level records of lakes, the nonartesian aquifer, and the
Floridan aquifer show that lake levels and the water table are
above the piezometric surface in most of Orange County (figs. 50
and 51) and rain will infiltrate and recharge the Floridan aquifer
in most parts of the county if the confining bed overlying the
aquifer is not impermeable. A study of the geologic logs of wells
shows that the confining bed generally is much thinner and more
permeable in the rolling highlands in the western part of the area
than it is in the rest of the county (figs. 8, 6, and 89); therefore,
rain can infiltrate to the Floridan aquifer much more easily in the
highlands than in the lowlands.
Analysis of the hydrographs of wells in the Floridan aquifer
(figs. 87, 41, 52, and 53) and rainfall records show that the water
levels in wells in the highlands respond to rainfall much more
rapidly and with much greater magnitude than do wells in the rest
of the county. This indicates that much more recharge is entering
the Floridan aquifer in the highlands than elsewhere.
Another method of delineating recharge areas is by analysis
of the mineral content of water from the aquifer. In general, water
in recharge areas is less mineralized than in other areas.
Therefore, if allowance is made for the varying solubilities of the
materials in and above the aquifer and if there is no outside
contamination, the less the mineralization of the water the closer
it is to recharge areas. Figure 55 shows the dissolved solids in
water in the aquifer in Orange County. The values when analyzed
in conjunction with the piezometric maps indicate that there is an
effective recharge area in and near western Orange County.
A third method of evaluating recharge areas is by computing
the quantity of water which enters and leaves an area by
underground flow. The difference between the two is the net
recharge within the area. The net recharge plus any discharge
(pumpage, spring flow or natural seepage) is the recharge within
the area. The net recharge (outflow minus inflow) within Orange
County was calculated to be an average rate of about 85 mgd in
1961. Pumpage was about 65 mgd, spring flow and seepage were
estimated to be 110 mgd; therefore, total recharge was about 210
mgd. The weakness of this method is that the transmissibility
(T) of the aquifer may not be uniform and the T values used in
the computation may not be representative of the aquifer.















EXPlA-4v4 IW
l56-."-3' lK t$r 4 *Sr%( J UiMl a MIS 54f i 'L


NOLE


C 0 U F T Y

c 0 U Y


f I I f' -, ,f II' ', t t 1 r r I 6k r P I I I I
N r 20 6 6 o2 9W0
0-1. 2 3 4 .- 8 s 0 J ,m


Figure 55. Dissolved solids in water from wells that penetrate the Floridan
aquifer, Orange County. Florida.






WATER RESOURCES OF ORANGE COUNTY


However, the relation between inflow, outflow, and recharge within
the county are probably reasonably accurate. These relations
indicate that about 93 percent of the water flowing through the
county originates within the county.
A fourth method is to compute the surface runoff by sub-basins
within the county. Rainfall, which is the only natural source of
recharge, must move in one of three directions: (1) upward by
evaporation or transpiration; (2) laterally through streams,
canals, or pipes; or (3) downward by infiltration through a
permeable soil. The water that moves downward must eventually
move horizontally through the water-bearing material to points
of discharge. An examination of the topography and stream-flow
pattern of a region shows whether the water that enters the
ground seeps into nearby streams from the nonartesian aquifer,
or infiltrates to the artesian aquifer. Average rainfall is reasonably
uniform throughout central Florida, therefore, a basin with a low
rate of surface runoff must contribute more ground-water recharge
per square mile than an area with a higher rate of surface runoff-
providing evaporation and transpiration losses are uniform.
Figure 54 shows the average runoff from stream basins in
Orange County for the period 1960 through 1963 and the deficiency
of runoff in relation to runoff in the Econlockhatchee basin. The
average runoff from the basins in the western part of the county
is from 8.1 to 11.9 inches less than the runoff from the
Econlockhatchee River basin in the eastern part where an
examination of the geology and hydrology indicates that relatively
little recharge to the artesian aquifer can occur.
A single stream basin may contain different types of terrain
that vary widely in their ability to recharge the aquifer; therefore,
the average rate of runoff from the basin may not give a true
picture of the recharge in different parts of the basin. For
example, the Wekiva River basin contains areas from which no
surface runoff occurs and all water that is not evaporated or
transpired recharges the aquifer. The basin also contains areas
where no recharge can occur because the piezometric surface is
above the land surface and all water that is not evapo-transpired
runs off in streams.
To help define the areas within the basins that are most
effective in providing recharge to the aquifer, use was made of
the general soils maps of Orange and Lake counties. The soils in
central Florida are classified into four general groups based on
their surficial drainage characteristics. Group I comprises areas


115






REPORT OF INVESTIGATIONS NO. 50


dominated by well to excessively well-drained soils; Group II, areas
dominated by moderately well-drained soils; Group III, areas
dominated by somewhat poorly drained soils; and Group IV, areas
dominated by poorly to very poorly drained soils.
Because water that drains downward from the surficial soil
must go either into the underlying artesian aquifer or seep into
nearby streams, soil types, when used in conjunction with
stream-flow patterns, give a good indication of the relative
effectiveness for recharge of the different areas. Figure 54 shows
(1) the extent of the possible recharge area for Orange County,
(2) the relative rate of stream flow by basins, (3) the relative
effectiveness of various parts of the recharge areas based on soil
types, and (4) areas from which there is no surface outflow. The
figure shows that most of the recharge to the Floridan aquifer
takes place in the highlands of western Orange County and
adjacent areas of Lake and Polk counties. Much of this highlands
area is closed basin sinkhole topography covered by thick permeable
sand that rapidly absorbs rainfall. The water in the sand can then
seep through the semi-permeable beds overlying the limestone and
recharge the aquifer. The sand hills act as temporary storage areas
that prevent surface runoff and reduce evapotranspiration. The
areas from which there is no surface runoff are outlined in Figure
54. In much of the remaining area that is dominated by
excessively well-drained soils, the surface runoff is probably very
small.
Evapotranspiration is probably actually less in the rolling
highlands than in the Econlockhatchee basin area because of the
greater average depth to the water table and the relative absence
of swamps which have very high evapotranspiration rates. No
attempts have been made to evaluate this factor; and in the above
discussion it was assumed that evapotranspiration is uniform
throughout the county.
The prime recharge areas of the Floridan aquifer in Orange
County are not sharply defined and all gradations exist between
very effective and very ineffective areas. Figure 54 is intended
to show the general area that is most effective in recharging the
Floridan aquifer. Some recharge occurs wherever the water table
is above the piezometric surface.

DISCHARGE AREAS
Discharge of ground water from the Floridan aquifer in Orange
County is by (1) outflow into northern Lake County, into Seminole


116






WATER RESOURCES OF ORANGE COUNTY


'County, and into Brevard County; (2) upward leakage into the
St. Johns marsh and Rock Springs marsh; (3) pumpage within
the county and (4) spring outflow.
Major springs that discharge ground water from Orange
County are Wekiva Springs and Rock Springs in Orange County
and Sanlando Springs in Seminole County. In addition, water
discharges from numerous smaller springs in Orange and Seminole
counties. An unknown quantity seeps upward to the water-table
aquifer in Rock Springs marsh and St. Johns marsh.

QUALITY OF WATER
The quality of water in the Floridan aquifer varies greatly
throughout the county, but varies little with time at a particular
location and depth. Exceptions to this may occur in wells that
penetrate a zone containing highly mineralized water. Heavy
pumping in such wells may result in a deterioration of quality of
water. Some of the water from wells in the Cocoa well field became
highly mineralized due to heavy pumping in 1962. The quality
of the water in the Cocoa wells is further discussed under the
section, "Salt-Water Contamination."
Geology is the major factor influencing the quality of water
in the Floridan aquifer in Orange County. The limestone that
underlies all of the county is soluble. The solubility is greatly
enhanced in the presence of carbon dioxide. The weak carbonic acid
formed when carbon dioxide dissolves in water reacts with
limestone to bring appreciable quantities of calcium bicarbonate
into solution until equilibrium is reached. Other constituents in the
limestone will also be dissolved in smaller quantities. If the
limestone is dolomitic, larger quantities of magnesium will be
dissolved. A weight ratio of calcium to magnesium in the water of
about 3 to 1 indicates that the limestone is dolomitic.
In general, the dissolved solids are less than 150 ppm in water
from the Floridan aquifer in western Orange County and exceed
2,000 ppm in water from the flowing wells along the St. Johns
River. Figure 55 shows that the dissolved solids in artesian water
increase from west to east in the county. The analytical data used
in preparing figure 55 are from typical wells penetrating the
Floridan aquifer. Most of the wells are supply wells. Some test
wells were drilled in areas where existing wells were not available,
and data from these wells were also used in preparing figure 55.
Figure 55 further illustrates that western Orange County is a
major recharge area for the Floridan aquifer. The water in the


117






REPORT OF INVESTIGATIONS No. 50


Floridan aquifer is less mineralized in western Orange County
because it has been in the aquifer a short time. As the water
moves eastward across the county, the dissolved solids gradually
increase to about 500 ppm and then increase more rapidly to
greater than 2,000 ppm, near the St. Johns River. The high mineral
content of artesian water in the eastern part of the county is
probably due in part to incomplete flushing of saline water that
entered the aquifer when the sea last covered Florida.
Dissolved hydrogen sulfide gas is present in the water
discharged by most of the wells penetrating the Floridan aquifer
in Orange County, particularly water from the flowing wells.
Hydrogen sulfide gas has a very pronounced odor and gives water
a pronounced taste. There are two possible sources of this gas in
natural water. One is the reduction of sulfates by organic material
under anaerobic (absence of oxygen) conditions, resulting in the
decomposition of metallic sulfide by free carbon dioxide. In some
cases hydrogen sulfide may be formed from the anaerobic reduction
of organic matter with which the water comes in contact. The
concentration of hydrogen sulfide in deep well water is highly
variable, ranging from traces to over 4 ppm. Hydrogen sulfide is
easily removed from water by aeration.
Figure 56 shows the hardness of water from wells that penetrate
the Floridan aquifer in Orange County. The hardness of water in
Orange County is caused almost entirely by the presence of calcium
and magnesium salts. In the western and central parts of the
county, the calcium and magnesium is combined with bicarbonate
and the hardness is designated as carbonate hardness, formerly
called temporary hardness. In eastern Orange County most of the
calcium and magnesium in water from the Floridan aquifer is
combined with chlorides and smaller amounts are combined with
sulfates and bicarbonates. Hardness in excess of that combined
with bicarbonate or carbonate is designated noncarbonate hardness,
formerly called permanent hardness. The artesian water from well
832-056-1 in eastern Orange County had a hardness of 1,010 ppm
and a noncarbonate hardness of 888 ppm which indicates that the
calcium and magnesium is combined mostly with noncarbonate
ions.
Figure 57 shows the range of chloride concentrations in water
from the Floridan aquifer. The low concentrations of chlorides in
the western and central parts of the county indicates that the sea
water and residual salts have been completely flushed from the
aquifer since this part of Florida was last covered by the sea.


118










EXPLANATION
I50-25 Numbr is hordnls in pOM-s per million


INOLE


C 0 U N T Y


150 250


oC U NTY
C 0 U N T Y


W
02




0


r

I2
03

o

03

0


zt



U


Figure 56. Hardness of water from wells that penetrate the Floridan
aquifer, Orange County, Forida.














EXPLAIATi ON




SEMI 14 OLE

OL NGE U N T Y

LIS 0 T :UNTY 1
LSS THAN 10 \



oRLANDOD
0 .25 ao c




250.*500 d
S-\\


Figure 57. Chloride concentration in water from wells that penetrate the
Floridan iiuifer, Oran e County Floidn._







WATER RESOURCES OF ORANGE COUNTY


Eastward across the county the chloride concentration increases,
which indicates incomplete flushing of the highly mineralized water
from the aquifer. Of the wells inventoried in the county, artesian
well 832-056-1 east of Christmas yielded water with the highest
concentration of chloride (1,750 ppm). Well 832-053-1 in Brevard
County yielded water with a chloride concentration of 6,200 ppm.
Sea water contains an average of about 19,100 ppm chlorides.
Table 13 gives the analyses of water from selected wells in the
Floridan aquifer in Orange County. Well 844-133-1 is in the
northwestern part of the county and well 832-056-1 is a flowing
well near the St. Johns River. Figure 58 shows the chemical
composition of water from the selected wells listed in table 13. In
figure 58 the bicarbonate is shown as carbonate. Carbonate is
present in water when the pH value exceeds 8.2. Some of the
artesian water in Orange County contains small amounts of
carbonate, but most of the alkalinity is due to bicarbonate. Figure
58 shows that the artesian water in western Orange County is
high in calcium bicarbonate whereas the highly mineralized water
in the eastern part of the county is high in sodium chloride.
Mineralization of ground water generally, but not always,
increases with depth. Figure 44 shows the relation of dissolved
solids content and hardness of ground water to depth of wells in
the Orlando area. Figure 44 shows that the water in the upper
part of the Floridan aquifer (150-400 feet) in the Orlando area is
slightly higher in mineralization than the deeper water
(1,200-1,500 feet). The water is more mineralized in the upper part
of the aquifer because the soft limestone is more soluble than the
hard dolomitic limestone at the 1,200 to 1,500 feet level. However,
the mineralization in the 400-600-foot dolomite zone is similar to
the mineralization in the 1,200-1,500-foot dolomite zone.
The average calcium to magnesium ratio in water from the
upper zone is 5.5 to 1 and the average calcium to magnesium ratio
in water from the lower zone is 4.0 to 1. The lower calcium to
magnesium ratio in the lower zone indicates that the limestone is
dolomitic. Water in contact with pure dolomite usually has a
calcium to magnesium ratio of about 3 to 1.
The water from one of the Orlando supply wells was analyzed
for minor elements and the following results were obtained:
Well: 833-122-13
Depth: 1,445 feet. Cased to: 945 feet
Diameter: 28 inches. Yield: 4,000 gpm
Temperature: 77F


121












TABLE 13. ANALYSIS OF WATER FROM SELECTED WELLS IN THE
FLORIDAN AQUIFER IN ORANGE COUNTY.
Analyses in ppm except Specific Conductance, pH, and Color

Hardness
as CaCO,

3 M 5 ~

cofl- w' w CS CL = sw,
Well No. CO:ez 3 m U 0
tion o I

844-133-1 12-19-63 126 11 0.33 20 5.8 6.0 1.1 91 4.0 5.5 0.2 0.0 99 74 0 161 8.0 5
836-128-3 9-24-62 170 7.2 .11 42 7.3 5.5 .8 154 6.8 10 .2 .0 156 135 9 280 7.4 5
826-115-1 4-14-61 435 25 .03 50 18 16 1.2 220 18 23 .5 .0 260 199 18 440 8.0 5
822-111-3 5- 3-61 476 25 .32 104 7.9 31 1.4 320 38 38 .3 .0 404 292 30 691 7.6 30
828-101-1 3-31-61 495 23 .07 51 47 64 3.0 260 82 116 .7 .0 515 320 108 916 8.1 5
"832-058-1 7- 3-57 200 19 .01 144 56 354 21 2 24 250 630 .3 1.1 1,560 590 406 2,710 7.7 10
832-056-1 12-10-63 480 14 5.3 210 116 870 33 156 492 1,650 .4 .4 3,460 1,000 872 5,790 8.0 18









WATER RESOURCES OF ORANGE COUNTY


123


100 -- -- --- --00
CI

90 ------ ----- 90



80 "~ 80


U)

o
6 I t

S60 60
)

50 -50
0 50

4) -- --
40C NaK K -- 40

Mg
o Mg- ----
L 30- ... -_ 30



20 Co 20

"i
I'


10 -- 10

SiOe /.

0 0
C-~------------------------------------------|-I1-I-U

Figure 58. Composition of mineral content of water from selected wells in
the Floridan aquifer.






REPORT OF INVESTIGATIONS No. 50


Analytical results in micrograms per liter
Aluminum 13 Germanium < .29
Beryllium < .57 Iron < .29
Bismuth < .29 Manganese < 1.4
Cadmium < 1.4 Molybdenum .54
Chromium < 1.4 Nickel .63
Cobalt < 1.4 Lead < 1.4
Copper < 1.4 Titanium < .57
Gallium < 5.7 Vanadium < .29
Zinc < 5.7

These concentrations are well within the recommended limits
set by the U. S. Public Health Service. The symbol < indicates
that the concentrations are less than the values shown which are
the lower detection limits.
The temperature of the water in the Floridan aquifer in Orange
County ranges from 71 to 77F (See fig. 59.). In general, the
temperatures of the water increase with increased depth in the
aquifer. This is probably due to the natural geothermal gradient
of the earth.

SALT-WATER CONTAMINATION

The only known occurrence of salt-water contamination of
ground water in Orange County is in the eastern part of the county
(fig. 58). The high salt content of the water in this area is
probably due to incomplete flushing of sea water that entered the
aquifer when the ocean last covered this part of Florida, rather
than to direct encroachment from the present-day ocean. In
coastal areas where fresh water and sea water are in hydrostatic
balance with each other, the Ghyben-Herzberg ratio can be used
to calculate the approximate depth at which sea water will be
found. The Ghyben-Herzberg ratio is based on the relative weight
of fresh water and sea water (1:1.025) and indicates that 41 feet
of fresh water are required to balance 40 feet of sea water. This
means that for every foot of fresh water head above msl, there
should be at least 40 feet of fresh water below msl. Applying
this ratio in the Cocoa well field area in eastern Orange County
(fig. 5) where the average piezometric head is about 40 feet above
msl (fig. 47), there should be fresh water in the aquifer to a depth
of at least 1,600 feet below msl; yet a pilot well drilled in the area


124












EXPLANATION


S E H 0 L E


C 0 U N T y


*a *B


,a *T


C 0 U U T Y
C 0 U 14 T Y


S w '25 0 s' J20 o1 aIMO'
0 I 2 3 4 r 6 7 8 9 no Mn'l


Figure 59. Temperature of ground water in Orange County, Florida.


0 A GE
0 R A N G E






REPORT OF INVESTIGATIONS NO. 50


was in very salty water (more than 5,000 ppm chloride) at 1,200
feet below msl.
The chloride content of water from a nearby well was about
300 ppm at a depth of 600 feet. This concentration exceeds the
U. S. Public Health Department's standards for public water
supply (250 ppm chloride) and the well was destroyed. Other wells
in the well field were in fresh water to depths of 700 feet or more.
It appears that the areas of salt-water contamination are to
some degree, controlled by the permeability of the rock and the
rate at which water can move through and flush out the salty
water.
In general, salty water is found at shallower depths east of
the Cocoa well field and probably at greater depths to the west.
In the Orlando area, there is no salty water to a depth of at least
1.500 feet (the deepest known water well). It is not known where
the salty water in the aquifer wedges out between the Cocoa well
field and the City of Orlando because there are no deep wells in
this area.
When a well is pumped, water moves toward the well from all
directions. If the well casing extends into the aquifer, the water
that is slightly above the bottom of the casing can move into the
well most easily because it is assisted by gravity; however, a well
also draws water from below the bottom of the casing and to some
extent even from below the bottom of the open-hole portion of the
well. If salty water is present below the bottom of a well, pumping
may cause it to move upward and enter the well. If the well is shut
down for an extended period, the heavier salt water will slowly
settle.
The ultimate extent of the zone of influence caused by pumping
the well depends upon the rate of pumping, the permeability of
the aquifer and the recharge. The well will obtain its water from
the most readily available source; therefore, if a well is pumped
at a moderate rate, most of the water will come from the area
above or at the same altitude as the openhole part of the well.
However, if the well is pumped heavily, a larger percentage of the
water will come from below the bottom of the well. Surging action
in the aquifer also tends to increase salt water movement.
Therefore, in areas where salty water is known to exist at depth in
the aquifer, wells should be as shallow as practical and be pumped
as continuously as possible at moderate rates to minimize the
danger of salt-water encroachment. Wide spacing of wells will also


126






WATER RESOURCES OF ORANGE COUNTY


prevent the formation of deep cones of influence and retard the
upward movement of salty water.
Because the salt water in the aquifer in Orange County is
apparently residual rather than direct encroachment from the
ocean, there is a finite amount present and it is gradually being
removed by natural flow in the aquifer. The quality of the water
should improve naturally as the salty water is discharged and
replaced by fresh water from the recharge area. However,
considering the great thickness and areal extent of the aquifer, the
amount of salty water in storage, and the slow rate of movement
of the water, thousands of years may have to elapse before any
freshening is noticed. The freshening process possibly could be
speeded by putting a line of wells along the St. Johns River that
were cased deep into the lower salty zone. If these wells were
allowed to flow or were pumped, they would rmove some of the salty
water and increase the flow of fresh water from the recharge area.
However, the cost of such an operation would be high, the disposal
of the salty water would be a problem, and the rate and amount
of improvement are unknown. A comprehensive analysis of the
economics and hydrologic practicality of such a project would have
to be made.
The question, "will pumping in the eastern part of the county
increase the danger of salt-water intrusion in -the Orlando area?",
is of interest to the residents of the Orlando area. Pumping in the
eastern part of Orange County might cause an increase in the salt
content of the water in the vicinity of the pumped wells and
possibly even cause some salt-water intrusion in areas east of the
well field, but it is unlikely to adversely affect the quality of ground
water in areas to the west of the well field. The natural gradient
of the piezometric surface in Orange County is toward the east
(fig. 47) and salt water in the eastern part of the county would
have to flow up gradient to reach the Orlando area. Pumping in
the eastern part of the county increases the natural gradient and
further decreases the possibility of salt water reaching Orlando.
An exception to this would be if water levels throughout Orange
County were lowered to the extent that salt water that might be
at depth in the aquifer could move upward in response to the
Ghyben-Herzberg principal (See page 124). However, if this
should happen, the wells in the eastern part of the county would
probably become too salty for use long before the Orlando area was
affected.


127






REPORT OF INVESTIGATIONS NO. 50


DRAINAGE WELLS

HISTORY

The first drainage well in Orange County was drilled about
1904. Since that time about 400 drainage wells have been drilled
in the county. The data on 392 drainage wells will be listed in an
Information Circular in preparation (1967) that will be titled
"Water Resources Records of Orange County, Florida." Quite a
few drainage wells probably are not included because prior to
1939 it was not necessary to obtain a permit to install such wells;
and even after 1939, a number of wells probably were installed
without permits. No public record has been kept of many drainage
wells. The most active year for drilling of drainage wells was 1960
when about 35 wells were constructed.

