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Water resources of Indian River County, Florida ( FGS: Report of investigations 80 )
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 Material Information
Title: Water resources of Indian River County, Florida ( FGS: Report of investigations 80 )
Series Title: ( FGS: Report of investigations 80 )
Physical Description: x, 75 p. : ill., diagrs., maps ; 23cm.
Language: English
Creator: Crain, Leslie J
Hughes, Gilbert Homer ( joint author )
Snell, L. J ( Leonard John ), 1907-
Publisher: State of Florida, Division of Resource Management, Bureau of Geology
Place of Publication: Tallahassee ;
Publication Date: 1975
 Subjects
Subjects / Keywords: Water-supply -- Florida -- Indian River County   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Leslie J. Crain, G. H. Hughes, and L. J. Snell.
Bibliography: Bibliography: p. 75.
 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 - 000222000
oclc - 02048815
notis - AAY9242
System ID: UF00001267:00001

Full Text






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STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Harmon Shields, Executive Director



DIVISION OF RESOURCE MANAGEMENT
Charles M. Sanders, Director



BUREAU OF GEOLOGY
Charles W. Hendry, Jr., Chief



REPORT OF INVESTIGATIONS NO. 80



WATER RESOURCES OF
INDIAN RIVER COUNTY, FLORIDA



By
Leslie J. Crain, G. H. Hughes, and L. J. Snell



Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
BUREAU OF GEOLOGY
FLORIDA DEPARTMENT OF NATURAL RESOURCES
and the
BOARD OF COMMISSIONERS, INDIAN RIVER COUNTY
and the
CITY OF VERO BEACH


Tallahassee, Florida
1975














DEPARTMENT
OF
NATURAL RESOURCES



REUBIN O'D. ASKEW
Governor


BRUCE A. SMATHERS
Secretary of State



PHILIP F. ASHLER
Acting Treasurer



RALPH D. TURLINGTON
Commissioner of Education


ROBERT L. SHEVIN
Attorney General



GERALD A. LEWIS
Comptroller



DOYLE CONNOR
Commissioner of Agriculture


HARMON W. SHIELDS
Executive Director








LETTER OF TRANSMITTAL


Bureau of Geology
Tallahassee
August 28, 1975


Governor Reubin O'D. Askew, Chairman
Florida Department of Natural Resources
Tallahassee, FL 32304

Dear Governor Askew:
The Bureau of Geology of the Division of Resource Management, Florida
Department of Natural Resources, is publishing as its Report of Investiga-
tions No. 80, a study, "Water Resources of Indian River County," by Leslie
J. Grain, G. H. Hughes, and L. J. Snell, of the U. S. Geological Survey.
This study is to document the water resource potential in an area where
substantial growth is anticipated. This type of regional study is most im-
portant to the planning of the development of the county, as it enables one to
realistically anticipate the quantity and quality of the water resource which
may be developed and where potential problems can be expected to occur.
It is hoped this type of study will be of substantial benefit to those persons
and agencies responsible for the conservation of the resource.

Respectfully yours,
Charles W. Hendry, Jr., Chief
Bureau of Geology














































Completed manuscript received
May 19, 1975
Printed for the
Florida Department of Natural Resources
Division of Resource Management
Bureau of Geology

Tallahassee
1975



iv






FOREWORD


At the time of his death in January 1972, Leslie J. Crain was engaged
in conducting an investigation of the water resources of Indian River County.
He had completed all field investigations, and had started writing the report.
Two of his colleagues, G. H. Hughes and L. J. Snell, volunteered to complete
the report. As a result of Les Crain's scholarly and professional manner in
carefully laying out the groundwork for this report, Messrs. Hughes and Snell
were able to complete the report much in keeping with his views. They have
done a creditable job-one we think Les Crain would have been pleased with.


Clyde S. Conover
District Chief, Water Resources Division
U.S. Geological Survey, Tallahassee, Florida








CONTENTS
Page
Abstract 1___ ..........
Introduction _________ .__...........8..... 3
Purpose and scope 3
Approach 3 .. .-....-....... 3
Water utilization and problems ... ......................... ...... 5
Population and economy .5..... ......... ...... 5
Previous investigations .. .... 7
Well numbering system ....... 7
Acknowledgments ........ 8
Physical setting of the area ..____ .......-............... 8
Location _____________..... 8
Topography and drainage 8
Climate __________. 10
Geology ... ... ........... 13
Formations ___._..._....___...........15
Hydraulic character of the rocks ............ ......................... 16
Hydrologic cycle ..-,......18
Ground-water hydrology .... .. ....... ........... .... 18
Shallow aquifer ... ... ..... ..... ..... ............ 18
Recharge ............... .... .......21
Discharge ._ .,.. ._ 25
Potential development ..... .... ... ......... ................................... 25
Floridan aquifer -.. .. ........ ...... ..... ............. .. 26
Recharge and discharge ..._. ............26







CONTENTS (continued)

Page
Surface-water hydrology ..... .......................... ....... ..... .... .. ........ .................. 1

St. Johns M arsh ................... .................... ....................... ... ..... ... .. ....... ............... 81

Drainage Districts ..................... ............................... .. .... 5

Indian River Farms Drainage District .................. .. 85

Fellsmere Farms Drainage District .................... ............ .. 38

St. Johns Drainage District ................ 39......... .. .. .

Sebastian River Drainage District ........ ............................ ...... 41

Surface water summary ..................... ................ .. .. ..... 42

W ater quality ...... .......... ...................... ......... ... ......... ...... .......................... .... 43

Chemical quality of ground water ......................... ......... .... ... 43

Shallow aquifer ......................... ......... ..... 43

Floridan aquifer .... .... ..................... ............... ...................... .... .......- 47

Salt-water encroachment .... .. ................ .................. ....... ............... .. 54

Chemical quality of surface water ..... .............. ....................., .. 58

St. Johns Marsh ... .............................. ...... ................ 58

Drainage districts............................... ... .. .......... .. ................. ....... ............. .. 59

W after use ............... .. ... .................................................. .......... ...... ....... 70

Conclusions .. ........... ....... ..... .. ..... ....... 72
References ................... .. .... .......... .................. .... ... ................. ............ ................. 75







ILLUSTRATIONS

Figure Page
1. Map showing the location of Indian River County and explana-
tion of well numbering system-.... .......... ... ..... 4
2. Map of Indian River County showing location of some of the
wells inventoried, and gaging stations; chloride concentrations
shown for shallow-aquifer wells only ..........-....... ................ 6
3. Block diagram showing generalized physical features and geo-
logic formations of Indian River County (Faults and strati-
graphy from Bermes, 1958) .. .. ..... 9
4. Photograph of St. Johns Marsh and clearing operations in
Indian River County ...... .. ........ .................................................. 11
5. Photograph of young citrus grove, drainage ditches and pump-
ing station in reclaimed m arsh land ........................... .................... ............ 12
6. Graphs showing annual precipitation, cumulative departure
from average, and monthly distribution for 1941-70 at Vero
B each ......... ........... .... ...... ......... ..................... ................ 13
7. Generalized section of geologic formations in Indian River
County (Stratigraphy from Bermes, 1958) ....................................... 14
8. Block diagram of Indian River County showing principal aqui-
fers, movement of ground water, and the hydrologic cycle.......... 17
9. Map of Indian River County showing the potential yields of
wells tapping the shallow aquifer ........................ .... ................ 19
10. Fence diagram, or hydrologic sections, in shallow aquifer in
the Vero Beach area ............................. .. 20
11. Lithologic sections of shallow aquifer north and west of Vero
B each ... .. ... .... ....... ....... ......... ...................................- ........ 21
12. Hydrographs of wells tapping the shallow aquifer at Winter
Beach and Vero Beach, and rainfall at Vero Beach for 1970......... 23
13. Map showing altitude of top of the Floridan aquifer in Indian
River County (Faults by Bermes, 1958; and Vernon, 1951.)...... 27
14. Map showing contours on potentiometric surface of Floridan
aquifer in Indian River County in May 1970..... .............................. ....... 29
15. Hydrographs of two wells in Floridan aquifer in Indian River
Farms Drainage District ..... .. .............................. ......................... 30
16. Map showing contours on potentiometric surface of Floridan
aquifer in Indian River County in October 1951 ................................ 32
17. Graph showing month-end level of St. Johns Headwaters near
Vero Beach and Blue Cypress Lake, 1956-70 ..... ..................................... 33
18. Stage-duration curves for St. Johns Marsh and Blue Cypress
Lake _. .._........ .............................................. 34
19. Map showing magnitude and direction of flow in drainage
canals at selected points in Sebastian River and Indian River
Farms Drainage Districts, May 5-8, 1969 ............................................ 36
20. Graph showing combined monthly discharges of North, Main,
and South Canals, in Indian River County, 1956-70 ....................... 37
21. Graph showing average of lowest mean discharge during given
number of consecutive days of climatic year of North, Main,
and South Canals for periods before (1952-54) and after (1956-
65) gated-control structures were installed .........-................ 39


viii
Vill







ILLUSTRATIONS (Continued)
Figure Page
22. Flow-duration curves for selected canals in Indian River
C county ................................................... .................................... ............. ............ ...... 40
23. Graph showing relation between monthly discharge of Fells-
mere canal and combined monthly discharges of North, Main,
and South Canals, 1956-67 .......... ...................... 41
24. Map showing chloride concentration of water in wells of in-
dicated depths in the Floridan aquifer in Indian River County... 48
25. Chloride concentration of water from wells in Floridan aqui-
fer along section A-A' in northern Indian River County, 1968-
70 (see fig. 24 for location of section) ............ ..................... ................. 49
26. Chloride concentration of water from wells in Floridan aqui-
fer along section B-B' in southern Indian River County, 1969-
70 (see fig. 24 for location of section) ................................................. 50
27. Graph showing relation of chloride concentration to depth of
well in Floridan aquifer, Indian River County ..................................... 52
28. Map showing water levels in shallow aquifer in vicinity of
Vero Beach well field, April 22, 1971..... ........................ ...................... 55
29. Map showing water levels in shallow aquifer in vicinity of
Beach well field, July 23, 1971 ...................... .............. .. .... .. 5
30. Map showing chloride concentration of water in shallow aqui-
fer near Vero Beach, April 8, 1970 and April 22, 1971 ........... 58
31. Graph showing relation between specific conductance of water
and concentration of selected chemical constituents in water
of canals in Indian River County ................................................................... 62
32. Duration curve for specific conductance of water in Main
Canal at V ero B each ..... .......................................... ......................................... ..... 63
33. Graph showing daily discharge and specific conductance of
water in Main Canal at Vero Beach during a relatively dry
spell in A pril and M ay 1969 ................................................................................. 64
34. Graph showing daily discharge and specific conductance of
water in Main Canal at Vero Beach during a relatively wet
spell in September-November 1969 ................. ................ ..................... 65
35. Map showing specific conductance and chloride concentration
of water in drainage canals at selected points in Sebastian
River and Indian River Farms Drainage Districts, May 6-8
19 6 9 ....................................................... ............................................... 6 6
36. Map showing specific conductance of water in drainage canals
at selected points in Sebastian River and Indian River Farms
Drainage Districts from field determinations on October 8,
1969 ............................................................... ... ......................................................... ............. 6 7
37. Map of Sebastian River and Indian River Farms Drainage
District showing areas in citrus and in improved pasture in
1968, based on information from U. S. Soil Conservation
S service .................. ............. ............... .. ......... .......................................................... 68
38. Graph showing estimated water use and population for Indian
River County ..... ....... ............. ............... .. ................ ... ........ .. 71







TABLES

Table Page

1. Yearly discharge of selected canals in Indian River County....... 38

2. Chemical analyses of ground water in Indian River County 44

3. Chloride concentration in water from wells in the shallow aqui-
fer in Indian River County, 1968-71 .... 45

4. Chloride concentration in water from wells in the Floridan
aquifer in Indian River County, 1967-71 __51

5. Chemical analyses of surface water and rainfall in Indian River '
County 60, 61






CONVERSION FACTORS


Multiply English unit
feet (ft)
inches (in)
miles (mi)
square miles (mi2)
gallons per minute (gal/min)
cubic feet per second (ft3/s)
cubic feet per second
per square mile [ (ft3/s) /mi2]
gallons (gal)


By To obtain metric unit
0.3048 metres
25.4 millimetres
1.609 kilometres
2.590 square kilometres
6.309 x 10 2 litres per second
2.832 x 10 2 cubic metres per second
cubic metres per second
1.093 x 10 2 per square kilometre
3.785 litres









WATER RESOURCES OF INDIAN RIVER COUNTY


by
Leslie J. Crain, G. H. Hughes, and L. J. Snell



ABSTRACT


Indian River County, on the Atlantic coast in southern Florida, includes
525 square miles, most of which is less than 50 feet above sea level. About
half the area is developed; pasture and citrus groves predominate. The popula-
tion tripled during 1950-70, from 11,872 to 35,992, and is expected to more
than triple again by the year 2000. Water use, largely for agriculture, is
about four times the average per capital use in Florida. About 135 Mgal/d
(million gallons per day) was withdrawn in 1970 from ground- and surface-
water bodies in the county (not including saline water for thermo-electric
production); only 3 mgd was for public water supply. Withdrawals are ex-
pected to increase about 50 percent during the next 30 years to about 194
Mgal/d. About 23 Mgal/d of the 59 Mgal/d increase will be for public supply,
almost entirely from the shallow aquifer. Irrigation has been mainly from wells
in the Floridan aquifer, but the 36 Mgal/d increase in irrigation use is ex-
pected to come from surface-water sources.

Rainfall at Vero Beach averages 51.3 inches, almost two-thirds of it during
the summer and early autumn. Large streams do not exist. Runoff is to the
north through St. Johns Marsh into the St. Johns River basin and eastward
to Indian River through several improved channels and canals. Blue Cypress
Lake is the only large body of fresh water in the county; Indian River, the
lagoon between the mainland and an offshore bar, is at sea level and highly
saline.

A shallow aquifer consisting of sand, shell and some silt and clay, is
present in all of the county, its base reaching depths of 150 feet. The aquifer
is underlain by the Hawthorn Formation which acts as a confining bed to
retard upward movement of water from the underlying Floridan aquifer.
Water from the shallow aquifer is of good quality-chloride concentrations gen-
erally are less than 60 milligrams per litre; dissolved solids less than 500
milligrams per litre-and is the principal source for municipal and domestic
uses. Recharge is primarily from rainfall in the county. Within the drainage
districts the shallow aquifer receives some recharge of water withdrawn from
Floridan-aquifer wells for irrigation. The area of greatest potential well yield
-where the shallow-aquifer wells yield from 250 to 1,000 gallons per minute





BUREAU OF GEOLOGY


of good quality water-is in the eastern part of the county. This 100-square-
mile area lies east of a line that extends from a point 4 miles northwest of
Wabasso southwest to where State Road-60 crosses Ten-mile Ridge about 10
miles west of Vero Beach, and thence south to the county line. About 76
Mgal/d of water are estimated as available in that area from wells about 40 to
120 feet deep. Some additional water is available from the shallow aquifer in
other parts of the county where wells yield less than 250 gallons per minute.
Throughout the county the composition of the shallow aquifer varies con-
siderably. Discontinuous layers, or lenses, of cemented or otherwise imper-
meable materials are present near Indian River; these appear to act as
barriers to salt-water intrusion from the river. Extensive development of the
shallow aquifer for municipal water supply will require careful regulation of
land use to promote natural recharge to the aquifer and to maintain water
quality.
The Floridan aquifer underlies the county at a depth of 300 to 600 feet.
Recharge to the Floridan aquifer is almost entirely from the area west and
outside of the county. Discharge from the aquifer is from wells, primarily
for irrigation, and natural discharge to the ocean. Throughout much of the
county withdrawals of water for irrigation use appear to have caused a
decline of 10 to 15 feet in the level of the potentiometric surface of the
Floridan aquifer over a 20-year period (1951-70); however, part of the
apparent decline is attributed to seasonal rather than long-term effects. Water
levels appear to have stabilized toward the end of the period. A high chloride
concentration is the common objectionable characteristic of Floridan-aquifer
water in the county; in general, the concentration increases with the depth
from which water is withdrawn. In spite of its high chloride concentration,
the water has proved valuable; water having chloride concentrations as high
as 2,000/milligrams per litre has been used for irrigation. Withdrawals in-
creased from about 50/Mgal/d in 1951 to about 100/Mgal/d in 1970. On
the basis of the chloride concentration of water from Floridan-aquifer wells
sampled in 1951-52 and 1968-71, chlorides have increased in some wells and
decreased in others, but apparently have not changed appreciably over large
areas of the county. Past changes in chloride concentrations to some extent
may be obscured by seasonal bias in the data available for comparison. Sea-
sonal variations in recharge and in rate of withdrawals seemingly would affect
the comparability of the data collected at different times of the year. Chloride
concentrations probably will not increase significantly if the present rate of
withdrawal is maintained.
About 420 Mgal/d of surface water (non-saline) is available for develop-
ment in the county including 217 Mgal/d discharged into Indian River from
three drainage districts, 23 Mgal/d discharged into Indian River from the






REPORT OF INVESTIGATION NO. 80


area between the districts and the river, and 180 Mgal/d that moves north-
ward from St. Johns Marsh into St. Johns River. The drainage-district dis-
charge contains some excess Floridan-aquifer water from wells intended for
irrigation. The chloride concentration of the drainage-district discharge in
1970 averaged slightly less than 200 milligrams per litre, but varied widely
between wet and dry spells. Potentially, the surface-water supply is more than
ample to provide for the projected increase in irrigation use; however, most
of the surface water occurs as storm runoff that must be temporarily stored to
render it useful at a later time. St. Johns Marsh appears to be the likely place
to store large quantities of water if facilities are provided. Flood water from
drainage districts could be pumped into the marsh, stored, and pumped back
to the districts when needed. Water for the predicted increase in thermo-
electric cooling water requirements can, as at present, be obtained from the
almost unlimited supply of saline water in Indian River.

