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 Title Page
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 Contents
 Abstract
 Introduction
 Introduction
 Geographic and geologic settin...
 Water control and management
 Hydrologic effects of water control...
 Course and compromises of future...
 Developmental plans
 Alternatives for future water...
 Summary
 References
 Appendix
 Copyright


FGS










STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Randolph Hodges, Executive Director




DIVISION OF INTERIOR RESOURCES
Robert O. Vernon, Director




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




Report of Investigations No. 60


HYDROLOGIC EFFECTS OF WATER CONTROL AND
MANAGEMENT OF SOUTHEASTERN FLORIDA




By
S.D. Leach, Howard Klein, and E.R. Hampton
U.S. Geological Survey



Prepared by the
U.S. GEOLOGICAL SURVEY
in cooperation with the
CENTRAL AND SOUTHERN FLORIDA FLOOD CONTROL DISTRICT,
the
BUREAU OF GEOLOGY
FLORIDA DEPARTMENT OF NATURAL RESOURCES,
and
OTHER STATE, LOCAL AND FEDERAL AGENCIES


TALLAHASSEE, FLORIDA
1972











DEPARTMENT
OF
NATURAL RESOURCES




REUBIN O'D. ASKEW
Governor


RICHARD (DICK) STONE
Secretary of State




THOMAS D. O'MALLEY
Treasurer




FLOYD T. CHRISTIAN
Commissioner of Education


ROBERT L. SHEVIN
Attorney General




FRED O. DICKINSON, JR.
Comptroller




DOYLE CONNER
Commissioner of Agriculture


W. RANDOLPH HODGES
Executive Director










LETTER OF TRANSMITTAL


Bureau of Geology
Tallahassee
December 7, 1971


Honorable Reubin O'D. Askew, Chairman
Department of Natural Resources
Tallahassee, Florida

Dear Governor Askew:


Since about the turn of the century the natural hydrologic regimen in
southeastern Florida has been modified by man. The higher, dryer land was
the first to be utilized and progressively more of the lower, wetter lands have
been utilized through water control and management.

This report very adequately portrays the effects of this management
n the hydrology of southeastern Florida, and it is a significant contribution
to an understanding of the water resources in this part of Florida.



Respectfully yours,



Charles W. Hendry, Chief
Bureau of Geology

















































Completed manuscript received
November 23, 1971
Printed for the Florida Department of Natural Resources
Division of Interior Resources
Bureau of Geology
by News-Journal Corporation
Daytona Beach, Florida

Tallahassee
1972










CONTENTS


A abstract ............ ........... .... .. ....... .
Introduction .....................................................
Purpose and scope ...................................
Acknowledgm ents ....................................
Previous investigations ..............................................
Geographic and geologic setting ........................................
Physiography and drainage ..........................................
Climate .............................................. ..........
G eology ............ .........................
Population distribution and water-use trends .............................
Population ....................................................
W ater use ....................................................
M municipal .....................................
A agricultural ....................................
W ater control and management ........................................
History of water-control works ........................................
Water-management practices and problems ..............................
Hydrologic effects of water control and management .....................
Flow through the Everglades ................................... ....
Rate of overland flow ......................................
Flow through Tamiami Canal outlets ................................
Changes in flow through Tamiami Canal outlets ....................
Conservation areas ...............................................


Rainfall and storage .................................
Seepage ..................................
Changes in discharge from the major canals ...............
Water-level changes along the coastal ridge and vicinity .......
Changes in well-field areas and sea-water intrusion .........
M iami municipal well fields ..........................
Fort Lauderdale well fields ...........................
The course and compromises of future water development ......
Developmental plans ........................... ......
Implementation of Area B and east coast backpumping plans
Conveyance canals to south Dade County .................
Southwest Dade plan of improvement ....................


Lower east coast agricultural areas .......
Alternatives for further water development ..
Reduction of losses to the ocean ..........
Maintaining water quality ...............
Summary ...............
References ..............................
Appendix ........... .........


Page
1
3
5
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6
7
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8
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15
17
18
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20
21
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23
24
25
25
29
36
42
45
45
52
57
67
68
74
80
82
82
84
86
88
88
88
92
96
100
104


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ILLUSTRATIONS


Figure
1. Map showing the Central and Southern Florida Flood
Control project structures and hydrologic features
in southeastern Florida, 1968 .................. .......
"2 Physiographic provinces of southern Florida .............
3. Graph of maximum, minimum, and average annual rain-
fall of the eleven long-term index rain gages in
southeast Florida, 1940-65 ..........................
4. Map of annual rainfall in the area of investigation
for 1956, a relatively dry year, using U.S. Weather
Bureau data ........................................
5. Map of annual rainfall in the area of investigation
for 1947, one of the wettest years of record, using
U.S. Weather Bureau data ............................
6- Map showing deviation from the annual average rainfall
at 24 U.S. Weather Bureau gages, 1941-60. The
records of several rain gages located outside the
area were also used to aid in determining the shape
of the isohvetal lines .................................
7. Map of Florida's lower east coast showing the con-
figurations of the natural drainageways (transverse
glades) and locations of major canals through the
coastal ridge .......................................
8. Comparison in population trends in Dade, Broward, and
Palm Beach counties of Florida's southeast coast ..........
9_ Comparison of city of Miami municipal fresh-water
supply and Dade County population over the years ........
10. Relation between the Tamiami Canal outlets' dis-
charge and the average distance a particle of
water would travel in the Everglades in a day ............
11I Accumulation of the average monthly distance
traveled by a particle of water in the Everglades,
based on flow in the measuring section north of
the Tamiami Canal ................................
12. Hydrographs of monthly mean discharge through the
Tamiami Canal outlets, showing a comparison of
the three wettest runoff years and 1944, one of
the driest years of record since 1940 ..................
13. Monthly mean discharge southward toward Everglades
National Park through the Tamiami Canal outlets,
Levee 30 to Monroe, Florida, 1940-69 .................
14. Profiles of maximum, minimum, and average water
levels in the Everglades just north of the Tamiami
Canal during 1955, a relatively dry year. Also shown
is the altitude of zero overland flow southward ...........


IS. Profiles of maximum, minimum, and average water
levels in the Everglades just north of the Tamiami
Canal during 1960, a relatively wet year. Also
shown is the altitude of zero overland flow south-
ward and the peak profile of 1947 prior to the construction of Levee 30 ....