POLLUTION

The possibilities of pollution of ground-water supplies by
drainage wells was described in detail by Unklesbay (1944) and
by Telfair (1948). Unklesbay states (Ibid p. 25), "water which
drains from roadside ditches or street gutters, and especially that
discharged from septic tanks, is almost certain to be polluted, and
the freedom of circulation allowed by cavernous limestone may
permit such waters to enter supply wells without being subject to
filtration." Telfair (p. 8-9) shows that in a test at Live Oak, where
the limestone aquifer is similar to that in Orange County, salt
put in a well was detected in an observation well 600 feet away 15
minutes later. Thus, water can move through the aquifer at speeds
of at least 40 feet per minute if hydrologic conditions are favorable.
Under natural conditions, ground water moves very slowly-
usually less than a few feet a day. However, when the natural
conditions are altered, as occurs when drainage from a well builds
up a local mound and pumping from a nearby supply well creates
a cone of depression, the gradient between the two wells is greatly
steepened so that in cavernous limestone, water moves rapidly
from a drainage well to a supply well.
The quality of the water flowing down drainage wells in Orange
County varies from practically pure rain water to highly polluted
water. An example of polluted water entering the aquifer is a
drainage well (826-125-1) that receives water used to flush cow
barns at a dairy as well as surface drainage. The water entering


128






WATER RESOURCES OF ORANGE COUNTY


this 142-feet deep well carries appreciable quantities of cow
manure. On January 8, 1964, the water draining into the well had
the following concentrations in ppm: sodium, 58; potassium, 54;
chlorides, 64; fluorides, 3.8; and phosphates, 34. All of these
concentrations are much higher than the natural water of the area.
Water from a 289-foot deep well (836-125-2) which is 1,000 feet
downgradient from well 836-125-1 had the following mineral
concentrations in ppm on March 16, 1964: sodium, 15; chlorides, 13;
and fluorides, 0.6. These concentrations are abnormally high for
the area and indicate that polluted water from the drainage well
is probably entering the supply well. Another drainage well near
Winter Garden (833-134-2) receives water from tile drains that
underlie a citrus grove. On January 8, 1964 the water entering this
well had the following concentrations of mineral constituents in
ppm: sodium, 15; potassium, 15; sulfate, 156; chloride, 48; fluoride,
2.0; and nitrates 104. All of these concentrations are much higher
than the concentrations in the natural water in the area. The
higher than normal concentrations of potassium and nitrates
definitely indicate pollution from fertilizer.
General areas where bacterially polluted water has been found
in some wells by the Orange County Health Department are shown
in figure 60. Most wells in the indicated areas are probably not
polluted but the map shows areas where pollution is more prevalent
than in other areas of the county. Orange County Health
Department records show that in the 5-year period 1959-1964
approximately 50 wells showed evidence of bacterial pollution. The
indicator bacteria are not harmful but indicate that harmful
organisms could be present. It is probable that many private wells
have at some time contained polluted water, but it was not
discovered because samples were not taken for bacterial analyses.
A salt test similar to the Live Oak test was made in Orange
County in March 1961 by the Orange County Health Department.
A drainage well located in the northwestern corner of Lake Pleasant
in the northwestern part of Orange County was suspected of
causing pollution in nearby supply wells. Within a few hours after
water from the lake was allowed to drain into the well on September
24, 1960, water from supply wells in the area became polluted.
Water pumped from the Northcrest Public Supply well which is
located 1,000 feet to the northwest and cased 60 feet deeper than
the bottom of the drainage well suddenly became muddy, high in
bacteria count, and had an unpleasant taste and odor. The pollution
cleared up after the drainage well was shut down and returned


129















EXPLANATION
O
krlls 0! pollvlon


INOLE


C O U N T Y


0 R A N G E


0 U NTY


0 I 2 3 4 5 6 7 8 9 10 miles


Figure 60. General areas where bacterially polluted water has been reported
from some wells, Orange County, Floriida. (Aftovr ,n ethlisRh'e mnn






WATER RESOURCES OF ORANGE COUNTY


when the drainage well was operated again. It seemed almost
certain that the drainage well was the source of contamination, but
the Orange County Health Department decided to make a more
exhaustive check.
Background data were collected for several months on the
natural chloride (salt) content of five supply wells located from 100
to 1,000 feet from the drainage well (fig. 61). The background
chloride content ranged from 9 to 12 ppm. On March 13, 1961,
500 pounds of common salt was put into the drainage well and
water samples were taken at intervals from the supply wells.
When the Northcrest supply well, 1,000 feet from the drainage


Figure 61. Location of wells used in salt test in Lake Pleasant area.


131





REPORT OF INVESTIGATIONS NO. 50


well, was sampled 20 minutes and 150 minutes after the salt was
put in the drainage well, no rise in chloride content was noted.
However, the chloride content of the water in the Northcrest supply
well rose sharply (from 12 ppm to 47 ppm) when the well was sam-
pled 18 hours after the salt was put into the well. The salty water
reached the supply well sometime between the 21/2 hour and the 18
hour sample collections. Water was not injected into the drainage
well during the test and this may have somewhat delayed the
dispersal of the injected salt. The other supply wells which were
closer to the drainage well but shallower than the Northcrest well
and which were pumped at a lower rate showed rises in their
chloride content at times ranging from /:. hour to 26 hours after
the salt was put into the drainage well.
Some of the major factors which control the rate of movement
of water from a drainage well to a supply well are:
1. The distance between wells.
2. Rate of flow down the drainage well.
3. Pumpage rate of supply wells.
4. Relative depth intervals of the open-hole part of the two
wells.
5. Permeability of the material between the two wells.
6. Relative orientation of the two wells.
The limestone underlying Orange County is like a huge sponge
with large and small cavities and channels interconnected both
horizontally and vertically. Little is known of the maximum
horizontal extent of the channels in the rock, but it is possible that
some may extend thousands of feet-perhaps even for miles.
Therefore, one supply well a considerable distance from a drainage
well may be polluted while another well, much closer but with a
poorer hydraulic connection to the drainage well, may be
uncontaminated.
Drainage wells expose a large part of the artesian aquifer to
radioactive contamination in the event of a nuclear attack. In its
natural state, the artesian aquifer is protected from radioactive
fallout by the overlying clayey sand which would filter out any
fallout. However, rain water would wash the fallout from roofs
and streets and carry it down drainage wells. Radioactive material
so distributed throughout a large part of the aquifer would cause
contamination that might last for many years.
Water running down drainage wells often carries large
quantities of air into the aquifer. This air sometimes blows back
through the drainage well causing the well to spout and sometimes






WATER RESOURCES OF ORANGE COUNTY


migrates to supply wells causing them to lose prime or to cease
production.

OTHER ASPECTS OF DRAINAGE WELLS

An aspect of drainage wells that must be considered in any
longrange appraisal is accelerated solution of the limestone that
forms the aquifer. Solution of limestone is largely controlled by
the amount of carbon dioxide dissolved in the water. When water
filters slowly through the semipermeable beds overlying the
limestone, some carbon dioxide escapes and some reacts with shell
contained in the sandy clay. Therefore, the strength of the carbonic
acid solution entering the limestone is reduced. Also the recharge
is distributed fairly uniformly over a wide area. Drainage wells,
however, deliver large quantities of water with a relatively high
carbon dioxide content to a small area. Therefore, solution of the
limestone is accelerated in the vicinity of drainage wells.
Solution of limestone is a process which is going on all the
time and collapse of the surface material (sinkhole formation) is
a natural phenomenon. Under natural conditions the chances of a
sinkhole forming under a building are very small considering the
very small percentage of the county which is covered by buildings
and the small number of new sinkholes formed each year. However,
because drainage wells are concentrated in urban areas and speed
up the process of solution, they increase the possibility of buildings
being damaged by sinkhole formations.
Sinkholes are generally caused by solution and collapse of
limestone in the upper part of the aquifer; therefore, drainage
wells which are cased several hundred feet into the limestone
would probably not appreciably increase the danger of sinkhole
formation. However, most drainage wells in Orange County are
cased only to the top of the limestone.
Old drainage wells and old abandoned wells in general are a
danger in another way. The water table is above the artesian
pressure surface in most of the county and if corrosion creates
holes in the casings below the water table, nonartesian water can
run into the well. This running water may carry surface sand down
the well and out into solution channels in the limestone and
eventually cause surface subsidence or collapse even though there
is no collapse of the limestone. The danger of such subsidence
will increase with time; therefore, wells should be inspected
periodically to be certain their casings are sound. Abandoned wells


133






REPORT OF INVESTIGATIONS NO. 50


should be completely filled with cement or other fill. They should
never be plugged at the top and covered over because their location
may be forgotten and buildings constructed at the site with the
possibility that ground subsidence at sometime in the future may
cause appreciable damage and even loss of life.

PUMPING TESTS
The ability of an aquifer to transmit water is expressed by the
coefficient of transmissibility (T), defined as the quantity of water,
in gpd, that will move through a vertical section of the aquifer
1-foot wide and extending the full saturated height of the aquifer,
under a unit hydrologic gradient at the prevailing temperature of
the water (Theis, 1938, p. 892). The capacity of the aquifer to
store water is expressed by the coefficient of storage (S), defined
as the volume of water released from or taken into storage per unit
surface area of the aquifer per unit change in head normal to that
surface. The leakage coefficient (P/m) is a measure of the ability
of the confining beds above and below the aquifer to transmit
water to the main producing zone. It is defined as the quantity of
water that moves through a unit area of the confining bed with a
head difference across the bed of unity.
The above aquifer coefficients can be determined by analyzing
the changes in water levels in observation wells at known distances
from a well pumped at a constant rate.
Four pumping tests to determine the coefficients of the Floridan
aquifer were made in Orange County (See fig. 2). Three of these
tests were of wells in the upper zone of the aquifer and one was in
the lower zone. In each case background data were collected before
and after the tests to eliminate extraneous effects, such as natural
fluctuation, from the drawdown curves.
The corrected drawdown data (s) were plotted versus time since
pumping began (t), divided by the square of the distance from the
pumped well to the observation well (r) (s versus t/r2). The
resulting curves were analyzed through use of a family of leaky
aquifer type curves developed by Cooper (1963). This family of
curves is based on the equation for nonsteady flow in an infinite
leaky aquifer developed by Hantush and Jacobs (1955, p. 95-100)
and described by Hantush (1956, p. 702-714). The equation assumes
a permeable bed overlain by less permeable beds through which
water, under constant head, can infiltrate to the aquifer. The
equation also assumes that the aquifer is homogeneous and
isotropic; that water flow is laminar, and that the wells are open


134






WATER RESOURCES OF ORANGE COUNTY


to the entire thickness of the aquifer. The transmissibility and
storage coefficients obtained by the leaky aquifer method apply to
the main producing zone, and the leakage coefficient applies to the
less permeable overlying beds.
Test 1 was made in the eastern part of the City of Orlando on
February 17, 1961, with the cooperation of the Orlando Department
of Water and Sewers. A 12-inch drainage well (831-122-4) on Lake
Davis was pumped for 11 hours at 1,100 gpm and the resulting
decline in water levels (drawdown) was recorded in four nearby
wells. The water was discharged into Lake Davis and did not
appreciably change the surface hydrologic conditions. Irregular
discharge from supply wells and irregular recharge through other
drainage wells in the city made it difficult to delineate the effects
from the drawdown curves caused by pumping the test well. This
may account in part for the wide range in the values of the
coefficients in Test 1 (table 14). Some of the variation in coefficients
may be caused by different well depths and casing depths; but the
principal cause of the wide value range in coefficients is probably
the non-homogeneous and anisotropic character of the limestone
aquifer.
Test 2 was made in October 15-16, 1962 at Long Lake, about 6
miles northwest of Orlando. A 20-inch drainage well (836-128-1)
was pumped for 24 hours at 1,535 gpm and drawdown was recorded
in two nearby wells. The values of the aquifer coefficients as
determined from the more distant observation well (471 feet) were
in reasonable agreement with the values determined from other
tests in the upper zone of the aquifer; but the transmissibility value
from the well near to the pumping well (63 feet) was much lower.
The cause of the difference is problematical, but it may be due
partly to a direct underground connection between the pumped
well and the nearer observation well and partly to the large
quantity of sand that fills the solution channels in some parts of
the aquifer. The direct connection between the wells was discovered
when the turbine pump column was installed in the 20-inch well.
As each section was lowered into the well, it caused a surge of
about 2 inches in the observation well. The sand in the aquifer was
discovered during the drilling of the more distant observation well.
The sand probably restricted the flow of water from some directions
and the channelization enabled a higher than normal percentage
of the water to flow from the vicinity of the nearby observation
well. This probably caused an abnormal drawdown pattern in the
nearby observation well. As in test 1, the non-homogeneous and


135






TAIILE 14. IIESULTS OF IL'M'ING TESTS IN ORANGE COUNTY.


Distance to
observation Pumping Transmissi- Leakage
well rate ability (gpd)
(ft.) (gpm) (gpd 'ft.) Storage (ft -/)

Test No. 1
0 1,100 ..... .......
750 455,000 .00071 0.131
950 440,000 .00310 .312
1,900 745,000 .00083 .074
3,900 745,000 .00083 .049
Test No. 2


Well
number

831-122-4
831-122-15
831-121-6
831-121-7
831-122-18


836-128-1
836-128-2

836-128-3


825-107-3
825-1074

825-108-1

825-109-1



832-120-13
832-120-14


Depth
of
well
(ft.)

364
350
335
428
435


387
320

365


509
515

761

300



1,247
1,240


Casing
depth
(ft.)

77
88
115
315
114


147
123

153


244
335

252

226



1,063
1,053


130,000

412,000
Test No. 3


350,000

550,000

545,000


Test No. 4


4,300,000


.00116

.00067



.00007

.3017

.00063




.00000007


0.317

.074



0.002

.001

.004




.00009


Maxi-
mum
draw-
down
(ft.)

3.30
2.90
.66
.26
.14


7.50
6.30

1.28


19.50
6.52

1.77

.30




.10


Test
dura-
tion
(hrs.)

11
11
11
11
11


24
24

24


30
30

30

30



10
10


Remarks

Pumped well







SPumped well
Surged for 2
min.



SPumped well
Surged for 1
min.
DD in first 15
see.
DD started at 3
hrs.


Pumped well
Surged 20 min.


0
63

471


0
129

2,400

11,300


0
900


1,535





2,100









3,200


F I I -






WATER RESOURCES OF ORANGE COUNTY


anisotropic character of the aquifer plus possible turbulent,
non-radial flow made analysis of the data uncertain.
Test 3 was made in the City of Cocoa well field in eastern
Orange County on January 3-4, 1963. One of the Cocoa supply wells
(825-107-3) was pumped for 30 hours at 2,100 gpm and drawdown
was recorded in three nearby wells. The values of the
transmissibility and storage coefficients derived from the
observation well nearest (129 feet) to the pumping well were
appreciably lower than the values for the more distant wells
(2,400 and 11,000 feet). As in test 2, solution channels in the
limestone aquifer may have caused abnormal drawdown patterns
in the closer wells. This explanation is supported by the fact that-
the water level in the nearest observation well surged for about a
minute after pumping started. The aquifer coefficients determined
from the more distant wells are probably more representative of
the aquifer in eastern Orange County.
The average coefficient of transmissibility from the nine
determinations made in the upper zone of the Floridan aquifer in
Orange County is 485,000 gpd/ft. All determinations but one-
well 836-128-2 in test 2-are within about 50 percent of the average
figure; and a general transmissibility coefficient of about 500,000
gpd/ft seems reasonable for the upper zone of the aquifer. The
average coefficient of storage is .0016. The range of values for
he coefficient of storage is much greater than the range of values
for the coefficient of transmissibility and the storage coefficient
value is probably less reliable.
The leakage coefficient, which is the ability of the beds
overlying the aquifer to transmit water, has a wide range; but
the values for tests 1 and 2 are consistently greater than the values
for test 3. The average leakage coefficient for tests 1 and 2 is 0.16
gpd/ft2/ft' while the average for test 3 is only 0.0024
gpd/ft/ft'. These data support other evidence that indicates that
test sites 1 and 2 are in the most effective part of the recharge
area while test site 3 is in a relatively ineffective part (See Floridan
aquifer-areas of recharge).
The fourth test of the Floridan aquifer was made in the City of
Orlando on March 13-14, 1964. This test was made in the lower
zone of the Floridan aquifer with the upper zones cased off. A
supply well of the City of Orlando (832-120-12) was pumped at a
rate of 3,200 gpm for 101/ hours and drawdown was recorded in
a well 900 feet away (832-120-14). The observation well surged
for about 20 minutes after the supply well was turned on, and the


137






REPORT OF INVESTIGATIONS NO. 50


total drawdown was only about 1 inch. This probably indicates a
very cavernous spongelike formation with solution channels
forming an interconnected system. The cavernous nature of the
lower zone of the Floridan aquifer is shown also on the logs of
wells drilled into it. Only one observation well was available,
therefore the coefficients computed from well 832-120-14 could not
be checked to determine if they are representative of the aquifer
in the area of influence of the pumped well.
The record of test 4 was difficult to analyze because of the small
drawdown, the surging of the well, and the relatively large amount
of extraneous influence on the water level in the observation well.
However, the coefficient of transmissibility of 4.3 million gpd/ft
probably is of the correct order of magnitude. Similar results were
obtained in a similar test made by Mr. Charles Black of Black and
Associates, consulting engineers, Gainesville, on two other wells
cased into the lower zone of the Floridan aquifer in Orlando (oral
communication, 1962).
Thus, the lower zone of the aquifer in the Orlando area appears
to have about 8 times the water transmitting capability of the
upper zone. A transmissibility of 500,000 gpd/ft indicates a very
productive aquifer. The transmissibility of over 4 million shows
the aquifer to be one of the most productive in the country.
The principal difficulty in determining aquifer coefficients in
Orange County is that the Floridan aquifer is not homogenous and
isotropic as assumed in the mathematical model aquifer. Also there
are no wells in the area that are open to most of 2,000 feet of the
aquifer. Therefore, the coefficients in table 14 are at best
approximations of the characteristics of different sections of the
aquifer. Flow net analyses using the discharge of springs in the
county and also using pumping rates in the Cocoa well field indicate
transmissibility values of about 2 million gal/day/ft. This value
may be more representative of the average T of the Floridan
aquifer in Orange County than is table 14.
When a well in the lower zone of the Floridan aquifer is pumped,
the cone of influence spreads very rapidly for a.distance of several
miles. The pumping records of two wells in the Primrose plant in
Orlando (832-120-3 and 832-121-20) were compared with the
recorder chart from an observation well (833-120-3), 1.4 miles
from the Primrose plant for a period of one month. Small, but very
sharp and distinct, changes in water level in the observation well
were detected each time one or both of the supply wells were turned
on or off. (See fig. 42). Because the wells draw water from a large


138






WATER RESOURCES OF ORANGE COUNTY


area and are locally recharged, the water levels reach equilibrium
quickly. Most of the drawdown in the vicinity of the pumping well
occurs within the first 15 minutes after pumping begins.

WATER USE
Water use in Orange County has increased greatly in the past
and is expected to continue to increase in the future (fig. 62). In
1963 all municipal, domestic, and industrial supplies (except
cooling) and nearly half the agricultural supplies of water were
obtained from wells. Most surface-water supplies were obtained
from the many lakes in the county. Streams were rarely used
because they usually go dry during droughts. Lake water was used
mostly for agriculture, cooling, and recreation.
Some of the figures of water use for 1963 given in this report
are considerably below the estimates for 1960 given in the Interim
Report (Lichtler, Anderson, and Joyner, 1963, p. 45). The decrease
is undoubtedly due to a refining of the estimates rather than an
actual decrease. The use of water in 1963 was probably somewhat
greater than in 1960.

GROUND WATER
Pumpage of ground water in Orange County is estimated to
have averaged about 60 mgd in 1963. Of this total, about 39 mgd
was pumped by municipal water systems. The largest user of
ground water in. Orange County is the Orlando Utilities
Commission which delivered an average of about 22 mgd in 1963
to users in and around Orlando. The city supplied water at a rate
of about 1 mgd to the Martin Company which develops and
manufactures missiles.
The City of Cocoa pumped an average of about 9.5 mgd from
its well field in eastern Orange County in 1963. This well field
supplies water to Cape Kennedy and Patrick Air Force Base in
addition to supplying the Cities of Cocoa, Cocoa Beach, and
Rockledge.
The City of Winter Park pumped an average of about 5 mgd
in 1963, and eight other public water systems in Orange County
including the Cities of Maitland, Winter Garden, Apopka, and
Ocoee pumped a total of about 2.5 mgd.
The 79 privately-owned water systems in Orange County
pumped about 3.3 mgd in 1963.
Self-supplied industrial water in Orange County in 1963 was
determined in a study by the Florida Division of Water Resources


139






REPORT OF INVESTIGATIONS NO. 50


5

500,000

400,000

300,000

200,000

100,000


0 '
1910


1920 1930 1940 1950 1960 1970 1980


Figure 62. Changes in population and water use.

to be about 5.3 mgd. Most of this water is used in citrus processing
and packing. The self-supplied industrial use was less in 1963
than in 1960, largely because some of the citrus processing plants
which had used large quantities of water had altered their
operations so that less water was required.







WATER RESOURCES OF ORANGE COUNTY


No survey of individually-supplied domestic water use in
Orange County was made because of the time that would be in-
volved and the fact that very few of these wells have meters or any
means of determining how much water is used. Individual water
use was determined by multiplying the population so supplied
(66,000) by the per capital domestic use of 100 gallons per person
per day as determined in areas supplied by public water systems.
Total individual domestic use in Orange County is estimated to be
about 6.6 mgd.
Treatment of ground water for public use consists of
chlorination for sterilization or chlorination plus aeration to
remove hydrogen sulfide gas from the water.
Agricultural use of ground water in Orange County in 1963 was
estimated to be about 5.5 mgd. Most of the agricultural use of
ground water is for the irrigation of some of the 63,000 acres of
citrus in the county. The use of ground water for irrigation of
citrus is increasing rapidly and this trend is expected to continue.
Recent studies by the Citrus Research Institute at Lake Alfred
have shown that irrigation can increase citrus yield by 25 percent
or more, and the percentage of groves that are irrigated is
increasing. Most lakes that are practical sources of irrigation
water are in use; therefore, most new irrigation supplies must be
obtained from-wells. Some groves that were formerly irrigated
from lakes are now irrigated from wells because residents on the
lakes objected to water being withdrawn from the lakes during
droughts when the lake levels were already low.
Another factor tending to shift irrigational use from lake water
to well water is the increasing use of permanent overhead
sprinkler-type irrigation systems as opposed to portable perforated
pipe systems. In general, there is less clogging of the sprinkler
heads from well water than from lake water unless the lake is
exceptionally clean.
Permanent sprinkler systems are more expensive to install than
portable systems; however, the lower cost of operation (mostly
labor) usually makes the permanent-type systems less expensive
in the long run. Another advantage of permanent-type systems is
that the water can be applied when it is needed, whereas labor for
portable irrigation systems is not always available when it is
needed most. Because permanent irrigation systems are relatively
simple and inexpensive to operate once they are installed, they are
used more frequently. This will probably increase the quantity of
water used for irrigation.


141






REPORT OF INVESTIGATIONS NO. 50


Owners, managers, and caretakers in charge of a total of about
39,000 acres of citrus trees in Orange County (62 per cent of the
acreage in the county) were asked about their irrigation practices.
They reported that about 14,000 acres (36 percent of the acres
inventoried) were irrigated in 1963 with an average of about 6
inches of water per year. About 45 percent of the water used came
from wells, the remainder coming from lakes. Assuming that
irrigation practices on the 24,000 acres of citrus groves not
inventoried are similar to the practices on the 39,000 acres
inventoried, water use in citrus irrigation in Orange County in 1963
averaged about 10 mgd or about 11,000 acre feet per year.
An estimated 1 mgd of ground water was used in 1963 to
irrigate approximately 1,500 acres of pasture in Orange County.

SURFACE WATER
Use of surface water for irrigation of citrus groves in Orange
County was reported to have averaged about 5.5 mgd in 1963. An
additional amount was used from Lake Apopka to irrigate about
6,000 acres of row crops in the Zellwood muckland truck farming
area. No accurate figures are available on the amount of water
used because the water enters by gravity flow through a number
of individually-controlled pipes in the levee that separates the
farming lands from Lake Apopka. A rough estimate of water use
in the Zellwood area, based on normal water use of plants, is
between 5 and 10 mgd. However, Mr. Hodges, manager of the
Zellwood Drainage and Water Control District, reported (oral
communication, October 1962) that, on the average, more water
was pumped from the District into Lake Apopka than flowed into
the District from the lake. This is probably because of seepage of
ground water into the District from the surrounding sand hills and
Lake Apopka and the absence of downward leakage of rain water
within the District, because the piezometric surface is near or
above the land surface.
An average of about 110 mgd of surface water is used in cooling
the electric generators in the Orlando Utilities power plant in
Orlando. This water is pumped from Lake Highlands and
discharged into Lake Concord from which it flows into Lake
Ivanhoe and then back into Lake Highland. Because of this
circulation, little of the cooling water is consumed, and the only
effect is a slight rise in the water temperature of the lakes involved.
The Orlando plant was put on stand-by status in 1964 and is only
used during peakload times and during emergencies.


142







WATER RESOURCES OF ORANGE COUNTY


The most extensive use of surface water is for recreation.
Fishing, boating, swimming, and water skiing are all popular
sports in Orange County. The aesthetic value of lakes is difficult
to evaluate; but lakes certainly have contributed much to the City
of Orlando's reputation as "The City Beautiful." The 1,100 lakes
and ponds in Orange County also moderate the air temperature in
surrounding areas by releasing heat during cold weather and
absorbing heat during hot weather.

SUMMARY

Large quantities of potabje ,wajer are available from the
artesian (Floridan) aquifer in' all parts of Orange County except
in the extreme eastern part near the St. Johns River, where the
water is too mineralized for most purposes.
The maximum sustained rate at which water can be withdrawn
from the Floridan aquifer is not accurately known at present
(1964). However, the information currently available indicates
that, in most parts of the county, water can be withdrawn at a
rate at least several times the present rate without seriously
depleting the water resources of the county. Lesser quantities of
water are available in the surficial sand that forms the nonartesian
or water-table aquifer. In some areas moderate quantities of water
can be obtained from porous sand, gravel, or shell beds that form
secondary artesian aquifers within the confining bed that separates
the nonartesian and the Floridan aquifers.
The top of the cavernous limestone that comprises the Floridan
aquifer ranges from about 50 feet below the land surface in the
western and northwestern part of the county to about 350 feet
below the land surface in the southeastern part. The Floridan
aquifer in Orange County is known to be at least 1,400 feet thick.
Water level, chemical, and geological evidence indicate that the
aquifer is a hydrologic unit, but there are several different
permeable zones within the aquifer separated by less permeable
zones. The most productive zones in the Orlando area are dolomitic
layers-one at depths between 400 and 600 feet and the other at
depths between 1,100 and 1,500 feet. The limestone is overlain by
sand, clayey sand, and occasional lenses of relatively pure clay.
The water in the lirhestone in Orange County generally flows
northeast and eastward. The major recharge areas of the Floridan
aquifer in Orange County are the highlands in the western part
of the county and adjacent areas in Lake and Polk Counties.