INTRODUCTION
Indian River County is in southern Florida, on the Atlantic Coast. Vero
Beach, the county seat, is in the eastern part of the county, on Indian River,
a saline lagoon between the mainland and an offshore bar. The water re-
sources of Indian River County are of vital importance to its economy and
development. An accurate assessment of these resources is necessary before
any realistic planning for development or for the future growth of the area
can be undertaken.

PURPOSE AND SCOPE OF THE INVESTIGATION
Recognizing the potential water problems of Indian River County, the
Board of County Commissioners entered into an agreement with the U.S.
Geological Survey in 1968 for a detailed investigation of the water resources
of the county. The specific purposes of this study were to: (1) ascertain the
nature and mode of occurrence of the ground- and surface-water resources of
the county; (2) determine the chemical quality of the surface and ground
waters; (3) determine what changes may take place in the chemical quality
of the water in both the Floridan and shallow aquifers as a result of the ac-
tivities of man; (4) delineate the area and potential yield of the shallow aqui-
fer; and (5) determine what alternative actions could be taken to protect or
increase the availability of the water resources of the county and what further
studies may be necessary. The location of Indian River County is shown on
figure 1.
APPROACH
As a part of the study, water levels were measured periodically in about
300 wells and water-level recorders were installed on three wells in the county.





BUREAU OF GEOLOGY


Figure 1.-Location of Indian River County and explanation of well number-
ing system.

Available well logs were collected. Test borings were made in the shallow
aquifer and several small-diameter wells were installed. Water samples were
collected for chemical analysis from all wells inventoried.
Streamflow was measured and water samples were collected at several
sites on the canal system. A recorder was installed to continuously monitor
the quality of water in the Main Canal at Vero Beach. Figure 2 is a map of
the Indian River County showing locations of surface-water gaging stations
and also some of the wells inventoried. Many data from existing reports and
from the current statewide data-collection program of the U.S. Geological
Survey, which maintains several stream gaging stations and observation wells
in Lhe county, were utilized to provide historical information on the hydrology
of the county and to discern trends that are taking place.
This report was prepared under the direct supervision of Joel 0. Kimrey,
Subdistrict Chief, and the general supervision of C. S. Conover, District Chief,
U.S. Geological Survey.


I / -RIVER
INDIAN RIVER COUNTY






REPORT OF INVESTIGATION NO. 80


WATER UTILIZATION AND PROBLEMS
Use of water in Indian River County for irrigation and for domestic
purposes is continually increasing. On the basis of inventories by the Florida
Department of Natural Resources (1970, p. 73-96) and the U.S. Geological
Survey (Pride, 1973), fresh-water use in 1965 was 117 Mgal/d and in
1970, 135 Mgal/d. The Florida Department of Natural Resources projected
freshwater demand as follows: 1980, 147 Mgal/d; 2000, 194 Mgal/d; and
2020, 245 Mgal/d. This projection indicates an average increase of 10 to 15
percent in water use every 10 years. The distribution of water used to irrigate
citrus groves and pastures for cattle, and other agriculture, and for do-
mestic and industrial supply will vary as land use changes. Consumptive use
is greatest when water is used for irrigation. Water is not unlimited; changes
in the utilization of water probably will occur as the quantity and quality
of ground water and surface water change.
One pressing problem in Indian River County is the limited availability
of potable water to meet future demands. The eastern part of the county is
now (1974) experiencing rapid development and population growth. Almost
all the potable water in the county is withdrawn from the shallow aquifer.
The total acreage of irrigated agricultural land has increased rapidly over
the last few years and is expected to continue to do so. Most of the water used
for irrigation is obtained from the Floridan aquifer and there is concern about
declining artesian pressure and increase in the salinity of the water. The
quality of the water is already marginal for many uses and further deteriora-
tion in its quality would be serious. Even if water draft should be transferred
from the Floridan aquifer to the shallow aquifer there is concern whether the
shallow aquifer will be able to supply future demands and whether salt water
from the Indian River will encroach into the aquifer as pumpage increases.
The surface waters of the county are being used for irrigation in increas-
ing quantities; their use for this purpose will probably surpass that of ground
water in the future. However, the continual drainage of wetlands, particularly
in the St. Johns Marsh, has reduced the amount of surface water in storage
in the county. The possibility also has been raised of using surface water to
supplement natural infiltration by artificial recharge to the shallow aquifer.
There is concern, however, over the quality of the surface water for this
purpose, particularly in the canal systems.

POPULATION AND ECONOMY
According to the 1970 census, the population of Indian River County
was 35,992. Vero Beach, the largest city in the county, had a population of
11,908. Except for the 813 people in Fellsmere, almost the entire population










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EXPLANA TIION
WELL, LO TERM
1,0 WELL, PROJECT, NUMBER IS 0
CHLORIDE CONCENTRATION, I TIT
ILLIGR ST. JOHNS DRAINAGE DISTRICT I
A AGING STATION. LONG TERM C I 0 0 0
A AGING STATION. PROJECT
- DRAINAGE DISTRICT BOUNDARY ./ I A I I Q 01
(APPROXIUATE) I B I I
- MAI CANAL OR DITCH I L (SI sLat darL r I I |
CO U I T L C I


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0
0
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Figure 2.--Map of Indian River County showing location of some of the wells
inventoried, and the gaging stations, chloride concentrations shown
for shallow aquifer wells only.


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REPORT OF INVESTIGATION NO. 80


is in the eastern part of the county within about 10 miles of the Atlantic
Coast. Although most areas in the eastern part of the county are still rela-
tively unpopulated, this region is expected to experience a very rapid popula-
tion increase in the near future.

Principal sources of income in the county are agriculture, tourism, and
manufacturing. Citrus is the most important agricultural product, at present
grown on about 50,000 irrigated acres. The county is noted for its high quality
citrus, particularly for the fresh fruit market. At present there are seven citrus
packing plants in the county. The next most important agricultural pursuit is
cattle raising, on 125,000 acres of which about 20,000 acres is improved
pasture.
Tourism is expanding at an accelerating rate as more accommodations
and attractions are being developed. Since such a large part of the county,
particularly the beach area, is undeveloped, the growth in this industry un-
doubtedly will be tremendous.

The largest manufacturing plant in the county is the Piper Aircraft Cor-
poration assembly plant in Vero Beach.


PREVIOUS INVESTIGATIONS

Most useful in the preparation of this report was a report by Bermes
(1958). Other reports that were valuable were those of Parker and others
(1955), Brown and others (1962), and Puri and Vernon (1964). Also of
considerable use in the study were the reports of Spier, Browning, and
Stephens (1964-70), Florida Department of Natural Resources (1970), and
the annual data and other reports by the U. S. Geological Survey and U. S.
Department of Agriculture.


WELL-NUMBERING SYSTEM

The well-numbering system used to catalog wells in this report is that of
the U. S. Geological Survey. It is based on the location of wells within a
1-second grid of parallels of latitude and meridians of longitude (fig. 1). In
this system a 16-character number defines the latitude and longitude of the
southeast corner of a 1-second quadrangle in which the well is located. The
first six characters of the well number include the digits of the degrees, mi-
nutes, and seconds of latitude, in that order. The six digits defining the lati-
tude are followed by the letter N, which indicates north latitude. The seven
digits following the letter N give the degrees, minutes, and seconds of longi-






BUREAU OF GEOLOGY


tude. The last digit, set off by a period from the rest of the number, is assigned
sequentially to identify wells inventoried within a 1-second quadrangle.

ACKNOWLEDGEMENTS
Several individuals and organizations contributed information and assis-
tance in the collection of data for this report. Mr. John Sellars, Superinten-
dent, Vero Beach Water Department, was very helpful in supplying informa-
tion on the Vero Beach Well Field and the city water supply. Mr. G. B. Britton
also supplied much information on the Vero Beach Well Field; and Mr. Jack
Jennings, County Administrator, cooperated with the field studies, particularly
in the test-boring program. Mr. John Amos, Indian River Farms Drainage
District; Mr. Floyd E. Boyer, Airport Director; and Mr. C. Reed Knight,
Knight Bros. Fruit Company, were also very helpful in the test-boring
program.
Several well drillers gave assistance, including the Layne-Atlantic Com-
pany and McCullars and Associates; Mr. Adger Smith, Mr. Henry McLaugh-
lin, Mr. Henry Cooper, Mr. Tom Marshall, and particularly Mr. Hubert
Pippin, who supplied numerous well logs and allowed access to his files for
information on several wells. Mr. Mike Carlton, Soil Conservation Service,
U. S. Department of Agriculture, supplied much information on soils, irriga-
tion wells, and agricultural land use; Mr. William Spier, U. S. Department
of Agriculture, provided data on hydrologic studies made in the eastern part
of the county; and Mr. H. "Flip" Lloyd, of Lloyd and Associates, provided
information on test wells and allowed use of a well for observation purposes.
In addition, many industries, private water suppliers, grove and ranch
owners, and homeowners in the county provided information on their wells
and permitted access to their property.

PHYSICAL SETTING OF THE AREA
LOCATION
Indian River County is located on the Atlantic Coast of Florida about
midway down the peninsula (fig. 1). The county has a land area of 525 square
miles. It is bounded on the north by Brevard County, the west by Osceola and
Okeechobee counties, and on the south by Okeechobee and St. Lucie counties.

TOPOGRAPHY AND DRAINAGE
Indian River County lies in the coastal lowlands, an area of low relief
representing several ancient marine terraces each marking the ocean bottom
at times when the sea stood higher than it does now. Two terraces, the Pam-
lico and the Talbot, are found in Indian River County (fig. 3) The Pamlico







REPORT OF INVESTIGATION NO. 80


TALBOT TERRACE


Figure 3.-Block diagram showing generalized features and geologic forma-
tions of Indian River County (Faults and stratigraphy from
Bermes, 1958)

terrace covers the area from the coast inland about 24 miles to the western
edge of St. Johns Marsh. Most of the terrace is less than 25 feet above sea
level. The terrace is broken by at least three distinct ridges: an offshore bar,
the Atlantic Coastal Ridge, and "Ten-mile Ridge." At the coast the present
beach area is an offshore bar which rises to a maximum height of about 20
feet above sea level. Behind the beach is the shallow Indian River Lagoon and
on the mainland is the Atlantic Coastal Ridge, which reaches altitudes of more
than 50 feet. The Atlantic Coastal Ridge is a remnant of an offshore bar that
was formed in the Pamlico sea. West of the coastal ridge is a flat or shallow
trough-shaped area that is analogous to the present Indian River. About 7
miles west of the coastal ridge is a less pronounced ridge named the "Ten-
mile Ridge" (Puri and Vernon, 1964, p. 13). West of this ridge is the broad,
flat area of the St. Johns Marsh. At the western edge of the marsh, which is






BUREAU OF GEOLOGY


at an altitude of about 25 feet, the land begins a gradual rise and at an alti-
tude of about 40 feet above sea level flattens to a surface representing the
Talbot Terrace. Cooke (1939) presents a detailed account of the geologic his-
tory and mode of occurrence of these features.
The low ridges have a great effect on the surface-water drainage of the
county, although in recent decades man has altered the drainage pattern. A
few small streams enter the western part of the county, including the
St. Johns Marsh, from the areas of higher altitude to the west. Although the
marsh represents the headwaters of the St. Johns River, it has no well defined
channels nor prominent streams and water bodies other than Blue Cypress
Lake. Natural drainage was to the north through the entire width of the marsh.
The area between the Atlantic Coastal Ridge and the Ten-mile Ridge was
swampy and lacked prominent stream channels other than the South Prong of
Sebastian Creek at the north. Drainage was generally northward although
during periods of high water some water drained eastward through gaps in the
Atlantic Coastal Ridge.
The surface-water drainage system has been altered by man-made drainage
and is. in fact, being altered continuously. The present system is complex.
Agricultural encroachment in the marsh is shown by figure 4, which is a
photograph of marsh and drainage operations, and figure 5, which is a photo-
graph of a young citrus grove with drainage ditches and a pumping station.


CLIMATE

The climate of Indian River County is humid and subtropical. Based upon
records of the National Weather Service for 1941--69, the mean annual air
temperature at Vero Beach airport is 22.50C (72.60F) and the mean annual
precipitation is 51.3 inches. The temperature at Fellsmere is similar to that of
Vero Beach. but precipitation averages about 6 inches greater. Frosts and
freezing temperatures are occasional in the coastal areas but occur nearly
every year inland. High afternoon temperatures generally exceed 320C
(900F) throughout the summer. More than 60 percent of the annual rainfall
occurs in the summer during thunderstorms; winter and spring are relatively
dry.
Although the mean annual air temperature seldom varies more than a
degree or two from year to year the annual rainfall may very 100 percent.
During 1911-70 the lowest annual precipitation was 32.7 inches, in 1961; the
highest was 67.0 inches, in 1968. Graphs of the annual precipitation and av-
erage annual distribution at Vero Beach, and the cumulative departure from
normal are shown in figure 6. Although rainfall for individual years varies






































Figure 4.-St. Johns Marsh and clearing operations in Indian River County.





































4
d


Figure 5.-Young citrus grove, drainage ditches and pumping station in re-
claimed marsh land.


"*^ I









REPORT OF INVESTIGATION NO. 80


W

z

Q 0




J a

10 r-


0D 0 I' 0
V. ID ID C&0 C( D(
M 0 a) 0) a)


Figure 6.-Annual precipitation, cumulative departure from average and
monthly distribution for 1941-70 at Vero Beach.




widely, the number of years with above or below normal rainfall are about

equal. The cumulative departure graph shows that wet and dry periods exist

but that there is no long-term trend during 1941-70.



GEOLOGY


The occurrence, movement, availability, quality, and quantity of ground

and surface water in Indian River County are closely related to its geology.

The county is underlain mostly by marine limestone, dolomite, shale, sand,

and anhydrite that range in thickness from about 5,500 to 12,000 feet in vari-

ous parts of east central Florida. Only about the top 1,500 feet of sediments

that have b'ien penetrated by water wells will be discussed in this report.


w
UJ
auj



i -
W

z-
Sa:
04
3 0-
>0
~LL








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0






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W
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BUREAU OF GEOLOGY


Formation Name ne Physical and Water-bearing Character
SF t(feet)


I jc Fasrtn Anastasia 3 Sand, shell, cloy, coquina, and mixtures. Yields
SFor i r t tn mationr 100-150 Z moderate amounts of water, depending on
i0 ol(wesm r* prt of oun) permeability of deposits.
( t e a prt of county)
of county) _________________


Undifferentiated deposits
[ Tmlami (?) Formation 1


Hawthorn
Formation


50-125


125-200


* I l
t Undifferentiated 0-200
S- I M I Oligocene rocks
___ tI_


SCrystal River
Formation

o Williston and
SInglis Formations
0


25-100


25-125


Avon Park 50-250
Limestone

! 1__________


300-400


Shell, sandy cloy, clay, and cemented zones.
Generally low permeability and water yield.




Sandy clay, green and brown clays, and some
limestones. Generally impermeable; poor water
yield except from some thin shell and limestone beds




Gray to cream-colored clayey, granular limestone.
Poor water yields.


Gray to cream-colored porous massive limestone;
generally yields good quantity of water.

Tan to cream-colored granular, porous limestone.
Water yields generally less than the Crystal River
Formation.




Cream-colored to tan soft porous limestone.
Yields water from porous zones in some areas


Cream-colored to ton porous, chalky limestone
and hard crystalline limestone and dense
dolomite. Dense zones poorly permeable; water
yields vary.


Not commonly topped by wells in Indian River
County.


Figure 7.-Generalized section of geologic formations in Indian River County
(Stratigraphy from Bermes, 1958.)