Page


. . . ... 4
. . . ... 7


............. 10


............. 12


............ 13





. ........... 14




............ 16

. .......... 17

............. 19



....... 27




............ 28




........ 30


.. ....... 31




. ........... 32









ILLUSTRATIONS-continued


Figure
16. The relation between the annual discharge through the
Tamiami Canal outlets, Levee 30 to Monroe, and the
percent that flowed through the eastern section,
Levee 30 to 40-Mile Bend .........................
17. Map showing detail of the Tamiami Canal outlets sub-
divided into the three flow sections (Levee 30 to
Levee 67A, Levee 67A to 40-Mile Bend, and 40-Mile Bend
to M onroe, Florida) ................................
18. Monthly mean discharge of the Tamiami Canal outlets,
Levee 30 to Monroe, Florida, subdivided into three
sections, 1941-69 ................................
19. Cumulative annual discharge showing the effects of
construction on each of the three sections of the
Tamiami Canal outlets between Levee 30 and Monroe,
F lorida ..........................................
20. Schematic diagram showing direction of flow and
water levels in a typical west-to-east section,
from the Everglades through the coastal ridge
to Biscayne Bay. Conditions during a wet


Page



......... .. 35



......... .. 37


............ 38



......... .. 40


period, before and after water-management
systems were operational, as shown ..................................
21. Nomograph of rainfall-storage relation in the three
conservation areas ................................................
22. Estimated seepage eastward from Conservation Area 1
through and under Levee 40. Discharge data furnished
by the U.S. Corps of Engineers .....................................
23. Estimated seepage southward and eastward from
Conservation Area 2 through levees L-35 and L-36.
Discharge data furnished by the U.S. Corps of Engineers ...............
24. Estimated seepage southward and eastward from
Conservation Areas 3A and B through levees L-37,
L-33, L-30, and L-29. Discharge data furnished
by the U.S. Corps of Engineers ......................................
25. Generalized relation between annual rainfall at
index stations in the area and discharge to the
ocean from the Miami Canal for runoff years 1940-64 ....................
26. Cumulative runoff-year discharge to the ocean from
the Miami Canal related to the adjusted cumulated
annual mean rainfall from the eleven index rain gages.
Note the change in slope beginning 1955 and 1960.....................
27. Generalized relation between the annual rainfall at
index stations in the area and combined discharge
to the ocean from the West Palm Beach, Hillsboro,
and North New River canals, for runoff years 1940-64 ..................
28. Cumulative runoff-year discharge to the ocean from
the West Palm Beach, Hillsboro, and North New
River canals related to adjusted cumulated
annual mean rainfall from the eleven index rain
gages. Adjustments for inflow to and outflow
from Lake Okeechobee applied to runoff values .........................








ILLUSTRATIONS-continued


Figure
29. Map of Dade County showing contours of the low-water
levels of record. May-June 1945 (from Schroeder
and others. 1958. fig. 14) ............................
30. Map of Florida's lower east coast showing contours of
row-water conditions in May 1962 (adapted from
Sh-rwood and Klein, 1963. fig. 9 and McCoy and
Sherwtood 1968, fig. 8) ...........................
St. Map of part of Dade County showing contours of the
high-water conditions of September 1960 ................
32: Map of Florida's lower east coast showing contours
of the high-water conditions of June 1968 ................
3:3. rydrographs of well S-182 showing water-level
recession rates before and after construction of Canal 1 ....
34. Hydrograph of well G-616 in Broward County ............
35. EHdrographs of selected observation wells in southern
Dude County ........................................
;6. Maps of the Miami area in eastern Dade County showing
the sea-water encroachment at the base of the
Biscayne aquifer 1904-69 (Parker, Ferguson, Love,
and others. 1955, p. 589, Kohout, 1961, Leach and
Granthamn 1966) updated ...........................
37. Map of Florida's lower east coast showing the major
well fields, their pumping rates near the
end of 1970, and the extent of sea-water
encroachment at the base of the Biscayne
aquifer .................. ............... .... ....
S38. Map of the Miami well field showing water levels and
chloride conditions June 29, 1945 during uncontrol-
led conditions of Miami Canal .............. ......
39. Map of the Miami well field showing water levels
and chloride conditions April 7, 1966 during
controlled conditions of Miami Canal ..................
40. Maps of the Alexander Orr and Southwest well-field
areas of the city of Miami showing water-level
conditions March 21, 1951 (A) and May 24, 1962 (B)
(from Sherwood and Leach, 1962, fig. 17 and
Sherwood and Klein, 1963, fig. 8) ....................
41. Map of southeastern Broward County showing water-
level conditions February 15, 1941 (adapted
from Sherwood, 1959, fig. 9) ............... .......
42. Map of the Oakland Park area of Broward County show-
ing water-level conditions in the Prospect well
field August 7, 1956 (from Sherwood, 1959, fig. 11).
The total pumpage for the Prospect well field was 7 mgd ..
4:3. Map of the Oakland Park area of Broward County show-
ing water-level conditions in the Prospect well
field April 18, 1968 (map prepared by H. J. McCoy).
The pumpage for the Prospect well field was 30 mgd


and the western rock pit was 5 mgd ............................


Page


......... .. 58



..... ..... 59

.. ..... 60

............ 61

............ 62
............ 63

.. ... ..... 64




............ 67




............ 69


........ .. 70



............ 71




.. .......... 73


............. 75



............. 76








ILLUSTRATIONS-continued

Figure Page
44. Map of the Boca Raton area showing water-level
contours during the low-water conditions of April 12,
1967 (from McCoy and Hardee, 1970, fig, 14) ........................ 79
45. Graphs relating rainfall to the discharge of the
West Palm Beach Canal to the ocean, 1941-69. Also
shown is the pickup of flow in the canal reach
below S-5E from 1956. ....................................... 81
46. Map of southeastern Florida showing locations of
the Area A, Area B, and southwest Dade area in
relation to the Central and Southern Florida
Flood Control District works ......................... ............. 83
47. Map of the southern tip of Florida showing contours
of water level conditions in May 1962, a near-
record low-water condition. ...................... ............... 84








TABLES


Table


Page


1. Annual rainfall, in inches for the eleven long-term index
rain gages in the area of investigation for 1940-65. Also
tabulated are the annual averages for all stations and the
highest. lowest, and average values at each gage .....................
2. Pumpage by the three largest supply systems in Florida's
lower east coast ............................
3. Population for the three largest counties of Florida's
lower southeast coast and the amount of fresh water (in
1,000 Ac-ft per year) pumped and consumed for municipal,
industrial, and agricultural uses in 1965, and as estimated
for the year 2000 .................................................
4. Total and average discharge of three flow sections of the
Tamiami Canal showing a comparison between runoff and
calendar years for the period 1941-68 (for locations of the
three sections, see figure 17) .......................................
5. Estimated monthly and annual seepage in acre-feet to the
east and south through L-40, L-36, L-35, L-37, L-33, L-30
and L-29 from L-30 to L-67A .......................................
6. Generalized water budget in acre-feet showing annual move-
ment of water in the three combined conservation areas ................
7. Control structures in the area of investigation maintained
and operated by the Central and Southern Florida Flood
Control-D district ...................................................
8. Discharge through the Tamiami Canal outlets east of Levee
:30, in acre-feet. .................................................
9. Discharge through the Tamiami Canal outlets between Levee 30
and Levee 67A, in acre-feet ........................................
10. Discharge through the Tamiami Canal outlets between Levee 67A
and 40-Mile Bend, in acre-feet ....................................
11. Discharge through the Tamiami Canal outlets between 40-Mile
Bend and Monroe, Florida, in acre-feet ...............................
12- Tamiami Canal outlet bridges numbering system and mileage
from Monroe, Florida east to Dade-Broward Levee .......................