143






REPORT OF INVESTIGATIONS NO. 50


The major areas of discharge of ground water are springs in
Orange and Seminole Counties, seepage into St. John River and
Wekiva marsh, and underground flow into Seminole, Lake and
Brevard Counties.
Yields of 4,000 gpm or more can be obtained from large-
diameter wells finished in the limestones almost anywhere in the
county.
The water level (piezometric surface) in wells that penetrate
the Floridan aquifer ranges from about 15 feet above the land
surface in low lying areas of the county to more than 100 feet
below the tops of some sand hills in the rolling highlands. In the
Orlando area, the piezometric surface fluctuates as much as 20 to
25 feet from extreme wet to extreme dry periods partly because of
the variation in recharge from numerous drainage wells. In
outlying areas of the county the level fluctuates only about 5 to
10 feet.
The dissolved solids in the water of the Floridan aquifer are
less than 150 ppm in the western part of the county, 150 to 300
ppm in the central part of the county, 300 to 2,000 ppm in most
of the eastern part of the county, and over 2,000 ppm in a narrow
strip along the St. Johns River at the eastern border of the county.
The salty water in the aquifer is believed to be residual sea water
that entered the aquifer the last time Florida was under the sea
and has not been completely flushed. There is no evidence that
sea water is currently (1964) encroaching into Orange County.
The nonartesian aquifer is composed of sand generally within
40 feet of the surface. This aquifer will usually yield enough water
for domestic supplies, stock watering, and lawn irrigation. The
dissolved solids content of water from the nonartesian aquifer is
usually lower than that of the Floridan aquifer but it is often high
in color and iron content. The nonartesian aquifer is recharged by
local rainfall and discharges mostly by seepage into lakes and
streams, by downward seepage into underlying aquifers, and by
evapotranspiration.
The secondary (shallow) artesian aquifers are discontinuous
permeable beds of porous sand, gravel or shell. The yield of wells
in these aquifers varies greatly with the character of the beds-
at some sites large supplies can be developed, but usually yields are
moderate to small. The shallow artesian aquifers are recharged
by downward leakage from the water table where the water table
is above the piezometric surface and by upward leakage from the
Floridan aquifer where the piezometric surface is above the water


144







WATER RESOURCES OF ORANGE COUNTY


Stable. The chemical quality of the water in these aquifers depends
on the composition of the beds, the course taken by the water in
reaching the aquifer, and the length of time of contact.
The source of all of the surface water in Orange County is rain.
Water is stored on the surface in lakes, ponds, swamps, marshes,
and stream channels. Evapotranspiration removes about 70 percent
of the rainfall, runoff about 20 per cent, and underground outflow
probably less than 10 percent. Lakes are the most reliable sources
of surface water in Orange County. Swamps and marshes and
most of the streams go dry after only short droughts. The Wekiva
River flows at least 100 cfs at all times because of several large
contributing springs. The flow of the St. Johns River is maintained
in all but the most severe droughts but its flow declines to below
100 cfs in 40 percent of the years of record. The effluent of the
Orlando sewerage plant contributes about 11 cfs to the Little
Econlockhatchee River north of State Highway 50. All other
streams in the county either go dry or recede to extremely low
flow during dry periods.
On the average, rainfall exceeds evaporation and transpiration
from June through September; so lake levels, ground-water levels,
and streamflow tend to increase during these months. From
October through May, the reverse is true.
The average rainfall during the period of record 1935 to 1963
used in this report compares very closely with those for lake
periods since 1893 and therefore records are' probably represen-
tative of the long-term average condition and of future conditions.
- The amount of water that flows out of the county in streams is
estimated to average about 1,100 cfs (710 mgd), but it ranges from
as little as one tenth of this amount during droughts to more than
40 times this amount during floods. In addition, an average of
about 1,300 cfs (840 mgd) from sources outside the county flow
along the eastern border in the St. Johns River. Use of water was
about 22 billion gallons per year in 1963 and is expected to about
double by 1975. Ground water is used for municipal, industrial,
domestic and irrigational purposes. Surface water is used for
irrigation, cooling, and recreation.

CONCLUSIONS
The water resources of Orange County are very large and
generally are more than .adequate for the needs of the immediate
future. The most immediate water problems in Orange County are
pollution of ground-water reservoirs by drainage wells, pollution


145






REPORT OF INVESTIGATIONS NO. 50


of lakes, and damage to property by the large fluctuation in the
levels of certain lakes.
Draining excess surface water into the Floridan aquifer is
beneficial if the water is not contaminated. When properly
controlled, the practice increases recharge to the artesian aquifer,
thereby tending to maintain ground-water levels and improve the
quality of the ground water especially in the eastern part of the
county. The need to develop methods of draining surplus water
into underground storage without polluting or otherwise damaging
the ground water should receive early consideration.
The problem of stabilizing lake levels is more complex than
simply draining off water when levels are above average, because
this often results in lower than usual levels during droughts. If
abnormally low lake levels are to be avoided during droughts, water
that has been removed to prevent high levels must be replaced or
outflow from the lake must be reduced by a like amount.
Drainage of lake water to the sea during years of above average
rainfall results not only in loss of water from the lake but also loss
of ground water from the surrounding nonartesian aquifer. When
the lake level is lowered the slope of the water table is steepened
which causes more ground water to flow into the lake. Removal of
this water results in less water in storage in the nonartesian
aquifer to recharge the underlying Floridan aquifer and to
maintain lake levels during droughts.
Droughts have caused no serious problems in Orange County
in the past other than those associated with soil moisture deficiency
and adverse affects on the appearance of lakes. As the county
develops industrially, pressure to use its streams to remove wastes
may increase. Most of the streams are either dry or have only
small flow during droughts, so they cannot be used to remove
wastes without becoming excessively polluted. The base flow of
the streams can be increased by pumping water into them from
ground sources or by deepening in areas where the water table is
at or near the land surface during wet periods. However, perhaps
a better solution would be to process waste so it will not pollute the
water.
The availability of fresh water is a problem of increasing
importance as Orange County and the east-central Florida region
grow in population and industry. The amount of fresh water from
rainfall within the region is large; but except for the many lakes
in the western part of the region, suitable surface reservoirs are
scarce. Fortunately, an enormous ground-water reservoir-the


146







WATER RESOURCES OF ORANGE COUNTY 147

Floridan aquifer-underlies the area. This aquifer receives most
of its recharge in the highlands areas where the overlying materials
are thin and permeable. Extensive urban development would cover
large areas with building and pavement, thereby increasing surface
runoff and reducing recharge unless the increased runoff can
infiltrate into the soil in surrounding areas or be artificially
injected underground. Surface drainage in recharge areas can also
decrease recharge to the Floridan aquifer. Greater understanding
of the relationship between soils, streams, lakes, and ground-
water aquifers and the interchange of water between them is
needed if the effects of various existing and planned developmental
measures are to be evaluated.
The water supply of Orange County and part of the water
supplies of Seminole and Brevard counties comes from rain on or
near Orange County. Every effort should be made to retain as
much water in the area as possible even though immediate danger
of a water shortage doesn't exist.
Evaporation nearly equals average rainfall and there are nearly
twice as many years of below average as above average rainfall;
therefore, the years of above average rainfall which cause flooding
are of prime importance in recharging both surface and
ground-water reservoirs.
Flooding is a natural, though infrequent, phenomenon and areas
prone to flooding such as lake shores must be recognized if damages
are to be held to a minimum. The flood waters may some day be
vitally important to the area and their retention may necessitate
that some developments be moved. In some instances it may be
in the best interests of the area, and even less expensive, "to move
the houses away from the floods rather than move the floods away
from the houses."
Zoning laws may be used to prevent development in some areas
subject to flooding which are privately owned, and other flood
prone areas which are publicly owned can be made into parks and
recreational areas which would not be greatly harmed by
fluctuating water levels.
Artificial recharge of the Floridan aquifer in areas which are
especially absorbtive or through wells can increase water storage
and at the same time reduce peak floods in heavily developed areas.
Artificial recharge of the Floridan aquifer through wells can
be most effective in the eastern part of Orange County where the
piezometric surface is below land surface, lakes are scarce, and
natural recharge is slight. Enormous quantities of water run off







REPORT OF INVESTIGATIONS NO. 50


to the sea during wet periods, yet most streams go dry during
droughts. If holding basins can be obtained and economical water
treatment methods developed, much of this water can be stored in
the Floridan aquifer where it will tend to improve the quality of
the ground water, raise artesian water levels, and prevent
salt-water intrusion.
A detailed study and a pilot project on artificial recharge would
help to develop methods and evaluate its feasibility in insuring a
continuous adequate water supply for Orange County and the
east-central Florida region.

REFERENCES

Anderson, Warren, Lichtler, W. F., and Joyner, B. F.
1965 Control of lake levels in Orange County, Florida: Florida Geol.
Survey Inf. Circ. 47, 15 p.
Anderson, Warren, and Joyner, B. F.
1966 Availability and quality of surface water in Orange County,
Florida: Florida Geol. Survey Map Series No. 24.
Barnes, H. H., and Golden, H. G.
1966 Magnitude and frequency of floods, United States: pt. 2-B:
U. S. Geol. Survey Water-Supply Paper 1674, 409 p.
Black, A. P., and Brown, Eugene
1951 Chemical character of Florida's waters-1951: Fla. State Board
Cons., Div. Water Survey and Research Paper 6, 119 p.
Brown, D. W., Kenner, W. E., and Brown, Eugene
1957 Interim report on the water resources of Brevard County,
Florida: Florida Geol. Survey Inf. Circ. 11, 111 p.
Brown, D. W., Kenner, W. E., Crooks, J. W., and Foster, J. B.
1962 Water resources of Brevard County, Florida: Florida Geol.
Survey Rept. Inv. 28, 104 p.
Cole, W. S.
1941 Stratigraphic and palcontologic studies of wells in Florida-
No. 1: Florida Geol. Survey Bull. 19, 91 p.
1945 Stratigraphic and paleontologic studies of wells in Florida-
No. 4: Florida Geol. Survey Bull. 28, 160 p.
Collins, W. D., and Howard, C. S.
1928 Chemical character of waters in Florida: U. S. Geol. Survey
Water-Supply Paper 596-G, p. 177-233.
Cooke, C. W.
1939 Scenery of Florida interpreted by a geologist: Florida Geol.
Survey Bull. 17, 118 p.
1945 Geology of Florida: Florida Geol. Survey Bull. 29, 339 p.
Cooper, H. H., Jr.
1963 Type curves for nonsteady radial flow in an infinite leaky
artesian aquifer, in Bentall, Ray, Shortcuts and special problems
in aquifer tests: U. S. Geol. Survey Water-Supply Paper 1545-C,
p. 48-55.


148








WATER RESOURCES OF ORANGE COUNTY


Fenneman, N. M.
1988 Physiography of eastern. United States: New York, McGraw-
Hill Book Co., Inc., 714 p.
Florida State Board of Health
1961 Some physical and chemical characteristics of selected Florida
waters: June 1960, 108 p.
Gunter, Herman, and Ponton, G. M.
1931 Need for conservation and protection of our water supply, with
special reference to waters from the Ocala limestone: Florida
Geol. Survey 21st and 22d Ann. Repts., 1928-30, p. 43-55.
Hantush, M. C., and Jacob, C. E.
1955 Nonsteady radial flow in an infinite leaky aquifer: Am. Geophys.
Union Trans., v. 36, no. 1, p. 95-100.
1956 Analysis of data from pumping tests in leaky aquifers: Am.
Geophys. Union Trans., v. 37, p. 702-714.
Hem, J. D.
1959 Study and interpretation of the chemical characteristics of
natural water: U. S. Geol. Survey Water-Supply Paper 1473,
269 p.
Kenner, W. E.
1964 Maps showing depths of selected lakes in Florida: Florida Geol.
Survey Inf. Circ. 40, 84 p.
Kohler, M. A.
1954 Lake and pan evaporation in waterless investigations: Lake
Hefner Studies, Technical Report: U. S. Geol. Survey Prof.
Paper 269, p. 127-136.
Lichtler, W. F., Anderson, Warren, and Joyner, B. F.
1964 Interim Report on the water resources of Orange County,
Florida: Florida Geol. Survey Inf. Circ. 41, 50 p.
Lichtler, W. F., and Joyner, B. F. /
1966 Availability of ground water in Orange County, Florida: Florida
Geol. Survey Map Series No. 21.
MacNeil, F. S.
1950 Pleistocene shorelines in Florida and Georgia: U. S. Geol. Survey
Prof. Paper 221-F, p. 95-107.
Matson, G. C., and Sanford, Samuel
1913 Geology and ground waters of Florida: U. S. Geol. Survey
Water-Supply Paper 319, 445 p.
Meinzer, 0. E.
1923 The occurrence of ground water in the United States, with a
discussion of principles: U. S. Geol. Survey Water-Supply
Paper 489, 321 p.
Parker, G. G., Ferguson, G. E. Love, S. K., and others
1955 Water resources of southeastern Florida: U. S. Geol. Survey
Water-Supply Paper 1255, 965 p.
Powell, David P., and Lewis, Olin C.
Observation on soil and moisture relationships: U. S. Dept. of
Agriculture, Soil Conservation Service open-file rept.
Pride, R. W.
1958 Floods in Florida, magnitude and frequency: U. S. Geological
Survey open-file rept.


149







150 REPOT OF INVESTIGATIONS NO. 50

Puri, H. S. i : -:" h "
1953 Co61iwir j- o Miou of the Florida
Pa -Miidin !loi:ldsa Geol Survey Bull. 86, 345 p.
Puri, H. S., and Vernoni R. :
1964 Summwry'of:the geology of Florida and a guidebook to the
classic exposures: Florida Geol. Survey Special Publication No.
5 (revised), 255 p.
Rainwater, F. H., and Thatcher, L. L.
1960 Methods for collection and analysis of water samples: U. S.
Geol. Survey Water-Supply P'aper 1454, 301 p.
Sellards, E. H.
1908 A preliminary report on te'tindergroutnd water supply of central
Florida: Florida Geol. Survey Bull. 1, 103 p.
Sellards, E. H., and Gunter, Herman
1913 The artesian water supply of eastern and southern Florida:
Florida Geol. Survey 5th Ann. Rept., p. 103-290.
Stringfield, V. T.
1935 The piezometric surface of artesian water in the Florida
Peninsula: Am. Geophys. Union Trans., 16th Ann. Mtg., pt. 2,
p. 524-529.
1936 Artesian water in the Florida Peninsula: U. S. Geol. Survey
Water-Supply Paper 773-C, p. 115-195.
Stringfield, V. T., and Cooper, H. H., Jr.
1950 Ground water in Florida: Florida Geol. Survey Inf. Circ. 8, 6 p.
Theis, C. V.
1938 The significance and nature of the cone of depression in ground-
water bodies: Econ. Geology, v. 33, no. 8, p. 889-902.
U. S. Geological Survey
1943 Progress report on hydrologic studies of lake sources of
municipal water supplies of Orlando, Florida: Open-file rept.
1954 Water loss investigation: Lake Hefner studies, technical report:
U. S. Geological Survey Prof. Paper 269, 158 p.
U. S. Weather Bureau
1960 Climatological data, Florida, annual summary, 1960: v. 64,
no. 13.
Unklesbay, A. G.,
1944 Ground-water conditions in Orlando and vicinity, Florida: Fla.
Geol. Survey Rept. Inv. 5, 72 p.
Vernon, R. O.
1951 Geology of Citrus and Levy Counties, Florida: Fla. Geol. Survey
Bull, 33, 256 p.
Wander, I. W., and Reitz, H. J..
1951 The chemical composition of irrigation water used in Florida
citrus groves: Florida Univ. Agt. Exp. Sta. Bull. 480, 7 p.
White, W. A.
1958 Some geomorphic features of central peninsular Florida: Florida
Geol. Survey Bull. 41, 92 p.
Wilcox,
1955 lassificat~n and use of irrigation waters: U. S. Dept, of
Agriculture Circ. 969, 19 p.


";
dSSuy




Water resources of Orange County, Florida ( FGS: Report of investigations 50 )
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Permanent Link: http://ufdc.ufl.edu/UF00001237/00001
 Material Information
Title: Water resources of Orange County, Florida ( FGS: Report of investigations 50 )
Series Title: ( FGS: Report of investigations 50 )
Physical Description: ix, 150 p. : illus. , maps (part fold. col.) ; 23 cm.
Language: English
Creator: Lichtler, William F
Anderson, Warren ( joint author )
Joyner, Boyd F. ( joint author )
Geological Survey (U.S.)
Florida -- State Board of Conservation
Orange County (Fla.) -- County Commissioners
Publisher: Division of Geology
Place of Publication: Tallahassee
Publication Date: 1968
 Subjects
Subjects / Keywords: Groundwater -- Florida -- Orange County   ( lcsh )
Water-supply -- Florida -- Orange County   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by W. F. Lichtler, Warren Anderson and B. F. Joyner.
Bibliography: Bibliography: p. 148-150.
General Note: Prepared by the U.S. Geological Survey in cooperation with the Division of Geology, Florida Board of Conservation and the Board of County Commissioners of Orange County.
 Record Information
Source Institution: University of Florida
Rights Management:
The author dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law and all related or neighboring legal rights he or she had in the work, to the extent allowable by law.
Resource Identifier: aleph - 000824138
notis - AEB9333
lccn - 70629139
System ID: UF00001237:00001

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STATE OF FLORIDA
STATE BOARD OF CONSERVATION



DIVISION OF GEOLOGY
Robert O. Vernon, Director





REPORT OF INVESTIGATIONS NO. 50







WATER RESOURCES
OF
ORANGE COUNTY, FLORIDA

By
W. F. Lichtler, Warren Anderson, and B. F. Joyner
.U. S. Geological Survey


Prepared by the
UNITED STATES GEOLOGICAL-SURVEY -
in cooperation with the
DIVISION OF GEOLOGY, FLORIDA BOARD OF CONSERVATION
and the
BOARD OF COUNTY COMMISSIONERS OF ORANGE COUNTY



Tallahassee
.- 'lsOs ,




SCIENCE
LIBRARY





FLORIDA STATE BOARD
OF
CONSERVATION




CLAUDE R. KIRK, JR.
Governor


TOM ADAMS
Secretary of State



BROWARD WILLIAMS
Treasurer



FLOYD T. CHRISTIAN
Superintendent of Public Instruction


EARL FAIRCLOTH
Attorney General



FRED O. DICKINSON, JR.
Comptroller



DOYLE CONNER
Commissioner of Agriculture


W. RANDOLPH HODGES
Director


6o0

*r o*S'








LETTER OF TRANSMITTAL


STATE BOARD QF CONSERVATION
Division of Geology
Tallahassee
January 26, 1968

Governor Claude R. Kirk, Chairman
State Board of Conservation
Tallahassee, Florida

Dear Governor Kirk:

The Division of Geology of the Florida Board of Conservation
is publishing as our Report of Investigations No. 50, a study of
the water resources of Orange County, Florida, prepared by
Lichtler, Anderson and Joyner of the U. S. Geological Survey. This
report is a cooperative study between the Orange County Com-
mission, the Division of Geology, and the U. S. Geological Survey.
With the anticipated urban expansion of Orange County that
will be accompanied with the development of Disney World, the
water resources of the area must be adequate to meet the demands
of an expansion that will change a swamp to an urban area in a
space of five years. We feel that the water resources of Orange
County are adequate to meet these demands and we are proud
to be able to contribute in a substantial way to the development
of the area.
Respectfully yours,

Robert O. Vernon
Director and State Geologist
ROV:lam



















































Completed manuscript received
January 26, 1968
Printed for the Florida Board of Conservation
Division of Geology
By the E. 0. Painter Printing Company
DeLand, Florida

iv










CONTENTS

Page
Abstract ..................-- -....----.-------------.-------------------------------......--------- 1
Introduction ..-...---..---......................... ----------- ...-......-...- 2
Purpose and scope of investigation ........--..--.--.--------......-........--.....-.........-- 3
Acknowledgments ---.......-...-..-...-...----------------- ..-.--. ..-- .-----.... 3
Previous investigations ...........--...........--..------ ....--- .....-- ----- 4
Well-numbering system ........-.........---..-----....--------....--....--.-.....--....--..... 5
Description of the area --...-...--......---........----- ---------...--.-- 6
Location and extent ........................ ..... .................... ...-.......... ...--------- 6
Topography .......-.... .----------------............... .... ..------ -.....--...- 6
Climate .......-........ -------...------... --..-------..------... --- 10
Sinkholes --......----...----------.......-- ----....------------ ............... 10
Drainage ................. ........................................................... .......... ..................... 14
Geology --...--....-----------.......--.-.--.---------- ---. .---..---... 14
Form nations ............................. ............................... ................... .. 18
Structure .--........-----..-...................----------....-....-- -- -- --. -..... 22
Hydrology ..-..-.. --....----.......-...- ..-- --...... --- ------------........ -...-... .. --...... 23
Chemical quality of water .......-...........-- ..-- ...-- ..-------...-- .......-......-....... 23
Relation of quality of water to use -..------. ..---..---. .................-------- 24
Domestic use ..........---..--..--- ..-....- -------------- -----.--------- 29
Agricultural use -....... -- ------------------....................--...--- 30
Industrial use -...------........-...--- ...----------- --.... -...--...--..--.--..--..--- 32
Surface water --...............-..........---------------.... ------- --...-..-...-..--- 32
Occurrence and movement .......----..........- ------------... -- ... 32
Variation .-..................------.....----------...........-------.... ---- 33
Presentation of data ........-...---...-----------....----........----... ...... 35
Surface drainage ..---...... --.. ---.------.---------.........-- 43
Kissimmee River basin ................-------------------- ..-..-----.... 45
Reedy Creek ---..--- .--------------- ...----.....------.-----. 45
Bonnet Creek ...........-........---- ...-....-------------- ----.-----....------ 47
Cypress Creek ......-................----------------------------------- 48
Shingle Creek -....-.......-..... ...........----------------..-- ---.. ... 49
Boggy Creek -..--. -----.......---...... -...- -.. --....................------ 50
Jim Branch ---.............-..........-------------- -.....-. .....-------------.. 52
Ajay-East Tohopekaliga Canal .........-----..-..- __..--..-.----------..--- 52
St. Johns River basin .--...............---........ ----------...----------------. 53
St. Johns River .........-......... --------.............--------- 53
Small tributaries draining east ....--.....-.....--...----...-------...... 59
Lake Pickett ..-...-........---...........-----------.---------------- ---------- 61
Econlockhatchee River ....--..--....-......-- -------------..------.. 61
Little Econlockhatchee River .--. ------.. --..............----.....-------.---- 65
Howell Creek .-..-.............-----------------...----------------------- 67
Wekiva River .....--------------.............-------.........................................-------------------- 68
Apopka-Beauclair canal .........--- ............--.----- ------- ----- --.-------------- 71
Lakes -----............. .........---------............---------------- ------ 71