I


Lake City
Limestone


Oldsmar Limestone


---


-
---
-i;iLu
-
- -
--
--

c ---


I I
I I I


.. i- !j






REPORT OF INVESTIGATION NO. 80


FORMATIONS
The formations underlying Indian River County dip slightly southeastward
as shown in the block diagram in figure 3. They differ somewhat in composi-
tion and character and are the result of marine deposition during earlier
periods of the earth's history. Formations that are most commonly tapped by
wells in Indian River County are shown in figure 7.

Deposits of Pleistocene age, extending from land surface to depths of 100
to 150 feet are represented by the Anastasia and Fort Thompson Formations.
The Anastasia Formation is present along the coast and grades inland into
The Fort Thompson Formation in the vicinity of the Ten-mile Ridge. The
boundary between the two formations is not distinct. Generally the Anastasia
Formation is easy to recognize along the coast but loses its distinctive charac-
ter to the west. Along the beach the formation consists mostly of tan to buff
colored consolidated layers of coarse sand and shell fragments, cemented with
calcium carbonate to form sandstone, where sand grains prevail, and coquina,
where shell fragments dominate. Both the Anastasia and the Fort Thompson
are composed primarily of sand and shell fragments, the main differences
being that the grains and fragments are finer in the Fort Thompson and that
the Anastasia contains many cemented layers, whereas the Fort Thompson
Formation contains few.
Below the Fort Thompson and Anastasia Formations are deposits of Mio-
cene age whose thickness ranges from about 200 feet in the northwest part of
the county to over 300 feet in the southeast. The upper part of the Miocene
sediments, undifferentiated on figures 3 and 7, may be the equivalent
to the Tamiami Formation. They consist of a series of clays, sandy clays, shell,
with some cemented zones.

Underlying these undifferentiated deposits is the Hawthorn Formation,
also of Miocene age. This formation consists of green and brown clay, sandy
clay, and some limestone beds. In general, the Miocene sediments are much
finer-grained than the overlying Pleistocene deposits.

Underlying the Miocene deposits are several hundred feet of limestone and
dolomite. The youngest of these deposits are undifferented limestones of Oligo-
cene age (figs. 3, 7), which occur only in the eastern part of the county where
they have apparently been preserved through down-faulting. They are as much
as 200 feet thick.

Underlying the Oligocene limestones is a thick series of Eocene limestones.
Uppermost are rocks that constitute the Ocala group of late Eocene age. The
Ocala Group is present throughout the county and underlies the Oligocene
where it is present. In other parts of the County the Ocala Group directly






BUREAU OF GEOLOGY


underlies the Hawthorn Formation. These upper Eocene limestone beds consist
primarily of shell fragments and range in thickness from about 50 feet to 200
feet or more. The Ocala Group is divided, from younger to older, into the
Crystal River, Williston, and Inglis Formations. The Williston and Inglis
Formations have not been differentiated in this report (figs. 3, 7). (The-
stratigraphic nomenclature used in this report conforms to the usage of the
Florida Bureau of Geology. It conforms also to the usage of the U. S. Geo-
logical Survey except that the Ocala limestone is referred to as the Ocala
Group.)
Underlying the Ocala Group is the Avon Park Limestone, of middle Eo-
cene age. This limestone ranges in thickness from.50 to 250 feet and consists
of tan to white soft, chalky limestone with some layers of hard dolomite. The
next underlying unit, also of middle Eocene age, is the Lake City Limestone,
which may range in thickness from 300 to 400 feet or more. The Lake City
contains thick beds of dense dolomite.
Underlying the Lake City Limestone is the Oldsmar Limestone, of early
Eocene age, which is similar to the Lake City. It is seldom tapped for water
in Indian River County except perhaps by a few of the deepest wells. The
Eocene rocks are underlain by a thick sequence of Paleocene and older rocks
consisting of limestone, dolomite, and some anhydrite.
HYDRAULIC CHARACTER OF THE ROCKS
The most important aspect of the geology of Indian River County, insofar
as the county's ground-water hydrology is concerned, is the property of the
rocks to function as reservoirs for the storage of ground water and as a con-
duit for transmitting it. Two aquifers (deposits that will yield substantial
quantities of water to wells) are present in Indian River County: the shallow
aquifer, consisting of all the unconsolidated or partly consolidated permeable
deposits of the Anastasia and Fort Thompson Formations, which extend from
the land surface to a depth of about 150 feet; and the Floridan aquifer (Par-
ker and others, 1955), which consists of limestone and dolomite of middle
Eocene through Oligocene age underlying the Hawthorn Formation of Mio-
cene age. The two aquifers are separated by confining beds consisting of clay
and other fine-grained materials of the Hawthorn and younger formations.
These deposits will not generally yield water although some minor limestone
units and shell beds within the confining beds in the Hawthorn Formation will
yield some water to wells. Locally, where permeable limestone and dolomite
beds are present in the basal part of the Hawthorn Formation, that part of
the Hawthorn is included in the Floridan aquifer. The location of these aqui-
fers is shown in the block diagram in figure 8.
The ability of a material to transmit water is a function of its permeability.






REPORT OF INVESTIGATION NO. 80


J


Figure 8.-Block diagram of Indian River County showing principal aquifers,
movement of ground water, and the hydrologic cycle.

The ability of a material to store water is a function of its porosity.
The porosity of a material is the percentage of a unit volume of the material
that consists of voids or openings. The porosity of the shallow aquifer may be
as great as 25 percent or more. The porosity of the Floridan aquifer, on the
other hand, may be only a few percent. Most of the voids or openings in the
Floridan aquifer are due to the solution of the limestone; although some open-
ings may be several feet across, they constitute only a small part of the total
volume of rock.
Permeability depends on the amount and type of interconnection of the
pore spaces, and thus has an important influence on how much water an
aquifer will yield to wells. The difference in permeability of the two aquifers
has had an important effect on how they have been developed and utilized in
Indian River County. Because the voids in the shallow aquifer are small and
irregular, resistance to water movement is relatively high and water does not
move as readily as it does through the Floridan aquifer where the voids are






BUREAU OF GEOLOGY


large and interconnection of voids is good. Therefore, although the shallow
aquifer contains several times more water per unit volume than the Floridan
aquifer, the Floridan will transmit several times more water per unit volume
than the shallow aquifer. Yields of 300 to 500 gal/min are obtained from
10-inch wells in the shallow aquifer, but yields of as much as 3,000 gal/min
are obtained from 10-inch wells that tap the Floridan aquifer.

HYDROLOGIC CYCLE
The hydrologic cycle is the series of events whereby water circulates from
the land and oceans to the atmosphere and then back to the land and oceans.
The water is evaporated or transpired from the land surface and oceans, is
condensed into liquid water in the atmosphere, and is returned as precipita-
tion. When the precipitation reaches the earth's surface it infiltrates the
ground or runs off to lakes and streams and eventually finds its way back to
the oceans, except for the large part again evaporated or transpired by plants
I fig. 8).

GROUND-WATER HYDROLOGY
Ground-water hydrology concerns the manner in which aquifers are re-
charged, how water is discharged from them, and the quantity and quality
of water available from them for development.

SHALLOW AQUIFER
From place to place in Indian River County the shallow aquifer varies
considerably in physical characteristics--in permeability, for example-and,
consequently, the yields of wells in the aquifer also vary. These variations to
some extent were defined by hydrologic and geologic data obtainable for
several existing shallow wells and from the test-boring program. On basis of
such information, the county was divided, for purposes of demonstration in
this report, into three areas of differing potential well yield. In one area, wells
in general yield less than 100 gal/min; in the next, wells yield 100-250
gal/min, and in the third, 250-1,000 gal/min. Figure 9 outlines these areas
and shows that the area of greatest potential yield is near the coast, southward
from Sebastian. This area includes virtually all of the Indian River Farms
and Sebastian River Drainage Districts. The areas of moderate potential well
yield (100-250 gal/min) are in the east central part of the county and in the
far western part, beyond Blue Cypress Lake. The area of lowest potential yield
generally coincides with the St. Johns Marsh.
The areas of differing potential well yield delineated in figure 9 are, of
necessity, highly generalized. In some parts of the area of moderate potential







30' 80* 25'

I I


27 50'-



F45 M -










;';';*3^.Lu.:f ::;; X:
EXPLANATION


GREATEST POTENTIAL
WELL YIELDS AS MUCH AS 250-1000 GAL/MIN,

m 2r 35e
MODERATE POTENTIAL
WELL YIELDS AS MUCH AS 100-250 GAL/MIN


POOR POTENTIAL
WELL YIELDS LESS THAN 100 GAL/MIN
0 5 MILES
__j:5'


0- --- -4-- u 35 3-d 25 80 -2


80 45' 40' 351 30 25' 80~20


- 27O 50'





0


45 -4




01






7P 35'
0


Figure 9.-Potential yields of wells tapping the Floridan aquifer.







BUREAU OF GEOLOGY


EX L ANA TION
B W q. tnl TO WEQIUM WWO ODOWIG "ArTE" A*N
0 P L. W "POAN 1A11" -11D CWE*t1rD KY1111M
| M r.t SAN D t t ; SO ME SHE LL.
to*1- 'I t0 r10 tWM Mm IEIWc I.T,
L-AM E*;IM m cowwc U 1MD HELL; wswE MUi
WtL <<00 Pl" *9tT
h'^^Lntr~


Figure 10.-Fence diagram, or hydrologic sections,
the Vero Beach area.


of the shallow aquifers in


yield, for example, well yields may be low or high. Further, not all areas are
defined equally well. The area of greatest potential yield is the most thoroughly
documented; data were sparse for most of the area west of Ten-mile Ridge.

The cause of the variation in well yields is in part evident from inspection
of the lithologic logs of wells in different parts of the county. The logs for
numerous wells are presented graphically in this report: those for wells near
Vero Beach are shown in figure 10; those for wells north and west of Vero
Beach are shown in figure 11. Both figures provide information on the types
of materials likely to be penetrated when drilling new wells in places near the
existing wells whose logs are shown. In the beach area the aquifer contains a







REPORT OF INVESTIGATION NO. 80


rS-A I A 30' 5.
-. L: A ,TA I s-ME H L ILTY-SAN-
-1
St SHELL ,SA,

















11 E SCAIY'B t.LI..FINE -
SEA LEVEL L N LC s SHELL E MEL LEVEL
A 0 SOM E SHELL I 0 CSAD INOD
SOME CLA CEES NA
d M EO SAND CSD SE. Sk N G L




L" -, L;SESHELLK7



0 MILE
BEACH






wells tapping the aquifer there, of course, yield only small amounts of water.
v, the s s dd shw tht m of the l ELLs a i t b
SEA LEVEL SANDY CLAY VD OMESHELL A LEVEL















the aquifer contains a large percentage of runconsolidated shell and coarse






sand and a small percentage of fine sand, silt, and clay. In the area where the
potential yield is low and aquifer materials are unconsolidated, the aquifer
contains a large percentage of fine sand, silt, and clay and a small percentage
0 H TOIRECHARGE TN
af o f t NED SAhD n Sthe s
DO G COY CLAY rISE SAND & SHELL COME TO MED SAND, SAELL Sd
VAf iL!TU; SHELL GOOD WAE CARING AA
CEMENTED 0 J 1








TFigue al.-lithologic sections of ershallo aquifer north ad west of Verot
Beach.


large percentage of cemented materials. These are of low permeability and
wells tapping the aquifer there, of course, yield only small amounts of water.
The location of these layers of low permeability could not be determined
accurately by well inventory and test drilling because they are discontinuous
However, the studies did show that most of these layers are in the beach area,
are thin in the vicinity of Indian River, and are generally in the upper 30
feet or so of the aquifer. The layers diminish in number to the west and about
1 mile west of Indian River are not present, or, at least, are highly discontinu-
ous in the upper part of the aquifer. In the area of greatest potential yield,
the aquifer contains a large percentage of unconsolidated shell and coarse
sand and a small percentage of fine sand, silt, and clay. In the area where the
potential yield is low and aquifer materials are unconsolidated. the aquifer
contains a large percentage of fine sand, silt, and clay and a small percentage
of shell and coarse sand.

RECHARGE
The shallow aquifer in Indian River County is recharged mostly by direct
infiltration of rainfall, primarily at times when rainfall is substantially in ex-






BUREAU OF GEOLOGY


cess of evapotranspiration. There is little interchange between water in the
shallow aquifer and that in the Floridan aquifer because of the thick confining
bed formed by the undifferentiated deposits (Tamiami ? Formation) and
the Hawthorn Formation. However, within the irrigation districts an im-
portant quantity of water is added to the shallow aquifer by artificial recharge
of water withdrawn from Floridan-aquifer wells for irrigation.

The effect of rainfall infiltrating to the water table of the shallow aquifer
is evident in figure 12, which shows hydrographs of two wells tapping the
shallow aquifer. One well is in an area unaffected by pumping near Winter
Beach, about 4 miles north of Vero Beach; the other is in a heavily pumped
area at Vero Beach. The graph for the well near Winter Beach clearly shows
that the water level responds to heavy rainfalls by rising and to sparse or no
rainfall by declining. In the well at Vero Beach the response to rainfall is
partly obscured by the drawdown and recovery of the water level caused by
intermittent pumping.
The available hydrologic data are insufficient for a reliable determination
of the quantity of recharge received by the shallow aquifer in different parts
of the county; however, for the area of greatest potential well yield (fig. 9) a
useful determination can be made of the natural recharge to the shallow aqui-
fer. Natural recharge is considered to be the rehliarge received by the aquifer
before conditions were changed by irrigation and man-made drainage.
The natural recharge to the shallow aquifer is the rainfall that does not
return to the atmosphere by evapotranspiration and does not leave the area
directly as overland flow. Under natural conditions overland flow from the
area of greatest potential well yield probably was minimal because the land is
fat and the surficial materials are permeable. For this area, therefore, a
reasonable estimate of natural recharge to the shallow aquifer can be made
if the quantity of water lost by evapotranspiration can be determined.
Streamflow measurements provide one basis for an accurate determination
of evapotranspiration from large areas. This is because the flow of any stream
represents rainfall that has not yet returned to the atmosphere by evapotrans-
piration in its basin, but instead has flowed over the land surface to the stream
or moved into the stream as subsurface flow. Obviously, records from not
every stream are suitable to compute evapotranspiration. If water is introduced
into the stream by man's activities, or if the stream receives indeterminable
quantities of discharge from an aquifer that is not influenced by rainfall
within the stream basin, the estimate of evapotranspiration cannot be valid. A
'-areful examination of the hydrology of a stream basin must be made before a
stream can be selected whose flow record can be used to compute evapotrans-
piration.























NO RECORD;
I ---- HYDROGRAPH ESTIMATED

TEST WELL NEAR WINTER BEACH, IN LIGHTLY PUMPED AREA


---------__ "_._--- --
13




1|o li \ l. I .11 .Jdl lJlt I.. 1 1li,..],... .i J,_11 l i
S JANUARY FEBRUARY MARCH ARPIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER 'NOVEMBER DCEMBER
1970


Figure 12.-Hydrographs of wells tapping shallow aquifer at Winter Beach
and Vero Beach, and rainfall at Vero Beach for 1970.






BUREAU -OF GEOLOGY


None of the gaged streams in Indian River County meets all the criteria
for determining evapotranspiration; however, some streams in adjacent coun-
ties are influenced by similar climatic and hydrologic conditions and provide
data that can be transferred to parts of Indian River County. One such stream
is upper Taylor Creek near Basinger on which the U. S. Geological Survey has
maintained a gaging station since 1955. The loss of water in upper Taylor
Creek basin through downward discharge to the Floridan aquifer, man's with-
drawals by diversion or pumping, or by underflow bypassing the gaging sta-
tion is negligible. Likewise, additions to the basin's water supply, other than
rainfall, are negligible.

Based on 14 years of record, the yearly rainfall over upper Taylor Creek
basin averaged 48.0 inches and yearly streamflow averaged 12.5 inches. There-
fore, for the period of record, 35.5 inches of water (74 percent of the rainfall)
each year on the average was lost as evapotranspiration. This value should
apply reasonably well to the area of greatest potential well yield in Indian
River County. Thus, on basis of the average annual evapotranspiration (35.5
inches) and the average annual rainfall at Vero Beach (51.3 inches), natural
recharge to the shallow aquifer in this area over the long term averages about
16 inches (51.3 inches 35.5 = .15.8 inches).