105

111

112

113

114

115







HYDROLOGIC EFFECTS OF WATER CONTROL
AND MANAGEMENT IN
SOUTHEASTERN FLORIDA


By
S. D. Leach, Howard Klein, and E. R. Hampton


ABSTRACT

Most of the land in southeastern Florida presently utilized for urban,
suburban, and agricultural purposes was inundated all or much of the time
under natural predevelopmental conditions. Early settlement was on the
higher ground, where flooding during the rainy season was less probable.
Major urban expansion in the 1900's occurred in the vicinity of Miami, Fort
Lauderdale, and West Palm Beach. Drainage canals were extended inland
along natural drainageways, and through transverse glades. Urban areas
expanded westward on land formerly inundated or used for agriculture,
displacing agriculture to land farther inland to the east edge of the Ever-
glades.
The hydrologic regimen of the Lake Okeechobee-Everglades area has
undergone continuous modification since settlement began late in the nine-
teenth century. Before drainage and land reclamation in the northern part
of the Everglades, water levels in Lake Okeechobee and those in the Ever-
glades adjacent to the lake were about the same during periods of high wa-
ter; overflow occurred first at two low places when water stages reached 15
feet outflow along the south shore became general at a stage of about 18
feet. Modification of overland flow in the Everglades began when drainage
canals and levees were built around Lake Okeechobee beginning in 1881.
Most of the excavation for major drainage canals along the lower east coast
was completed by 1932 canals were either uncontrolled or inadequately
controlled, and continuous drainage resulted in lowered ground-water levels
and sea-water intrusion into the Biscayne aquifer in the Miami area. After
the 1943-45 drought, major canals through the coastal ridge were equipped
with control structures, which prevented overdrainage during dry periods
and prevented additional or reduced existent sea-water intrusion.
Extensive flooding which followed the heavy rains of 1947 demon-
strated the need to improve the water-control systems. The 1947 flooding
led to the establishment in 1949 of the Central and Southern Florida Flood
Control District, whose functions were to furnish flood protection to urban
and agricultural lands during rainy seasons and to provide facilities for
conserving water for alleviation of the effects of drought. Work on new
water-control facilities in collaboration with the U. S. Army Corps of En-






BUREAU OF GEOLOGY


gineers proceeded during the 1950's; water Conservation Areas 1 and 2
were enclosed by levees in Palm Beach ard Broward counties, and a large
area southeast of Lake Okeechobee was made useable for agriculture by
the system of levees, canals, and pumping stations. By the end of 1962,
water Conservation Area 3 was enclosed on the south side and for the
first time, surface flow in the Everglades north of the Everglades National
Park could be fully controlled. Conservation Area 3 was considered fully
enclosed by July 1967 except for a 7.1 mile stretch of levee between L-28
interceptor levee and the L-28 tieback levee on the west side. Additional
changes and modifications in the water-management structures are
planned for construction as needed.
The prime effect of the water-control works in south Florida has been
to facilitate the flow of water out of the Everglades by means of the canal
system, thereby changing the spatial and temporal distribution of runoff
from the Everglades. Prior to 1961, flow southward toward the Everglades
National Park and south Dade County through the Tamiami Canal outlets,
based on the 1941-61 record, averaged 252,600 acre-feet per year through
the Levee 30 to Levee 67A section, 128,900 acre-feet per year through the
Levee 67A to 40-Mile Bend section, and 201,000 acre-feet per year through
the 40-Mile Bend to Monroe section. During 1962-68, average annual
discharge through the Levee 30 to Levee 67A section was reduced to about
63.200 acre-feet, the discharge through the Levee 67A to 40-Mile Bend
section increased to about 323,600 acre-feet, and the discharge in the 40-
Mile Bend to Monroe section remained about the same. Adjustments in
operation of canals and control structures to meet changing needs have
changed the amount, timing, and distribution of seaward discharge of the
Miami, North New River, Hillsboro, and West Palm Beach canals which
drain the Everglades and transect the coastal ridges. Reduction in' flow to
the ocean began with completion of the levee systems east of the three
conservation areas in 1953. Discharge to the ocean through Miami Canal
was reduced an average of 185,000 acre-feet per run-off year for 1956-65,
and combined discharge from North New River, Hillsboro, and West Palm
Beach canals was reduced about 294,600 acre-feet per runoff year for
19.53-65, from the average discharge of 1940-52. Overall reduction of fresh
water flow to the ocean since 1953 as a result of flood and water-control
measures is about 20 percent of the fresh water that otherwise would have
been discharged to the ocean in southeastern Florida.
Before drainage, water levels were near or at land surface along much
of the coastal ridge area. One principal effect of pre-1945 land-reclama-
tion practices was the lowering of ground-water levels throughout the
coastal ridge and interior areas. Overdrainage of many coastal areas al-
lowed sea-water intrusion of canals and the Biscayne aquifer, the source
of nearly all potable water in the area. The overdrainage has been arrested
and. since 1954, water levels have tended to stabilize in most of Dade






REPORT OF INVESTIGATION NO. 60


County. Yearly peak water levels are considerably lower than in pre-flood-
control times, and yearly low water levels are higher than in pre-manage-
ment tires. Thus, during 1945, after a prolonged drought, salty water moved
up the Miami Canal and intruded the Biscayne aquifer in the vicinity of the
Miami well field, when water was being withdrawn at 30 mgd (million
gallons per day). In 1966, in a similar dry season, water was being with-
drawn at 80 mgd; minimum water levels near the center of the field were
about the same as in 1945, but sea-water intrusion was controlled. The
improved conditions of well-field production and salinity control are re-
sults of salinity barriers in canals and replenishment of water in well-field
areas from canals. Similar conditions prevail at other near-shore well
fields in the southeast Florida area.
Additional improvements in the hydrologic situation in places in
southeast Florida can be achieved by applying existing hydrologic manage-
ment practices to smaller, specific areas of need, generally by installing
additional salinity and water-control structures at key places in canals and
by carefully manipulating these to maintain ground water at the maximum
levels that allow flood protection to urban and suburban areas. Manage-
ment practices of this sort will aid prevention of sea-water intrusion during
dry periods and allow increased withdrawals of potable water from well
fields. Continuous replenishment of water in well fields will be from ca-
nals in the dry season, requiring careful attention to the overall quality of
water in the canals.


INTRODUCTION

Southeastern Florida is considered in this report to include that part
of the State, from the northern shore of Lake Okeechobee and the mouth
of the St. Lucie Canal southward to the tip of Florida and from the east
coast westward to about the middle of Hendry and Collier Counties (fig.
1). This-area is one of rapid urban expansion, where increasing quantities
of water are needed to satisfy growing requirements for municipal and
industrial supplies and other uses. The region could not have urbanized
.were it not for programs, started in the early 1900's, aimed initially toward
land reclamation, later toward flood control and water control, and finally
toward water management. Implementation of these programs has caused
major hydrologic changes throughout southeastern Florida. These changes
were characterized by modification in rates and duration of fresh-water
runoff, impoundment of water in water-storage areas, diversion of water
from historical flow patterns, adjustment in water-level gradients and
ranges in fluctuations, and changes in water quality. The area of south
Florida affected by drainage and reclamation encompasses about 5,800
square miles and is shown on figure 1. Included in the area of investiga-







BUREAU OF GEOLOGY


C d*oi .


1 e u" 9"0 15 0 I u s


I Figure 1. Map showing the Central and Southern Florida Flood
Control project structures and hydrologic features in
southeastern Florida, 1968






REPORT OF INVESTIGATION NO. 60 5

tion, which is coexistent with southeastern Florida as defined above, are
project structures and other control features of the Central and Southern
Florida Flood Control District (C&SFFCD).