Occurrence .- --..--- .........-... .....--- ... ............................... .........-............ 71
Surface area -....-.....-...-...........----. ..-------........-..... .......-----------....... 74
Depths .... .-........--. ..................... .........------------ ........----. 74
Altitudes ..-.--.-........-.......-........-...........----....--...-..-... ..-........--.....----.... 74
Seasonal patterns in lake-level fluctuations .......................--.---..-..-..--- 74
Range in lake-level fluctuations ....-..-..........--- ....----...-...-..-.......-- ...-- 77
Water quality in lakes --....--...-........---...................--- ------ 78
Control of lake stages .---..--..----....--......--. -----------...- ...--..-- 80
Problems ......------..-..........-...--...--.....----- ...................----....------. -----......................---..... 81
Ground water ...--... --------...... ......-.....------------........-..... ........- ....-.....-- ..--- ... 82
Nonartesian aquifers -..-..........-..-..-----. ..........---------------.--- 82
Water levels ..........---......-....-.....-----....-...........-- -- ...-..--.--....--- .... 83
Recharge .----.~---..- .-... ....------------------... ....------.. 86
Discharge .-....-- ---.. ... ----..... ----...---...--.--.--- -..........-- 86
Quality of water ..--.. -..-..--.....---------------... .....------.. --... ....--.-- ...87
Secondary artesian aquifers .----....-................-...-.....------. 88
Water levels ...-...---........ ..----------- .......-- ....------- ...-- 88
Recharge ..---........-..---.---....-------- ------------ 90
Discharge .--...---....----......---------------..-- .-- -.....- -....... 90
Quality of water -....-.--..-......... .......... ..... ........----- --- ..--....... ... 90
Floridan aquifer ------.......--.--........ ---------- --...-.---......-... 91
Aquifer properties ..---........ .......- --..---... --- .-- --- ......... 91
Zones of the aquifer ...-...-..-------....------------ --------...... 94
Interrelation of zones ...-.----........ --------------- -.......--.....-. 95
Piezometric surface .-------..._~.~............ .......-..--..--... 101
Fluctuations ..-. ---....-.....--------- ---.. ..----..----.... 106
Recharge areas --.......----.... ---------------- ----..------- 112
Discharge areas -..- -----............. .............. ...-- ......-........ .. 116
Quality of water ...-.......... .................................... ...................... .. 117
Salt-water contamination .....------........------- .---- -......-....-...--. 124
Drainage wells .--..-..--...-..-----....................----------------------------...............--..-..--.. 128
History .....--...--............... ..-.. ...-............... ................... .. 128
Pollution --... ..... ----------------------.........-..... ............-- .-- 128
Other aspects of drainage wells .-----...----.-........--....------------ ... 133
Pumping tests .....................-- ....-....................-..-. ....... ...... 134
Water use --------------------------------- ..................................... ...........-- 139
Ground water .--......-- ..------.~... .........-- ... ........ 139
Surface water .---------. .......---------------.... ...- .................. ....---- -- ...- ....-...... 142
Summary --------........----------------------------------............................................................................... 143
Conclusions ..-----.--------...... -------.........-----------------.................... 145
References ...---............---------------......................----------------------------- 148


ILLUSTRATIONS
Figure Page
Frontispiece. Aerial view of the Orlando business district looking north-
ward from Lake Lucerne .---......-----.....-....-.........--- ......--...... Facing p. 1
1 Location of Orange County and illustrating well-numbering system 5
2 Location of inventoried wells other than drainage wells, Orange
County, Florida ...........................- ......... ....-................---- -.................... 7







3 Topographic regions of Orange County, Florida ........................... 8
4 Sinkhole two miles west of Orlando formed in summer of 1953....... 12
5 Location of drainage wells in Orange County, Florida, 1964 ........... 15
6 Geologic sections --...-.........--.... ............................................... Facing p. 14
7 Configuration and altitude of top of the Avon Park Limestone,
Orange County, Florida ............................ ..-............... ........ -- ........ 19
8 Configuration and altitude of top of the limestone of Eocene age,
Orange County, Florida ..... .......--..----..-- ............... ....-... .....---- 21
9 Annual average discharge and average discharge for period of
record at three stations on streams draining from Orange County... 34
10 Annual rainfall at Orlando ...--............... ........................... ..... 35
11 Average, maximum, and minimum monthly mean discharges of
three streams draining parts of Orange County and rainfall at
Orlando .............................. ....................................................... .. 36
12 Monthly runoff from Econlockhatchee River basin 1949 and 1958 .. 37
13 Type and duration of surface-water stage and discharge records
and number of chemical analyses of surface water samples col-
lected at gaging sites in and near Orange County -..........--- .............. 38
14 Duration curves of daily flow for streams in and near Orange
County .................. .......... .... ..-------....- ..-..-- ...... .... .......... ............ 40
15 Estimated flow-duration curves for streams and springs for which
periodic or miscellaneous discharge data are available ....--............ 41
16 Stage-duration curves for selected lakes ............................--.. .. 42
17 Water-surface profiles for floods of selected recurrence intervals
on main stem of St. Johns River in Orange County .......--... .... 44
18 Drainage basins and surface-water data collection points .... Facing p. 44
19 Streambed profile for selected streams in the upper Kissimmee
River basin ...---...........-..-.... .........---------------- .. .......... ......... ...... 46
20 Streambed profiles of Boggy Creek and Jim Branch -...............-..... 51
21 Flow-duration curve for Myrtle-Mary Jane canal near Narcoossee 53
22 Low-flow frequencies for St. Johns River near Christmas .............. 55
23 Chloride concentration in water in St. Johns River from U. S. High-
way 192 to State Highway 16, northeastern Florida................-..--- ..-... 56
24 Specific conductance of water in St. Johns River near Cocoa ......-..- 57
25 Cumulative frequency curve for specific conductance of the St.
Johns River near Cocoa, October 1953- September 1963 .............--.. 58
26 Streambed profiles of small streams draining east into St. Johns
River .----....-......... ----..... ---... -.... ......--- -...... .--------------..... 60
27 Streambed profiles of Econlockhatchee River and selected tribu-
taries ---.---...... ..----- ------............... ......... ........- ..... .................-.. 62
28 Low-flow frequencies for Econlockhatchee River near Chuluota....... 64
29 Cumulative frequency curve of specific conductance of the Econ-
lockhatchee River near Bithlo, October, 1959 May, 1962 .--..----........-. 65
30 Relation of specific conductance to hardness and mineral content
for Econlockhatchee River near Bithlo -..........--.........-- .......... .-----...-. 66
31 Estimated flow-duration curves for Howell Creek near Maitland...- 68
32 Streambed profiles for Wekiva River and tributaries........--..-.....-----. 69
33 Low-flow frequencies for Wekiva River near Sanford --......-..---..-...-- 70
34 Estimated average monthly evaporation from lakes..............------.....--- 75
35 Comparison of average monthly change in stage of three lakes







with average monthly difference in rainfall and evaporation at
Orlando 76
36 Hydrographs for wells near Bithlo and Hiawassee Road showing
pattern of fluctuation of the water table_ 84
37 Relationship between water levels at Bithlo and rainfall at Orlando 89
38 Configuration and altitude of the top of the Floridan aquifer in
Orange County, Florida___- 92
39 Depth below land surface to the top of the Floridan aquifer in
Orange County, Florida __ 93
40 Distribution of reported cavities in Floridan aquifer in Orange
County, Florida ________- 96
41 Relationship between water levels in the upper and lower zones of
the Floridan aquifer at Orlando 97
42 Hydrograph of well 833-120-3 showing effects of pumpage in the
Orlando well fields __ 98
43 Configuration and altitude of the piezometric surface in the lower
zone of the Floridan aquifer in the Orlando area 99
44 Relation between dissolved solid and hardness of water depths of
wells in the Orlando area __ _-_ 100
45 Piezometric surface and areas of artesian flow of the Floridan
aquifer in Florida, July 6-17, 1961 __ 101
46 Contours of the piezometric surface at high-water conditions,
September 1960 __ 102
47 Contours of the piezometric surface at about normal conditions,
July 1961___ 103
48 Contours of the piezometric surface at about normal conditions,.
December 11-17, 1963 ____ ___ 104
49 Contours of the piezometric surface at extreme low water condi-
tions, May 1962 105
50 Piezometric surface relative to land surface datum, at high water
conditions, September 1960, Orange County Florida ____.__ 107
51 Piezometric surface relative to land surface datum, at low-water
conditions, May 1962, Orange County, Florida ___ --_ 108
52 Hydrographs of wells ____ 109
53 Range of fluctuation of the piezometric surface from September
1960 to May 1962, Orange County, Florida 110
54 Recharge areas to the Floridan aquifer in Orange County, and
selected adjacent areas, Florida __ Facing p. 112
55 Dissolved solids in water from wells that penetrate the Floridan
aquifer, Orange County, Florida __ _- 114
56 Hardness of water from wells that penetrate the Floridan aquifer,
Orange County, Florida 119
57 Chloride concentration in water from wells that penetrate the
Floridan aquifer, Orange County, Florida -_____ 120
58 Composition of mineral content of water from selected wells in the
Floridan aquifer _--- --_ 123
59 Temperature of ground water in Orange County, Florida 125
60 General areas where bacterially polluted water has been reported
from some wells. (After unpublished map prepared by Charles W.
Sheffield, Orange County Health Department)_ -- 130







61 Location of wells used in salt test in Lake Pleasant area____ 131
62 Changes in population and water use__ 140

TABLE
Table Page
1 Temperature and rainfall at Orlando, Florida __. 11
2 Summary of the properties of the Geologic formations penetrated
by water wells in Orange County _---_ -__________. ----16
3 Altitudes of terraces in Florida _.__ 22
4 Water quality characteristics and their effects ____------------------ 25
5 Drinking water standards for fluoride concentration _.-- ---_ 30
6 Water quality requirements for selected uses Facing p. 32
7 Sites where miscellaneous surface-water data have been collected 39
8 Ranges in quality of surface water in Orange County Facing p. 40
9 Chemical analysis of St. Johns River water, June 7, 1962 57
10 Minor elements in water from St. Johns River near Cocoa, May 11,
1962 ____-- __ _----------_---_______ 59
11 Discharge measurements of springs in Orange County, Florida.__- 72
12 Analysis of water from Lake Francis and Spring Lake 79
13 Analysis of water from selected wells in the Floridan aquifer in
Orange County, Florida ___ 122
14 Results of pumping tests in Orange County, Fla. --- 136



















































Aerial view of the Orlando business district looking northward from
Lake Lucerne.









WATER RESOURCES
OF
ORANGE COUNTY, FLORIDA

By
W. F. Lichtler, Warren Anderson, and B. F. Joyner

ABSTRACT

The population and industry of Orange County are expanding
rapidly but the demand for water is expanding even more rapidly.
This report provides information for use in the development and
management of the water resources of the area.
The county is divided into three topographic regions: (1) low-
lying areas below 35 feet (2) intermediate areas between 35 and
105 feet and (3) highlands above 105 feet. The highlands are
characterized by numerous sinkholes, lakes and depressions.
Surface runoff forms the principal drainage in the lowlying and
intermediate regions, whereas underground drainage prevails in
the highlands.
Lakes are the most reliable source of surface water as swamps
and most of the streams, except the St. Johns and Wekiva Rivers,
go dry or nearly dry during droughts.
Approximately 90 of the 1,003 square miles in Orange County
are covered by water. The southwestern 340 square miles of the
county drain to the south to the Kissimmee River. The remainder
drain to the north to the St. Johns River.
The water in the lakes and streams in Orange County generally
is soft, low in mineral content, and high in color. The quality of
the water in most of the lakes remains fairly constant except were
pollution enters the lakes.
Ground water is obtained from: (1) a nonartesian aquifer com-
posed of plastic materials of late Miocene to Recent age; (2) several
discontinuous shallow artesian aquifers in the Hawthorn Forma-
tion of middle Miocene age; and (3) the Floridan aquifer composed
of limestone of Eocene age.
The surficial nonartesian aquifer yields relatively small quan-
tities of soft water that is sometimes high in color. The shallow
artesian aquifers yield medium quantities of generally moderately
hard to hard water. The Floridan aquifer is the principal source





REPORT OF INVESTIGATIONS NO. 50


of ground water in Orange County. It comprises more than 1,300
feet of porous limestone and dolomite and underlies sand and clay
deposits that range in thickness from about 40 to more than 350
feet. Most large diameter wells in the Floridan aquifer will yield
more than 4,000 gpm (gallons per minute).
Water levels of the Floridan aquifer range from about 15 feet
above to more than 60 feet below the land surface. The quality of
the water ranges from moderately hard in the western and central
parts to saline in the extreme eastern part of the country.
The Floridan aquifer in Orange County is recharged by rain
mostly in the western part of the county. Drainage wells artificially
recharge the Floridan aquifer, but may pollute the aquifer unless
the quality of the water entering the wells is carefully controlled.
Urbanization in the recharge area and pollution can reduce the
amount of potable water available in the Floridan aquifer. Artificial
injection of good quality surplus surface water can increase the
amount of water available and improve its quality, especially in
the eastern part of the county where there is salty water in the
aquifer.
Use of ground water in 1963 was estimated to average about
60 mgd (million gallons per day) for municipal, industrial, domes-
tic and irrigational use. Use of surface water was estimated to
be about 5.5 mgd for irrigation. Surface water was also used for
cooling and recreation.


INTRODUCTION

The rapid increase of population and industry in Orange County
and nearby areas has created a more than commensurate increase
in the demand for water. Not only are there more people and
more uses for water, but the per capital use of water is increasing.
East-central Florida, as a growing center in missile development
and space exploration, is increasing in population and industry;
therefore, the increase in demand for water is expected to continue
and even to accelerate.
This report contains information on the quantity, chemical
quality, and availability of water in Orange County. The report
will be useful to people who have the responsibility of planning,
developing, and using the water resources of Orange County and
much of the East-central Florida region and to anyone interested
in water.






WATER RESOURCES OF ORANGE COUNTY


PURPOSE AND SCOPE OF INVESTIGATION

The purpose of this investigation is to furnish data that will
be useful in the conservation, development, and management of
the water resources of Orange County. Water is one of the most
important natural resources and Orange County, with more than
50 inches of annual rainfall, hundreds of lakes, and the Floridan
aquifer, is blessed with an abundant supply. However, the rainfall
is not evenly distributed throughout the year, or from year to
year, nor are there adequate storage reservoirs in all parts of the
county.
Knowledge of all factors affecting the water resources of an
area is necessary in planning for the protection, efficient develop-
ment, and management of water supplies. Recognizing this need,
the Board of County Commissioners of Orange County entered into
a cooperative agreement with the U. S. Geological Survey to
investigate the water resources of Orange County. The investiga-
tion is a joint effort by the three disciplines within the Water
Resources Division of the Survey under the direction of W. F.
Lichtler, project leader. The report was prepared under the
supervision of C. S. Conover, District Chief, Water Resources Divi-
sion, Tallahassee. It is the comprehensive report of the 5-year
investigation and also incorporates information contained in an
interim report (Lichtler, Anderson, and Joyner, 1964), a lake-level
control report (Anderson, Lichtler, and Joyner, 1965), a ground-
water availability map (Lichtler and Joyner, 1966), and a
surface-water availability map (Anderson and Joyner, 1966),
produced as byproduct reports of the investigation.
The report includes determinations of variation in lake levels,
stream flow, chemical quality of surface and ground waters and
ground-water levels, evaluation of stream-basin characteristics,
delineation of recharge and discharge areas, investigation of
characteristics of the water-bearing formations, assembly of
water-use information and interpretations of water data.


ACKNOWLEDGMENTS

The authors express their appreciation to the many residents
of Orange County who freely gave information about their wells
and to various public officials, particularly the Board of County
Commissioners, whose cooperation greatly aided the investigation.






REPORT OF INVESTIGATIONS NO. 50


Special appreciation is expressed to Fred Dewitt, County Engineer;
to Robert Simon and Jesse Burkett of the City of Orlando Water
and Sewer Department; and to L. L. Garrett and Gene Birdyshaw
of the Orlando Utilities Commission for their assistance.
Appreciation is given to the well drillers in and near Orange
County who furnished geologic and hydrologic data and permitted
collection of water samples and rock cuttings and measurements
of water levels during drilling operations, and to the grove owners,
managers and caretakers who furnished data on irrigational use
of water.
The Board of Supervisors of the Orange Soil Conservation Dis-
trict and Albert R. Swartz and other members of the technical
staff of the U. S. Soil Conservation Service gave much useful advice
and information and provided strong support and encouragement
during the course of the investigation.


PREVIOUS INVESTIGATIONS

Two previous investigations of the water resources of Orange
County have been made. A report by the U. S. Geological Survey
(1943) gives the results of a study of lakes as a source of
municipal water supply for Orlando. A detailed investigation by
Unklesbay (1944) deals primarily with drainage and sanitary wells
in Orlando and vicinity and their effect on the ground-water
resources of the area.
Other investigators have included Orange County in geologic
and hydrologic studies. Fenneman (1938), Cooke (1939), MacNeil
(1950), and White (1958) describe the topographic and geomorphic
features of Central Florida. Cole (1941, 1945), Cooke (1945), Ver-
non (1951), and Puri (1953) describe the general geology of Cen-
tral Florida and make many references to Orange County. Sellards
(1908), Sellards and Gunter (1913), Matson and Sanford (1913),
Gunter and Ponton (1931), Parker, Ferguson, Love, and others
(1955), D. W. Brown, Kenner, and Eugene Brown (1957), and
D. W. Brown and others (1962) discuss the geology and water
resources of Brevard County. Stringfield (1935, 1956) and
Stringfield and Cooper (1950) investigated the artesian water in
peninsular Florida, including Orange County. Collins and Howard
(1928), Black and Brown (1951), Wander and Reitz (1951), and
the Florida State Board of Health (1961) give information about
the chemical quality of water in Orange County.






WATER RESOURCES OF ORANGE COUNTY


WELL-NUMBERING SYSTEM

The well-numbering system used in this report is based on
latitude and longitude coordinates derived from a statewide grid
of 1-minute parallels of latitude and meridians of longitude. Wells
within these guadrangles have been assigned numbers consisting
of the last digit of the degree and the two digits of the minute
of the line of latitude on the southside of the quadrangle, the
last digit of the degree and the two digits of the minute of the line
of longitude on the east side of the quadrangle, and the numerical
order in which the well within the quadrangle was inventoried.
For example, well 827-131-3 is the third well that was inventoried
in the 1-minute quadrangle north of 28027' north latitude and west
of 81031' west longitude (See figure 1.).


Figure 1. Location of Orange County and illustration of well-numbering
system.





REPORT OF INVESTIGATIONS NO. 50


Wells referred to by number in the text can be located on
figure 2 by this system.

DESCRIPTION OF THE AREA

LOCATION AND EXTENT

Orange County is in the east-central part of the Florida
peninsula (fig. 1). It has an area of 1,003 square miles of which
about 916 square miles are land and about 87 square miles are
water. It is bounded on the east by Brevard County, on the north
by Seminole and Lake Counties, on the west by Lake County, and
on the south by Osceola County.
The estimated population of Orange County in 1963 was 290,000.
In that year, the estimated population of Orlando, the largest city
in the county, was 90,000 while Winter Park, the second largest
city, had an estimated population of 20,000. The growth rate of
Orange County's population has increased enormously since 1950
(See figure 63) and this trend is expected to continue. The
population of Orange County is expected to reach 530,000 by 1975.
The principal agricultural products in Orange County are citrus,
ornamental plants, vegetables, cattle, and poultry. In 1960 there
were about 67,000 acres of citrus groves, more than 600 nurseries
and stock dealers, about 6,000 acres of vegetables-mostly in the
Zellwood muck lands northeast of Lake Apopka-about 23,000 head
of cattle and about 180,000 laying hens in the county. )J

TOPOGRAPHY

Orange County is in the Atlantic Coastal Plain physiographic
province described by Meinzer (1923, pi. 28). The county is sub-
divided into three topographic regions: (1) the lowlying regions
where altitudes are generally less than 35 feet; (2) -intermediate
regions where altitudes are generally between 35 and 105 feet; and
(3) highland regions where altitudes are generally above 105 feet.
(fig. 3).
The lowland regions include the St. Johns River marsh, the
northern part of the Econlockhatchee River basin and the north-
eastern part of the county east of Rock Springs. Altitudes range
from about 5 feet above msl (mean sea level) near the St. Johns
River to about 35 feet above msl where there is a relatively steep
scarp in many places in Orange County. The St. Johns River marsh




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Figure 2. Location of inventoried wells other than drainage wells,
Orange County, Florida.


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Figure 3. Topographic regions of Orange County, Florida.






WATER RESOURCES OF ORANGE COUNTY


in the eastern part of the county is a part of Puri and Vernon's
(1964, figure 6) Eastern Valley. The low area east of Rock
Springs is a part of the Wekiva Plain and the Econlockhatchee
Valley is a small part of the Osceola Plain.
The intermediate region occupies most of the middle part of the
county between the lowlands and the highlands. Altitudes range
from 35 to 105 feet above msl but are mostly between 50 and 85
feet above msl. A characteristic area of ridges and intervening
lower areas parallel the Atlantic coast is best developed in the
area between Orlando and the Econlockhatchee River. These ridges
are believed to be fossil beach ridges from higher stands of the sea.
The intermediate region coincides, in general, with Puri and
Vernon's (1964, figure 6) Osceola Plain except for the area in the
northwestern part of the county which is a part of Puri and
Vernon's Central Valley.
The highlands occupy the western part of Orange County with
an island outlier in Orlando and vicinity. Altitudes are generally
above 105 feet but range from about 50 feet in low spots, such as
the Wekiva River basin, to about 225 feet above msl near Lake
Avalon on the western border of the county. The highlands contain
many lakes and depressions, most of which do not have surface
outlets.
The highland regions in Orange County include parts of Puri
and Vernon's Orlando Ridge, Mount Dora Ridge, and Lake Wales
Ridge.
The three topographic regions described above are approximately
equivalent to the Pleistocene terraces postulated by MacNeil (1950)
as the Pamlico terrace from about 8 feet to about 30 feet above
msl, the Wicomico terrace from about 30 feet to about 100 feet
above msl, and the Okefenokee terrace from about 100 to 150 feet
above msl.
Cooke (1939, 1945) has called the surface defined by the 42-
and 70-foot shorelines the Penholoway terrace and the surface
defined by the 70- and 100-foot shorelines the Wicomico terrace.
The areas in Orange County that are above 150 feet probably are
sandhills or altered remnants of higher terraces.
The water resources of Orange County are directly related to
the topography of the area. In general, the highlands are the
most effective natural ground-water recharge areas. They have
few surface streams but have many lakes and depressions. The
intermediate region ranges from good to very poor as a ground-
water recharge area. There are many lakes in some areas and none






REPORT OF INVESTIGATIONS NO. 50


in others. Surface streams in this region either go dry or recede
to very low flow after relatively short periods of drought. The
lowlands are ground-water discharge areas and contain few
lakes except in the mainstem of the St. Johns River. Streamflow
is more sustained than in the other regions because of water stored
in the lakes along the mainstem of the St. Johns River, spring
flow, and seepage of ground water from both the water-table and
artesian aquifers.

CLIMATE

Orange County has a subtropical climate with only two
pronounced seasons-winter and summer. The average annual
temperature at Orlando is 71.50F and the average annual rainfall
is 51.4 inches. (See table 1.) Summer thunderstorms account for_
most of the rainfall. Thunderstorms occur on an average of 83
days per year, one of the highest incidences of thunderstorms in
the United States (U. S. Weather Bureau, Annual Report 1960).


SINKHOLES

Sinkholes are common in areas such as Orange County that are
underlain by limestone formations. Rainfall combines with carbon
dioxide from the atmosphere and from decaying vegetation to
form weak carbonic acid. As the water percolates through the
limestone, solution takes place and cavities of irregular shape are
gradually formed. When solution weakens the roof of a cavern
to the extent that part of it can no longer support the sandy
overburden, sand falls into the cavity and a sinkhole forms on the
surface. (See figure 4.) Most of Orange County's natural lakes,
ponds, and closed depressions probably were formed in this manner.
Sinkholes range in size from small pits a few feet in diameter to
large depressions several square miles in area. Large depressions
are usually formed by the coalescence of several sinkholes.
Sinkholes may form either by sudden collapse of a large part
of the roof of a large cavern or by gradual infiltration of sand
through small openings in the roof of the cavity. The latter
condition is illustrated by the formation of a sinkhole in Canton
Street in Winter Park in April 1961. The sink was first noted as
a depression in the graded road. By the following day a hole about
6 feet in diameter had formed. In the next 2 days the hole gradually








TABLE 1. TEMPERATURE AND RAINFALL AT ORLANDO, FLORIDA

Normal Normal Maximum Minimum
daily daily Normal Normal rainfall3 rainfalls
maximum minimum average rainfall
temperature13a temperature2 temperature12 inches1'2 Inches Year Inches Year

January 70.7 50.0 60.4 2.00 6.44 1948 0.15 1950
February 72.0 50.7 61.4 2.42 5.64 1960 0.10 1944
March 75.7 54.0 64.9 3.41 10.54 1960 0.16 1956
April 80.5 59.8 70.2 3.42 6.18 1953 0.28 1961
May 85.9 66.2 76.1 3.57 8.58 1957 0.43 1961
June 89.1 71.4 80.3 6.96 13.70 1945 1.97 1948
July 89.9 73.0 81.5 8.00 19.57 1960 3.83 1963
August 90.0 73.5 81.8 6.94 15.19 1953 3.20 1960
September 87.6 72.4 80.0 7.23 15.87 1945 1.65 1958
October 82.6 65.3 74.0 3.96 14.51 1950 0.46 1963
November 75.6 56.2 65.9 1.57 6.39 1963 0.09 1950
December 71.6 51.2 61.4 1.89 4.30 1950 Trace 1944
Yearly 80.9 62.0 71.5 51.37 68.74 1960 39.61 1943

SAverage for 10 or more years.
"U. S. Weather Bureau records, 1931-60.
3U. S. Weather Bureau records, 1943-60.







































~ :$f; ~..