Natural recharge to the shallow aquifer would vary greatly from year to
year. of course, because of the large variation in the annual rainfall. Recharge
might have been as great as 30 inches in 1968, when rainfall was 67.0 inches,
and might have been virtually zero in 1961, when rainfall was only 32.7
inches.
As a check on the reasonableness of a natural recharge averaging 16 inches
per year, recharge to the shallow aquifer was determined for a lightly pumped
area in the county near Winter Beach. The determination was based on the
rise in water level recorded in one well in the aquifer. The rise in water level
was computed as the difference between the recorded water level at the end of
a clearly distinguishable rise and the level that would have resulted if the
water level had continued to recede without interruption. The projection of an
uninterrupted recession was made on basis of a representative water-level-
recession curve. After adjustment for porosity of the aquifer-a value of 25
percent was used-the rises in water level totalled 18 inches for the water year
ending September 30. 1970. During the 1970 water year, rainfall at Vero
Beach was close to normal. On this basis, an average annual recharge of 16
inches appears reasonable for the shallow aquifer in the area of greatest
potential well yield.
The 35.5-inch value for yearly evapotranspiration also would apply to the
areas of moderate potential well yield (fig. 9); however, natural recharge to






REPORT OF INVESTIGATION NO. 80


the shallow aquifer cannot be determined for these areas simply as the dif-
ference between rainfall and evapotranspiration, because an appreciable part
of the rainfall probably would leave the areas directly as overland flow into
St. Johns Marsh or South Prong Sebastian Creek. The surficial materials in
these areas in general are less permeable than in the area of greatest potential
well yield; furthermore, in the western part of the county the land surface is
not as flat. Hydrologic data are lacking for a valid determination of overland
flow from these areas.
Natural recharge also cannot be reliably determined for the area of low
potential well yield (fig. 9), although the recharge probably is small. This
area largely coincides with St. Johns Marsh which is covered by standing
water much of the time. Evapotranspiration from this area probably would be
about as great as the yearly lake evaporation which according to Kohler, Nor-
denson, and Baker (1957, pl. 2) averages about 48 inches in Indian River
County. On basis of the average annual rainfall at Vero Beach (51.3 inches),
about 3 inches of water would be available for both natural recharge and over-
land flow from the area. Inasmuch as the water table of the shallow aquifer in
this area is usually at or near the land surface, most of the 3 inches probably
leaves the area as overland flow northward to St. Johns River.

DISCHARGE
Over the long term all the recharge to the shallow aquifer is discharged
from the aquifer. Virtually all the natural discharge occurs as subsurface flow
into Indian River and St. Johns Marsh. Little water moves downward from
the shallow aquifer to the Floridan aquifer because of the confining bed previ-
ously mentioned. Water withdrawn from wells in the shallow aquifer at present
(1974) is small in relation to the natural discharge.

POTENTIAL DEVELOPMENT
The potential of the shallow aquifer for development as a water supply is
great but widely dispersed. Natural recharge averages 16 inches annually in
the area of greatest potential well yield (fig. 9) which covers 100 square
miles. The natural recharge over this large area represents a volume of water
that with temporary changes in storage could sustain a continuous pumping
rate of 76 Mgal/d. Such a rate would be about 25 times greater than the rate
of withdrawal for municipal supply in Indian River County in 1970. In
addition, a substantial quantity of water could be obtained from the shallow
aquifer in the areas of moderate potential well yield, which in aggregate cover
150 square miles, and some water could be obtained from the areas of low
potential yield.
Obviously, development of the shallow aquifer to the extent of capturing






BUREAU OF GEOLOGY


all, or almost all, the natural recharge would require wide distribution of wells
over a large area and, also, would require some changes in land use within the
well-field areas. For example, in these areas the drainage system would have
to be altered to maintain rainfall on the land surface for a time long enough
to infiltrate the ground rather than to rapidly remove the rainfall in drainage
ditches. A high water table probably would have to be tolerated during wet
periods. Furthermore, the use of Floridan-aquifer water to irrigate in or near
the well-field areas would have to be carefully regulated because the residue of
chloride left by evapotranspiration of the applied water would be dissolved and
carried downward into the shallow aquifer by the natural recharge.
Doubtless, it will not be either necessary or practicable to fully develop
the potential of the shallow aquifer over the entire county within the foreseeable
future. The capacity of the shallow aquifer along the coast is more than ade-
quate to meet the anticipated need for municipal supply (26 mgd by the year
2000). But even with careful selection and management, the required well
sites in aggregate will cover a large area. In this area land use will have to
blend compatibly with use of the shallow aquifer for water supply.

FLORIDAN AQUIFER
The Floridan aquifer underlies the entire county at depths ranging from
about 250 to more than 500 feet below sea level, as shown in figure 13. The
top of the aquifer dips generally to the southeast. The physical character of the
aquifer-lithology and permeability, for example--is generally uniform. Ac-
cording to Bermes (1958, p. 8, figs. 4-6) several faults are in the eastern part
of the county. In the areas of faulting in the eastern half of the county, the
top of the aquifer consists of thick Oligocene limestone of relatively
low permeability.

RECHARGE AND DISCHARGE
The Floridan aquifer is recharged primarily by rainfall west and north-
west of Indian River County. Water then moves eastward to discharge into the
Atlantic Ocean. Throughout most of Indian River County the potentiometric
surface of the Floridan aquifer is above the land surface, as indicated in figure
14, and water therefore tends to move upward from the Floridan aquifer into
the shallow aquifer; however, the upward leakage from the Floridan aquifer
doubtless is small because of the overlying confining bed formed by the undif-
ferentiated desposits (Tamiami ? Formation) and the Hawthorn Formation.
The potentiometric surface of the Floridan aquifer is below the land surface
in the western part of the county and in a few small areas along the Atlantic
Coastal Ridge; in these areas the Floridan aquifer may receive recharge from


















^ I/ ?/,I I I /^' \-

-- o I 7







0






STRUCTURE CONTOUR SHUWS ALTITUDE 0n
OF THE TOP OF THE FLORIDAN AQUIFER,
FEET BELOW SEA LEVEL: DASHED I ,, O
WHERE APPROXIMATE. CONTOUR PITERL
SO AN) 100 FEET 0 o i a F n i c o n r
WELL USED TO DETERMINE CONTOURS I SWSWAE Sta aw r i I-- -

D OOWNTIHOWN SIDE X I I ""
INFeRReD FAULT "
--------- I---------------------------------------------------------^ -----------




Figure 13.-Altitude of top of the Floridan aquifer in Indian River County
(Faults by Bermes, 1958; and Vernon, 1951.)
(Faults by Bermes, 1958; and Vernon, 1951.)





BUREAU OF GEOLOGY


the shallow aquifer but again the quantity would be small because of the con-
fining bed mentioned above.

Because of seasonal variation in the rate at which the Floridan aquifer is
recharged by rainfall, and also in the rate at which water is withdrawn from
the Floridan aquifer for irrigation, the level of potentiometric surface of the
Floridan aquifer fluctuates considerably throughout a year. Locally the level
of the potentiometric surface declines as much as 15 feet during dry periods,
usually April and May when irrigation requirements are greatest. When the
summer rains begin and ground water withdrawals are curtailed, the level of
the potentiometric surface rises rapidly, usually reaching a relatively high
level in September and October. Figure 15 shows the pattern of seasonal fluc-
tuation in the water levels of two wells (north well and south well) which tap
the Floridan aquifer in Indian River Farms Drainage District (fig. 2). Sea-
sonal fluctuations of 5 to 10 feet are common for the water levels in these
wells

The continued withdrawal of large quantities of water from the Floridan
aquifer-withdrawals for irrigation averaged about 50 Mgal/d in 1951 and
100 1Mgal/d in 1970-has gradually lowered the level of the potentiometric
surface of the Floridan aquifer in Indian River County. The perennial dis-
charge of Floridan-aquifer water from a large but unknown number of un-
capped flowing wells doubtlessly contributes to the general decline in level of
the potentiometric surface of the Floridan aquifer. According to Bermes
(1958, p. 24), the level of water declined 7 feet from 1913 to October 18,
1951. in a well at Fellsmere and had declined 10 feet in a well at Vero Beach
before 1936. Throughout much of the county the potentiometric surface of the
Floridan aquifer was 10 to 15 feet lower in May 1970 than it was in October
1951. as is evident from comparison of figure 14 with figure 16; however, the
decline in level from 1951 to 1970 would be considerably smaller than indi-
cated if appropriate adjustments could be made for the effect of seasonal
fluctuations in the level of potentiometric surface.

The level of the potentiometric surface of the Floridan aquifer doubtless
will decline further if the rate of withdrawal is increased beyond the 100
MAgal/d of 1970 but probably will not decline significantly if the present rate
of withdrawal is maintained. In Indian River Farms Drainage District the
water level in south well (fig. 15) has fluctuated without an obvious downward
trend since 1961. During this same time the water level of north well has de-
clined slightly but the relation between the levels of north and south wells has
been holding relatively constant since 1967. Whether a further lowering of
the potentiometric surface would prove harmful depends primarily on whether












80" 50'


S5EASTIAN


o p,
0 -
0 FELLSMER 0



take w



R INTERVAL FEET o u N


















DIRECTIONN OAN FLOW j MLEI
Ad 0 0

VERO
BEACH



-40- o
POTENTIOMETRIC CONTOUR OUT

2735 ED WHERE APPROXIMAE. CONTOUR INTER- 0 0 0 oSO
VAL 2S FEET DATUM, MEAN SEA LEVEL.

LAND-SURFACE CONTOUR A u, Ar ARKIYA
FEET ABOVE MEAN SEA LE'EL. Q 91L an,
CONTOUR INTERVAL25 FSEET S.UN I S-T !I T L U C I E CO0 U N T Y
-~ DIRECTION OF PLOW 5 4 5 M
0 WELL USED IN DETERMINATION OF CONTOURS
... .. ..--..... ...... .... _. .. ....... ......L.. .. .... ...L-. .- ..... _LJ _


Figure 14.-Contours on potentiometric surface of Floridan aquifer in Indian
River County in May 1970.

















20




15




w 10
U.
J







0
5
n-



a-


Figure 15.-Hydrographs of two wells in Floridan aquifer in Indian River
Farms Drasinae District.


NOTE: WATER LEVELS PLOTTED ARE THE
HIGH FOR THE MONTH. RECORDS FROM
AGRICULTURAL RESEARCH SERVICE.

159 1960 1961 1962 1963 1964 1965 1966 1967 19e


;8






REPORT OF INVESTIGATION NO. 80


it would cause further deterioration in water quality; this aspect is discussed
in a later section of this report.

SURFACE-WATER HYDROLOGY

Surface-water hyrdology pertains to the water that flows in rivers, creeks,
and canals, or that stands in lakes, ponds, and swamps. This section of the
report describes some aspects of the surface water in Indian River County as
it occurs in St. Johns Marsh, including Blue Cypress Lake, and in four drain-
age districts: Indian River Farms Drainage District, Fellsmere Farms Drain-
age District, Sebastian River Drainage District, and St. Johns Drainage Dis-
trict. The locations of surface-water gaging stations and drainage-district
boundaries are shown in figure 2.

ST. JOHNS MARSH
St. Johns Marsh is the headwaters of St. Johns River, the main stem of an
extensive network of streams that drains a large part of central and eastern
Florida. Over the years, a substantial part of the marsh has been enclosed by
levees and drained for agriculture. Flood water now can be diverted from St.
Johns Marsh to Indian River through a recently completed floodway (C-54)
that parallels the north boundary of Indian River County and empties into
Sebastian Creek.
Most of the water in St. Johns Marsh is from rainfall directly on the marsh,
but in the western part of the county a few small streams empty into the marsh
or into Blue Cypress Lake, which in turn overflows into the marsh. The level
of water in the marsh fluctuates with variations in rainfall. Fluctuations of the
water level at the gaging station, St. Johns Headwaters near Vero Beach, in
the south central part of the county are portrayed in figure 17. The stage at
this gage rises above 26 feet above sea level for short periods after excessive
rainfall and declines to less than 24 feet above sea level during extended dry
periods. The sharp declines in stage during dry spells in 1965, 1967-68, and
1970 probably are due partly to the withdrawal of water from the marsh for
irrigation. The stage fluctuates between 24 and 26 feet above sea level about
80 percent of the time, as shown by the stage-duration curve in figure 18.
The level of water in the marsh at the gaging station on the northern
boundary of Indian River County, St. Johns Headwaters near Kenansville
(fig. 2), is generally 1.5 to 2 feet lower than the level at St. Johns Headwaters
near Vero Beach. In recent years, however, the stage at St. Johns Headwaters
near Vero Beach has declined briefly below the stage at St. Johns Headwaters
'near Kenansville during exceptionally dry periods. This temporary reversal is












'91 SI 1


Ic) 17: MI' 40
I..~'-"


HOW AI IiTUE OF POTEIMT(ETI
SWJACE OF THE 1 FLOiMM AI M ER ,
a AW 'gHE WHBE( APPR OMUT8 '
,IXTM INTMAL is: i- eSri._-
a.c ', u, T r IR l r Iu 1 a I c a U N rC
--- I -- I n ; I c o u"=


Figure 16-Contours on potentometric surface of Fioridan aquifer in Indan
River County in October 195L


MI 4.1'


I











_j
w J -ST. JOHNS HEADWATERS NEAR VER0' BEAC0









..J SBLUE CYPRESS LAKE U \
w 2
2








l-----I-I-, ''----LA- --^
ww 24






8 1956 1957 195'5 1959 1960| 1961! 1962S 1965 1964 .. 1965' 1966 19'67 19
20



h9561 9595 156 959 1,960,1 19611 i 1962- 1963, 564 1965 1966; 1967 19


Figure 17.-Month-end level of St. Johns Headquarters near Vero Beach and
Blue CYpress Lake, 1956-70.






BUREAU OF GEOLOGY


28


27 -- --- ---- ---- ---- ---- ---- -----___
27
W /ST JOHNS HEADWATERS NEAR VERO BEA
W> 26 942-6 1
u 26

4


w %2
224 -..-......
W -BLUE CYPRESS LAKE

23


W 22
ST JOHNS HEADWATERS NEAR KENANSVILLE "
1942-69
> 21
tJ
-iI
520
I--

19

18
0 10 20 30 40 50 60 70 80
PERCENTAGE OF TIME WATER LEVEL EQUALED
OR EXCEEDED A GIVEN LEVEL


90 100


Figure 18.---tage-duration curves for St Johns Marsh and Blue Cypress Lake.

undoubtly caused by the withdrawal of irrigation water from the southern part
of the marsh.

The depth of water has not been determined for most of the marsh. From
a study of topographic maps of the area, the altitude of the land surface in
drained marshland that adjoins the present marsh is about 22 feet above sea
level or less. Presumably, the bottom of a large part of the present marsh is
at about the same altitude. Thus, when the water surface in the marsh at St.
Johns Headwaters near Vero Beach is at an altitude of 24 feet above sea level,
water is probably at least 2 feet deep over much of the marsh.

Blue Cypress Lake is the only sizeable fresh-water lake in Indian River
County. The lake has an area of 6,555 acres at altitude 24 feet above sea level
and is about 8 feet deep over much of its area. The lake level fluctuates in
much the same way that the marsh level fluctuates (fig. 17). Blue Cypress






REPORT OF INVESTIGATION NO. 80


Lake connects with Fellsmere Canal and during dry periods some lake water is
used for irrigation in Fellsmere Farms Drainage District.
Runoff northward through the marsh cannot be determined directly; how-
ever, an estimate can be made from data from nearby gaging stations. The
average discharge for St. Johns River at Melbourne (drainage area, 968
square miles) is 0.78 (ft8/s)/mi2. Jane Green Creek near Deer Park, in Bre-
vard County (drainage area, 260 square miles at mouth), has an average
discharge of 1.22 (ftP/s)/mi2 contributing more than the basin average from
its 27 percent of the total drainage area at Melbourne. That runoff indicates
that there must be considerably less unit discharge from the upper marsh. Tay-
lor Creek near Basinger, in Okeechobee County, just beyond the southwest
boundary of the marsh, has an average discharge of 0.95 (ft/s) /mi2, which
probably approximates the natural flow into the upper marsh from the west.
The ungaged area between the northern boundary of the county and Jane
Green Creek is 171 square miles and agricultural development is similar to
that in Indian River County. Using a runoff value of 0.9 (fta/s)/mi2 for that
area, it contributes about 154 ftW/s. The average flow northward in the marsh
at the north end of the county line, therefore, is estimated as about 280 ft3/s,
an average of only 0.52 (ft/s) /mi2, or 6.4 inches over the drainage area of
the St. Johns River south of the north county line.

DRAINAGE DISTRICTS
INDIAN RIVER FARMS DRAINAGE DISTRICT
Indian River Farms Drainage District is the largest of four districts which
together take in about half of Indian River County. This district covers an
area of about 115 square miles drained by three canals-North, Main, and
South Canals-each of which connects to an extensive network of smaller
canals and drainage ditches. The layout of the drainage system is shown in
figure 19.
The drainage system insures that excessive rainfalls drain rapidly from the
district and that the water table remains generally below the roots of the crops.
During dry periods the canal gates are closed to prevent excessive lowering of
the water table. Drainage ditches also are used to distribute supplemental irri-
gation water from wells in the Floridan aquifer. Discharge of the canals is a
combination of varying quantities of runoff, drainage from the shallow aqui-
fer, and irrigation water.
When flow is low, the discharge of North, Main, and South Canals is
highly variable because of the frequent opening and closing of canal gates.
Similarly, because of the manipulation of check gates and the intermittent use
of irrigation water, the distribution of low flow is highly variable within the








BUREAU OF GEOLOGY


80* 30'

\ I


27' 4' -




















27- 40 -


80 25'




27'
EXPLANATION
9il.t
INDICATES POINT Of MUARWUMNT)
NUMVtR IS DIICHAROC, CUBIC
FItT PEIR MCONO

DIrtCTION Of
FLOW AT TIME Of MIAIURtMINT.