PURPOSE AND SCOPE

This report was prepared by the U.S. Geological Survey in cooperation
principally with the Central and Southern Florida Flood Control District
(C&SFFCD) as part of the statewide program of water resource evalua-
tion. In addition, the Bureau of Geology, Florida Department of Natural
Resources, Broward, Dade, and Palm Beach counties, the cities of Fort
Lauderdale, Miami Beach, and West Palm Beach, the Miami Department of
Water and Sewers, the National Park Service, and the U.S. Navy extended
financial support for the report. All of these agencies are interested in the
hydrologic effects of drainage and reclamation of southeast Florida.
Although the results of several water-related investigations have been
published, the total hydrologic effects of drainage and reclamation have not
been clearly portrayed. The purpose of this report is to describe and evalua-
te from the mass of hydrologic information the effects that man's activities
have had on the hydrology of southeast Florida. Analysis of the data col-
lected, together with an evaluation of the effects of water management pro-
vide answers to such questions as:
1. What gross effects have the works of the C&SFFCD had on the
hydrologic regimen of southeast Florida?
2. What are the climatic conditions in the southeast Florida area today,
and how do they compare with conditions in the past?
3. Will the present and proposed flood-control system be adequate to
prevent flooding and to halt sea-water intrusion into the Biscayne
aquifer in coastal areas and to provide water to meet the demands
of the growing population and other demands?
In the process of answering the above questions, the history of the
construction of C&SFFCD works was compiled, the seepage beneath var-
ious levees was determined, a generalized water budget was estimated for
the conservation areas, and projection of water needs by the year 2000
have been made.

ACKNOWLEDGMENTS

Thanks are given to William V. Storch, Director, Engineering Di-
vision, and Robert L. Taylor, Chief of the Hydrology and Hydraulics
Branch, C&SFFCD; F.D.R. Park, Water Control Engineer, Dade County
Department of Public Works; Garrett Sloan, Director of the Miami De-
partment of Water and Sewers; J. Stanley Weedon,Water Control Engi-





BUREAU OF GEOLOGY


neer, Broward County; John G. Simmons, Director of Utilities, West Palm
Beach; and Frank Nix, Hydraulic Engineer, Everglades National Park,
for furnishing hydrologic data, and other information. Thanks are also
given to the Corps of Army Engineers, Jacksonville, for furnishing dis-
charge information on seepage through levees. The authors are indebted
to D. F. Tucker, the Florida District Cartographer, for the many useful
suggestions concerning the layout of the illustrations. This report was
prepared under the general supervision of C. S. Conover, District Chief,
Florida District.

PREVIOUS INVESTIGATIONS

Information concerning the water resources and geology of southeast-
ern Florida is contained in many published reports. Three of the earlier
reports that provided the authors with background material are: Matson and
Sanford's 1913 report and those of Stringfield in 1933 and 1936.
A comprehensive report on the geohydrologic environment of south
Florida based on data collected through 1946 by Parker, Ferguson, Love,
and others (1955) provided much background material for establishing the
hydrologic setting for the early years during the Everglades Drainage
District period, established in 1905, and was used as an aid in determin-
ing the effects of changes by the Central and Southern Florida Flood Con-
trol District. Several other reports bear on the hydrology of the southeast
Florida area. Reports by Schroeder, Klein, and Hoy (1958); Sherwood
and Klein (1963); and Sherwood (1959) provide considerable back-
ground information on the Biscayne aquifer and the geology. Reports by
Klein (1959) and Appel and Klein (1969)'on fresh-water supplies pro-
vided information on the effects of pumping from the highly permeable
Biscayne aquifer.
Reports by Sherwood and Leach (1962), Leach and Sherwood (1963),
Kohout and Leach (1964), and Leach and Grantham (1966) provide back-
ground information on canal hydrology, sea-water intrusion, and the
interconnection between the aquifer and the canals.
Information on seepage through levees was presented by Klein and
Sherwood (1961) and a general background on hydrology in segments of
the study area were provided by Hartwell, Klein, and Joyner (1963) and
Kohout and Hartwell (1967).






REPORT OF INVESTIGATION NO. 60


GEOGRAPHIC AND GEOLOGIC SETTING


PHYSIOGRAPHY AND DRAINAGE


Southeastern Florida generally is flat and low-lying. It has been divid-
ed into the Atlantic coastal ridge, sandy flatlands, the Everglades, the Big
Cypress Swamp, and the mangrove and coastal glades topographic-ecologic
(physiographic) provinces as shown on figure 2. The report area includes
all of south Florida generally east of the Big Cypress Swamp-Everglades


Figure 2. Physiographic provinces of southern Florida







BUREAU OF GEOLOGY


houtndary shown on figure 2. A more comprehensive description of the
physiographic areas shown on figure 2 is given by Parker, Ferguson, Love,
and others (1955, p. 141-155).
The Atlantic coastal ridge is about 5 miles wide, ranges from about 8
to 24 feet above mean sea level, and occupies about 600 square miles. It is
breached in many places south of Boca Raton by transverse glades most
which are sites of canals. The sandy flatlands province is between the
Atlantic coastal ridge and the Everglades, and in the report area it slopes
gently southward. Altitudes range from about 20 feet adjacent to Lake
Okeechobee to about 6 feet near Miami. It occupies about 1,200 square
miles of the report area. The Everglades is slightly lower than the sandy
flatlands; it is a seasonally inundated 4,000-square-mile area of organic
soils covered predominantly by sawgrass marsh and broken by elongate
"trtee islands." The Everglades area ranges in altitude from about 14 feet
near Lake Okeechobee to about sea level near Florida Bay. The man-
grove and coastal glades are mostly tidal flatlands subject to inundation
during high tide, particularly when winds are from the southwest. They
,cctrpy an area of about 1,100 square miles. They are not a part of the
fresh-water system described in this report.
Natural drainage in the report area was generally southward within
the Everglades and eastward from the Everglades across the sandy flatlands
and through the Atlantic coastal ridge via transverse glades. Present-day
drainage through the transverse glades is largely by way of canals.


CLIMATE


The climate of south Florida is subtropical. Average daily temperatures
range from about S2 F in the summer to about 680 F in the winter.
Rainfall was determined from the records of 11 National Weather Ser-
vice (L .S. Weather Bureau) gages selected as index stations because of their
long continuous operation (since. 1940) and their adequate distribution.
Missing record for a particular index station was estimated from one or
more of the nearby stations. Table 1 lists the long-term index rain gages,
the annual total rainfall for each, the average rainfall for the period of
record for each, and the annual average for all gages. Also shown is high
and low annual rainfall for each gage.
The annual rainfall in southeastern Florida occurs in distinct cycles.
The rainy season, normally June through October, contributes about 70 per-
cent. or about 41 inches of the 59-inch annual total, based on the 20-year
average of the index gages. The remaining 18 inches is distributed through-
out the other seven months.









Table 1. Annual rainfall, in inches, for the eleven long-term index rain gages in the area of investigation for 1940-65. Also tabu-
lated are the annual averages for all stations and the highest, lowest, and average values at each gage.