Figure 4. Sinkhole 2 miles west of Orlando formed in summer 1953. It was
:uhibscquently filled in and no further sinking has occurred.
W., n .u'. .... ...* ^. .- .. M ..,* . i !* *>**. *-


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WATER RESOURCES OF ORANGE COUNTY


increased in size to about 60 feet in diameter and to about 15 feet
in depth. The hole was filled and no further development has been
noted.
Another sinkhole formed in 1961 in Pine Hills, west of Orlando.
A depression about 1-foot deep and 50 feet in diameter that formed
on April 23 and 24 was marked only by a faint line in the sand
except where the outer edge intersected two houses. The floor of
one room, the carport, and the concrete driveway of one house were
badly cracked. The corner of the other house dropped about 6
inches. The slow rate of settlement was probably caused by a
gradual funneling of the overlying sand and clay into relatively
small solution channels in the limestone. The channels eventually
became filled and the subsidence ceased.
A sinkhole formed rather rapidly in Lake Sherwood on May 22,
1962. This spectacular sinkhole removed a section of the west-
bound lane of Highway 50 and about 3,000 cubic yards of fill were
required to repair the damage. According to eye witnesses, the
sinkhole formed over a period of about 2 hours.
Sinkholes are most likely to form in areas of active ground-
water recharge because the dissolving action of the water is
greatest when it first enters the limestone aquifer. As the slightly
acid water moves through the aquifer, it gradually reacts with
the limestone and is neutralized. The prevalence of sinkholes is
usually a good indication that the area is, or was in the past, an
area of active recharge.
Sinkholes can either improve or impede the recharge efficiency
of an area. In some instances, sinkholes breach the semipervious
layers that separate the surface sand from the aquifer and permit
water to enter the aquifer more readily than before. In other
instances, lakes that form in sinkholes become floored with
relatively impermeable silt, clay and organic material which retards
the downward movement of water.
Much remains to be learned about the solution of limestone by
water. Caverns have been discovered several thousand feet below
the surface, and evidence indicates that active solution is going on
at these depths. Present and future research by the U. S. Geo-
logical Survey and other agencies should provide much useful
information about this important subject and its relation to
ground-water movement and availability.






REPORT OF INVESTIGATIONS No. 50


DRAINAGE

The eastern and southern parts of Orange County aredraineed
rincpaly_byaurface streams. The St. Johns River and its
tributaries drain the eastern and nol le- arf he county while
Sb hngleCreek RedyrekBoggy Creek and canals in the uer
Kissimmee River-basin drain most of the south-central and south-
westernpartsofthecomunty. Many swamps and sioghsoccur in
the eastern and-southernpartsjof the-county because.of the poorly
developed-drainage.
Surface drainage in the western and northwestern parts- of
the county is mostyiitfcloshe-d depr eis6is' where itfeither seeps
into the ground or evaporates. A few sinklholes- niilhis area have
open connections with solution channels in the underlyingime-
stonfei-WaFter fat collects in these sinkholes drains directly into
t"es~olution channels. Most of the sinkholes, however, are floored
with relatively impermeable sediments and the rate of seepage
through these lake-filled sinkholes may be less than in areas
ad'dcent to the lakes.
"More than 300 drainage wellswer-drilled-hetween 1906_&n,
1961 in the upland area of the countyespecially in Orlando and
C-^-i;- 7---~--------------~- ------
icinity, to drain surface water directly into the arteianaquifei-
(fig. 5). The greatest activity was during 1960 when about 35
drainage wells were drilled. Considerable quantities of water-ae
drained underground in this manner, but the total amount is not
Io-iwh.n- ater haer t enter-s-I-e-aquifer through drainage w
ranges from- purea w water used to sh cow arns.


GEOLOGY

The occurrence, movement, availability,'quality, and quantity
of the ground water in Orange County are 'closely related to the
geology of the area. Therefore, knowledge of the structure,
stratigraphy, and lithology of the geologic formations is essential
to an evaluation of the ground-water resources.
---Orange County is underlain mostly by marine limestone,
dolomite, shale, sand, and anhydrite to about 6,500 feet at which
depth granite and other crystalline rock of the basement complex
occur. Only the top 1,500 feet of sediments that have been
penetrated by water wells will be discussed in this report. A
summary of the properties of the formations is given in table 2.














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200


300


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200


300


400


200


100

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Figure 6. Geologic sections.


200rn


EXPLANATION


LITHOLOGY



Shell



Marl


L I
Sand



Clay



Limestone



Dolomite



Cavity zone


GEOLOGY



Undifferentiated
Sediments


Hawthorn
Formation


Ocala Group



Avon Park
Limestone


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WATER RESOURCES OF ORANGE COUNTY


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TABLE 2. SUMMARY OF TIE PROPERTIES OF THE GEOLOGIC FORMATIONS PENETRATED BY
WATER WELLS IN ORANGE COUNTY, FLORIDA


Description of
material


Thick-
ness,
in
feet




0-200


Gray-green, clayey,
quartz sand and silt;
phosphatic s a n d;
and bu.T, impure,
phosphatic limestone,
mostly in lower part.


Cream to tan, fine,
soft to medium hard,
granular, porous,
sometimes dolomitic
limestone.


Water-bearing
properties



Varies widely in
quantity and qual-
ity of water pro-
duced.


Generally imper-
meable except for
limestone, shell,
or gravel beds.


Moderately high
transmissibility,
most wells also
penetrate under-
lying formations.


Aquifer


Non-artesian


Shallow arte-
sian, lower
limestone beds
may be part of
Floridan aqui-
fer.


Formation
name

Undiffer-
entiated,
may in-
clude
Caloosa-
hatchee
Marl


Series


Recent and
Pleistocene


Pliocene (?)


Miocene


Mostly quartz sand
with varying
amounts of clay and
shell.


0-200


0-125


Water level



0 to 20 feet below
the land surface
but generally less
than 10 feet.


Piezometric sur-
face not defined,
water level gen-
erally is lower
than nonartesian
aquifer and higher
than Floridan
aquifer.


Hawthorn


Ocala
Group


iI-




TABLE 2 CONTINUED

Upper section most- Overall transmis-
ly cream to tan, sibility very high,
granular, porous contains many in-
limestone. Often con- terconnected so- Piezometric sur-
Avon 400- tains abundant cone- lution cavities. Floridan face shown in fig-
Eocene Park 600 shaped Foraminifers. Many large capa- ures 10 and 11.
Limestone Lower section mostly city wells draw
dense, hard, brown, water from this
crystalline dolomite, formation.

Lake Over Dark brown crystal- Similar to Avon
City 700 line layers of dolo- Park Limestone.
Limestone Total mite alternating with Municipal supply
un- chalky fossiliferous of City of Or-
known layers of limestone. lando obtained
from this forma-
tion.


z
'.4





I-A






REPORT OF INVESTIGATIONS NO. 50


Geologic sections showing the formations and types of material
are shown in figure 6.


FORMATIONS

The oldest formation penetrated by water wells in Orange
County is the Lake City Limestone of middle Eocene age (about
50 million years old). The Lake City Limestone consists of
alternating layers of hard, brown, porous to dense, crystalline
dolomite and soft to hard, cream to tan, chalky, fossiliferous
limestone and dolomitic limestone.
The Lake City Limestone is distinguished from the overlying
Avon Park Limestone by the presence of the fossil Dictyoconus
americanus; however, in Orange County, the rock in the depth
interval (about 600-900 feet) where the top of the Lake City would
normally be has been partly crystallized and the fossils have been
badly damaged. Therefore, the exact location of the top of the
formation is unknown. No water wells penetrate the total thickness
of the Lake City, but the formation is probably more than 700 feet
thick.
The Avon Park Limestone conformably overlies the Lake City
Limestone and is composed of similar materials. The formation
is distinguished from overlying formations by the occurrence of
many sand-sized cone-shaped foraminifera. In many areas, the
Avon Park is composed mostly of the shells of these tiny single-
celled animals.
Contours on the top of the Avon Park Limestone are shown in
figure 7. The thickness of the Avon Park is not accurately known
because only a few wells penetrate the formation and the contact
with the underlying Lake City Limestone is indistinct, but the
Avon Park is probably 400 to 600 feet thick.
The Ocala Group' of the Florida Geological Survey overlies the
Avon Park Limestone and contains the Crystal River, Williston,
and Inglis Formations of late Eocene age. The limestone of the
Ocala Group in Orange County was deeply eroded and in some
areas entirely removed before the overlying formations were


'The term "Ocala Group" has not been adopted by the U. S. Geological
Survey. The Florida Geological Survey uses Ocala as a group name as
proposed by Puri (1953) and divided into three formations-Crystal River,
Williston and Inglis Formations.








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Ifisc. A


C O U N T
- - - - -


0 1 2 3 4 5 6 7 B 9 K1 miles


Figure 7. Configuration and altitude of top of the Avon Park Limestone,

Orange County, Florida.






REPORT OF INVESTIGATIONS No. 50


deposited. In south-central Orange County, formations of the
Ocala Group are missing, but in the northeast part of the county
near Bithlo the Ocala is about 125 feet thick. The contours on
the top of the Eocene limestones in figure 8 show the eroded surface
of the Ocala Group except where the Ocala is absent. In these
areas the contours represent the top of the Avon Park.
The Hawthorn Formation of Miocene age (about 25 million
years old) unconformably overlies the Ocala Group and, where the
Ocala is missing, the Avon Park Limestone. The clayey sand of the
Hawthorn Formation retards the vertical movement of water
between the water-table aquifer and the underlying limestone of
the Floridan aquifer. In most parts of the county the Hawthorn
retards, to varying degrees, the downward seepage of the water
from the water-table aquifer. In low lying parts of the county
where the artesian head is above land surface the Hawthorn
Formation retards the upward movement of water.
The lower part of the Hawthorn Formation usually contains
more limestone than the upper part. The limestone sections usually
contain much phosphorite and quartz sand and may grade into
sandstone known locally as "salt and pepper rock." In the
northwestern part of the county, the Hawthorn Formation has a
higher percentage of limestone than in the southeastern part.
Orange County lies in the intermediate/zone between the
limestone-clay type of Hawthorn in north-central Florida and the
clay-sand type of Hawthorn in south-central and southern Florida.
In Orange County the contact between the Hawthorn Formation
and the underlying Eocene limestone is usually quite distinct; but
the contact with the overlying deposits is gradational. The top
of the Hawthorn is usually placed at the first occurrence of appre-
ciable quantities of phosphorite or where a distinct and persistent
greenish color appears. The Hawthorn is thickest (about 300 feet)
in the southeastern part of Orange County and thinnest (about 50
feet) in the northwestern part of the county.
Undifferentiated sediments above the Hawthorn Formation
may include the Caloosahatchee Marl (which has been designated
Upper Miocene, Pliocene or Pleistocene by various workers)2;
thick deposits of red clayey sand which occur near the surface in
some areas in western Orange County; and marine terrace
deposits. The red clayey sand is used extensively in road building.


-The U. S. Geological Survey gives its age as Pliocene.







..... r I -% EXPLANATION
L A KE CoUNTY
ORAlGE COUNTY /


S/ i .CC ,,v l -' /..


-.15- .
C: ,, t w h "W, MM$ .... "t f ;e"


C 0L_. _.- Y1- --
C O UNT TY


Figure 8. Configuration and altitude of top of the limestone of Eocene age,

Orange County, Florida.


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REPORT OF INVESTIGATIONS NO. 50


The marine terrace deposits consist mostly of loose unsorted
quartz sand with varying amounts of organic matter and occasional
seams of clay. These sediments are generally thought to have been
deposited during interglacial times of the Pleistocene ice age when
sea level was higher than it is at present. Table 3 gives the
altitude of the more prominent terraces as defined by Cooke. Only
the Pamlico terrace with a shoreline at about 30 feet and the
Wicomico terrace with a shoreline at about 100 feet are well
developed in Orange County. The altitudes in Orange County
above 100 feet represent eroded remnants of the higher
Okefenokee and Coharie terraces or sand dunes formed during
higher stands of the sea.

TABLE 3. ALTITUDES OF TERRACES IN FLORIDA.

Brandywine 270 feet
Coharie 215 feet
Sunderlahd 170 feet
Wicomico 100 feet
Penholoway 70 feet
Talbot 42 feet
Pamlico 25 feet
Silver Bluff feet


STRUCTURE

The surface-of the limestones of Eocene age is shown in figure
8. This represents approximately the land surface as it was in
post-Eocene/pre-Miocene time after a long period during which
the limestone was above sea level and exposed to erosion. Figure 8
is one interpretation of limited data, and future studies based on
more complete information and regional interpretation may result
in drastic revision. For example, a steep-walled trough is shown
in the southeastern part of the county, whereas actually there may
be a fault in the St. Johns River valley as indicated on the geologic
section in figure 6.
Figure 7 shows contours on the top of the Avon Park Limestone.
The top of the Avon Park Limestone appears smoother than the
top of the overlying Ocala Group and was probably not eroded
except where the Ocala is missing. Therefore, the Avon Park
Limestone probably more nearly represents the regional dip of
shallow limestone formations underlying Orange County.






WATER RESOURCES OF ORANGE COUNTY


The irregularities in the surface of the Eocene limestone may
have been caused by deep erosion, but the contours on the top of
the Avon Park Limestone strongly suggest a fault in the St. Johns
River valley. Movement along this fault probably started in
post-Eocene time and continued into Miocene time.


HYDROLOGY

CHEMICAL QUALITY OF WATER

All waters except distilled water contain dissolved materials
in varying amounts. The type and amount of dissolved materials
is influenced by many factors such as source, movement, geology,
topography, climate, biological action, and cultural changes.
Rain falling through the atmosphere picks up small quantities
of dust particles, atmospheric gases, and windblown salts. In
areas near the ocean, the amount of salts picked up by rain may
be appreciable especially if it is blown inland from the ocean. In
industrialized areas the atmosphere generally contains exhaust
gases and particles that are readily picked up by rain. The type
and amount varies with the industry. Rain may also pick up
radioactive fallout from nuclear explosions. To date, however, the
amount of radioactive materials in water has remained far below
tolerable limits.
When rain reaches the earth, it begins to dissolve or pick up
in suspension varying amounts of the materials contacted. The
carbon dioxide dissolved from the atmosphere and from decaying
organic matter- on the earth's surface react with the water to
form a weak carbonic acid. Carbonic acid greatly increases the
ability of water to dissolve inorganic materials especially limestone
such as underlies Orange County.
Surface water moves more rapidly than ground water,
consequently, its time of contact with soils and rocks is shorter.
This is one reason for lower mineralization in surface water than
in ground water. Surface water is usually higher in color than
ground water because surface water dissolves living and decaying
organic materials that it contacts. Decaying organic matter
consumes dissolved oxygen from the water and releases. carbon
dioxide.
When water percolates into the ground, the rate of movement
is greatly reduced. When water percolates very far through soils





REPORT OF INVESTIGATIONS No. 50


and rocks, any bacteria or color present will usually be removed.
The fluctuations in the quality and temperature of ground water
are smaller than in most surface-water bodies because of the long
period of time required for ground water to percolate downward
to the aquifer and then laterally through the aquifer to the point
of discharge.
Dissolved mineral constituents in water are usually reported
in parts per million (ppm) (one unit weight of a constituent in a
million unit weights of water). Hardness of water is caused by
the presence of alkaline earth metals, mostly calcium and
magnesium, and is expressed as an equivalent quantity of calcium
carbonate. Specific conductance is a measure of the ability of water
to conduct an electric current and may be used in estimating the
dissolved mineral content. The most important dissolved con-
stituents can usually be related to specific conductance (fig. 25).
Color is expressed in units of the platinum-cobalt scale. The
symbol pH is a measure of the acidity or alkalinity of a solution,
and is expressed as the negative logarithm of the hydrogen-ion
concentration.

RELATION OF QUALITY OF WATER TO USE

The amount and type of dissolved and suspended materials in
water determines its value for a particular use. Water suitable
for one use may be entirely unsatisfactory for another. For
example, sea water is used for cooling purposes, whereas it is
unsatisfactory for most other industrial use. Water used in the
manufacturing of products such as high-grade paper and textiles
must be very low in dissolved solids.
Table 4 shows the more common characteristics of water
quality. Some constituents in water can be removed inexpensively
whereas other constituents can be removed only by expensive
distillation. Hardness of water may be removed by the relatively
simple and inexpensive ion-exchange method which replaces the
calcium and magnesium with sodium from common table salt.
Iron, color, and turbidity may be economically removed by
flocculation, settling, and filtration. The removal of sodium,
chloride, and sulfate is difficult and expensive.





TABLE 4. WATER-QUALITY CHARACTERISTICS AND THEIR EFFECTS.

Constituent
or property Source or cause Effects


Silica (SiO)


Dissolved from practically all
rocks and soils, commonly less
than 30 ppm. High concen-
trations, as much as 100 ppm,
generally occur in highly al-
kaline waters.
Dissolved from practically all
rocks and soils. May also be
derived from iron pipes,
pumps and other equipment.
More than 1 or 2 ppm of iron
in surface waters generally
indicate acid wastes from
mine drainage or other
sources.
Dissolved from practically all
soils and rocks, but especially
from limestone, dolomite, and
gypsum. Calcium and magne-
sium are found in large quan-
tities in some brines. Magne-
sium is present in large quan-
tities in sea water.


Forms hard scale in pipes and boilers. Carried over in steam of
high pressure boilers to form deposits on blades of turbines. In-
hibits deterioration of zeolite-type water softeners.




On exposure to air, iron in ground water oxides to reddish-brown
precipitate. More than about 0.3 ppm stains laundry and utensils
reddish-brown. Objectionable for food processing, textile processing,
beverages, ice manufacture, brewing and other processes. U. S.
Public Health Service (1962) drinking-water standards state that
iron should not exceed 0.3 ppm. Larger quantities cause unpleasant
taste and favor growth of iron bacteria.



Causes most of the hardness and scale-forming properties of water;
soap consuming (see hardness). Waters low in calcium and magne-
sium desired in electroplating, tanning, dyeing, and in textile manu-
facturing.


Iron (Fe)


Calcium (Ca) and
Magnesium (Mg)










TABLE 1 CONTINUED

Constituent
or property Source or cause Effects


Sodium (Na) and
Potassium (K)


Bicarbonate (HCO,)
and Carbonate (CO,)



Sulfate (SO4)





Chloride (Cl)


Dissolved from practically all
rocks and soils. Found also
in ancient brines, sea water,
industrial brines, and sewage.
Action of carbon dioxide in
water on carbonate rocks such
as limestone and dolomite.


Dissolved from rocks and soils
containing gypsum, iron sul-
fides, and other sulfur com-
pounds. Commonly present in
mine waters and in some in-
dustrial wastes.
Dissolved from rocks and
soils. Present in sewage and
found in large amounts in an-
cient brines, sea water, and
industrial brines.


Large amounts, in combination with chloride, give a salty taste.
Moderate quantities have little effect on the usefulness of water for
most purposes. Sodium salts may cause foaming in steam boilers
and a high sodium content may limit the use of water for irrigation.
Bicarbonate and carbonate produce alkalinity. Bicarbonates of cal-
cium and magnesium decompose in steam boilers and hot water
facilities to form scale and release corrosive carbon-dioxide gas.
In combination with calcium and magnesium, cause carbonate
hardness.
Sulfate in water containing calcium forms hard scale in steam
boilers. In large amounts, sulfate in combination with other ions
gives bitter taste to water. Some calcium sulfate is considered bene-
ficial in the brewing process. USPHS (1962) drinking water stand-
ards recommend that the sulfate content should not exceed 250 ppm.

In large amounts in combination with sodium, gives salty taste to
drinking water. In large quantities, increases the corrosiveness of
water. USPHS (1962) drinking-water standards recommend that
the chloride content should not exceed 250 ppm.




TABLE 4 CONTINUED
Constituent
or property Source or cause Effects


Fluoride (F)


Dissolved in small to minute
quantities from most rocks
and soils. Added to many
waters by fluoridation of mu-
nicipal supplies.


Decaying organic matter, sew-
age, fertilizers, and nitrates
in soil.





Chiefly mineral constituents
dissolved from rocks and soils.
Includes some water of crys-
tallization.
In most waters nearly all the
hardness is due to calcium and
magnesium. All of the metal-
lications other than the alkali
metals also cause hardness.


Nitrate (NO,)







Dissolved solids



Hardness as CaCO,


Fluoride in drinking water reduces the incidence of tooth decay
when the water is consumed during the period of enamel calcifica-
tion. However, it may cause mottling of the teeth, depending on the
concentration of fluoride, the age of the child, amount of drinking
water consumed, and susceptibility of the individual. (Maier, F. J.,
1950, Fluoridation of public water supplies, Jour. Am. Water Works
Assoc., vol. 42, pt. 1, p. 1120-1132).
Concentration much greater than the local average may suggest
pollution, USPHS (1962) drinking-water standards suggest a limit
of 45 ppm. Waters of high nitrate content have been reported to
be the cause of methemoglobinemia (an often fatal disease in in-
fants) and therefore should not be used in infant feeding. Nitrate
has been shown to be helpful in reducing inter-crystalline cracking
of boiler steel. It encourages growth of algae and other organisms
which produce undesirable tastes and odors.
USPHS (1962) drinking-water standards recommend that waters
containing more than 500 ppm dissolved solids not be used if other
less mineralized supplies are available. Waters containing more
than 1,000 ppm dissolved solids are unsuitable for many purposes.
Consumes soap before a lather will form. Deposits soap curd on
bathtubs. Hard water forms scale in boilers, water heaters, and
pipes. Hardness equivalent to the bicarbonate and carbonate is
called carbonate hardness. Any hardness in excess of this is
called non-carbonate hardness. Waters of hardness up to 60 ppm
are considered soft; 61 to 120 ppm, moderately hard; 121 to 180
ppm, hard; more than 180 ppm, very hard.








TA11LE 1 CONTINUED


Constituent
or property

Specific conductance
(micromhos at 250C)


Hydrogen ion
concentration (pH)


Color


Hydrogen sulfide
(H.S)


Source or cause


Mineral content of the water.



Acids, acid-generating salts,
and free carbon dioxide lower
the pH. Carbonates, bicarbon-
ates, hydroxides, and phos-
phates, silicates, and borates
raise the pH.
Yellow to brown color of some
waters is usually caused by
organic matter extracted from
leaves, roots, and other or-
ganic substances. Objection-
able color in water also results
from industrial waste and
sewage.
Probably the reduction of sul-
fates to sulfides by organic
material under anaerobic con-
ditions in deep wells. In
some cases, it may be derived
from the anaerobic reduction
of organic matter with which
the water comes in contact.


Effects


Indicates degree of mineralization. Specific conductance is a meas-
ure of the capacity of the water to conduct an electric current.
'Varies with concentration and degree of ionization of the con-
stituents.
A pH of 7.0 indicates neutrality of a solution. Values higher than
7.0 denote increasing alkalinity; values lower than 7.0 indicate
increasing acidity. pH is a measure of the activity of the hydrogen
ions. Corrosiveness of water generally increases with decreasing
pH. However, excessively alkaline waters may also attack metals.

Water for domestic and some industrial uses should be free from
perceptible color. Color in water is objectionable in food and
beverage processing and many manufacturing processes. The
USPHS (1962) states that color should not exceed 15 units in
drinking water.



Causes "rotten-egg" odor and causes corrosion. Limits of tolerance
are generally less than 0.5 ppm. Since hydrogen sulfide is a gas
it is easily removed from water by aeration.