L1
I-,




H-I I
'I


H.-2
L)


Figure 19.-Magnitude and direction of flow
points in Sebastian River and
Districts, May 5-8, 1969.


in drainage canals at selected
Indian River Farms Drainage






REPORT OF INVESTIGATION NO. 80


Figure 20.-Combined monthly discharges of North, Main, and South Canals,
in Indian River County, 1956-70.

drainage system. The pattern of flow indicated in figure 19 is based on dis-
charge measurements made May 5-8, 1969. The pattern of flow varies locally
from day to day as different areas are irrigated.
The average yearly discharge of Main Canal is slightly greater than the
combined discharges of North and South Canals, as indicated in table 1. The
seasonal variation in discharge from each canal is about the same as that indi-
cated by the distribution of the combined discharges of the three canals in
figure 20; however, during low flow the discharges of North and South Canals
are smaller in relation to the discharge of Main Canal than is indicated by the
relative magnitudes of the average yearly discharges. This seeming anomaly
probably results from a change in the low-flow regimen of the canals after in-
stallation of the canal gates in 1955-56. The change in the low-flow regimen is
evident from a comparison of canal discharges before and after the gates were
installed. During low flow in 1952-54, before gates, the combined discharges
of South and North Canals were greater than the discharge of Main Canal,






BUREAU OF GEOLOGY


Table 1.-Average yearly discharge of four canals in Indian River County

Average yearly
Canal Date Span discharge
(fts/s) (Mgal/d)
North Canal near Vero Beach 1951-70 31.6 20.4
Main Canal at Vero Beach 1949-70 80.9 52.3
South Canal near Vero Beach 1950.70 40.9 26.4
Fellsmere Canal near Fellsmere 1955-67 136.0 87.9


as shown in figure 21. After the gates were installed, the low-flow discharge
decreased in North and South Canals but increased in Main Canal. This
change in the low-flow regimen of the canals probably accounts for the dif-
ference in the shape of the lower part of the flow-duration curves shown in
figure 22 for North, Main, and South Canals.
During 1951-70 the combined discharges of North, Main, and South Canals
averaged 153 ft3/s, which equals a runoff of about 18 inches per square mile
of drainage area. The indicated runoff is probably substantially greater than
would occur from the same area in its natural state. Part of the increase results
from the fact that the drainage system expeditiously removes from the district
some water that formerly would have evaporated from wet areas that now are
kept relatively dry. The use of irrigation water from the Floridan aquifer also
increases the runoff from the district. Any irrigation water that is wasted into
the canals increases the runoff directly; but the use of irrigation water during
dry spells also raises the average level of the water table with the result that
seepage from the shallow water aquifer into canals is increased over that which
otherwise would occur.

FELLSMERE FARMS DRAINAGE DISTRICT
Fellsmere Farms Drainage District, the second largest of the four, takes
in an area of about 78 square miles. The area is drained by an extensive net-
work of canals and drainage ditches that connect with Fellsmere Canal, which
runs along the northern boundary of Indian River County and empties into
North Prong Sebastian Creek.
The discharge of Fellsmere Canal averaged 136 fts/s during 1955-67. The
seasonal distribution of canal flow is similar to that shown in figure 20 for the
combined discharges of North, Main, and South Canals. Inasmuch as the dis-
charge of North, Main, and South Canals averaged about the same for 1955-67
as for 1951-70, the discharge of Fellsmere Canal also probably was about the
same for the two periods. Hence, the values of average discharge given in table







REPORT OF INVESTIGATION NO. 80


0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
CONSECUTIVE DAYS OF FLOW
Figure 21.-Average of lowest mean discharge during given number of con-
secutive days of climatic year for North, Main, and South Canals
for periods before (1952-54) and after (1956-65) gated-control
structures were installed.

1 are comparable, even though the available record is much shorter for Fells-
mere Canal than it is for the other canals.
In terms of inches of runoff from the given areas of the two drainage dis-
tricts, the discharge from Fellsmere Canal is 23.6 inches compared to 18 inches
for the three canals of Indian River Farms. The relation between the monthly
discharges, shown in figure 23, from the two districts suggests that the dif-
ference in runoff accrues during periods of high and medium flow rather than
during periods of low flow. Apparently Fellsmere Canal picks up storm runoff
from some area outside the given boundaries of the drainage district, possibly
from St. Johns Marsh and Blue Cypress Lake.

ST. JOHNS DRAINAGE DISTRICT
St. Johns Drainage District takes in an area of about 44 square miles that
lies west of Indian River Farms and south of Fellsmere Farms. Excess rainfall






BUREAU OF GEOLOGY


PERCENTAGE OF TIME A GIVEN DISCHARGE WAS EQUALED OR EXCEEDED


9999


Figure 22.-Flow-duration curves for selected canals in Indian River County.


and drainage from the shallow aquifer are pumped from drainage ditches into
an elevated canal. The canal empties into a reservoir that covers about 3
square miles on the western end of the district. The reservoir overflows into St.
Johns Marsh. During dry spells the stored water is used for irrigation within
the district. Water also can be taken into the district from St. Johns Marsh by
gravity flow. The discharge from St. Johns Drainage District was not meas-
ured in this investigation.








REPORT OF INVESTIGATION NO. 80


0 100 200 300 400 500 600 700 800 900
COMBINED MONTHLY DISCHARGES OF NORTH, MAIN,
AND SOUTH CANALS, CUBIC FEET PER SECOND


1000 1100


Figure 23.-Relation between monthly discharge of Fellsmere Canal and com-
bined monthly discharges of North, Main, and South Canals,
1956-67.


SEBASTIAN RIVER DRAINAGE DISTRICT

Sebastian River Drainage District takes in an area of about 18 square
miles in the form of a 2-mile wide strip bounding the northwest corner of In-
dian River Farms. Drainage from this district empties into South Prong Sebas-
tian Creek (fig. 2); however, the creek also receives drainage from all or part
of an area of about 50 square miles west of the district.

South Prong Sebastian Creek has been measured at irregular intervals
since 1954. A total of 49 discharge measurements were made through 1971. the
discharges ranging from 1,780 ft3/s on October 18, 1956 to 9.4 fte/s on June
6, 1956. Ten of the 49 measurements were of discharges greater than 200 ft"/s.

Based on the average of 16 low-flow measurements made at intervals of 6 to
8 weeks during 3 different periods of sustained low flow-February-August
1955, January-June 1966, and February-October 1958-the low flow of South
Prong Sebastian Creek is equal to about 30 percent of the combined low flow
of North, Main, and South Canals. Flood flows of South Prong Sebastian Creek


800


700

0
z
W 600
U)
w
0. 500
I-
w
U- 400


S300


S200


100


n


DASHED LINE REPRESENTS THE RATIO OF
DRAINAGE AREA OF FELLSMERE CANAL
TO COMBINED DRAINAGE AREA OF
NORTH, MAIN, AND SOUTH CANALS.
- T 2*--


_ __


v






BUREAU OF GEOLOGY


appear to be substantial and they should follow closely the seasonal distribution
indicated for flood flows of North, Main, and South Canals in figure 20. Thus,
the average yearly flow of South Prong Sebastian Creek at the gaging station
(fig. 2) is estimated to be 30 percent of the combined average yearly flow of
North, Main, and South Canals, or about 46 ft3/s.
The surface-water discharge as measured at gaging stations is not all the
water that flows eastward to Indian River, because the gaging stations are up-
stream from the discharge point and runoff from the intervening areas is not
measured. The total measured and estimated flow of 335 ft3/s is therefore
increased to 370 ft3/s to include runoff from such ungaged areas.


SURFACE-WATER SUMMARY

Surface water in Indian River County is derived from rainfall within the
county, some surface inflow from Okeechobee County into Blue Cypress Lake
and St. Johns Marsh, and Floridan-aquifer water which is used for irrigation
by the several drainage districts. Surface-water discharge leaves the county
through Fellsmere Canal and Sebastian Creek in the northeast; North, Main,
and South Canals in the east; the movement of water northward through St.
Johns Marsh; and minor flows in the coastal areas directly to the ocean and
Indian River (lagoon).
The average discharge of the North, Main, and South canals totals 153
fta/s (99 Mgal/d), or 18 inches, from the 115-square-mile Indian River Farms
Drainage District, which includes 22 percent of the county. The average dis-
charge of Fellsmere Canal is 136 ft/s (88 Mgal/d), or 23.6 inches, from the
78 square miles of the drainage district plus some water from the 394 square
miles in both Indian River and Okeechobee counties which flows into Blue
Cypress Lake. An average flow of 46 ft3/s (30 Mgal/d) is estimated for South
Prong Sebastian Creek, which drains the 18-square-mile Sebastian River
Drainage District and all or part of about 50 square miles west of the drainage
district.
The quantity of flow northward through St. Johns Marsh is not definitely
known but may average about 280 ft3/s (180 Mgal/d). An additional 35 ft3/s
(23 Mgal/d) is estimated as runoff from ungaged coastal areas. The total sur-
face-water discharge from the county is then about 650 ft3/s (420 Mgal/d).
Surface -water discharge from drainage districts includes some Floridan aqui-
fer water withdrawn for but not consumed in irrigation.
All the surface water, except that in Blue Cypress Lake, is hard, but the
chemical quality varies considerably between the dry and the wet periods.
With the exception of Indian River, and rainfall, dissolved solids in waters







REPORT OF INVESTIGATION NO. 80


sampled range from 74 mg/1 in Fort Drum Creek at Sunshine State Parkway
in July 1970 to 1,070 mg/l in South Prong Sebastian Creek in April 1968,
most of the samples in the canals and marsh were in the 400-700 mg/1 range.
Data in Table 5 for South Prong Sebastian Creek and for Fellsmere Canal
indicate that chloride concentration from 1955-58 to recent years has not
increased noticeably. Although an increase would have been expected because
of the increase in irrigation, changes may not have been noted from periodic
samplings because of the rapid changes in water quality with variations in
rainfall and irrigation practices. Generally, the surface water in the county is
usuable for irrigation and most other uses except that which becomes heavily
concentrated during dry periods and that in drainage canals which at times
contains a large proportion of Floridan aquifer water having more than 250
mg/1 of chloride.

WATER QUALITY

The chemical constituents of natural waters vary in concentration accord-
ing to the source of the water and the solubility of the materials through or
over which the water has moved. The chemical quality of water in Indian
River County largely determines the quantity of water that is suitable for
development. Water with high concentrations of certain chemical constituents
may be unsuitable for human consumption, for irrigation, or for specific in-
dustrial uses. Even though the water resources of Indian River County are
large, much of the water is unusable, or of limited usefulness, because of its
poor chemical quality.

CHEMICAL QUALITY OF GROUND WATER
Although constituents other than chloride are present in all water, includ-
ing rain, chloride represents the principal water-quality problem throughout
Indian River County. Table 2 lists the concentrations of the major chemical
constituents of water from five wells tapping the shallow aquifer and 15 wells
tapping the Floridan aquifer. Table 3 lists chloride concentrations of water
from 76 wells that tap the shallow aquifer. The chloride data for the shallow-
aquifer wells of tables 2 and 3 are also shown in figure 2.

SHALLOW AQUIFER
The quality of water from shallow-aquifer wells varies from place to place
within the county. Outside the drainage districts, chloride concentrations of
shallow-aquifer water generally are less than 250 mg/1 (fig. 2 and table 3),
and dissolved-solids concentrations are less than 500 mg/l (table 2). In gen-
eral, on basis of the limits of concentrations of chemical constituents recom-














Table --Chemical analyses of ground water in Indian River County.


Haord .ce


Vai *l E eI
SI | |j I j j


273937N1802335.1 66 4-8.70
273937M0602548.1 58 4-8.70
27394010804750.1 ZR-2SA 11 3-10.65 20
4-13-66 20
5.24-67 21
5-.868 22
5-19-69
5-15-70 20
5-13-71 22
Z740000802459.1 City We11 119 3.5-69 24
No. 9
27454810803037.1 87 12-17-69 24
City Ull 9-4-68
No. 11


Shallow Aquifer
118 5.7 44 0.5 39 0 68 0.2 0 482 319 0
107 3.9 30 .2 322 0 50 .3 .7 387 284 20
1.7 102 18 .6 318 0 24 .3 0 319 264 4
97 15 .4 298 0 24 .3 1.1 297 251 7
1.7 97 2.1 12 .4 304 0 17 .2 .9 340 251 2
107 2.3 14 .5 318 ,9 23 .3 3.5 414 277 16
.18 104 2.1 15 .5 310 1.2 '23 .3 1.1 362 269 15
1.5 97 2.0 12 .4 276 .8 26 .2 .5 327 251 15
104 2.0 13 .4 308 .8 26 .2 .5 368 268 16
110 6.5 40 1.3 320 35 66 .3 .1 476 302 40
101 10 40 3.9 258 0 9 .4 .3 443 295 1
.25 113 4.5 230 5 54 4 451 300

Floridan Aquifer


0




0

0


725 7.9 30
7.0 5


8M 4-23-69
4.10-70
4-2-70
21l-23 690 1-16-69
960 3-26-69
966 12-3-69
1165 1-16-69
890 4-9-69
2020 4-9-70
300 1-16-69
651 2-14-69
650 1-29-69
786 2-13-69
810 4-16-69
480 3-5-69
City Park 8-17-65
Wall


26 17
13
.6
24 19
26 16
27 16
24 16
5.5
.8
22 15
25 26
25 21
17
13
17
36


80 53
61 42
50 65
55 52
74 55
101 69
68 67
90 94
144 160
22 34
50 46
42 38
130 77
102 68
53 39
.01 60


197 7.9 176 122
142 6.8 210 120
358 18 102 168
224 13 192 132
196 8.0 176 122
312 9.6 164 160
425 23 148 186
473 14 100 96
1580 58 32 276
129 9.9 176 47
140 11 188 80
17Q 14 158 140
380 11 152 210
293 9.1 158 166
80 5.6 178 83
390 16 174 140


483 .7 .1 1110 429 285
238 .7 0 816 340 168
660 .9 0 1430 403 319
465 .8 .1 1140 361 203
442 .7 0 1110 442 278
660 .6 0 1420 552 418
760 1.0 0 1630 457 335
1806 .5 .1 1900 631 549
2920 1.1 0 5170 1030 1010
212 .9 0 574 201 57
280 1.2 .3 805 325 171
262 1.3 0 810 270 140
800 .7 0 1720 663 538
640 .7 0 1390 553 423
192 .8 .4 610 301 155
700 .7 .6 1490 417 274


27350110803021.1
273633M0803643.1
27380210802238.1
27383380802339.1
27400810802553.1
27402310802914.1
27403910802315.1
27420330802929.1
27420680802255.1
274309N0802450.1
274309110802653.1
27433720802339.1
27455730803430.1
27463530803636.1
27510830802710.1


1720
1320
2600
1900
1720
2620
2920
3450
9400
1000
1300
1320
3060
2410
940
2800










REPORT OF INVESTIGATION NO. 80 45

Table 3-Chloride concentration in water from wells in the
shallow aquifer in Indian River County, 1968-71.