1940 54.9-1 59.,12 64.28 70.75 6-1.28 70.37 6.1.28 66.22 58.98 6-1.28 69.30 64.28
1941 63.53 70.2:3 65.37 55.01 57.37 7647 7-1.00 63.34 6.1.79 6.7-1 72.88 66.16
1942 65.82 51.51 0 .5,4 5 5.3.05 615.39 6:3.31 6.3.25 68.87 58.5.1 54,-1.3 69.47 61.74
1943 43.20 -13.52 18.55 -17.38 58.39 56.80 52.78 62.86 -16.97 58.96 51.95 51.9-1
1944 5.12 40.56 -14.75 -13.09 :39.29 1.15 57.51 .19 -15.68 41.60 -11.42 45. 21
-1





1945 50.69- 53.02 60.31 51.99 10.98 4.328 54.12 -12.28 5-1.75 53.55 62.69.30 52.60
19416 7.94 61.8 62.23 -17.70 55.374 6..7 0.00 5 3.3 54.93 1.0 .16.67 61.887 58.01

1947 84.68 88.11 106.08 102.36 78.25 9.1.07 97.20 78.39 7:3,11 82.76 105.22 90.02
1948 62.98 -19.24 7-1.945 70.87 73.03 70.67 1.50 78.87 58.59 58.47 63.627 65.71
1949 53.5203 43.529 8.97 47.3875 6-1.86 5.32 527.1 62.1- 52.15 589.26 .51.67 61.08
1950 51.053 36.8 60.91 5.399 52.0398 55.96 58.57 -19.17 -1.865 56.96 51.92 52.560
1951 62.18 56.22 -13.72 :37.3-1 55.-141 -15.6-1 6-1.9.5 8.7 -7. 9 .6 3921 52.843 48.017
195472 57.75 5883.26 106.21 102.36 53.35 8.07 970.-18 .18.9-1 5573.11 82.76 150.87 590.302
194853 62.31 6849.13 7.80 76.75 70.82 703.99 80. 65.187 -1.359 583.-19 71.62 69.96
1954 .5.1 5.29 68.972.2 85.80 7-1.09 67.732 78.2391 62.26 70.08 -19.99 73.21 617.9308
1955 51.0 46.892 35.8 -1159.32 5 50 52.59 -576 -1.47 44.8 -16.196 37.31.92 524.543
1956 39.5185 .12.07 293.702 :39.235 47.0- -15.37 13.93 :37.0 7.968 2.9721 5238.10 4-0.48
1957 71.26 69.91 69.21 72.15 (7.5335 58.22 7.73 70.87.9 61.9 8.22 62.9 0 .87 53.31
1958 62.310 68.1367 6721.41 7.75 75.28 7:3.00 80.132 51.49 60.3 59.33 671.18 66.35
1959 72.99 70.15 8172.62 79.70 89.90 87.09 9785.63 89. 87.78 6749.99 78.6-1 81.20

1960 69.50 5:3.55 72.0-1 00.4-8 68.8.1 82.12 77.7-1 70.26 60.90 7:3.91 66.77 68.74
1961 40.85 -19.28 -10.2:3 35.5.1 41.10 .15.75 36.6-1 .41.70 -3.76 -14.1,05 :37.76 -11.51
1962 61.51 -17.72 -11.92 56.11 50.67 55..5 55.70 12.27 51.59 56,06 -48.56 51.61
1963 -19.87 -11.10 -16.615 59.3-1 5-14.9-1 62.65 -15.29 -16,08 54.6:3 62.11 53.31 52.39
1964 45.13 60.26 4.17.67 66.99 69.67 61.09 59.46 60.20 62.2:3 55.28 79.30 60.606
1965 55.56 61.83 55.99 59.76 60.8-1 -146.30 58.23 58,40 40.57 -19.-19 58.20 55.02
Average 58.07 56.03 59.32 59.58 60.32 62.81 6(4.1:3 58.15 55.91 57.15 60.35 59.26
High 84-1.68 88.11 106.08 102.36 89.90 94.07 97.20 8').33 87.78 82.76 105.22 90.02
Low 39.5.5 36.69 29.02 35.54 39.29 -15.37 :36.6.1 :,7.00 40.57 39.21 :37.31 -10.-48









































Figure 3. Graph of maximum, minimum, and average annual rainfall of the eleven long-term index gages in southeast Florida, 1940-65







REPORT OF INVESTIGATION NO. 60


The extremes in annual rainfall for 11 long-term index stations (table 1)
range from 106 inches in 1947 to 29 inches in 1956. Both extremes were
at the station 5 miles west of Dania in Broward County. The maximum
and minimum rainfall recorded each year at any one of the 11 stations is
shown in figure 3, along with a bar graph to show the average by year of
the 11 stations. Extremes in rainfall range from about 19 inches greater
than the yearly average of the 11 stations to about 18 inches less than the
yearly average of the 11.

Rainfall patterns for a dry year, 1956, and a wet year, 1947, are shown
in figures 4 and 5. A comparison of the figures shows the wide range in
rainfall between the dry year and the wet year. The isohyetal lines of rain-
fall for 1956 shown on figure 4 used data from 33 rain gages for which
records for the year were complete. The 1956 year is a typical dry year as
compared with other dry years except for the wet cell near the intersection
of the Miami and North New River canals. In 1956, the coastal and interior
areas received about the same amount of rainfall.

The isohyetal lines of rainfall for 1947, shown in figure 5, used data
from 47 rain gages for which records for the year were complete. In 1947
a hurricane in September and one in October crossed south Florida and
yielded much of the excessive rainfall along the coast. In other years of
above-normal rainfall, the data show that the coastal ridge generally
receives more rainfall than the interior.

The deviation from the 1941-60 average rainfall (57.34 inches) for the
24 rain gages that have complete records is shown in figure 6. Several rain
gages outside the area were also used to aid in determining the shape of the
isohyetal lines. These lines show the deviation from the average of all 24
gages and indicate that the coastal ridge annually receives several inches
more rainfall than the Everglades.

A further examination of figure 6 reveals that Lake Okeechobee receiv-
ed on the average about 7 inches less per year than the average of the 24
rain gages. Also, the rainfall deviation has a gradient over the lake from
near average along the southeastern shore (zero isohyetal) to 11 inches
below average (-11 isohyetal) along the northeastern shore.

The figure shows a wide variation in rainfall over the three water con-
servation areas. Rainfall averaged about 2 inches per year above the 57-
inch 24-gage average in Conservation Area 1, 1 inch below the average in
Conservation Area 2 and about 4 inches below the average in Conservation
Area 3.







12 BUREAU OF GEOLOGY


EXPLANATION


Figure 4. Map of annual rainfall in the area of investigation for 1956,
a relatively dry year, using U.S. Weather Bureau data








REPORT OF INVESTIGATION NO. 60


BIG CYPRESS


EXPLANATION


Figure 5. Map of annual rainfall in the area of investigation for 1947,
one of the wettest.years of record, using U.S. Weather Bureau
data
































































Z! iV

4 L^
%J


I' .

SEXPLUATION

of all ~i ir -<
.ra Wr .4Ie
td ked k ske nn
VI Vale Is deletion frea Ite
S10 Mre mre VkMI .
(1*41-1M1.
Re in .
0 tox bone i a10
an 0.
Laws
o Fo w
-


Figure 6. Map showing deviation from the annual average rainfall at
24 U.S. Weather Bureau gages, 1941-60. The records of sev-
eral rain gages located outside the area were also used to aid in
determining the shape of the isohyetal lines


BUREAU OF GEOLOGY


0 a IL=.
d::






REPORT OF INVESTIGATION NO. 60


GEOLOGY
Sedimentary deposits, mostly sand and limestone, underlie south-
ern Florida. The geologic units of particular importance to the water
resources of the area are the highly permeable limestone and sandstone
units that compose the Biscayne aquifer and the younger deposits of
sand that underlie beach and dune ridges and some terraces.