1






WATER RESOURCES OF ORANGE COUNTY


DOMESTIC USE

Water used for human consumption should be pathologically
safe, low in turbidity and color, and free from taste and odor.
Federal drinking water standards were first established in 1914 to
control the quality of water used on interstate carriers and for
culinary purposes. These standards have been revised several
times, most recently in 1962 by the U. S. Public Health Service.
They have been endorsed by the American Water Works
Association as minimum standards for all public water supplies.
Some of the U. S. Public Health Service's recommended limits
for the various dissolved constituents and physical properties are
given under the column of effects in table 4. Following are
additional U. S. Public Health Service's recommended limits for
dissolved chemical substances in drinking water.

Substance Concentration (ppm)
Alkyl Benzene Sulfonate (ABS) 0.5
Arsenic (As) 0.01
Copper (Cu) 1
Carbon Chloroform Extract (CCE) 0.2
Cyanide (Cn) 0.01
Fluoride (F) See table 5
Manganese (Mn) 0.05
Phenols (CGH,OH) 0.001
Zinc (Zn) 5

The U. S. Public Health Service states that the presence of the
following toxic substances, in excess of concentrations listed shall
constitute grounds for rejection of the supply for drinking water:

Substance Concentration (ppm)
Arsenic (As) 0.05
Barium (Ba) 1.0
Cadmium (Cd) 0.01
Chromium (Hexavalent) (Cr+G) 0.05
Cyanide (CN) 0.2
Lead (Pb) 0.05
Selenium (Se) 0.01
Silver (Ag) .05






REPORT OF INVESTIGATIONS NO. 50


Unpolluted water rarely contains excessive concentrations of the
above toxic substances. In highly industrialized areas, objectionable
amounts of toxic substances are sometimes found in water. Two
samples, one from the St. Johns River at low flow and the other
from a typical Orlando supply well, were analyzed for minor ele-
ments. The cadmium, chromium and lead concentrations were less
than .0014 ppm.
The U. S. Public Health Service's standards for fluoride in
drinking water are based on climatic conditions, because children
drink more water in warmer climates and, consequently, consume
more fluoride. Table 5 lists the drinking water standards for
fluoride concentration. Where fluoride occurs naturally in water,
it should not exceed the upper limit in table 5. Where fluoridation
is practiced by water treatment plants, the concentration should be
held between the lower and upper limits. The U. S. Public Health
Service states that the presence of fluoride concentrations more
than twice the optimum values in table 5 constitutes grounds for
rejection of the supply. The yearly normal maximum daily
temperature in Orange County is 80.90 F; therefore, the optimum
amount of fluoride in drinking water is 0.7 ppm and the
concentration should not be below 0.6 ppm or above 0.8 ppm.
Fluoride concentrations in Orange County water are usually less
than 0.8 ppm and often less than 0.4 ppm.


AGRICULTURAL USE

The primary non-domestic uses of water on the farm are for
livestock consumption and for irrigation. The quality standards of

TABLE 5. DRINKING WATER STANDARDS FOR FLUORIDE
CONCENTRATION.

Yearly normal maximum Recommended fluoride control
daily temperatures oF limits in ppm
Lower Optimum Upper

50.0- 53.7 0.9 1.2 1.7
53.8- 58.3 0.8 1.1 1.5
58.4- 63.8 0.8 1.0 1.3
63.9- 70.6 0.7 0.9 1.2
70.7- 79.2 0.7 0.8 1.0
79.3- 90.5 0.6 0.7 0.8






WATER RESOURCES OF ORANGE COUNTY


water for human consumption have already been discussed. Very
little information is available on quality of water standards for
livestock watering, but it is assumed that water safe for human
consumption is safe for animals. In general, animals can tolerate
higher mineralization than man.
The Department of Agriculture and Government chemical
laboratories of Western Australia list the following limits for
dissolved solids in ppm:

Poultry 2,860
Pigs 4,290
Horses 6,440
Cattle, dairy 7,150
Cattle, beef 10,000
Adult sheep 12,900
Investigators have found that water with a dissolved-solids
content of more than 15,000 ppm is dangerous if used continuously
for livestock watering. The water from the Floridan aquifer in
eastern Orange County is the most highly mineralized. The water
from a few wells exceeds 3,000 ppm in dissolved solids but none
exceed 4,000 ppm.
The chemical quality of water is important in evaluating its
usefulness for irrigation. The quality requirements for irrigation
varies with the nature and composition of the soil and subsoil,
topography, quantity of water used and method applied, climate,
and type of crops grown. Good soil drainage is important where
irrigation is practiced. Water of good quality for irrigation may
not produce good crops on poorly drained land, whereas highly
mineralized water may often be used successfully on open-textured
well-drained soils.
There is much published material on the quality requirements
of irrigation water for various crops grown under varying
conditions. U. S. Department of Agriculture Circular 969 entitled,
"Classification and Use of Irrigation Water" by L. V. Wilcox
(1955), classifies irrigation water based on electrical conductivity
in micromhos/centimeter. The dividing point between four classes
is 250, 750, and 2,250 micromhos. Wilcox points out that ". .. in
classifying an irrigation water, it is assumed that the water will
be used under average conditions with respect to soil texture,
infiltration rate, drainage, quantity of water used, climate, and
salt tolerance of the crop." All water in Orange County is suitable
for irrigation. The artesian water in the eastern part is high in






REPORT OF INVESTIGATIONS NO. 50


mineralization, but because of adequate flushing during-the rainy
season it is used successfully.

INDUSTRIAL USE

Water quality requirements for industry are so varied that it is
impossible to set standards to meet the demands of all users. For
some purposes, such as cooling, water of poor quality is often used
when better quality water is not available. Water for some
processes and for use in high-pressure steam boilers must approach
the quality of distilled water. In general, most industrial water
should be low in dissolved solids, soft, uniform in quality and
temperature, and noncorrosive. Table 6 gives the quality
requirements for several selected industries. The greatest
industrial use of water in Orange County is for citrus processing
and canning. (See section on use of water.) With a minimum of
treatment most of the water in the county is suitable for most
industrial uses.


SURFACE WATER

OCCURRENCE AND MOVEMENT

Most of the surface water in Orange County is from rain
within the county, but some flows into the county from adjacent
areas of higher elevation. Some of the streams that provide water,
such as the St. Johns River, also drain parts of Orange County.
The amount of water on the land surface is determined by
climate, geology, and topography. Only part of the rainfall remains
on the surface long enough to be useful. Losses by evaporation
and infiltration begin immediately and continue indefinitely unless
the supply becomes exhausted. Some of the water that infiltrates
into the soil and to the aquifers returns to the surface as seepage
or as spring flow into lakes and streams. The part of the rain that
doesn't evaporate or infiltrate collects in topographic depressions
to form lakes, swamps, and marshes, or enters a stream channel
and flows out of the county.
It is estimated that about 70 percent of the rain that falls on
Orange County returns to the atmosphere by evaporation and
transpiration, about 20 percent flows out of the county in streams
and about 10 percent flows out underground.




--- ----- ------------l----i_-






TABLE 6. WATER QUALITY REQUIREMENTS FOR SELECTED USES1

(Allowable limits in parts per million)




S- -

Use = O ""10 CS P Other requirements(

Air Conditioning 0.5 low 1 No corrosiveness, slime formation
Baking 10 10 .2 low .2 P

Boiler feed water
0-150 PSI 20 80 80 3000-500 5 40 50 200 8.0 -
150-250 PSI 10 40 40 2500-500 3 20 30 100 8.4 -
250-400 PSI 5 10 10 1500-100 0 5 5 40 9.0 -
Over 400 PSI 1 2 2 50 0 1 0 20 9.6 -
Brewing
Light beer 0-10 0-10 .1 500-1500 75-80 low .2 50 50-68 6.5-7.0 10 60-100 100-200 30 P NaC1 less than 275 ppm
Dark beer 0-10 0-10 .1 500-1500 80-150 low .2 50 50-68 6.5-7.0 10 60-100 200-500 30 P NaC1 less than 275 ppm
Carbonated Beverages 1- 2 5-10 200-250 0.1-0.2 850 50-128 low 0-0.2 250 250 0.2-1.0 P
Confectionary 0.2 50-100 low .02 7.9 P No corrosiveness, slime formation
Dairy industry 0 180 0.1-0.3 500 none 17 30 60 P
Food Canning and Freezing 1-10 __ 50-85 0.2 850 30-250 none 1.0 7.5 8.6 400-600 1.0 P
Food Equipment washing 1 5-20 10 .2 850 none 250 1.0 P

Food Processing, general 1-10 5-10 10-250 .2 850 30-250 low- 1.0 P
Ice 1- 5 5 .2 300 30-50 10 _- P
Laundering 50 .2 -
Plastics, clear, uncolored 2 2 53 .02 200 -

tAmerican Water Works Association 1950 and Water Quality Criteria, McKee and Wolf 1963
-P indicates that potable water, conforming to USPHS standards, is necessary
-Peas 200400, fruits and vegetables 100-200, legumes 25-75


















































































































































































'-~--U----~-- 'C-------' ------C~~--- ---Q--------





WATER RESOURCES OF ORANGE COUNTY


VARIATION

Part of the difficulty in managing the water resources of an
area stems from variations in the amount of water stored on and
beneath the earth's surface in the area. These variations are
brought about because rainfall is extremely variable and
intermittent, while evaporation, transpiration, surface outflow, and
underground outflow though also variable are relatively continuous.
Figure 9 shows the average discharge in cfs (cubic feet per second)
per square mile for each year of record at three stations draining
parts of Orange County. Figure 10 shows the annual rainfall at
Orlando for this period. Comparison of these two figures reveals
that the pattern of variations in runoff and rainfall are similar but
not identical. The years of high flow agree well with the years of
high rainfall and except for a 1-year attenuation of Wekiva River
caused by depletion of ground-water storage, so do the years of low
flow and low rainfall. Streamflow may average above normal during
a year following a wet year because of the carry-over of storage
from the wet year even though rainfall is below normal. After a
severe drought, streamflow may average below normal and even
decrease during a year of above-normal rainfall because of the
large amounts of water required to replenish the depleted soil
moisture before an excess to provide runoff becomes available.
The flow of Wekiva River is much less variable than that of
Econlockhatchee River and St. Johns River because it is maintained
by the flow of large springs that discharge from a vast highly
permeable ground-water reservoir (Floridan aquifer). The base
flow of the Econlockhatchee and St. Johns Rivers is maintained
mostly by seepage of water from the relatively thin and low
yielding water-table aquifer. Their channels are very shallow so
that a small drop in the water table causes a sharp reduction or
cessation of ground-water inflow.
Figure 11 shows that the distribution of monthly runoff during
the year corresponds in a general way to the distribution of rainfall,
but there are some apparent discrepancies. Although average
rainfall for months March, April, May, and October is about equal,
runoffs for these months differ widely. Average runoff decreases
from March to May because evaporation and transpiration losses
increase during this period (See fig. 41.). Runoff for October is
higher than that for May because in October evaporation is less
and storage, which increased during July, August, and September,






REPORT OF INVESTIGATIONS No. 50


Figure 9. Annual average discharge and average discharge for period of
record at three stations on streams draining from Orange County.


WEKIVA RIVER NEAR SANFORD
Drainage area-200 sq. mi, approximately
Average-1.38 cfs per sq. mi.


:~::::'~i~~itsii:l:;::.,,...:..r ::.;~r~::....::~ ::tg~i~~i~ ;:II!:t::~;: -c~i
~: ,;;,,: ~~~:::~ ~= ~:::a::~::::W; n:: X.:~






WATER RESOURCES OF ORANGE COUNTY


Figure 10. Annual rainfall at Orlando.


is released to the streams. There is some indication that this
storage effect carries over into November.
In a given year the distribution of flow for a particular station
may differ markedly from that representing average conditions.
Contrasting distributions of flow for Econlockhatchee River are
shown in figure 12 for 2 years in which total runoff was about the
same.


PRESENTATION OF DATA

The data used for this report were obtained during the period
October 1935 to September 1963. If the physical conditions in the
basin remain unaltered and no drastic changes in the climate take
place, values for the next 28 years should be very similar to those
for this period. The 28-year moving average of annual rainfall at
Orlando beginning in 1893 has varied from the 71-year average
by no more than 3.8 percent, indicating that conditions during







10
AXM.IMUM
*220





VMRAVERAGE Gi
AVERAGE ERAGE
U), _1.0

MM AVERAGE % 1.0





.10 MINIMUM MINIMUM z o



W RST. JOHNS RAINFALL
E A D RIVER HATA VEAT
..: NEAR .RVE. ORELANDOA

01 AMJAA JFMAMJAJASOND
0
Figure 11. Average, maximum, and minimum monthly mean discharges of
three streams draining parts of Orange County, and rainfall at Orlando.





WATER RESOURCES OF ORANGE COUNTY


ECONLOCKHATCHEE
RIVER NR. CHULUOTA
WI Total 13.13 in.
o 1958
Z2

U-
z 2 ----------


I


r 4
Total 13.85 in.

i- 1949
z





LLJ. |< M=" < .i.l-n Z
T >> I I iiiiiiiiiiiiiiii iiD



Figure 12. Monthly runoff from Econlockhatchee River basin-1949 and 1958.


the period October 1935 to September 1963 are representative of
the long-term average. The average for the 28-year period
1936-1963 differed from the 71-year average by only 0.01 of 1
percent. The value of this report is premised on the applicability
in the future of analyses based on past record.
Surface-water data have been collected at 62 sites in the county.
Data on the chemical quality of surface water have been collected
at 35 of these sites since 1953. Figure 13 lists the sites where data
have been collected systematically and shows the number of water
samples analyzed, the types of stage and flow record collected,
and the periods of record. Table 7 lists the sites where miscellaneous
records have been collected.







REPORT OF INVESTIGATIONS No. 50


Stalton N l


I AdaCr Lake, o Orlndo
;2 y-E'.lt Tahoo:kalgqo Cnr Norcoossee
3 Apopka-o eauclair Canal at control nr Asatula
4 AooPaedB-. uclar iLt at S.R. 448 nr Astatulo
A .Ipophk, Lake, at Winter Garden 5
T ia t' Laoke nr Orlando __ __
7 3Bellla, Lake. at Windermere
aB B Sand Lake at Doctor Phillips
19 #l9y Creek nr Kissimmee

II (lnter, Lake, O1 Wlndormetr




I .'.voirw Creek it Vineland
|In i uilan Canal nr Wewainotee
1cr, Lake, at Mount Datw
S Eonlacknttchlee River nr Btthlo 34
i c-tiackllatchee ~ver nr ChuluOta 3
Lik,- ta? Orlando
1 Hr!Hat', nr no, k J7



4 ;,t Creek nr Ctr'itmas
5 iJoans Lake at Oakland 4

SILittle Lake Fnirvew a Orlando
I Matland, Lake, ot Wlnler Park

29 Mary Jane, Lake, nr Norcoaee 2
(3 Mary Jane-CHart Canal nr Norcoossee
3, Myrtle-Mary Jane Canal rr NorCOOSSee
32 Park Lake ot Orlando
It Ponidetri, Lake, fn COCO0 730
-4 RAowe.na, Lake, at Orlando
j1 5t Jornn River nr Christmas 47
36 St Jaons River nr Cocoa 170
i' St jahns River Flood Profile
rk Sh n ile Creek t olrport, nr KisSimmee
'1 Sh~il'iln Creek nr Vineland 22
4 1 Silver Lake, at Orlando
- p I oheor. Lake, nr Orlando
-42 $LQinq Lake of Orlando
4,3 Sun, Lake, at Orlando
4-4 Susa5nnah, Lake, nr Orlando I
4 ake :ailO, Lake, at Orlando
46 Weikiv River nr Sanlord
4I Wnanonro (Franci, ) Lake nr Plymouth 2


EXPLANATION

I Tr"111TT' I I IITIll,11' wY LL 1111 1 111 117333I
. . . . . .


Daaly to weekly stage
Monthly :1aJe or annual flood crest

Periodic discharge measurements
Daily stage and discharge


Figure 13. Type and duration of surface-water stage and discharge records
and number of chemical analyses of surface water samples collected at gaging
sites in and near Orange County.





WATER RESOURCES OF ORANGE COUNTY


TABLE 7. SITES WHERE MISCELLANEOUS SURFACE-WATER DATA
HAVE BEEN COLLECTED.

No. of
chemical
Station no. Station analyses

48 Bonnet Creek near Vineland 3
49 Christmas Creek near Christmas 1
50 Howell Creek near Maitland 2
51 Jim Branch near Narcoossee 2
52 Little Wekiva River near Forest City 1
53 Mills Creek near Chuluota 1
54 Reedy Creek near Vineland 2
55 Roberts Branch near Bithlo
56 Rock Springs near Apopka 7
57 Second Creek near Christmas 1
58 Settlement Creek near Christmas
59 Taylor Creek near Cocoa 1
60 Tootoosahatchee Creek near Christmas
61 Wekiva Springs near Apopka 5
62 Witherington Spring near Apopka 1


Table 8 gives the ranges in quality of surface water at selected
sites in and near the county.
Many of the data on surface water are presented as flow-
duration curves, stage-duration curves, flood-frequency curves,
and low-flow frequency curves.
Flow-duration curves (figures 14 and 15) are cumulative
frequency curves that show the per cent of time specified discharges
were equaled or exceeded during a given period. In a strict sense
flow-duration curves apply only to the period in which the data
used to develop the curve were obtained. Flow-duration curves
are useful for predicting future flow distribution only if the data
used represent the long-term distribution and if the climate and
basin characteristics remain unaltered. Flow-duration curves
based on less than 5 years of record were adjusted on the basis of
concurrent records at a nearby site having a long-term record. The
curves were thus made more representative of the longer periods.
Flow-duration curves were estimated for the sites having only a
few periodic observations by correlating these observations with
concurrent data for nearby stations where data were complete.
The shape of a flow-duration curve indicates the physical
characteristics of the basin it represents. A curve that is steep









* wo-- -^--^a --

2 o--- --a ---S:_- -
3P:": -^^:


5. Boggy reek near Taft (October 1959 to September 1962)
adjusted to (October 1935 to September 1962).

6. Shingle creek at airport near Kissimmee (October1958 to September
1962) ad used to (October 935 to September 1962).

7.Little Eceaockhatchee Rivernear Union Park (October 1959 to5eptem'-
S ber 1962) adjusted to(October 1935 to September 1962).

8. Cypress Creek at Vinelond October 1945 to September 1962),


L S John RiverwnearChristmas (October 1934 to Sepltmber 1962).

S.St. Johns Rivw near Cocoa (Oclober 1953 to Septmber 1962),
adjusted to October 1934 to September 1962).

SEcrdoahotlchee River near Chuluoo (October 1935 to September 1962).

4.Wehiva Rivernear Sonford (October 1935 to September 19621.


2
o


- -- 05
---3


'\ lM2


40 50 60 70 80 90 95 .98. 99 995 99.89999.95
PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN


99.99


20 30


FiRure 14. Duration curves of daily flow for streams in and near


w:--- \ ^s.--"^ S --- -- --- ---- -- ------ - --~ ---





100
10 10-0-- -- ^^ ^ ^ -- -- -- -- -- --







.ol-- I I I -. 1 -- ----- %" -\ I -- --- --- I=- to-- 'a


4


IW i .- 1 IV I


10 20 50 40 50 60


001 005 0.2 0 5. 0 I





C~a~a~-r~--- _.~~~ ~ ............~ ......._ .. .... -... ~..~..~ ~~__-~--r~u~----- ...






REDUCTION


RATIO


4x










TABLE 8. RANGE IN QUALITY OF SURFACE WATER IN ORANGE COUNTY, FLORIDA

(Chemical Analyses in parts per million, except specific conductance, PH, and color)
II II II I M ,


So arce


I0 B3og Creek near Taft
13 Econloekharchee River nr. Bithlo
13 E-onlockhatchee River nr. Chuluota
1 Ear: Lake near Narcoossee
25 .oahns Lake at Oakland
3 Lake Apopka at Winter Garden
iJS Lake MairLand at Winter Park
25 Lir:e E-onlockhatchee River near
Union Park
a Rock Springs near Apopka
35 Sc. Johns River near Christmas
; t. Johns River near Cocoa
::D Shingle Creek near Vineland
51 V-akiva Springs near Apopka


Period
of
Record


11/59-7/63
10/59-7/63
5/53-7/58
10/54-7/63
10/59-7/63
10/59-7/63
10/59-7/63

1/60-7/63
4/56-7/63
9/52-7/63
10/53-9/63
11/59-7/63
4/56-6/62


21
34
36
17
4
5
5

25
7
47
170
22
5


0.8-10
.0- 8.9
1.7-12
.5- 4.1
.0- 1.6
5.1-15
.0- .9

.3-11
8.2-10
.2-11
.0-16
.0- 8.8
8.9-11


.01-.33
.02-.50
.01-.60
.00-.31
.01-.18
.01-.27
.00-.04

.01-.66
.00-.35
.00-.43
.00-.49
.03-.73
.00-.42


3.8-8.8
2.6-26
3.6-51
1.7-8.8
7.2-8.0
28-38
18-24

5.4-16
27-30
7.5-162
8.4-136
2.8-21
28-30


8
ao

E
.3
g

J
==
s


0.7-4.3
.2-27
1.0-14
.5-2.9
2.9-6.1
8.8-13
4.9-6.8

.6-4.8
7.1-9.7
2.2-77
2.1-56
.5-3.9
7.7-10


5.5-14
1.8-15


.7-112
.9-11
10-20
8.4-23
9.3-14

5.2-16
3.9-5.1
11-621
12-454
4.7-35
4.7-5.4


0.8-2.8
.2-1.5


6.0-8.0
3.3-13
3.7-5.2

.2-2.4
.3- .7

.0-14
.0-5.1
.4- .8


9- 34
8- 83
10-112
3- 13
7- 13
104-186
57- 72

9- 51
94-105
21-138
21-136
5- 62
103-123


1.2-6.4
.0-6.4
1.0-58
.2-16
26-42
15-20
24-31

1.2-6.8
16-18
2.0-364
2.5-156
.0-19
6.0-12


9-18
3.0-23
8.0-179
7.5-16
18-24
16-25
15-20

9.5-20
5.0-8.0
20-1150
21-900
8.0-37
7.0-8.5


a


0.1-0.7
.0- .8


.1- .3
.4- .6
.1- .5

.0- .4
.0- .3
.0- .5
.0- .7
.1- .5
.1- .3


0
z

a


Dissolved solids


Calculated


0.0- .9 29-73
.0-1.3 16-108
.0-14 32-468
.0-1.4 20-52
.0- .4 77-111
.9-3.7 149-229
.0-2.8 104-131

.0- .8 35-75
.0-2.7 121-129
.0-2.8 57-2350
.0-5.3 67-1760
.0-4.3 25-150
.0-2.7 123-134


Residue


59-134
32-163


114-146
206-285
128-154

69-146
123-140
-2830
103-2320
53-168
131-139


Hardness as CaCO,


Calcium Non-
Magnesiuml carbonate


13- 30 0-14
8- 74 0-19
13-162 5-71
9- 31 6-20
30- 44 20-38
106-150 0-25
65- 88 22-32

16- 48 4-20
102-110 19-25
28-720 11-672
30-570 9-494
12- 66 0-19
104-114 11-24


0
C4

4o


,a
0-


55-121
24-1971
55-873
38-110
150-202
333-385
195-230

58-146
212-223
110-4060
107-35002
48-268
215-240


a
0
"s
(_


4-210
35-400
40-600
30-170
25- 80
20- 45
5- 10

20-400
0- 10
45-220
45-280
45-200
0-5


6.2-8.0
5.7-7.8
6.2-7.6
5.4-6.3
5.8-6.5
7.0-7.9
6.6-7.6

5.6-8.0
6.8-7.8
6.3-7.5
6.4-7.7
5.7-7.8
7.3-7.6


I I %


i I


i


I


I


I


I


-


I I I i I I I









WATER RESOURCES OF ORANGE COUNTY


oeo i o g oQ i e to ie o 3o oeo
IQOO0 ==
-00 1 \ .. ...




w=oo ,. = ==
SJim GreCft ne hrists,

%oe, ===- == =^--^ == =^== 4, Reedy Gfeek ow Vinelond,
--- -= f=@=y o r

10^v- =-




^ -= --- r^ -^ ----- IB%
aN 1
\ ,'l ,


5 hingle Geek near Vinelond,

6, gennet l eeN@ ne@f Vineland,

?, WOkivo Spfinug neor Anepka,

8 Rock Spfino_ nwef AeeO t,


^ \\
==
___=
___ = -
_it~Z~ 'j=


PERCENT OF TIME DISCHARGE EQUALED OR EXCEED0E THAT SHOWN
Figure 16. Estimated flow-duration curves for streams and springs for
which periodic or miscellaneous discharge data are available.


throughout its range indicates a highly variable stream having
little or no surface storage or ground-water storage. A curve with
a flat slope throughout its range indicates the release of water
from surface- or ground-water storage which tends to equalize the
flow. A curve that flattens out at its lower end indicates the
release of ground-water storage at low flow. A curve that flattens
at its upper end indicates release of storage from lakes or swamps
at high flow.
Flow-duration curves are useful for water power, water supply,
and pollution studies.
Stage-duration curves (figure 16) present stage data in the
same way flow-duration curves present flow data. The limitations







42 REPORT OF INVESTIGATIONS NO. 50


'o02 -- ILake Butler at Windermere (1941-63),


S- -_ -. 2, Johns Lake at Oakland (1959-63) adjusted to
(1941-63),

94 -- -
3, Bass Lake near Orlando (1959-63) adjusted to
21 (1941-63),


e. 4 Lake Corrine near Orlando(1943-49) (1959-63)


84 5,Lake Sllvr at Orlando(1959-63) adjusted to
:: I (1941-63),


G 6. Lake Conway at Pine Castle (1952-63).