Well Depth Date of C1
Number Local No. (feet) *mple

273336M0802232 127 3-26-69 38
27363910802328 86 1-6-69 77
273704110002521 66 1-9-69 240
273713N0802422 80 12-11-68 210
27373180802122 20 6-15-71 92

27373410002329 93 5-28-70 172
273741110802320 67 2-23-71 156
27374310002131 8 4-15-69 1455
27375730802500 71 2-24-71 124
27375910802422 70 2-23-71 86

27375930802507 67 2-25-71 94
27380080802539 67 2-24-71 54
27380110802553 54 2-24-71 58
27380380802515 63 2-25-71 122
273804H802118- 14 2-25-71 88

27380530802423 81 2-23-71 95
273809N0002602 45 1-9-69 105
27381110802603 45 2-24-71 354
27381380802403 66 12-11-68 41
27383280802419 67 2-23-71 116

27383810802408 86 2-23-71 72
27383880802647 51 5-5-70 221
27383910802338 81 2-23-71 64
27384210802447 Teat 55 4-8-70 36
27384530802333 45 1-10-69 85

27384610802332 49 1-10-69 74
27385230802337 46 1-10-69 115
27385380802410 Tesc 48 4-8-70 136
27385610802122 24 2-25-71 78
27385810802142 18 4-15-69 220

27385880802330 Test 54 4-8-70 76
27390380802548 Test 61 4-8-70 50
27390730802419 City-2 79 4-22-71 20
27390830802339 46 1-10-69 102
27391330802420 City-4 81 26

27391580802130 16 2-24-71 72
27391880802130 14 2-24-71 121
27392330802137 16 2-24-71 314
27393110802132 22 1-10-69 84
27393710802335 66 4-22-71 66

27393910802452 City-11 90 9-3.68 54
27394210802542 58 4-22-71 52
27395280802548 92 1-9-69 76
2740000802459 City-9 119 2-11-69 72
27400110802349 Test 66 4-8-70 81
27400330802606 79 4-8-70 75
27400410802416 67 4-30-70 32
27402210802512 107 5-20-68 462
27403880802427 68 4-17-69 50
27464310803901 60 6-10-70 158

27404410603943 60 6-10-70 178
27404530802151 14 4-22-69 80
274055NM002505 Test 54 4-8-70 167
27414710802623 66 4-10-70 60
274156N0805410 70 5-20-70 12

27430030802537 89 1-17-69 45
27433211004633 L26 3-31-70 101
27445230802612 17 12-4-68 37
2746.07N602609 55 4-17-69 170
2745158002537 .eat 53 4-8-70 11,025

27455410802415 28 4-1-69 498
27455500603428 78 2-13-69 17
27460010803601 66 2-12-69 600
274612N0003600 70 4-16-69 470
27461330003553 45 4-16-69 115

2746351U602908 120 6-11-70 85
27463930802701 74 4-9-70 139
27471310802732 89 4-17-69 50
27471510802731 88 4-17-69 95
27492330802817 63 4-16-69 35
27504610802920 79 4-16-69 100






BUREAU OF GEOLOGY


mended by the U. S. Public Health Service (1962), the shallow-aquifer water
outside the drainage districts is of a quality acceptable for domestic use.

Chloride is exceptionally high in the water from some wells near Indian
River, as might be expected, because of the high salinity of the river. But the
chloride appears to decrease rapidly with distance from the river. For example,
figure 2 shows that near Wabasso the water from a test well in the shallow
aquifer at the edge of Indian River has a chloride concentration of 11,025
mg/I, but concentrations are only 37 mg/l and 170 mg/1 for water from two
nearby wells less than 1 mile inland. On the east side of Indian River-on the
offshore bar near the southeast corner of Vero Beach-the chloride concentra-
tion of shallow-aquifer water is 1,455 mg/l, but the concentration is less than
100 mg/l in the water from two wells that are nearby but slightly further
inland- Also on the offshore bar, northeast of Wabasso and about midway
between Indian River and the ocean, a well yields water whose chloride con-
centration is 498 mg/l. In this general area of the offshore bar, however, a
high chloride concentration in water of the shallow aquifer probably results
from the use of Floridan-aquifer water to irrigate nearby areas.

Although the chloride concentrations of water from wells that tap the
shallow aquifer at relatively short distances from Indian River is acceptably
low for domestic use, the intrusion of saline water into the shallow aquifer is
a threat along the river where the aquifer is heavily pumped. The problem of
salt-water encroachment in the shallow aquifer is discussed in a later section
of this report.
Within the drainage districts, the quality of the shallow-aquifer water de-
pends largely on the extent to which Floridan-aquifer is used to irrigate. In
general, the concentrations of chemical constituents are much higher for
Floridan-aquifer water than for shallow-aquifer water (table 2). When crops
are irrigated, most of the applied water is consumed by evapotranspiration,
leaving behind in the soil a residue of minerals previously contained in solu-
tion. Part of these minerals, at least, especially the highly soluble chloride
compounds, are in time dissolved by rainfall. Some of the rainfall runs off into
drainage ditches and some of it moves downward to recharge the shallow
aquifer, carrying with it in each instance whatever minerals it contains in
solution. Of course, some of the water applied to irrigate crops may move
directly down into the shallow aquifer, taking with it virtually all of the chemi-
cal constituents it contained when applied. Thus, a substantial part of the
chemical constituents of the Floridan-aquifer water applied to irrigate crops
eventually reaches the shallow aquifer. The concentration of chemical con-
stituents of the shallow -aquifer water is thereby substantially increased.
The quality of the shallow-aquifer water may be expected to vary locally






REPORT OF INVESTIGATION NO. 80


within the drainage districts, of course, depending on both the quality and
quantity of Floridan-aquifer water that is used to irrigate a given area. For
example, assume that during dry periods of the year 8 inches of Floridan-
aquifer water having a chloride concentration of 400 mg/l are applied to an
area and, also, that all the applied water is consumed by evapotranspiration,
leaving all the chloride in the soil. Assume further that runoff from the area
is zero, that the annual recharge to the shallow aquifer from rainfall is 16
inches, that initially both the rainfall and the shallow-aquifer water are free
of chloride, and that all the chloride left in the soil is dissolved by the 16 in-
ches of water that recharges the shallow aquifer. If these assumed conditions
were to hold over a long time span, the shallow-aquifer water eventually would
reach a chloride concentration of 200 mg/I. If the quantity of applied water
is held constant, the eventual chloride concentration of the shallow-aquifer
water varies directly with the chloride concentration of the Floridan-aquifer
water. Thus, in the preceding example, if the chloride concentration of the
Floridan.aquifer water were assumed to be 800 mg/1 rather than 4.00 mg/l,
the eventual chloride concentration of the shallow-aquifer water would be
400 mg/l rather than 200 mg/1. Similarly, if the chloride concentration of the
Floridan-aquifer water is held constant, the eventual chloride concentration
of the shallow-aquifer water varies directly with the quantity of water that is
applied to the area.
The high chloride concentrations (600 mg/1 and 470 mg/1) of water
from two shallow-aquifer wells near Fellsmere (fig. 2) probably resulted from
the use of Floridan-aquifer water to irrigate areas near the wells. The chloride
concentration of 115 mg/l for water from the nearby shallow-aquifer well is
an indication of differences in quality of the shallow aquifer water that can
occur locally within the drainage districts. Local differences in the quality of
Sshallow-aquifer water also are indicated in the areas adjacent to Vero Beach.
Floridan-aquifer water is not widely used to irrigate within the city limits of
Vero Beash but it is used to irrigate citrus in some adjacent areas.

FLORIDAN AQUIFER
Chloride concentrations and well depths are listed in table 4 for water
from 86 Floridan-aquifer wells. The same data are also shown in figure 24,
which shows the location of the wells sampled and the location of two chloride
profiles. The profile along an east trending line through Fellsmere and Wa-
basso, based on data from 15 Floridan-aquifer wells, is shown in figure 25. A
profile across the county eastward through Vero Beach, based on data from 8
wells is shown in figure 26. The profile through Fellsmere (fig. 25) shows
high chloride concentrations for wells tapping the upper part of the aquifer
near Fellsmere and in the Fellsmere Farms Drainage District. These high




















0 DRAINAGEE 11

1 0 bl



- -- 8 1 0 \"
O '0 / DISTRICT EL .
On o W a








EXPLANATION i


I I IlNDIAN RIVER FARMS \~ \
0 oe0




O WELL. LONtG I M 0
o WELL, PROJECT I ST. JOHNS DRAINAGE DISTRICT I
A GAINGO STATION. LOW TIM 0 00 O
A AGING STATION. PROJECT AINAE DISTR
-- DAINAM DISTRICT oi i A i *
---- MAIN CANAL OR DITCH AI -" r" _a-- iL. --.
LO OI=Cw INTRIw. MILLIGRAMS PER LITRE, I is T r 0
DEPCTm OF WELL. FET I I I LU
CHLORIDE R E R 37 E R 38E R 39 E
I I I I I 1 .. Ik-LAI-II IIi I|- ..I I
Figure 24.-Chloride concentration of water in wells of indicated depths in the
Floridan aquifer in Indian River County.


I' "a







REPORT OF INVESTIGATION NO. 80


S 10 A'
ATLANTIC
S OCEAN SEA
LEVEL

-I0o
-00

-OO
-300'


-400


EXPLANATION
INDICATES ALTITUDE OF WELL
BOTTOM; NUMBER IS CHLORIDE
CONCENTRATION, MILLIGRAMS
PER LITRE.


1 I I I I I
5 10 15 20 25 30
DISTANCE. MILES
Figure 25.-Chloride concentration of water from wells in Floridan aquifer
along section A-A' in northern Indian River County, 1968-71
(see fig. 24 for location of section.)


concentrations probably are associated with the upward movement of more
saline water in the lower part of the aquifer as a result of uncontrolled flowing
wells or locally heavy withdrawals. Because the chloride concentration is so
variable, it cannot be reliably predicted for a new well in any particular area.

The chloride concentration of water from Floridan-aquifer wells is lower
(140 to 300 mg/1 at depths as great as 700 feet) along the coastal ridge than
elsewhere. The potentiometric surface is below land surface in some places
along the coastal ridge (fig. 14). Some recharge to the Floridan aquifer prob-
ably occurs in the coastal ridge area, although the quantity presumably would
be small because of the thickness of the confining layer. The possible relation
between the low chloride concentrations and recharge to the Floridan aquifer
in this area could be considered as a subject for future investigation.

The quality of Floridan aquifer water, as judged by its chloride concentra-
tion, appears not to have deteriorated appreciably in most parts of the county


--500'

- -600'

- -700'

-800'

-900'

--1000
35
























-20d0


-- APPROXIMATE TOP OF FLORIDAN AUIFER -300


0
4so -oo'





560 00
65 aS270 laO
-800'

EXPLANATION
I61 INDICATES ALTITUDE OF WELL
BOTTOM; NUMBER IS CHLORIDE 900
CONCENTRATION, MILLIGRAMS
PER LITRE.
I I I, I I -I00 '
5 10 15 20 25 30 35
DISTANCE, MILES



Figure 26.-Chloride concentration of water from wells in Floridan aquifer.
along section B-B' in southern Indian River County, 1969-70 (see
fig. 24 for location of section.)












TABLE 4-Chloride concentration of water from wells in the Floridan aquifer, 1967-71 (milligrams per litre)


Depth Data of CL Depth Dce of CL
IslLAa. LsaL (at go) *st 11 a. toul 3a. ([ft)1 jI -
27332 2030209 1,o20 .u4-71 72 27445a 02tU t-172 MO 4--70 439
2733306002621 900 -14-71 215 274452M002755 -247 620 5-17-4 304
2733313U602353 900 -1-71 492 2744S36271 3 2.146 450 51748 305
273406i0232 -.252 MO -2-70 1Us 2744S63 02757 R-151 625 2.1449 330
273431 02210 -.245 So0 -21-49 228 27U459X 905 416 5.21.70 00
273502L503021 560 4-23-69 210 274501010221 R*-0 00 6-10-71 318
273"100o0223 450 5-21-70 262 273402130130 9 4-10.49 230
2735132i 0252 .-2M 760 5-20- 490 27415tP 02A 1 -24-47 540 0
273515I02522 75 12-12-68 39 27452f06O230 400 4-10.9 320
27352UI 0224 700 5.21-70 340 274549U02MS2 -73 800 5-2447 510
2735270002*30 750 5-21-70 322 274552102422 l2 950 1-2949 92
272329u002600 B-256 700 -9-71 408 274553OMM40 R-72 800 5-24-7 0 0
273719M0M210 3-248 677 2-12-0 305 274557O03430 786 21-U. 100
2737256m 254 & 255 575 6-11-71 282 274536l 60302 174 $40 4-14 495
273814MM0252 1-24 671 12-4-9 440 274401U0318 1-175 00 5-4-70 i 6184
27"819I0M2601 R-228 750 2-1449 270 2744027MO4930 -189 630 .-21-70 298
27382 3 026M 9 -213 700 12-17-64 618 2744001M2n 4 0 4.1049 320
273311000461 a-20 1969-71 O0 27446 L30301 457 4-16-69 485
27840M060506 -227 750 5-21-70 M5 274627M03421 960 2-124-9 825
2739100M00232 -.20 550 5-7-70 310 274435060319 650 2-1241 610
2739531002748 -.208 700 3-6-49 315 274663M0322 550 2-1249 932
274005M0249 M.230 720 3-22-71 140 26341MM022 720 3-.249 7135
2760151002350 635 12-12-48 208 274635M1OS6030 .-183 640 5 .24 405
2740390M0215 t3-231 1,165 1-1649 70 2744631 02MM36 110 -.-69 470
2740 21000813 3-210 .650 3-- 390 27461Nu 010322 700 3-.249 00
2741136M04755 B-188 700 ,.27-70 5$0 27444002UM0 4 Z-201 -84 1-249 535
27411430M749 550 5-27-70 525 2744602 mDM38 I-32 730 U14 49 MS
274115602916 886 12-3-49 563 2744446902438 .-50 750 1-29-69 690
274116W02650 .*216 63 4-10.70 345 274647UM" 34 I169 SS 64-10- 678
274121U M2417 3.233 635 4.1-70 21 27463003MO 02M 380 4-1049 545
2741102756 615 4-.2469 343 27472o 02 360 4-10.49 615
2742006 2255S 2,020 4.6-70 2,920 2747A 1 02743 510 U121-70 27
274U228M04633 400 4-149 450 274815002M41 1-33 340 5O *48 54
274226M022o 3 .t-2.4 500 4-1-70 382 274432W60212 -S1 450 -16-71 220
214231716002S3 a-21 MO -6.-71 230 2749W9 0329 M-61 1,150 4-16-71 57 00
27424a00M2713 -299 r401 6.9-71 32u 2748M401203 500 4-.270 no0
274309002450 I- 23 00o 1-.1-6 212 27491U 03425 180 42W 3-22-70 68
2763095M02M33 0-259 651 214-69 210 27142761-02M1* 700 4-70 435
2743106t 02933 23-5 400 2-649 582 27493010M 3017 6 6-10-71 420
274313M0237 800 3-27-70 370 2735047M2024 6 00 4-16- 300
275117 10270 480 3-.49 220
2742333m04493 450 3-31-70 338
276337110239 3 o-11 650 1.2949 262
276430500M132 460 4-10.4 63
2744040I02330 6 -114 5M 1-29-9 400
27645023"0159 -104 1,000 4-1.70 69
OI
r,,










































500 600 700 800 900 1000 1100 1200
DEPTH OF WELL, FEET

Figure 27.-Relation of chloride concentration to depth of well in Floridan
aquifer, Indian River County.






REPORT OF INVESTIGATION NO. 80


since 1951, when many wells were sampled (Bermes, 1958, p. 67-72). The
chloride concentration was determined during 1968-71 for 86 Floridan aqui-
fer wells (table 4), including 43 wells that were sampled during the 1951-52
investigation. Of these 43 wells, 32 increased in chloride during the approxi-
mately 20-year interval, and 11 decreased. The increases were as much as 296
mg/I, with a median of about 80 mg/1; the decreases were as much as 550
mg/1, with a median of about 50 mg/l; seven of the wells had changes of
10 mg/l, or less.
Indications of changes in chloride also lack consistency in the plot of
chloride concentration to well depth in figure 27, which includes the chloride
data for all Floridan-aquifer wells sampled during the two investigations. Al-
though the areal distribution of the sampled wells to some extent differed for
the two studies, the preponderance of wells sampled in each instance were in
the eastern part of the county within about 10 miles of the coast.

In the 36-square mile area south of Vero Beach (T33S, R39E), chlo-
ride concentrations of 14 wells sampled in 1968-71 averaged 450 mg/1 com-
pared to 424 mg/1 for 23 wells sampled in 1951-52. In the adjacent area to the
north (T32S, R39E), chloride concentrations of 16 wells sampled in
1968-71 averaged 334 mg/1 compared to 313 mg/1 for 21 wells sampled in
1951-52. In the area still farther to the -north (T31S, R39E), chloride
concentrations for 13 wells sampled in 1968-71 averaged 462 mg/1 compared
to 488 mg/1 for 45 wells sampled in 1951-52. Thus, in the eastern part of the
county, a small increase in chloride concentration is indicated for wells gen-
erally south of Winter Beach; a small decrease is indicated for wells to the
north.
Of the Floridan-aquifer wells sampled in the 1951-52 investigation, 55 per-
cent were sampled in October through February, when ground-water with-
drawals for irrigation presumably would be least, and only 32 percent were
sampled in March through June, when withdrawals presumably would be
greatest; of the Floridan-aquifer wells sampled in the 1968-71 investigation,
73 percent were sampled in March through June and only 20 percent in Octo-
ber through February. If the chloride concentration increases with the rate of
withdrawal, samples of the more recent investigation might be expected to
show the higher concentrations.
The chloride data of the two investigations show obvious changes in the
chloride concentration of water withdrawn from some Floridan-aquifer wells;
however, analyses of the data do not indicate that the chloride concentration
has changed appreciably for the county as a whole, even though the rate of
withdrawal has increased since 1951. The present rate of withdrawal (about
100 Mgal/d) probably can be maintained without appreciable deterioration






BUREAU OF GEOLOGY


in water quality. A continuing program for sampling the water from Floridan-
aquifer wells would detect incipient changes in quality should they occur.