The Biscayne aquifer underlies most of Dade County, central and
eastern Broward County, and southeastern Palm Beach County; it ranges in
thickness from a few feet in the central parts of the Everglades to more
than 250 feet in coastal Broward County. The aquifer yields all the fresh
ground water used in the three counties, except for eastern and north-
eastern Palm Beach County, where supplies are obtained from sedi-
ments of lower permeability.

The rocks that compose the Biscayne aquifer of southern Florida
overlie a thick sequence of relatively impermeable clayey materials
which in turn overlie the permeable limestone formations of the Floridan
aquifer. Beneath much of southern Florida, the Floridan aquifer contains
water under sufficient artesian pressure to flow at the surface, but the
water generally contains dissolved constituents in excess of the limits
recommended for drinking water by the U.S. Public Health Service (1962).

A comprehensive description and discussion of the geology of
southern Florida is presented by Parker, Ferguson, Love, and others
(1955).



POPULATION DISTRIBUTION AND WATER USE TRENDS


Early settlement in southeastern Florida was on the higher ground
of the Atlantic coastal ridge (figure 2) because flooding during the rainy
season was less probable there. The areas of major urban expansion were
in the vicinity of Miami, Ft. Lauderdale, and West Palm Beach. As drainage
canals were extended inland and improved, water levels were lowered
sufficiently to permit construction along the transverse glades, the
natural drainageways that traverse the coastal ridge, and in areas
immediately west of the coastal ridge. Figure 7 shows that alignments of
several of the major canals generally follow the natural drainageways
through the coastal ridge. As drainage progressed, urban areas expanded
to the west along the drainageways on lands formerly used for agricul-
ture, displacing agricultural lands farther inland to the eastern edge of
the Everglades.







BUREAU OF GEOLOGY


Figure 7. Map of Florida's lower east coast showing the configurations
of the natural drainageways (transverse glades) and locations
of major canals through the coastal ridge







REPORT OF INVESTIGATION NO. 60


POPULATION

The region is one of extremely rapid growth in population and
economy since 1940. Local planning agencies estimate that the growth


Figure 8- --Comparison-in population trends in Dade, Broward, and
S PalmBeach counties of Florida's southeast coast






BUREAU OF GEOLOGY


rate will continue. The following tabulation shows combined population
increases for Dade, Broward, and Palm Beach Counties:

1940.........................390,000
1950 ... ..................... 695,000
1960 ....................... 1,500,000
1965........................ 1,870,000
1970...................... 2,217,000

By the year 2000 the population of the three counties is expected to
approach 4.2 million. Figure 8 shows the long-term rate of population
growth in three counties of Florida's lower east coast. In addition many
tourists visit the lower east coast each year. The major influx has been
during the winter, but in recent years summer tourism has increased
substantially.


WATER USE
MUNICIPAL
Rapid population increases and the periodic influx of millions of
tourists have created major fluctuating stresses on municipal water-
supply systems. The municipal systems have succeeded in meeting these
demands by planning 10 to 15 years in advance of current needs. For-
tunately, the water resources of the region have been adequate despite
local problems of contamination by sea-water intrusion and seasonal
droughts. Pumpage figures in table 2 show rates of increase in municipal
water use for the three largest supply systems-Miami, Fort Lauderdale,
and West Palm Beach. All municipal supplies are obtained from ground-
water sources except that for West Palm Beach, which obtains its supply
from lakes immediately inland from the coast.


Table 2 Pumpage by the three largest supply systems in Florida's lower east coast
Average day Peak day Average
City Year million million for year
gallons gallons 1000 Ac/ft
Miami 1960 96.8 137.8 108.4
1965 131.1 173.7 146.8
1970 153.1 212.0 171.5
Fort Lauderdale 1960 20.0 35.6 22.4
1965 28.6 46.9 32.0
1970 40.7 60.2 45.6
West Palm Beach 1960 11.7 14.6 13.1
1965 13.9 18.2 15.6
1970 17.0 29.3 19.0







REPORT OF INVESTIGATION NO. 60


The Department of Water and Sewers of the city of Miami estimates
that by 1980 its daily pumpage during the peak of the tourist season
(January-March) will be about 250 mgd (million gallons per day). The
Department serves Miami, Miami Beach, Hialeah, Coral Gables, and some
nearby communities. In addition, many other smaller municipalities
such as North Miami, North Miami Beach, Hollywood, Pompano Beach,
Boca Raton, and Lake Worth operate separate municipal systems which
show comparable increases in withdrawal rates. The graph in figure 9


0 2


DADE COUNTY POPULATION,


8 10 12 14
HUNDRED THOUSANDS


Figure 9. Comparison of city of Miami municipal fresh-water supply
and Dade County population over the years.







BUREAU OF GEOLOGY


relates Dade County population growth to the increase in pumping by the
city of Miami. The steepening of the curve indicates the per capital use of
water in the county has increased over the years.


AGRICULTURAL

Agriculture is the largest user of water in Dade, Broward, and Palm
Beach counties. In addition to pumping more water for irrigation than
all other users combined, agricultural users consumed about six times
more water than the other users in 1965. The supplemental water pump-
ed for irrigation is withdrawn directly from canals and from the Biscayne
aquifer. As noted in table 3, irrigation use is projected to increase nearly
two and a half times by the year 2000.

The fresh-water demand for the year 2000 for Dade, Broward, and
Palm Beach Counties, the three largest counties of Florida's lower east
Table 3. Population for the three largest counties of Florida's lower
southeast coast and the amount of fresh water (in 1000 Ac-ft
per year) pumped and consumed for municipal, industrial, and
agricultural uses in 1965, and as estimated for the year 2000.
WATER USE 1965 2
County Popula- Municipal Industrial Agriculture
ti Pumped Consumed Pumped Consumed Pumped Consumed
Broward 480,000 83 21 3.3 0.1 95 40
Dade 1,100,000 225 22 8.5 4.6 214 86
Palm Beach 290,000 43 8.5 6.3 1.1 654 262
Totals 1.870,000 351 51.5 18.1 5.8 963 388

WATER USE 2000 4
Count Popula- Municipal Industrial Agriculture
tion3
Pumped Consumed Pumped Consumed Pumped Consumed
Broward 1,370,000 237 60 9.4 0.3 271 114
Dude 1,970,000 403 39 15 8.2 383 154
Palm Beach 910,000 135 27 20 3.4 2,050 822
Totals 4,250,000 775 126 44.4 11.9 2,704 1,090
SAdapted from Florida Development Commission data.
Written communication on Water Use 1965, R. W. Pride.
3 County population projections developed by the Florida Social Sci-
ences Advisory Committee (total occupants less tourists).
SThe 2000 year water-use estimates are based on water use in 1965
and population projections.






REPORT OF INVESTIGATION NO. 60


coast, was estimated on the basis of a comparison of the total amount
of fresh water pumped and consumed in 1965 (table 3), assuming that
per capital use will remain constant and the ratio between water pumped
and watei consumed also will remain constant. Estimates for the year
2000 show that Dade, Broward, and Palm Beach Counties will pump
3,523,000 and consume 1,230,000 acre-feet of fresh water annually. The
consumptive use of water in the year 2000 will be 782,600 acre-feet
more than the 445;300 acre-feet consumed by the three counties in 1965.
Water consumed is water removed from the local hydrologic system and
no longer immediately available for man's use. This increased consump-
tion equals about 700 mgd, or about one and three quarter times the
consumption in 1965 for all uses. Most of this additional consumption
of water occurs during the dry season each year.