7,Lake Apopka at Winter Garden (1942-63),


S_8 Lake Moitland at Winter Pork(1945-52)(1959-63)


S' 9,Lake Francis near Plymouth (1959-63) adjusted
4 ...to (1941-63),


10 Lake Dora at Mount Dora (1942-63).






SO -12,Lake Hart near Norcoossee (1941-63),


f -13.Lake Poinsett near Cocoa (1941-63),


2- 14,Lake Cone near Christmas (1933-63) records for
0 10--= 00 St0. Johns River near Christmas,
O 1o 20 30 40 O 60 70 80 0 90 100
PuRCENT OF TIME ALTITUDE UALeD OR EXCLDEOD THAT SHOWN

Figure 16. Stage-duration curves for selected lakes.






WATER RESOURCES OF ORANGE COUNTY


in the use of flow-duration curves for predicting future flows are
applicable to the prediction of future stages by use of stage-
duration curves based on short records can be adjusted to longer
periods by correlation with records for a long-term station. This
has been done for the stage stations established for this
investigation.
Knowledge of the magnitude and probable frequency of floods
is essential to the proper design and location of water-related
structures such as dams, bridges, culverts, levees, etc., and any
other structures that may be located in areas subject to periodic
flooding. Such knowledge is also useful in solving problems
associated with flood insurance and flood zoning.
Because flood-frequency information is often needed for
locations where no flow data are available, methods have been
devised that permit determination of the probable magnitude and
frequency of floods at any point along a stream.
Methods of determining the probable magnitude and frequency
of floods of recurrence intervals from 1.1 to 50 years on streams in
Orange County are given in U. S. Geological Survey Water-Supply
Paper 1674 (Barnes and Golden, 1966).
Because of the importance of stage in floods on the main stem
of the St. Johns River, stage-frequency data are presented in
the form of water-surface profiles for floods of recurrence intervals
of 2.33, 5, 10 and 30 years (figure 17). These profiles are for the
reach between the southern Orange County line and State
Highway 46.
A low-flow frequency curve shows the average interval between
the recurrence of annual low flows less than the indicated values.
Curves for durations of 7, 30, 60, 120, and 183 days, 9 months, and
1 year are given. These curves are useful in determining whether
the natural flow of a stream is adequate for a particular
development and, if not, how much the natural flow must be
augmented from storage or some other source. In Orange County
only the St. Johns River, the Econlockhatchee River, and the
Wekiva River has sufficient low flow to warrant analysis.

SURFACE DRAINAGE

Surface water from the southwestern 341 square miles of
Orange County drains southward into the Kissimmee River.
Surface water from the eastern and northern 662 square miles of
the county drains northward into the St. Johns River. Figure 18













1 vr =,- ,,....




,,,-___ _..._ i ___,,_ __ ,
o14o a ,

A Ja






-II









i DISTANCE IN MILES ALONG MAIN STEM OF ST. JOHNS RIVER i,
,' Figure 17. Water-surface profiles for floods of selected recurrence intervals ", ".*. : ,,
"__________________^ on main stem of St. Jo1--- River in Orange County.
8, ~:

5. 1 15-2025 0 3
DITNEI IE LN AI TMO T ON IE
Fiue1.Wtrsraepoie o loso eetdrcrec nevl
stmo S.Jl -Rve nOrneCony











S 81000' 55'


ORANGE COUNTY
EXPLANATION
- Major Drainage Divide
-- Tributary Drainage Divide
-...... High-water Line from Profile Gages
_L_ Cities and Towns
Surface Water Data Collection Point
A Quality-of-water Data Collection Point,Surface Source
19 Station Number Refers to Figure 13 and Table 7,8,11 and 12


e'Cf-J71" R tf


0 1 2 3 4 5 6 7 8 9 10 miles
I ^ I I 1 1 I


Figure 18. Drainage basins and.surface-water collection points.


80050'
-I 28*50'


25'


_1


2 1 11



























































































































































d
r






WATER RESOURCES OF ORANGE COUNTY


shows the drainage basins and the surface-water data-collection
points in Orange County.
Parts of some of the basins delineated on figure 18 are closed
basins that do not contribute direct surface runoff.
The efficiency of a stream in removing surface water from the
land is closely related to the average slope of its bed. During the
flood of March 1960, rainfall on Jim Creek basin above State
Highway 520 (drainage area 22.7 sq mi) and on Boggy Creek
basin above the station near Taft (drainage area 83.6 sq mi) was
about the same. Even though the contributing area of Boggy
Creek is more than three times that of Jim Creek, its peak flow
was only 3,680 cfs whereas that of Jim Creek was 3.750 cfs. This
anomaly can be explained in part by the reduction of the peak flow
on Boggy Creek by storage in lakes and swamps. It is due mostly,
however, to the fact that the slope of Boggy Creek (3 feet per
mile) is about half that of Jim Creek. Streambed profiles for most
of the streams in Orange County are included in this report.

KISSIMMEE RIVER BASIN

Reedy Creek

Reedy Creek drains 49 square miles in the southwest corner of
Orange County. The drainage from about 22 square miles of this
basin in Lake County flows into Orange County. The drainage
area above the gaging station near Vineland (station 54) is 75
square miles.
Land surface altitude in Reedy Creek basin in Orange County
ranges from 75 feet above msl at the southern county line to 210
feet at Avalon fire lookout tower. The eastern part of the basin
consists of relatively flat swampy terrain interspersed with islands
of low relief. The western part consists of rolling hills interspersed
with lakes and swamps. The divide between Reedy Creek basin
and Bonnet Creek basin to the east is rather indefinite, and there
is some interchange of water between basins. Figure 19 shows a
profile of the bed of Reedy Creek.
At Reedy Creek near Vineland (station 54, 1 mile south of the
county line, the minimum flow observed was less than 0.01 cfs in
May 1961. The maximum flow was 1,910 cfs at the peak of the flood
in September 1960.
The average flow of Reedy Creek near Vineland is estimated to
be 55 cfs or 0.73 cfs per square mile. Average yearly runoff from




































DISTANCE FROM COUNTY LINE, IN MILES

Figure 19. Streambed profiles for selected streams in the upper
Kissimmee River basin.






WATER RESOURCES OF ORANGE COUNTY


the entire basin is estimated to be 10 inches. Average yearly runoff
from the western part of the basin is probably less than 4 inches
and that from the eastern part 14 inches or more. Curve No. 4
(fig. 15) is the estimated flow-duration curve for Reedy Creek near
Vineland. Note that the variability in flow (the steeper the slope
of the duration curve the more variable the flow of a stream) is
less during the upper 10 per cent of flow than during the middle
80 percent. This is due to the storage effect of lakes and swamps
which tends to distribute high flow over a longer period of time.
The stream is dry about 10 percent of the time.
Analyses of water collected from Reedy Creek at station 54
at low flows on June 15, 1960 and May 23, 1961, show the water
to be very soft and low in mineral content. At almost zero flow on
May 23, 1961, the hardness was 11 ppm and the mineral content,
based on a conductivity measurement, was estimated to be 24 ppm.
The low mineral content in the water indicates Reedy Creek
probably does not receive very much ground-water inflow.

Bonnet Creek

Bonnet Creek and its tributary, Cypress Creek, drain 55 square
miles of Orange County, east of Reedy Creek basin. The part of
the Bonnet Creek basin that is drained by Cypress Creek differs
hydrologically from the rest of the basin.
Land surface altitude in Bonnet Creek basin ranges from abut
75 feet at the county line to 195 feet near Windermere. Altitudes
in the western part of the basin, the part excluding Cypress Creek
basin, range from about 75 to 130 feet. This area is mostly flat
and swampy but it contains several lakes of moderate size and
islands of low relief. Figure 19 shows profiles of stream beds in
Bonnet Creek basin.
The minimum flow observed at Bonnet Creek near Vineland
(station 48), 1 mile south of the county line, was 0.4 cfs in May
1961 and the maximum flow was 1,180 cfs at the peak of the flood
in September 1960.
The average flow at station 48 is estimated to be 33 cfs or
0.60 cfs per sq. mi. Average yearly flow from the entire basin is
estimated at 8.1 inches. Prorating this yield between the 30 square
miles of Cypress Creek basin, for which the gaged yield is 4.4
inches, and the remaining 25 square miles of the western part of
the basin gives an average yield of 12.6 inches from the western
part. Curve 6 (figure 15) is the estimated duration curve for






REPORT OF INVESTIGATIONS NO. 50


Bonnet Creek. The upper part of the curve reveals the similarity
between Bonnet Creek and Reedy Creek basins. The lower part,
however, reveals that a base flow is maintained in Bonnet Creek
by ground-water seepage. It is unlikely that Bonnet Creek dries up
during even the most severe droughts.
The water in Bonnet Creek has a slightly higher mineral content
and less color at low flow than the water in most other streams in
the county. On November 24, 1959 the mineral content was 107
ppm, the hardness was 66 ppm and the color was 10 units. The
higher mineral content and lower color are caused by ground-water
inflow.
At high flow the water in Bonnet Creek has a low mineral
content, is soft, high in color and low in pH. At high flow on
July 24, 1963, the mineral content was 35 ppm, hardness 17 ppm,
color 400 units, and the pH was 4.5. The low mineral content was
caused by dilution by rain water runoff. The high color was caused
by organic material being flushed from swamps. Some of the
organic material is slightly acidic which lowered the pH to 4.5.
Water with a pH of 4.5 is corrosive.

Cypress Creek

Cypress Creek basin is comprised of about 8 square miles of
lakes, 2 square miles of swamps, and 22 square miles of rolling
hills in the eastern part of Bonnet Creek basin. Altitudes range
from 90 feet at its junction with Bonnet Creek to 195 feet near
Windermere.
The flow from Cypress Creek has been gaged at Vineland
(station 15) since 1945. The annual runoff averaged 4.4 inches and
ranged from a minimum of 0.27 inch in 1962 to a maximum of 17.72
inches in 1960. During the 18 complete years of record, flow ceased
at least once in each of 13 years. The longest period of no flow
was 107 days in 1956. The maximum flow recorded was 354 cfs in
September 1960. Curve No. 8 (figure 14) is the duration curve for
Cypress Creek. The flattening of the slope at its upper end indicates
the stabilizing effect of the large lakes in this basin. Cypress Creek
is dry about 10 per cent of the time.
At high flow on July 24, 1963 the water in Cypress Creek was
similar in quality to the water in Bonnet Creek. The mineral
content was 32 ppm, hardness 18 ppm, color 450 units, and the pH
was 4.4. No analytical data is available on the water in Cypress
Creek at low flow.






WATER RESOURCES OF ORANGE COUNTY


Shingle Creek

Shingle Creek drains 83 square miles of Orange County west
of U. S. Highway 441 and south of State Highway 50.
Altitudes range from 70 feet at the county line to 175 feet near
Windermere. The basin is relatively flat and altitudes are generally
less than 105 feet except for rolling hills on the western fringe. A
closed depression occupies 3.3 square miles of the northern part of
the basin. Figure 19 shows a profile of the bed of Shingle Creek.
Continuous records of stage and discharge for Shingle Creek
near Kissimmee (station 38) have been obtained since October
1958. The average flow during the period October 1958 to
September 1963 was 62.9 cfs. The long-term average is estimated
to be 52 cfs, or 0.60 cfs per square mile, by comparison with records
for Econlockhatchee River near Chuluota. Periodic observations
of stage and discharge near Vineland (station 39) have been
obtained since September 1959. The average flow here is estimated
to be 27 cfs or 0.60 cfs per square mile. The unit values of runoff
at the two sites show the hydrologic characteristics of the basin
to be homogeneous. Average yearly runoff from the basin is about
8 inches. The maximum discharge during the period of record at
station 38 was 3,320 cfs and at station 39, 1.740 cfs, both in March
1960. In most years, there is no flow for many days at either site.
Curve No. 6 (figure 14) is the adjusted flow-duration curve for
station 38 and curve No. 5 (figure 15) is the estimated flow-
duration curve for station 39. The similarity in the shape of the
two curves is another indication of the homogeneity of basin
characteristics. The fact that Shingle Creek is dry about 20
percent of the time points up the poorly developed state of its
channel which is not incised deeply enough to intercept the water
table when ground-water levels are low.
The water in Shingle Creek near Vineland (station 39) generally
has a low mineral content and is soft. At low flow, however, the
mineral content is as high as 150 ppm and the water is moderately
hard, 66 ppm, which indicates that ground-water inflow occurs in
this stream. At high flow the pH was low (5.7) and the color was
high. The iron content was as high as 0.73 ppm. Some of the iron
probably combines with organic compounds in the color. The
relatively high sodium (35 ppm) and chloride (37 ppm) indicates
pollution as the ground water in the area is generally less than 10
ppm in chlorides and low in sodium. Table 7 shows the ranges in
quality for 22 water analyses from November 1959 to July 1963.






REPORT OF INVESTIGATIONS NO. 50


Boggy Creek

The Boggy Creek drainage basin includes 86 square miles of
the county in and south of Orlando. An area of about 11 square
miles in the upper part of the basin has no surface outlet and
drains underground.
Altitudes range from 60 feet at the county line to about 125
feet in the upper basin. The lower part of the basin is flat and
contains many swamps and marshes but relatively few lakes.
The upper part of the basin is rolling hills interspersed with many
lakes. Figure 20 shows a profile of the bed of Boggy Creek.
Periodic measurements of the discharge of Boggy Creek near
Kissimmee (station 9) were made from January 1955 to September
1959. Since September 1959, continuous records of the discharge
of Boggy Creek near Taft (station 10) have been collected. The
maximum discharge during the period of record was 3,680 cfs in
March 1960, and the minimum was 0.1 cfs in June 1961. Average
discharge for the period October 1959 to September 1963 was 54.2
cfs at station 10. Comparison of this record with records for
Econlockhatchee River indicates a long-term average of 48 cfs
or 0.57 cfs per square mile. Average yearly runoff is 7.7 inches.
The fact that this average yield, like that of Reedy, Bonnet, and
Shingle Creeks, is less than the average for the state as a whole
may be attributed to the relatively larger proportion of non-
contributing area in the basin. Curve No. 5 (figure 14) is the
adjusted flow-duration curve for station 10. Comparison of the
curve with that for station 38 shows the basins to have similar
characteristics except that base flow is higher at station 10. This
higher base flow may be attributed to a slightly better channel
development and extensive canalization in the basin.
The water in Boggy Creek is soft, low in mineral content and
high in color. At station 10 the water hardness ranged from 13 to
30 ppm, the mineral content from 29 to 73 ppm, and color from 40
to 210 units. The analytical data on water from this station
indicates that most of the water is direct surface runoff. Table 8
gives the ranges in water quality for 21 analyses from November
1959 to July 1963.























o
Ij
C)

0


Figure 20. Streambed profiles of Boggy Creek and Jim Branch.






REPORT OF INVESTIGATIONS NO. 50


Jim Branch

Jim Branch drains 5.8 square miles in the south-central part
of Orange County. Altitudes in the basin range from 75 to 85 feet.
Figure 20 shows a profile of the bed of Jim Branch.
The maximum flow of Jim Branch near Narcoossee (station
51) has not been determined. A dry stream channel has been
observed at station 51.
Water collected from Jim Branch on May 23, 1961, was very
soft (9 ppm) and low in mineral content (30 ppm, estimated from
its conductivity).

Ajay-East Tohopekaliga Canal

This canal drains approximately 171 square miles, of which
54.5 square miles are in Orange County and 116.5 square miles are
in Osceola County.
Altitudes of the drainage area in Orange County range from 60
to 90 feet. The topography is fairly flat and is characterized by
swamps in the northern part and by lakes in the southern part.
Periodic measurements of the flow in Ajay-East Tohopekaliga
Canal near Narcoossee (station 2) have been made since 1942. The
maximum measured discharge was 1,420 cfs in March 1960. A
reverse flow of 0.25 cfs was measured in February 1946. The
average discharge, based on the relation between drainage area
and average discharge at several points on the main stem of the
Kissimmee River, is estimated to be about 170 cfs or 1.0 cfs per
square mile.
The flow into Orange County from an area of 111 square miles
in Osceola County has been measured in Myrtle-Mary Jane Canal
near Narcoossee (station 31) since November 1949. The maximum
flow into the county via this canal was 990 cfs in September 1960.
In September 1956, the flow reversed for 2 days and flowed out
of the county at the rate of 17 cfs. The average discharge in this
canal for the period of 1950 to 1963 was 109 cfs or 0.98 cfs per
square miles. Average annual runoff is 13.6 inches at station 2
and 13.3 inches at station 31. This indicates fairly uniform yield
from all parts of the basin. Curve 2 (figure 15) is the estimated
flow-duration curve for station 2 and figure 21 is the flow-duration
curve for station 31. The flatness of the upper parts of these curves
indicates the large amount of storage in the lakes and swamps in
this basin.







WATER RESOURCES OF ORANGE COUNTY


I1


0.1
0.01


0.050.10.2 0.5 I 2 5 10 20 30 40 50 60 70 80 90 95
PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN


Figure 21. Flow-duration curve for Myrtle-Mary Jane Canal near Narcoossee.



Water from Ajay-East Tohopekaliga Canal, collected at station
2 during low flow on May 23, 1961, was very soft (16 ppm), and
low in mineral content (39 ppm, estimated from its conductivity).


ST. JOHNS RIVER BASIN


St. Johns River


The St. Johns River is the eastern boundary of Orange County.
Small tributaries drain 174 square miles of Orange County directly
to the St. Johns River. An additional 490 square miles of the county
are drained to the St. Johns River by tributaries which flow across
the county line from the south before joining the main stem.


I I I II I I I I I I I I I I\


000 I I-
700-1----- 1 1
500 Period of record'
October 1950 to September 1962
300-------
200---

100
70 -_FLOW TO NORTH
50
50----- ----- --- -- --- -------

30 -1--
20

NOTE.--No flow 2,87 percent of time
10 OTH.-- --- -- _
7 \
5-

3-
2


07 --- FLOW TO SOUTH
0.5

0.3
0.2!


1






REPORT OF INVESTIGATIONS NO. 50


The average slope of the St. Johns River is less than 0.3 of a
foot per mile in its approximately 26-mile reach along the border
of Orange County. At flood stages, the river falls from an altitude
of about 17.5 feet at Lake Poinsett to about 10.5 feet at the
northern county line. At the minimum stages in 1945, the river
fell from 8.0 feet to minus 0.4 foot in this reach. Figure 17 shows
probable flood altitudes for the St. Johns River for selected
recurrence intervals.
Stage and discharge records have been collected at St. Johns
River near Christmas (station 35) since December 1933 and at
St. Johns River near Cocoa (station 36) since October 1953. The
average discharge for the period of record at station 35 was 1,379
cfs. For the 10-year period October 1953 to September 1963, the
average discharge at station 35 was 1,463 cfs; and at station 36,
1.237 cfs. The maximum flow during the period of record at station
35 was 11,700 cfs in October 1953. There was no flow at station
35 for periods during March, April, and June 1939. Average yearly
runoff is 13.2 inches at station 35 and 12.8 inches at station 36.
The slightly higher yield at station 35 may be due partly to the
absence of lakes, where evaporation losses are high, and partly
to upward seepage of artesian water in the area between the two
stations. Curves 1 and 2 (fig. 14) are flow-duration curves for
stations 35 and 36. As indicated by the curve, about 99 percent
of the time flow at station 35 exceeds that at station 36 but 1
percent of the time evaporation and transpiration demands on the
river exceed the seepage into the river causing a loss in flow
between the stations. Figure 22 shows the magnitude and
frequency of annual minimum flow for selected durations at
station 35.
Analyses of water collected daily from the St. Johns River near
Cocoa (station 36) from October 1953 to September 1960, and a
continuous record of its conductivity since June 1959 show that the
quality of the water varies greatly. Table 8 gives ranges for the
various dissolved constituents.
Except for color the quality of the water in the St. Johns River
near Cocoa is good during normal and high flows. During droughts
when low flows occur, the water in the St. Johns River becomes
highly mineralized. During extended droughts, as occurred in 1962,
very little water flows into the St. Johns River above the Wekiva
River. Most of the low flow comes from seepage of highly
mineralized artesian water from the Floridan aquifer. Along the
reach of the river adjacent to Brevard County, the Floridan aquifer







WATER RESOURCES OF ORANGE COUNTY


3000

2000
Drainage area: 1418 sq. mi.
Average flow: 1379 cfs
a 1000 --
Zo






2 200
m3 flows \ 41 ofs

10


5. 50 --- -- --- --- --- -- 10 1 3-- 0 -- -
R R LOW-FLOW FREQUENCY IN Y
Example: For a 10-year recurrence
interval the 7-day minimum flow o ,n
20 h is 22.5 cfs and the l-year mini-
mun flow is 415 cfs ss w e

I 10


1.05 1.1 1.2 1.5 2 3 4 5 7 10 15 20 30
RECURRENCE INTERVAL IN YEARS
Figure 22. Low-flow frequencies for St. Johns River near Christmas.


is overlain by a thin aquiclude (impervious formation) through
which there is considerable leakage. In addition, there are many
wells heavily pumped for irrigation, and the excess water flows
through drainage ditches to the St. Johns River. Many artesian
wells flow wild along the banks of the river. Consequently, during
extended droughts the mineral content of the water in the St. Johns
River above the Wekiva River approaches that of the highly
mineralized artesian water.
The water in the St. Johns River was very highly mineralized
during the drought in the spring and early summer of 1962. Figure
23 shows a chloride profile of the river from headwaters to Green
Cove Springs from May 29 to October 24, 1962. This extended
reach of the river is shown for comparative purposes. Figure 23







56 REPORT OF INVESTIGATIONS No. 50



sA?



S -- -River


""oL o t
ORKANGCE, Q 1 s,',Sr .S'
.COUN TY low


















Figure 23. Chloride concentration in St. Johns River, northeastern Florida.


variable, especially from the headwaters to State Highway 46 and
in the lower reaches where salt-water encroachment occurs. At
'000 1-$Go
























analyses of water in the St. Johns River on June 7, 1962 at State
Highways 520 (station 36), 50 (station 5), and 16.
Highway 50 was caused by more ground-water inflow. The high
























concentrations of dissolved minerals at 'State Highway 16 are
*i I |
<0: I I I'I --'n.















caused by dilution from relatively fresh spring flow.
Figure 23. Chloride concentration in St. Johns River, northeastern Florida.

shows that the quality of the water in the St. Johns River is highly
variable, especially from the headwaters to State Highway 46 and
in the lower reaches where salt-water encroachment occurs. At
low flow the most abundant constituent in the water is chloride,
but sodium, sulfate, calcium, and magnesium are also present in
high concentrations. Table 9 presents a comparison of the chemical
analyses of water in the St. Johns River on June 7, 1962 at State
Highways 520 (station 36), 50 (station 35), and 16.
The increase in concentration from State Highway 520 to State
Highway 50 was caused by more ground-water inflow. The high
concentrations of dissolved minerals at'State Highway 16 are
caused by sea-water encroachment. The lower concentrations at
low flow between the Wekiva River and U. S. Highway 17 are
caused by dilution from relatively fresh spring flow.
As the rainy season began in late June 1962, the flow in the
St. Johns River increased and the quality of the water improved.








WATER RESOURCES OF ORANGE COUNTY


TABLE 9. CHEMICAL ANALYSES OF ST. JOHNS RIVER WATER,
JUNE 7, 1962.