SALT-WATER ENCROACHMENT
One of the real problems in the development of the shallow aquifer is the
possibility of salt-water encroachment. Salt-water encroachment is possible
whenever salt and fresh water are in contact in an aquifer and the equilibrium
between the two is upset by withdrawals of fresh water from the aquifer either
by pumping or drainage. As fresh water is recharged to the aquifer, it floats
upon the salt water because, due to a lower dissolved-solids concentration, fresh
water is slightly less dense than salt water. Some mixing takes place within the
zone of diffusion at the interface of the two waters but the slow rate of move-
ment of the waters in the aquifer and the lack of turbulent flow tend to retard
mixing. However, the difference in density between fresh water and salt water,
whose dissolved-solids concentration is typical of that of sea water, is such
that to support a fresh-water head of 1 foot above sea level under static con-
ditions a thickness of 41 feet of fresh water overlying the salt water is required.
Accordingly, if the fresh water were lowered 1 foot by pumping, for example,
the level of the salt water could rise 40 feet. This, therefore, is the cause for
concern about salt-water encroachment, since relatively small changes in water
levels can result in relatively large changes in the position of the fresh-salt-
water boundary.
The possibility of salt-water encroachment must be considered in any
coastal area of Indian River County where the shallow aquifer is heavily
developed. For example, in the vicinity of Vero Beach, where pumping of wells
caused water levels to decline to and below sea level, salt water encroachment
can be expected. Figure 28 shows the areas where water levels were at or be-
low sea level on April 22, 1971. Salt-water encroachment had not occurred
as yet, perhaps because of the short periods of time that water levels were low
or because geologic conditions retarded encroachment. Water levels for July
23, 1971 (fig. 29), during the rainy season, show an appreciable rise from
those for April, near the close of the dry season.
Two favorable geologic conditions prevail which retard salt-water encroach-
ment. As shown in figure 10, one condition is that the aquifer is underlain
by a relatively impermeable formation which retards any upward movement
of deeper salt water. The other condition is the fact that the shallow aquifer in
the area of the Indian River contains cemented layers of low permeability
near the land surface and under the Indian River which retard the movement
of water. This zone of low permeability minimizes the discharge of fresh
ground water from the shallow aquifer into the Indian River, thereby main-
taining relatively high ground-water levels near the coast.

















O


oI








O
P-4







T 32 S.
T 33 S.


00
0


Figure 28.-Water levels in shallow aquifer in vicinity of Vero Beach well
field, April 22, 1971.


















































40 E.


T 32 S.
T 33 S.


well field, July 23, 1971.






REPORT OF INVESTIGATION NO. 80


The effects of heavy pumping on chloride concentration in the water at
Vero Beach well field and elsewhere to some extent can be evaluated by exami-
nation of the available water-quality data. In areas where development is
slight, analyses of water-quality samples indicate that salt-water encroachment
has not occurred. Water samples were collected from several wells as much as
70 feet deep in the Wabasso-Sebastian area; many of the wells were adjacent
to the Indian River. The choride concentration of the water from these wells
was low-in many less than 50 mg/1-indicating that the salt-water front was
east of those wells and beneath the Indian River. However, a 53-foot deep test
well near the edge of Indian River east of Wabasso (fig. 2) yielded water with
a chloride concentration of 11,025 mg/l, indicating that fresh water did not
extend far out under the river.
Many water samples were collected from wells in and around the Vero
Beach well field, where a large amount of water is withdrawn from the shal-
low aquifer. This is the area where salt-water encroachment would be likely.
In addition, three small diameter test wells were installed east of the well field
-about 1 mile from the Indian River and about half a mile from the man-
grove salt marsh-to monitor changes in the chemical quality of the water in
that critical area. Figure 30 is a map of the Vero Beach area showing the loca-
tions of the wells in the shallow aquifer and the chloride concentration of the
water sampled, mostly on April 8, 1970 and April 22, 1971.

At that time water levels in the well field were about their lowest for the
year and pumping rates were higher than average. Analyses of the samples
showed that the chloride concentrations of the water from wells in the area of
the well field along the ridge is lower than that of water from wells outL-de
the well field. Some chloride values for shallow wells in or near the city of
Vero Beach are higher, probably because citrus groves adjacent to the city are
irrigated with water from the Floridan aquifer. Water from the Floridan
aquifer is not used for irrigation in the well-field area.
It appears that even under low-water conditions no influx of salty water is
taking place from Indian River into the shallow aquifer. This is also suggested
by an examination of the water-level contour map of the well-field in figure
28. The cone of depression around the well field seemingly is not deep nor
extensive enough to induce flow of salt water toward the well field from the
east.
Samples of water were also collected from April 1970 to August 1971 from
three test wells just east of the well field. Because of their proximity to the
Indian River these wells should be the first to reflect an increase in chloride
concentration of water in the aquifer if encroachment occurs from the river.
The chloride concentration of water in these wells was low, ranging from 51






BUREAU OF GEOLOGY


26 TK ST 5 ( T. 32 S.
OF VERO BECH WELW LL6 64 \ T. 33 S.
Si-



1 04 J22 0124 086
0 1, 2 I MILE I
R 39 E. R. 40 E.
Figure 30.-Chloride concentration of water in shallow aquifer near Vero
Beach, April 8, 1970 and April 22, 1971.

to 94 mg/1. Actually, the chloride concentration in water from all three wells
was lower in 1971 than in 1970.

CHEMICAL QUALITY OF SURFACE WATER
ST. JOHNS MARSH
As indicated by the chemical analyses shown in table 5 for St. Johns
headwaters near Vero Beach and St. Johns headwaters near Kenansville, the
chief chemical constituents of marsh water are, as in most waters, calcium,
sodium, magnesium, bicarbonate, sulfate, and chloride. Because marsh water
is diluted by rainfall and runoff during wet seasons and concentrated by
evapotranspiration during dry seasons, the concentration of chemical con-
stituents in the marsh water are low when the water level of the marsh is
high, and high when the marsh water level is low. When the water was
sampled in May 1966 (figs. 17 and 18) the level was slightly below average.
For higher water levels in the marsh, concentration of chemical constituents
will be lower than indicated by the analyses for May 24, 1966. When
themarsh was sampled on April 18, 1968 the water level was unusually low.
The concentrations indicated by the analyses for the April 18, 1968 sam-






REPORT OF INVESTIGATION NO. 80


ples probably are representative of the highest concentrations that likely will
occur at the sites sampled. The cause of the marked difference between con-
centrations of chemical constituents in the water from St. Johns headwaters
near Vero Beach and that from St. Johns headwaters near Kenansville (dis-
solved solids 4.29 and 802 mg/l, respectively, on April 18, 1968) is not known,
but may be caused by Floridan-aquifer water that drains from irrigated land
upstream from the Kenansville gage.

The water of Blue Cypress Lake is similar in chemical quality to the water
at St. Johns headwaters near Vero Beach, particularly when their water levels
are in the middle or upper range of fluctuation. With the general decline in
water level from May 1966 to April 1968, the increase in concentration of
chemical constituents was much greater for St. Johns headwaters near Vero
Beach than for Blue Cypress Lake. The difference is in part caused by the
lake being deeper than the marsh; the increase in concentration brought about
by a given amount of evaporation is less for the lake than for the marsh.


DRAINAGE DISTRICTS
The chemical quality of water in the canals is generally about the same
for the several drainage districts (table 5) but it varies widely with the rela-
tive proportions of rainfall, irrigation water from the Floridan aquifer, and
leakage from the shallow aquifer that make up the canal water at any given
time. The variation in chemical quality was determined for Main Canal at
Vero Beach by continuous measurement of specific conductance of the water
from April 1969 to March 1971. The specific conductance of water varies with
chloride and with the sum of chemical constituents in the water as shown in
figure 31.

The specific conductance of canal water generally increases during dry
seasons, when the canal is transporting substantial quantities of irrigation
water, and decreases during wet seasons, when rainfall dilutes the unused
irrigation water and flushes the system along with the chemical residue left
by evapotranspiration. From April 1969 to March 1971 the specific conduc-
tance of water in Main Canal at Vero Beach ranged from about 300 to 1,800
micromhos, but, as indicated by the duration curve in figure 32, was between
700 and 1,600 micromhos about 80 percent of the time. When weighted by
daily discharge, specific conductance for October 1969 September 1970 av-
eraged 850 micromhos, corresponding to a chloride concentration of about
150 mg/l. Seasonal variations in specific conductance of water in Main Canal
are portrayed in figure 33 (dry season) and figure 34 (wet season).
At any given time the concentration of chemical constituents in the water








TAIIL 5,.-Chemical analysue of surface water and rainfall in Indian Itlver County
(Chemical constituents in milligrams per litre),


Dissolvved Solid.





Date


South Canal at Vero Beach, Fla.
6-1-55 227 1,180
5-11.56 103 653
5-23-66 153 6.7 .01 83 35 152 7.0 170 91 330 .5 .4 790 351 212 1,470 7.7 45
4-6-68 3.7 25 7.2 .05 81 11 1.2 59 2.0 232 30 106 .4 1.2 ,44 413 452 248 58 720 7.4 45 8,8 105

Indian River at Wabasso, Fla.
5-23-66 l.9 .00 371 1,115 9,220 396 160 2,330 16,800 1.8 15 30,400 5,660 5,520 45,900 6.7 5
4-17-68 25 2.6 .03 406 1,210 7.4 10,400 350 168 2,620 18,600 1.4 .0 .22 33,700 6,000 5,860 48,800 7.4 5 6.9 82
5.5-69 28 215 615 1,180 8,650 3,070 7.6 96

Port Drum Creek at Suuahlne State Parkway
7.23-70 41.4 26 6.3 .35 11 2,7 .10 13 .8 1.6 20 .4 0 .22 74 129 39 9 136 6.9 200 4.9 60

Rainfall at Forest Service Tower
3-26-70 0.1 0.4 0.1 0.8 0 0 1.2 1.5 0 0 4 11 2 2 11 5.6 0 0

Rainfall at Vero Beach WIll Field
3-26-70 .2 .9 .3 1.3 0 .1 .8 2.2 .1 0 6 6 3 2 16 5.6 0
Canal G-3 at N, Winter Beach above Lateral G
5-5-69 30 7.6 .03 50 10 52 3.0 122 43 101. .3 .1 .09 327 369 166 66 570 7.5 50
Canal A-10 at SR 505 above Lateral A
5-5-69 30 13 .04 150 37 134 9.5 250 194 308 .7 .1 .25 969 1,100 526 321 1,600 7.8 50

Canal D-4 at 25 feet south of Citrus Road
5-6-69 28 8.5 .03 79 26 105 7.9 144 101 235 .7 .1 .08 634 699 304 186 1,100 7.2 50

Range Line Canal at SR 60 above Junction with R-3
5-6-69 24 9.6 .03 112 17 81 2.9 244 79 185 .5 0 .27 607 679 350 150 1,020 7.7 45

Canal D-6 at Citrus Road, 50 ft upstream froa Lateral D
5-6.69 30 9.1 .03 77 20 76 4.4 194 78 148 .6 .1 .07 509 571 275 116 860 7.5 50

Lateral A at Lindsay Road, 50 ft uptream fror A-.
5-6-69 24 4.7 .03 71 24 100 5.8 164 74 218 .5 .1 .32 579 654 276 141 1,000 7.5 45

A lateral at Oslo Road, 10 ft upatream from Junction with C-4
5-6-69 30 9.6 .04 73 35 163 5.9 144 76 368 .6 .1 .08 802 920 326 208 1,420 7.4 50






TABLE 5.-Chemical analyses of surface water and rainfall in Indian River County (Continued)
(Chemical constituents in milligrams per litre).


5-7-69

5-7-69 28 3

5-8-69 26 6

5-8-69 25 4

5-8-59 25 4

5-24-66 4.4
4-18-68 22 16
7-29-69 144 29 14

5-24-66 1.6
8-9-66 .8
4-18-68 31 1.3
4-30.70 28 2.7

5-24-66 9.3
4-18-68 25 13


4-27-55
4-30-56
5-13-57
5f3-58
6-13-66 9.6
4-18-68 71 24 9.9

4-27-55
4-30.56
5-23-66 42 15
4-18-68 39 25 9.3

6-1-55
5-12-56
5-23-66 9.4 7.1
4-17-68 18 25 8.4

6-1-55
5-12-56
5-23-66 80 9.6
4-17-68 14 27 4.9


.9 .06 32

.3 .08 55

.2 .07 27

.1 .02 111

0.12 19
.02 55
.21 .75

.07 19
.19 13
.03 28
.20 14

.28 72
.04 92


.03 68
.03 108



.02 92
.04 80



.02 62
.03 87



.01 82
.03 88


6.3

9.8

3.5
7Un d
37


Canal -2 at Rosedale Road nd SR 611
79

Lateral J at Oslo Road above Junction vich J-2
33 1.4 88 19 64 .2 0 .06

Canal, at bridge on SR 510
53 2.9 128 32 115 .3 .1 .07

Unoed lateral at SR 510, near Fellomere
18 .7 72 8.4 37 .2 .1 .05
canal at !1. Winter Beach Road, 750 fc west of Range Line Can
174 4.3 184 108 410 .6 .1 .08


St. Johns Headvaters ner Vero Beach, Fla.
3.6 23 0.1 42 9.2 50 0.4 0.3
16 3.0 76 2.1 140 28 158 .5 5.1 0.17
12 1.1 54 2.3 200 76 81 .5 .1 .08
Blue Cypress Lake near Fellonere, Fia.
3.4 20 .4 48 1.3 44 .2 .7
2.4 17 .6 32 1.6 34 .3 .4 .17
4.2 .44 27 1.1 68 7." 57 .2 1.1 .07
2.9 .30 18 .9 4.0 36 .2 .4 .09

St. Johns Readu terms near Kenansville, Fla.
18 76 1.1 164 74 163 .6 .7
40 12 128 4.6 160 158 275 .6 .2 .10

South Prong Sebastian Creuk near Sebastian, Fla.
215
305
124
198
15 64 3.5 164 39 140 .4 .7
48 10 209 7.7 200 124 452 .7 .1 .23

Fellsere Canal near Fellmare, Fla.
111
220
22 98 3.1 228 61 205 .5 .5
14 1.8 63 2.3 201 39 128 .6 1.0 .04

North Canal near Veto Beach, Fla.
114
93
13 51 1.9 176 34 102 .3 .4
30 3.7 118 6.5 196 83 250 .5 .1 .15
ailn Canal at Vero Beach
168
200
29 120 5.2 188 79 251 .6 .0
37 4.9 163 7.2 196 90 330 .6 .1 .23


72 390

203 242 106 34 360 7.4 60

137 408 178 73 600 7.6 80

134 168 82 23 236 7.0 100
al
940 1,130 429 278 1,650 7.4 30

131 55 20 237 6.5 160
429 506 206 91 770 7.2 80 2.8 32
415 480 238 74 690 7.4 50 3.2 41

115 62 22 224 7.1 100
86 122 42 16 180 6.8 120
161 218 88 32 302 7.4 80 9.6 123
96 143 48 22 190 7.6 100 7.5 97


494 254 119 918 7.1 45
802 858 408 277 1,400 7.2 30 1.2 14

1,170
1,450
665
1,010
421 231 96 750 7.3 80
1,070 1,130 478 314 1,920 7.5 25 6.8 80

700
1,130
609 320 133 1,090 7.9 50
438 507 259 94 770 7.4 50 5.7 68

739
602
359 208 64 663 7.9 45
684 723 344 183 1.280 7.4 40 8.5 101

985
1,150
669 324 170 1,220 7.7 55
823 873 377 216 1,470 7.4 60 8.7 107












1200


1000


800


600


400


200


0 200 400 600 800 1000 1200 1400 1600 1800 2000
SPECIFIC CONDUCTANCE, MICROMHOS AT 25 C

Figure 31.-Relation between specific conductance of water and concentration
of selected chemical constituents in water of canals in Indian
River County.