WATER CONTROL AND MANAGEMENT


HISTORY OF WATER CONTROL WORKS


The hydrologic regime of the Lake Okeechobee-Everglades area has
undergone continuous modification since settlement began late in the
nineteenth century.

The northern part of the Everglades immediately south of Lake
Okeechobee was covered by a thick layer of peat that supported dense
vegetation, chiefly sawgrass. During the rainy seasons and for several
months afterward, water stood above the surface at varying depths,
and large losses by evapotranspiration resulted (Parker, Ferguson, Love,
and others, 1955, p. 333). Overland flow through the dense vegetation
was nearly imperceptible and resembled flow through a permeable
aquifer, rather than the surface flow of a wide river. In the southern part
of the Everglades, the soil is thin, rocks crop out in many places, and
vegetation is less dense; consequently, overland flow there is more rapid.
Under natural conditions, most of the water in a particular area of the
upper (northern) Everglades was derived from rain on that area or
inflow from the area immediately to the north.

In the northern part of the Everglades, before land was drained and
reclaimed, water levels in Lake Okeechobee and those in the Everglades
adjacent to the lake were the same during periods of high water. When
water stages in the area reached about 15 feet, overflow probably occur-
red first at two low places: part of the water flowed westward into the
headwaters of the Caloosahatchee River and part southward -into the






BUREAU OF GEOLOGY


Everglades in a narrow reach. Outflow along the south shore became
general at a water stage of about 18 feet and "sizeable volumes of water
moved slowly in flat, broad sloughs toward tidewater" (Parker, Ferguson,
Love, and others, 1955, p. 332).
Modification of the overland flow in the Everglades began when
drainage canals and levees were built around Lake Okeechobee. Deepen-
ing of the natural flood channel from Lake Okeechobee to the Caloosa-
hatchee River was an early venture. Drainage operations began in July
1882, and by early 1883 a shallow canal connected the Caloosahatchee
River to Lake Okeechobee (Parker, Ferguson, Love, and others, 1955, p.
328).
Land drainage and reclamation in the Everglades during 1905 under
the Everglades Drainage District began with the construction of two
dredges on the banks of New River where Ft. Lauderdale now stands.
The dredges were used to excavate four major channels from Lake Okee-
chobee to the Atlantic Ocean, and by 1913, the North New River Canal
was open from Ft. Lauderdale to Lake Okeechobee. The Miami Canal
was open except for the lower 6-mile section that was completed by May
I, 1913, the Hillsboro Canal was completed except for a 5-mile section,
and the West Palm Beach Canal was under construction. The above four
canals were completed and fully operational by 1921; they extended
from the southeast shore of the lake across the Everglades and coastal
ridge to the ocean. Hurricane gates were constructed at the lake ends of
the canals. The gates were closed during hurricanes to minimize water
damage to nearby agricultural land in reclaimed parts of the Everglades
from the storm tides generated in the lake. The gates were also closed
when the water level of the lake was higher than that of the drainage ca-
nals adjacent to the lake.

Construction of the St. Lucie Canal began in 1916, and water
first flowed through the canal in 1924. During 1935-46, the St. Lucie
Canal was the main controlled outlet for the regulation of the water level
of the lake.
Construction of a low muck levee on the south and east sides of Lake
Okeechobee was begun in 1921 and completed in 1924. This levee was
overtopped and breached in 1926 and 1928 by hurricane-driven storm
surge. A second, higher earth levee was constructed between 1924 and
1938 on the east, south, and west sides of the lake. The total length of
this levee was 85 miles, and the top elevations ranged from 34 to 38
feet.
As new land southward and eastward from Lake Okeechobee and
along the east edge of the Everglades in Palm Beach, Broward, and Dade
counties was used for agriculture, greater areas came under water control,






REPORT OF INVESTIGATION NO. 60


and drainage facilities were improved through efforts of several drainage
districts. These lands were effectively drained, and flood waters were dis-
posed of rapidly. Thus a large part of the overland flow from the Ever-
glades was diverted through the canal systems to the ocean.
Most of the excavation for major drainage canals along the lower
east coast was completed by 1932. The canals were either uncontrolled
or inadequately controlled, and the continuous drainage to the ocean
during dry seasons resulted in intrusion of sea water into the Biscayne
aquifer, which threatened municipal water supplies in Miami. After the
1943-45 drought, the major canals through the coastal ridge were equip-
ped with salinity-control structures, which could be opened to discharge
flood water during the rainy season and closed to prevent overdrainage
of fresh water from the Biscayne aquifer and consequent salt-water
encroachment during dry periods.
The heavy rains of 1947 resulted in extensive flooding of the uiban
and agricultural areas of southeast Florida, which demonstrated the need
for improvement in the water-control systems. As a result, more effective
programs to handle flood waters were developed, which led to the
establishment in 1949 of the C&SFFCD, whose functions were to furnish
flood protection to urban and agricultural lands during rainy seasons and
to provide facilities for conserving water for alleviation of the effects of
drought and for control of salt-water encroachment.

Work on the C&SFFCD facilities in collaboration with the U.S. Army
Corps of Engineers proceeded on an intermittent basis during the 1950's.
Water Conservation Areas 1 and 2 were enclosed by levees in Palm Beach
and Broward Counties, and a large area southeast of Lake Okeechobee was
zoned for agriculture and made useable by the system of levees, canals,
and pumping stations (fig. 1).

WATER MANAGEMENT PRACTICES AND PROBLEMS


Water control to protect agricultural areas from flooding was either
by gravity flow or by pumping from canals toward Lake Okeechobee and
by pumping into the water conservation areas. Water flowed southward by
gravity through canals and control structures or was pumped to Conserva-
tion Area 3 where it moved slowly southward toward the Everglades
National Park. Also, that part of the water in Conservation Area 1 which
was in excess of the regulation level was diverted to Conservation Area 2,
and the excess in Conservation Area 2 was moved to Area 3 through
spillways. Establishment of the levees and water conservation areas
in the Everglades and the beginning of reductions in the flow of canals






BUREAU OF GEOLOGY


to the ocean were the first compensating steps toward reverting toward
the original drainage patterns and water conditions in the Everglades.
By the end of 1962, Conservation Area 3 was enclosed on the south
side, and, for the first time, the surface flow in the Everglades north
of the Everglades National Park could be fully controlled. Conserva-
tion Area 3 was considered fully enclosed by July 1967 except for a
7.1-mile stretch of levee between the L-28 Interceptor levee and the L-28
tieback levee on the west side. According to plans, additional changes and
modifications in water-management structures are to be constructed as
needed. A list and description of the various control structures built or
operated by the C&SFFCD through 1969 is given in table 7 in the ap-
pendix.