Analysis State Highway State Highway State Highway
(ppm) 520 50 16

Chloride 900 1,150 2,050
Sodium 454 606 1,270
Sulfate 150 248 315
Calcium 136 160 196
Magnesium 56 77 79
Hardness 570 716 814


As indicated by figure 23, the quality of the water in the headwaters
improves early with increased flow, but remains poor downstream
until the highly mineralized water stored in the lakes is flushed
out. The chloride concentrations in the water on October 24, 1962
indicate that most of the highly mineralized water was flushed
from the river.
Figure 24 shows a cumulative frequency curve of specific
conductance of the water-the percent of time the specific






I O


400

20


S40 ----------N6--------I9




| 10---- --- -- == -

05 1 2 5 10 20 3040 50 60 70 80 90 95 98 99995 999 99.99
PERCENT OF TIME SPECIFIC CONDUCTANCE WAS EQUALED OR EXCEEDED
Figure 24. Cumulative frequency curve for specific conductance of the
St. Johns River near Cocoa, October 1953 September 1963.








58 REPORT OF INVESTIGATIONS NO. 50

conductance equals or exceeds values shown-in the St. Johns
River near Cocoa from October 1953 to September 1963. For
example, the conductance was 3,000 or greater for 2 percent of the
time during the period of record. Figure 25 shows the relation of
specific conductance to sodium, hardness, chloride and mineral
content in water of the St. Johns River near Cocoa.
By using figure 24 in conjunction with figure 25 the percentage
of time that the various constituents would exceed a given value
can be estimated. For example, from figure 25, if the chloride
content was 250 ppm, the specific conductance would be about 1,020
micromhos. From figure 24 a conductance of 1,020 micromhos or
greater would occur about 18 percent of the time.
From October 1953 to September 1963, the mineral content and
chloride concentration in water in the St. Johns River near Cocoa
exceeded the U. S. Public Health Standards for drinking water
during the following periods: April 21 to September 10, 1956;
June 21 to July 31, 1961; October 13, 1961 to August 21, 1962;


4,000


3,5 0 /, --- --

3.00HARDNESS

00 SODIUM C-- / ORIDE MINERAL CONTENT
CHLORIDE







2000
2.000










500

0 --- -- -- -


800 1,000
PARTS PER MILLION


1200


1,400


1,600


Figure 25. Relation of specific conductance to hardness, chloride, sodium, and
mineral content for St. Johns River near Cocoa.


1,800


--








WATER RESOURCES OF ORANGE COUNTY


and June 20 to July 31, 1963. This would be about 15 percent of
the time in the 10-year period of record.
A spectrograph analysis for minor elements was made on water
collected from the St. Johns River near Cocoa at low flow on
May 11, 1962. The results in micrograms per liter are given in
Table 10. Micrograms per liter can be converted to ppm by dividing
by 1,000. The symbol > indicates that the concentrations are less
than the values shown which are the lower limits of detection.

Small Tributaries Draining To East

The eastern part of the county between the main stem of the
St. Johns River and the Econlockhatchee River, amounting to
about 180 square miles drains to the St. Johns River by numerous
small tributaries. Table 7 shows data pertinent to these tributaries.
Figure 26 shows profiles of the beds of several of the small
tributaries.
The hydrologic characteristics of all these small streams are
probably similar to those of Jim Creek. Curve 3 (fig. 15) is the
estimated flow-duration curve for Jim Creek near Christmas
(station 24). The relative straightness of this curve indicates the
small amount of storage both on the surface and in the ground in
this area. Its steepness is indicative of the extreme variability
associated with steep bed slope and absence of storage. As indicated
by the curve, streams in this area are dry about 20 percent of the
time. The average flow at station 24 is estimated to be 26 cfs or


TABLE 10. MINOR ELEMENTS IN WATER FROM ST. JOHNS RIVER
NEAR COCOA ON MAY 11, 1962.
(Quantitative results in micrograms per liter. The symbol < indicates
concentrations are less than the values shown which are the
lower limits of detection)

Aluminum 66 Germanium < 0.29
Beryllium < 0.57 Manganese < 1.4
Bismuth < 0.29 Molybdenum < 1.4
Cadmium < 1.4 Nickel 1.9
Cobalt < 1.4 Lead < 1.4
Chromium < 1.4 Titanium < 5.7
Copper < 1.4 Vanadium 0.54
Iron 5.1 Zinc < 5.7
Gallium < 5.7






































4 5 6 7 8 9 10 II 12 13 14
DISTANCE FROM ST, JOHNS RIVER, IN MILES

Figure 26. Streambed profiles of small streams draining east into
St. Johns River.






WATER RESOURCES OF ORANGE COUNTY


1.15 cfs per square mile. Average runoff from the area is estimated
at 15.6 inches.
During the low flow period from June 14 to 17, 1960, the
dissolved mineral content in the water in the small tributaries
draining eastward into the St. Johns River was estimated from
conductivity measurements to range from 33 ppm in Taylor Creek
to 86 ppm in Second Creek. The mineral content in the water in
Christmas Creek was estimated on basis of its conductivity, to be
52 ppm on May 24, 1961, when the other small tributaries were dry.

Lake Pickett

Lake Pickett and its contributary drainage area occupy 8.1
square miles. Mills Creek drains Lake Pickett to the Econlock-
hatchee River. Altitudes in the Lake Pickett drainage basin range
from 60 to 75 feet.
The hardness of the water in Mills Creek at Chuluota (station
53) on May 24, 1961, was 7 ppm and the mineral content, estimated
from its conductivity, was 21 ppm. The pH of the water was 5.9
indicating that it is slightly corrosive. The water quality of Lake
Pickett is similar to that of Mills Creek.

Econlockhatchee River

The Econlockhatchee River drains 117 square miles of Orange
County. The width of drainage basin ranges from 2.5 to 9.5 miles
with the average in Orange County being 6.2 miles. The basin is
about 14 miles east of Orlando and spans the county from south to
north. The drainage from 17 square miles of the basin in Osceola
County enters Orange County. Altitudes in the Econlockhatchee
River basin in Orange County range from 20 to 90 feet. Figure 27
shows profiles of the beds of Econlockhatchee River and several of
its tributaries.
The Econlockhatchee River basin and the area drained by small
tributaries to the St. Johns River are unusual for Orange County
in that they contain only three lakes of significant size. These
basins do, however, contain many swamps and marshes.
Continuous records of the flow of the Econlockhatchee River
near Chuluota (station 19) have been collected since 1936, and
periodic measurements of the flow of the Econlockhatchee River
near Bithlo (station 18) have been made since September 1959.
The maximum flow of record at station 19 was 11,000 cfs and at





































5 6 7 8 9 10 11 12 G 14 16 r7 s8 1 20 21 22 23 24 25 26 27 28
DISTANCE FROM COUNTY LINE, IN MILES

Figure 27. Streambed profiles of Econlockhatchee River and selected
tributaries.







WATER RESOURCES OF ORANGE COUNTY


station 18, it was 7,840 cfs, both in March 1960. The minimum
flow at station 19 was 6.7 cfs in June 1945. The river flow ceases at
station 18 in most dry years. The average flow at station 19 was
275 cfs or 1.06 cfs per square mile for the period 1936 to 1963.
The estimated average flow at station 18 is 88 cfs or 0.74 cfs
per square mile. Runoff from the part of the basin above this
station is estimated to be 10 inches per year. Average runoff from
the entire basin above station 19 is 14.4 inches per year. Runoff
from the area above station 26 on Little Econlockhatchee River is
estimated to be 10 inches per year. Prorating the 10 inches of
runoff from the 146 square miles above stations 18 and 26 with the
14.4 inches from the 260 square miles above station 19 gives an
average yearly runoff from the intervening 114 square miles of 20
inches. About 11/ inches (11 cfs) of the 10-inch increase in runoff
from the lower basin over runoff from the upper basin is accounted
for by the effluent from Orlando's sewage plant. The remaining 8.5
inches is accounted for by higher base flow resulting from
ground-water seepage into the more deeply incised channel in the
lower basin and possibly upward seepage of artesian water. Curve
3 (fig. 14) is the flow-duration curve for station 19 and curve 1
(fig. 15) is the estimated flow-duration curve for station 18. Note
the similarity in the shape of the curves up to 50 percent duration
when direct runoff is the main source of flow. Above 50 percent
the curve for station 18 falls off rapidly to no flow at 75 percent
reflecting the absence of base flow whereas the curve for station
19 continues on at about the same slope reflecting the base flow
supplied by the sewage effluent and ground-water seepage.
Low-flow characteristics of Econlockhatchee River at station 19
are shown by figure 28. The streamflow indicated by these curves
is somewhat more than occurs within Orange County.
A continuous record of conductivity from October 1959 to June
1962 and analyses of water collected periodically to July 1963 from
the Econlockhatchee River near Bithlo (station 18), show the water
to be high in color, soft, and low in mineral content. Table 8 gives
the ranges of mineral constituents from October 1959 to July 1963.
The color is always greatest during the early part of high-flow
periods. The pH of the water was as low as 5.7 during high-flow
periods which indicates that the water would be slightly corrosive.
The high percentage of calcium bicarbonate detected during
low-flow periods indicates that ground-water inflow may occur.
Figure 29 shows a cumulative frequency curve of specific
conductance of the water in the Econlockhatchee River near Bithlo







REPORT OF INVESTIGATIONS NO. 50


I I I


I I I


70


50




30


Drainage area 260 sq.mi.
Average flow: 277 cfs

I LI I I


1.01 1.05 I.I 1.2


-Th


1.5 2 3 4 5 7 10 15 20
RECURRENCE INTERVAL, IN YEARS


Figure 28. Low-flow frequencies for Econlockhatchee River near Chuluota.


1000


LOW-FLOW FREQUENCY
00 'Example: For a IO-year recurrence
Interval the 7-day minimum flow .
is 12.5 cfs and the I-year minimum
0 flow is 112 cfs




0
0-







0






0



0\
s o








P _(0_)__ -- _


0
z 20
0
2o
U
(,



UJ
Q-


U
z
I-

W


_ _


* y\








WATER RESOURCES OF ORANGE COUNTY


6,000 I I I I -1 1--
6,009



4,000 --








600

400


_OO .... --



100


05 2 ( I I 2) 3) 4) 5 3


90 95


98 99 9R5


999 9999


PERCENT OF TIME SPECIFIC CONDUCTANCE WAS EQUALED OR EXCEEDED
Figure 29. Cumulative frequency curve of specific conductance of the
Econlockhatchee River near Bithlo, October, 1959 May, 1962.

from October 1959 to May 1962. Figure 30 shows the relation of
specific conductance to hardness and mineral content for the
Econlockhatchee River near Bithlo. Hardness and mineral content
were the only properties of the water that could be related to the
specific conductance for the Econlockhatchee River. The sodium,
chloride, and sulfate content is usually very low. By using figure 29
in conjunction with figure 30, the percentage of time that hardness
and mineral content would exceed a given value can be estimated.

Little Econlockhatchee River

The Little Econlockhatchee River drains 71 square miles of
Orange County east of Orlando. Altitudes in this basin range from
about 35 feet near the county line to 127 feet at the eastern edge
of Orlando. Figure 27 shows a profile of the bed of the Little
Econlockhatchee River.
A few lakes exist along the western rim of the basin but none
exist elsewhere. Many swamps and marshes temporarily store
water and thereby reduce the magnitude of peak flows in the river.


--







REPORT OF INVESTIGATIONS NO. 50


V 'II / /






HARDNESS
1 20
I o ---- -/ -- ----- --- ---- -
MINERAL CONTENT

I


0 1



0 -- /f


20 10 20 30 40 50 60 70 80 90 I00 110
PARTS PER MILLION
Figure 30. Relation of specific conductance to hardness and mineral content
for Econlockhatchee River near Bithlo.

The flow from the upper 27 square miles of the basin has been
gaged since October 1959 at Little Econlockhatchee River near
Union Park (station 26). The maximum and minimum flows at this
station were 1,640 cfs in March 1960 and 0.1 cfs in June 1961. The
average flow of the period October 1959 to September 1963 was
24.5 cfs.
The long-term average is estimated to be 20 cfs or 0.74 cfs per
square mile. Average runoff from the area above station 26 is
estimated at 10 inches per year. Curve 7 (figure 14) is the
flow-duration curve for station 26. The steepness and straightness
of this curve indicate a highly variable stream in a basin having
little surface or ground-water storage.
Analyses of water collected from the Little Econlockhatchee
River at station 26 show that the quality is similar to that of the
Econlockhatchee River. Table 8 gives ranges of concentrations and
properties of water in Little Econlockhatchee River.







WATER RESOURCES OF ORANGE COUNTY


Howell Creek

Howell Creek drains about 20 square miles in Orange County,
mostly in the suburban areas of Maitland, Winter Park, and the
northern half of Orlando. Altitudes in the Howell Creek basin
range from about 55 to 125 feet.
This basin contains a chain of lakes connected by natural
channels, canals, and culverts, beginning at Spring Lake at Orlando
(station 42), at an altitude of about 88 feet and ending at Lake
Maitland at Winter Park (station 28), at an altitude of about 66
feet. Several other lakes are connected to the chain of lakes by
canals or culverts. Lake Underhill at Orlando (station 45), in the
Boggy Creek basin, is connected to Lake Highland in the Howell
Creek basin by a culvert.
The flow of Howell Creek near Maitland (station 50) has been
measured several times. The maximum discharge of record as
determined from the stage-discharge relation was about 160 cfs
in September 1960. Flow at this site ceases when the level of Lake
Maitland is below about 65.5 feet with the center board of the
control out or about 66.0 feet with the center board in. The levels
of many of the lakes in the basin are partly controlled by drainage
wells and the flow from the basin is accordingly modified.
The average flow at station 50 is estimated to be 40 cfs or 2
cfs per square mile. Runoff is estimated to average about 27 inches
per year; more than half of the average annual rainfall. This yield
is much greater than elsewhere in the county despite the high
percentage of area covered by lakes from which the loss by
evaporation probably approaches the total rainfall on the lakes and
water discharged to the aquifer through drainage wells. This high
yield is due to the large percentage of area covered with pavement
and roofs from which runoff is a high percentage of rainfall.
Figure 31 shows estimated flow-duration curves for station 50. The
percentages indicated are for the time the control was in one or
the other of the conditions indicated and not for the total period
of record. A record of board changes is not available, so a
consolidated flow-duration curve cannot be prepared.
The water in Howell Creek and Lake Maitland are similar and
are of good quality except for moderate hardness which indicates
ground-water inflow. Hardness at high and low lake levels was 65
and 88 ppm, respectively. Table 8 gives ranges for other dissolved
constituents and properties of the water in Lake Maitland.







REPORT OF INVESTIGATIONS NO. 50


160


140
0
z
0
La 120
01--

100





z
U.







< 40
'I,
0


2 5 10 20 30 40 50 60 70 80


90 95


PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN

Figure 31. Estimated flow-duration curves for Howell Creek near Maitland.

Wekiva River

The Wekiva River and its tributaries, the Little Wekiva River
and Rock Springs Run, drain about 130 square miles in Orange
County. Altitudes in this basin range from about 15 feet at the
northern county line to about 195 feet near Windermere. Figure 32
shows profiles along the beds of streams in the Wekiva basin.
The area near the stream channels is flat and swampy, and
ranges in altitude from about 15 to 30 feet. From the edges of
these flat swamps, rolling hills rise abruptly to altitudes ranging
between 60 and 100 feet. More than half of the Wekiva River
basin in Orange County consists of rolling hills interspersed with
lakes and sinks. There is no surface outflow from this area.
Records of the daily stage and discharge of the Wekiva River
near Sanford (station 46) have been collected since October 1935.
The topographic drainage area at this station is about 200 square
miles. The average discharge for the period 1935-63 was 276 cfs.


FOR PART OF TOTAL
TIME WHEN CENTERBOARD
WAS NOT IN PLACE



FOR PART OF TOTAL
TIME WHEN CENTERBOARD
WAS IN PLACE


0051I 02 05 I







WATER RESOURCES OF ORANGE COUNTY


ALTITUDE, IN FEET ABOVE MEAN
A 8 8


LEVEL


COUNTY LINE











8 I




-STATE HIGHWAY 434


-Withrington Springs



o 3 STATE HIGHWAY 436
PREVATT LAKE
LAKE CORONI
_, STATE HIGHWAY 43!
\ -LAKE McCOY
STATE HIGHWAY 435
RIVERSIDE ACRES
S--- U.S. HIGHWAY 441-



o \ -_U.S. HIGHWAY 441

-LAKE WEKIVA


P
In


-LAWNE LAKE

STATE HIGHWAY 50

I ______________ _______________


Figure 32. Streambed profiles for Wekiva River and tributaries.

The maximum discharge was 2,060 cfs in September 1945 and the
minimum, 105 cfs in June 1939.
Curve 4 (figure 14) is a flow-duration curve for station 46.
The flatness of this curve indicates the small amount of surface
inflow in relation to the very high base flow of this stream. The


2

co
0
m


0-

0
0
a
2


r


z
m



In





REPORT OF INVESTIGATIONS NO. 50


average flow at this station is the same as that at Econlockhatchee
River near Chuluota (station 19), yet the peak flow is less than
one-fifth that at station 19 and the minimum flow about 16 times
that at station 19. At station 46, the maximum flow is only 20
times as great as the minimum flow while at station 19, the
maximum flow exceeds the minimum flow by more than 1,600 times.
This great difference in variability is due to the fact that about
one-third of the rain that falls on Wekiva River basin and nearby
areas seeps downward into the artesian aquifer where it is stored
until released slowly through many springs whereas little of the
rain that falls on Econlockhatchee seeps into the artesian aquifer
but instead remains on or near the surface from where about
one-fourth of it runs off very rapidly. Figure 33 gives low-flow
frequency curves for Wekiva River.

500 -.----.-.



365 days Average flow: 275 cfs
/273 days
400 1 83 days
S \ l 20 days LOW-FLOW FREQUENCY
S60 days Example: For a 10-year recurrence
S30 days interval the I-day minimum flow is
CL
\ / 139 cfs and the 365-days minimum
300-- -flow is 221 fs
u
U A

-C


near Sanford.


1.01 1.1 1.2 1.5 2 3 4 5 7
Recurrence interval in years
Figure 33. Low-flow frequencies for Wekiva River






WATER RESOURCES OF ORANGE COUNTY


The flow of Rock Springs, Wekiva Springs, and Witherington
Spring (stations 56, 61, and 62) near Apopka in the Wekiva River
basin have been measured occasionally since 1931. Table 11 shows
the results of these measurements.
The average flow from Wekiva Springs is estimated to be 74 cfs
and from Rock Springs, 60 cfs. Curves 7 and 8 (figure 15) show
flow-duration for Wekiva Springs and Rock Springs, respectively.
The extremely flat slope of these curves is due to the small variation
in flow characteristic of ground-water sources.
The quality of water from Rock and Wekiva Springs is similar
to that of the ground water in the area, and it varies only slightly
with flow. Table 8 gives ranges of dissolved constituents and
properties of the water in Rock and Wekiva Springs.

Apopka-Beauclair Canal

This canal drains Lake Apopka and the surrounding areas. The
total area drained by the canal is about 180 square miles, of which
about 120 square miles is in Orange County. Altitudes in this basin
range from about 65 feet in the mucklands adjacent to Lake
Apopka to 225 feet near Lake Avalon.
The flow in Apopka-Beauclair canal near Astatula was measured
periodically at station 3 from 1942 to 1948. Since July 1958 the
daily flow has been determined at station 4. During the period
of record, the maximum flow at station 4 was 754 cfs in March
1960 and the minimum flow was estimated to be about 1 cfs during
periods when a control structure in the canal was closed. The
average flow at station 4 during the period 1958-63 was 118 cfs.
Flow-duration curves and flow-frequency curves have no signifi-
cance at this station because of the artificial regulation of the
flow; therefore none are given.
The quality of the water in Apopka-Beauclair canal is similar
to that in Lake Apopka. The water quality of Lake Apopka is
discussed under the following section on lakes, swamps, and
marshes:

LAKES

OCCURRENCE

Orange County has about 1,100 permanent bodies of open water
ranging from small water-filled sinks to widening of stream









TABLE 11. DISCHARGE MEASUREMENTS OF SPRINGS IN ORANGE COUNTY, FLORIDA.

Downstream location
Discharge of measuring section
Name of spring and Date of in relation to head
station number measurement (cfs) (mgd) of spring (feet)


Rock Springs (56)
















Wekiva Springs (61)


2- 5-31
3- 8-32
2-10-33
1-30-35
11- 7-35
12- 6-35
1- 4-36
1- 4-36
6- 7-45
5- 9-46
4-26-56
11-24-59
11-24-59
6-17-60
10-17-60
5-25-61

3- 8-32
2-10-33
11- 7-35
6- 7-45
5- 9-46
4-27-56


55.9
51.9
54.2
62.8
57.1
62.8
54.9
56.2
52.5
59.1
54.7
70.0
72.4
78.2
83.2
68.4

63.9
66.9
72.5
64.8
67.5
62.0


36.1
33.5
35.0
40.6
36.9
40.6
35.5
36.3
33.9
38.2
35.4
45.2
46.8
50.5
53.8
44.2

41.3
43.2
46.9
41.9
43.6
40.1


50
50
40
80
50
500
600
60
50
30
1,000
150
1,200
1,250
1,250
1,300

100
100
300
200
150
200




TABLE 11. CONTINUED


Witherington Spring (62)


11-25-59
6-17-60
10-17-60
5-25-61

8- 8-45
10-19-60


300
200
150
150


4,200
4,750






REPORT OF INVESTIGATIONS NO. 50


channels. Lakes occur in all parts of the county, but the vast
majority of them are in the western half.

SURFACE AREAS

The surface areas of lakes in Orange County range from less
than one acre for some sinkhole lakes to 31,000 acres for Lake
Apopka. The area of a lake continually changes. If the range in
stage of a lake is large and its shores slope gently, changes in its
area are large. If the range in stage is small or if the shore is
steep, changes in area are small.

DEPTHS

The shallowest of the permanent lakes in Orange County is
Lake Poinsett. This lake was only 2-feet deep when it was at its
lowest level in 1945. The deepest body of water in the county is
Emerald Spring, a sinkhole near Little Lake Fairview. Emerald
Spring was sounded to a depth of 334 feet.
Depth contours for 73 selected lakes in Florida were shown by
Kenner (1964). Six of these lakes are in Orange County.

ALTITUDES

At its lowest level, Lake Cone, a widening of the St. Johns
River, was only about 2 feet above msl. A small lake near Tangerine
is shown on the U. S. Geological Survey topographic map to be at
an altitude of 158 feet.
The altitude of a lake's surface seldom remains constant very
long. Figure 16 shows the percent of time that specific altitudes
were equalled or exceeded for selected lakes in Orange County.

SEASONAL PATTERNS IN LAKE-LEVEL FLUCTUATIONS

Lake levels fluctuate in response to the net differences between
rainfall and evaporation with modifications by surface- and
ground-water inflow and outflow. Table 1 shows the monthly
averages and extremes of rainfall at Orlando and figure 34 shows
the estimated monthly averages of evaporation from lakes in
Orange County. Average monthly evaporation from lakes in Orange
County was computed by multiplying average pan evaporation at
Orlando as determined by the Weather Bureau by monthly
coefficients determined from evaporation studies at Lake










WATER RESOURCES OF ORANGE COUNTY


8






7






6



V)
w

5
z


z



O
i-


0
w' 3

w


J F M A M


J A S 0 N D


Figure 34. Estimated average monthly evaporation from lakes.


Okeechobee between 1941 and 1946 (Kohler, 1954). Departures

of lake evaporation from average are small in comparison to
departures from average in rainfall. Figure 35 shows the monthly
average change in stage of three lakes in Orange County in

comparison with the monthly differences in the average rainfall
and average evaporation. In general, when the difference is


~y?)~:l,.'. Lj"

.:;..r;.ii ~"~


"* ~~PI." g~r
ri-.
r .
r .
.1.
-
-?r-1' :'
., *'r;L. '~
*- ,~
...,.,
-6 r: .
~~~
I*~ c-~ Jl
v-r-r I.xr*''

..I 'I i f







0.4


0.3

0,2

S0.1
c
J 0.0
w- oo
z
S--0.1

-0.2

-0.3

-0.4
w
| 0.3
w
W 0.2
U.
0z 0.1
I
(j o,o



S-0.I

D ,

w -0,1
uj -O


Figure 35. Comparison of average monthly change in stage of three lakes
with average monthly difference in rainfall and evaporation at Orlando.


B-LAKE BUTLER M-LAKE MAITLAND


JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.


A-LAKE APOPKA