--------^

DISSOLVED SOLIDS (CALCULATED SUM),'






do
p *
S -
'" S .L rI
J .,- e
-= CHLORIDE-
"woo







REPORT OF INVESTIGATION NO. 80


1800

1600

1400

1200

1000

800

600

400


200


10 20 30 40 50 60 70 80
PERCENTAGE OF TIME SPECIFIC CONDUCTANCE
EQUALED OR EXCEEDED A GIVEN VALUE


90 100


Figure 32.-Duration curve for specific conductance of water in Main Canal
at Vero Beach.

varies widely within the drainage system, as indicated for Sebastian River
and Indian River Farms Drainage Districts in figures 35 and 36. Figure 35
shows the areal distribution of both specific conductance and concentration
of chloride of water samples taken from the drainage ditches and canals May
5-8, 1969. Because rainfall during the preceding several weeks was scant,
a substantial quantity of irrigation water probably was used before and dur-
ing the sampling period; specific conductances ranged from 230 to 1,800 mi-
cromhos and chloride concentrations ranged from 33 to 430 mg/1. Based on
field measurements on October 8, 1969 (fig. 36) specific conductances ranged
from 160 to 1,220 micromhos. The general reduction in specific conductance
resulted from dilution of irrigation water in the canal system by rainfalls dur-
ing September and the first few days of October 1969.
As discussed earlier, when Floridan-aquifer water used for irrigation flows
in a canal, the canal water has a higher specific conductance and greater
amount of chloride than when Floridan water is not being transported. Hence,
the chemical quality of the water in the drainage ditches and canals is related
to the land use. Most of the land in Sebastian River and Indian River Farms


NOTE: CURVE BASED ON AVERAGE VALUES
SOF SPECIFIC CONDUCTANCE FOR 673
DAYS DURING APRIL 1969-MARCH 1971.
L I I I I I I I







BUREAU OF GEOLOGY


2000


SPECIFIC CONDUIT


1000





500



In
0

z
O40
X C



0 CI
100-



U 0







0.


Figure 33.-Daily discharge and specific conductance of water in Main Canal
at Vero Beach during a relatively dry spell in April and May 1969.








REPORT OF INVESTIGATION NO. 80


1000



500


ain
to
0
W Cn
In


0-.
uo
oU-
(L








U)


Figure 34.-Daily discharge and specific conductance of water in Main Canal
at Vero Beach during a relatively wet spell in September-Novem-
ber 1969.


Drainage Districts is in citrus or improved pasture but some parts still are not
farmed. Figure 37 shows the extent to which the land was planted in citrus
or improved pasture in 1968. Statistical analyses of the specific conductance
of water in the drainage ditches on May 5-8 and October 9, 1969, showed
that the specific conductance of water in the drainage ditches is proportional
to the ratio of the area of irrigated land (citrus and pasture) to the total area
drained by individual ditches.

The specific conductance of water passing the gaging stations on the canals
generally decreases with increasing discharge. This relation does not hold for
variations in discharge that are caused by differences in proportion of irriga-
tion water being transported. Similarly, the relation does not always hold for







BUREAU OF GEOLOGY


80* 25'





EXPLANATION

430
INDICATES SAMPLING POINT. UPPER
NUMBER IS SPECIFIC CONDUCTANCE,
MICROMT AT 25B Ci LOWER
NUMBER IS CHLORIDE CONCENTRATION,
MILLIGRAMS PER LITRE.

ARROW INDICATES DIRECTION OF
FLOW AT TIME OF MEASUREMENT.


27 45' -





















27' 4C -


1 1/2 0 II
----


I I
80* 30 80* 25'


Figure 35.-Specific conductance and chloride concentration of water in drain-
age canals at selected points in Sebastian River and Indian River
Farms Drainage Districts, May 5-8, 1969.


80S 30'

K'


- 27 45'





















-27 40















-27 35'





-- 27 35'


27 34 --














80 30'


80* 30' 80' 25'


Figure 36.-Specific conductance of water in drainage canals at selected points
in Sebastian River and Indian River Farms Drainage Districts
from field determinations on October 8, 1969.


REPORT OF INVESTIGATION NO. 80


80* 25'





27 45'
EXPLANATION
01050
*eoso
INDICATES SAMPLING POINT; NUMBER
IS SPECIFIC CONDUCTANCE,
MICROMHOS AT 2Se C

ARROW INDICATES DIRECTION OF
FLOW AT TIME OF MEASUREMENT.





-IS
I.



LI
H-1





270 40'


270 45' -























270 40'-


I 1/2 0 I
| I I


27 35 -







BUREAU OF GEOLOGY


27 4c -


l I/2 0 I MIL


0 6A

O4T
0-7



7`5-?c
; g &> _


27" 33-


80* 3(








SE8AS


DRAI


*^ ,




n-


80* 25'
I


TI A
A

-I 14 I ARA IN

I RI

NA E G-3 #
A- 11 -

ICT I
SNORH CANAL


~I 1
------------2--r
A l 4 I. t A-3 .a:
-- IR- -A
;;/; %-


C-I
7 77 57777


4


LAN ACTION

r"1
iA IN CITRUS

IMIOVOD PASTURE


-- 27 40'


--


m^6A q KW


I ~ e '


;LA


I=-


TI I'


~--~ '


"-" 19-


C7 -


80* 30'


-.10 B-10


- -6 *.


I
80" 25'


Figure 37.-Map of Sebastian River and Indian River Farms Drainage Dis-
tricts showing areas in citrus and in improved pasture in 1968,
based on information from U. S. Soil Conservation Service.


- 27' 45'


- 27 35'


'4 a1
Y 4
IA 5ra


J.B 8


A- :;9

A-8




A-6


M'4


- --~ ------


- -- % 0 -


I~-c---~mnr~---rrrr*c -- --- a -------


_T1- ^ &*


-~~~--- ------ --~ --


- &A


5 -7 8-7
-J1 ^ --- .. ...


-- '-I'_._ t_ ._ ,- "


0'






REPORT OF INVESTIGATION NO. 80


periods of low flow in South, Main, and North Canals because the low flows
of these canals are subject to regulation by gates. If the gates remain closed
long enough, the discharge at the gaging station represents drainage from the
shallow aquifer that enters the reach of canal between the gates and the gaging
station. Under these conditions the chemical quality of the canal discharge im-
proves and the specific conductance of the water decreases with decreasing
discharge.

If several assumptions are allowed, a gross estimate can be made of the
quantity of irrigation water taken from the Floridan aquifer for use within
the Indian River Farms Drainage District provided that the concentration of
chloride in the Floridan aquifei is known. The assumptions are: that the Flori-
dan aquifer water is the only source of chloride and that the change in the
quantity of chloride stored in the drainage system is negligible compared to
the flow of chloride through the system. During the 1970 water year (October
1969 to September 1970) the average specific conductance of the discharge
from the Main Canal was about 850 micromhos when weighted by daily dis.
charge. From figure 31' this corresponds to an average chloride concentration
of about 150 mg/l. The same chloride concentration is assumed to apply to
North and South Canals during this same time. Total discharge of the 3 canals
averaged 191 efs during the year. The product of the average discharge times
the average chloride concentration represents the total load of chloride leaving
the drainage district during the 1970 water year.
During April and May 1970, when a substantial quantity of irrigation
water was used, specific conductance of water in Main Canal ranged from
about 1,500 to 1,800 micromhos. On the assumption that the upper end of the
range represents pure Floridan aquifer water, the chloride concentration of
Floridan aquifer water averaged about 400 mg/1 (fig. 31). From the load of
chloride discharged from the district and the chloride concentration of the
input, the quantity of Floridan aquifer water supplied to the district is deter.
mined as 72 ftW/s (46.5 Mgal/d) or about 8.5 inches of water over the entire
area of the district.
Some of the chloride discharged from the drainage district is derived from
sources other than Floridan aquifer water, of course, but the quantity of chlo-
ride derived from such sources appears to be relatively small, at least for the
purpose of this discussion. On March 26, 1970 (table 5) the chloride concen-
tration of rainfall was 2.2 mg/1 at Vero Beach well field and 1.5 mg/l at
Forest Service Tower about 27 miles inland. Specific conductance and chloride
concentration of rainfall from five separate rains during the period January
to May 1970 averaged 24 and 6.7 and 17 and 5.2 at the two sites, respectively.
The chloride concentrations of March 26 are fairly well in line with the av-






BUREAU OF GEOLOGY


erage yearly concentrations of chloride given by Gambell and Fisher (1966,
fig. 4) for bulk precipitation along the Atlantic Coast in North Carolina and
Virginia. They showed that from August 1962 to July 1963 the average chlo-
ride concentration of rainfall was 1.5 to 2 mg/l along the coast of the main-
land and that it decreased to less than 0.5 mg/l about 70 to 80 miles inland.
If the chloride concentration of rainfall on Indian River Farms averaged as
much as 3 mg/l the yearly rainfall would add less chloride to the land than
is added by half an inch of irrigation water from the Floridan aquifer.
Similarly, the quantity of chloride leached from the sand and shell of the
shallow aquifer is probably small. The chloride concentration of the native
water of the shallow aquifer probably is less than 20 mg/l (table 3) which
indicates that most of the chloride initially in the sand and shell has been
leached by rainfall over many years. Thus, allowing for the minor quantities
of chloride added from other sources, slightly less than 8 inches of Floridan
aquifer water might be required to account for the chloride discharged from
Indian River Farms during water year October 1969 September 1970.

WATER USE
Water use may represent withdrawal use, which is water withdrawn from
surface- and ground-water sources for consumptive or non-consumptive use,
or it may represent non-withdrawal use, such as the water used for waste
dilution, recreation, or fish propagation. Non-withdrawal use is not considered
in this report.
Water withdrawn, as the term is used herein, is water that must be di-
verted from its source in order to be used, whether for domestic use, waste
disposal, industrial processing, cooling, irrigation, or other purposes; some
of the water may later be returned to a stream or to the ground and again
become available for use.
Consumptive use of water includes water which enters into a product
through vegetative growth and food processing or is lost through evaporation.
Consumptive use is large for irrigated crops, averaging about 75 percent of
the water applied to the crops in St. Johns River basin (Florida Department
of Natural Resources, 1970, p.86). Consumptive use is relatively small for
some cooling and industrial processes.
Water use in Indian River County was determined by the U. S. Geological
Survey in 1965 and 1970 (Pride, 1970, 1973). Estimates of present and future
water needs have been made by the U. S. Soil Conservation Service and the
Florida Department of Natural Resources (1970). Projected water needs for
years 1980, 2000, and 2020 are shown in figure 38 along with projected popu-
lation of Indian River County.







REPORT OF INVESTIGATION NO. 80


400


300




200




100


MUNICI PAL

0 0 0
- 0O Oa
a) 0) <


Figure 38.-Estimated water use and population for Indian River County.

Municipal use in Indian River County is expected to increase from about
3 Mgal/d in 1970 to about 26 Mgal/d in the year 2000 and 49 Mgal/d in
2020, primarily because of the growth of municipalities along the coast. The
shallow aquifer in the eastern part of the county will yield sufficient water
for the foreseeable needs but development of the aquifer probably will require
important changes in land use. The well fields required to obtain large quan-
tities of water from the shallow aquifer of necessity will be widely distributed
and in aggregate will take up a large area. In order that recharge to the
shallow aquifer shall be adequate to provide for the withdrawal of large
quantities of water, rainfall would need to be maintained in the well-field areas
long enough to infiltrate to the water table; that is, rainfall would need to be
ponded in the well-field areas rather than be removed rapidly from the areas
in drainage ditches. Furthermore, because of the relatively high chloride
concentration of Floridan-aquifer water, the use of such water to irrigate
within the well-field areas would need to be carefully regulated to insure that
the shallow-aquifer water remains at a quality acceptable for domestic use.
Irrigation use in the county is expected to increase from about 132 Mgal/d
in 1970 to 168 Mgal/d in the year 2000 and 196 Mgal/d in 2020. In 1970 irri-
gation water was obtained mostly from the Floridan aquifer; the increased need






72 BUREAU OF GEOLOGY

for irrigation water is expected to be met by diversions from surface-water sources
with no appreciable increase in withdrawals from the Floridan aquifer. The
&20-Mgal/d of surface water estimated as available in Indian River County
is more than ample for the foreseeable needs; however, all this water is
not readily obtainable for irrigation use. Of the 420 Mgal/d, 217 Mgal/d are
discharged into Indian River from Indian River Farms. Fellsmere Farms. and
Sebastian River Drainage District. An additional 23 Mgal/d is discharged
dir-tly into Indian River from ungaged areas between the drainage districts and
the river. An estimated 180 Mgal/d moves northward from the county into St.
Johns River. Most of the surface-water discharged from the county occurs as
storm runoff, which is unevenly distributed in time, as is evident in figure 20.
Little water is needed for irrigation during or immediately after storms. The
storm rnmoff could be used for irrigation subsequently only if it were stored.
Flood water from the drainage districts could be stored in St. Johns Marsh,
for example. making it available to irrigate when needed. Large pumps could
move water from the districts to the marsh. and from the marsh back to the
districts. In general. however, the St. Johns Marsh receives rainfall from the
same storms that produce excess water in the drainage districts, and, of
course, at the same time the marsh discharges some of its water northward
to the St. Johns River. Thus. large storage facilities would be needed to make
use of any substantial part of the 420 Mgal/d of surface water estimated as
available in Indian River County.
Withdrawals of saline water for cooling purposes are expected to increase
from about 75 Mgal/d in 1970 to 190 Mgal/d in 1980. Saline water is avail-
able almost without limit from Indian River. Thus, the need for saline cooling
water can easily be met. The application of suitable precautions would mini-
mize any deleterious effects of the heated water that is returned to Indian
River.

CONCLUSIONS
The fresh-water supply in Indian River County potentially is more than
ample for the foreseeable needs; however, present land use to a large extent
conflicts with developing the full potential of the supply.
The more than 76 Mgal/d of water estimated as available from the shallow
aquifer is sufficient in quantity and suitable in quality for public supply and
domestic uses which are projected to be 26 Mgal/d in the year 2000. The
shallow aquifer in the eastern third and the extreme western part of the county
has the best potential for withdrawal of more water. Closely controlling the
pumping of the shallow aquifer near Indian River will avoid salt-water intru-
sion. Present pumping practices used in the Vero Beach well field seemingly
are adequate to minimize salt-water contamination in that area. The intermit-






REPORT OF INVESTIGATION NO. 80


tent and impervious lenses of material in the shallow aquifer, which seem to
retard ground-water movement between Indian River and the Vero Beach
well field, may or may not be present all along the coast of the county. The
shallow-aquifer wells required to produce water for the large projected ie-ed
of necessity will be widely distributed over a large area. Careful regulation
of land use in the well-field areas would promote recharge to the shallow
aquifer and maintain good water quality. Closely controlling the use of
Floridan-aquifer water to irrigate in or near the well fields would limit the
increase in chloride in the shallow aquifer resulting from such use.

The use of water for irrigation is expected to increase from 132 Mgal/d
in 1970 to 168 Mgal/d in the year 2000. At present (1970) about 100 Mgal/d
is supplied from the Floridan aquifer; 32 Mgal/d from surface-water sources,
chiefly Blue Cypress Lake. The quality of Floridan-aquifer water varies
greatly throughout the county; in general, the quality is good enough for
irrigation of citrus and improved pasture but not good enough for public
supply. Since 1951 the quality of Floridan-aquifer water has worsened in some
wells and improved in others, but apparently has not changed appreciably
over large parts of the county. The level of the potentiometric surface of the
Floridan aquifer apparently has declined several feet since 1951-with an
increase in withdrawals from 50 Mgal/d at that time to 100 Mgal/d at present
(1970)-but the level appears to have stabilized since the late 1960's. The
present rate of withdrawal probably can be maintained without appreciate
deterioration in water quality. A continuing program for sampling the water
from Floridan-aquifer wells would detect incipient changes in quality should
they occur.

About 420 Mgal/d of surface water (non-saline) is available in the
county including 217 Mgal/d discharged into Indian River from three drain-
age districts, 23 Mgal/d discharged into Indian River from ungaged areas
between the districts and the river, and 180 Mgal/d that moves northward
from St. Johns Marsh into St. Johns River. The surface water from the drain-
age districts includes some excess Floridan-aquifer water from wells intended
for irrigation. The available surface water is more than ample to meet the
foreseeable needs for irrigation; however, most of the surface water occurs as
storm runoff that must be temporarily stored to render it useful at a later
time. St. Johns Marsh appears to be the likely place to store large quantities
of water if facilities are provided. Flood water from the drainage districts
could be pumped into the marsh, stored, and pumped back to the districts
when needed.

Withdrawals of saline water for cooling purposes are expected to increase
from about 75 Mgal/d in 1970 to 190 Mgal/d in 1980. The need for saline






74 BUREAU OF GEOLOGY

water can easily be met from Indian River with suitable precautions to mini-
mize any deleterious effects of heated water that is returned to Indian River.
A continuing program for monitoring the level and quality of water in an
extensive network of wells tapping the shallow and Floridan aquifers would
help in detecting and evaluating signs of deterioration in water quality in the
county. Special studies would establish the relation of the quality of Floridan-
aquifer water to the depth from which water is withdrawn and the rate of
withdrawal. Such studies also would help to define the extent to which the
perennial discharge from uncapped flowing wells contributes locally to the
deterioration of water quality.







REPORT OF INVESTIGATION NO. 80


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