During 1946 to 1962 and concurrent with the construction of the
flood-control works in the Everglades area, the urban east coast was
undergoing accelerated economic development. Housing expanded west-
ward from the coastal ridge in Palm Beach, Broward, and Dade Counties,
resulting in new urban areas requiring drainage and protection against
flooding.
The need to conserve fresh water, particularly the reduction of
discharge of surplus water to the ocean, was emphasized by the regionally
low water levels during the droughts of 1955-56 and 1961-65. The ability
of the system to cope with flood problems was demonstrated during the
extremely wet years of 1957-60, when no appreciable flooding occurred
in the areas protected by drainage works. Extensive damage did occur in
southern Dade County, where the drainage system was not improved to
cope with rainfall of the intensity that accompanied Hurricane Donna in
1960. The south Dade flood-control plan has since been implemented, and
the works are nearly complete.


HYDROLOGIC EFFECTS OF WATER CONTROL
AND MANAGEMENT

The prime effect of the early water-control works in south Florida
has been to increase the flow of water out of the Everglades through
canals. Because the source of much of the flow in the canals in southeast-
ern Florida is from Lake Okeechobee and the Everglades, any changes
in the hydrology caused by impoundment of water or diversion of water
from normal courses in the Everglades will be reflected in the discharge
of those canals. In order to evaluate the effects that changes in water-
control and flood-control practices have brought about, the rainfall-runoff
relation for the primary canals that traverse the Everglades was examined,
and the annual discharges of fresh water to the ocean were analyzed.






REPORT OF INVESTIGATION NO. 60


The history of the development of well fields in the Biscayne aquifer,
the relation of reduced water levels to sea-water intrusion, and the rela-
tion of municipal well fields along the Atlantic Coastal Ridge to present
day water-management practices indicate the extent that natural hydro-
logic conditions have been altered by water-management practices.


FLOW THROUGH THE EVERGLADES

Before attempts were made to reclaim lands for agriculture south-
east of Lake Okeechobee, flow through the Everglades area was moslty
southward toward the Gulf of Mexico and Florida Bay, and, during the
peak period of the rainy season, to the Atlantic Ocean through the
transverse glades (fig. 7). Only during extremely wet years, did water
in Lake Okeechobee overflow southward. The extent that the Everglades
drainage basin changed from year to year depended upon the amount and
distribution of rainfall during each year. During wet years, the effective
drainage basin for the Everglades probably extended to or beyond Lake
Okeechobee. On the other hand, during dry years and dry seasons, the
effective drainage area of the Everglades was greatly reduced and did
not include Lake Okeechobee.

RATE OF OVERLAND FLOW

A number of previous workers in the Everglades area have observed
that water flows slowly southward out of Lake Okeechobee into the Ever-
glades. Bogart and Ferguson (p. 332, in Parker, Ferguson, Love, and others,
1955), stated, "overflow of the south shore became general at stages of
17 to 18 feet, and sizable volumes of water moved slowly in flat, broad
sloughs toward tidewater. The largest slough (known as the Everglades)
extends as a grassy marsh, 35 to 50 miles wide, from south and southeast
shores of the lake to the end of the Florida peninsula, 100 miles to the
south...." On page 333, the above authors state "In its natural state, only
a minor part of the rainfall and the overland flow from Lake Okeechobee
left the Everglades as surface drainage. Overland flow was extremely
slow because land slopes generally averaged about 0.2 ft. per mile, and
interconnecting natural drainage channels were extremely shallow and
were choked with vegetation. During and after the rainy season, water
stood at varying depths over the surface of the organic soils. These con-
ditions naturally led to large losses through evaporation and trans-
piration."
It is of more than academic interest, therefore, to determine the
natural rate of overland flow through the Everglades and the distance






BUREAU OF GEOLOGY


water moves in the basin within a runoff year (April 1-March 31). To
determine the rate of overland flow, an east-west section was selected
immediately north of the Tamiami Canal and extending from Levee 30
westward to Monroe in Collier County (fig. 1). The section was selected
because of the availability of semimonthly discharge information from
1940 for the outlets along the Tamiami Canal. Overland flow at this section
is probably greater than elsewhere in the Everglades because vegetation
is less dense near the Tamiami Trail than it is to the north and evapotrans-
piration is less there than it is to the south. The discharge information
incorporates several prolonged droughts such as 1944-46, 1950-52,
1955-56, and 1961-65 and the extremely wet years 1947-48, 1958-60.
Examination of the discharge records showed that southward flow
occurred as soon as water was only slightly above the general land
surface of the Everglades. Elevations along the measuring section at which
flows occurred initially are referred to as the effective land surface.
Effective land surface elevations were determined from each of the
water-level gages along the Tamiami Canal. To determine the cross section-
al area for the different flow sections, the water depth above the effective
land surface was ascertained from the profile gage readings along the
Tamiami Canal; the water depth was then multiplied by the length of sec-
tion represented by each gage. This section extends from halfway between
two gages. past a given gage, and halfway to the next gage. By using the
basic equationQ=VA, where Q is discharge through the canal outlets in
cubic feet per second and A is the area of flow section in square feet, V,
the velocity of water movement in feet per second, can be determined
and then converted to feet per day. It is assumed that flow is evenly dis-
tributed within each section, as defined above, and that the discharge
measured through the Tamiami Canal outlets represents the flow in the
nearby section.

Discharge data for 1960, which show a wide range of discharges,
and random discharge data from other years were used to determine the
rate of flow through the Everglades and the adjoining section of the Big
Cypress Swamp. The maximum rates of southward water movement at
the Tamiami Canal section were computed to be 1,550 feet per day during
October 1947 and 1,480 feet per day during September 1960. The average
velocity for the 1960 runoff year (defined as April 1 through March 31)
was about 860 feet per day. The minimum rate of southward overland
movement is zero, when water levels decline below land surface. Figure
10 shows the relationship between the rate of water movement, in feet
per day, and the total instantaneous flow through the Tamiami Canal
outlets. The monthly cumulative distances of water movement, based on
the curve in figure 10, for three wet years and one dry year are shown in
figure 11. The distances shown indicate that even during the excessively


















Q:
z
0



oc
U.

CL


LU

u
0O


0- 200 400 600 800 1000 1200 1400 1600 1700
DISTANCE TRAVELED, FEET PER DAY
Figure 10. Relation between the Tamiami Canal outlets' discharge and the average distance a particle of water would travel in the -
Everglades in a day








BUREAU OF GEOLOGY


EXPLANATION
RUNOFF YEAR DISTANCE


......... 1944
-1947

---1959


6.5 miles
42.5 miles
50.3 miles
45.2 miles


NOTE: RUNOFF YEAR (APRIL-MARCH)


Figure 11. Accumulation of the average monthly distance traveled by a
particle of water in the Everglades, based on flow in the
measunng section north of the Tamiami Canal






REPORT OF INVESTIGATION NO. 60


wet years 1947, 1959, and 1960, water from the vicinity of Lake Okeecho-
bee probably did not reach as far south as the Tamiami Canal, because
Lake Okeechobee is more than 60 miles to the north. Although it is unlikely
that water in the northern part of the basin ever reached the Tamiami
Canal, the upbasin water supplies are important because they maintain
gradients that sustain the slow southward flow through the Everglades.
The graphs in figure 11 show that the total estimated distance that
water traveled in the Everglades during a runoff year was greatest during
1959, the year of greatest total flow. However, the peak flow through the
Tamiami Canal outlets for the 1959 runoff year was only about half the
peak flow for 1947 or 1960, as shown in figure 12. Comparison of the
graph for 1944, a dry year, to those for wet years shows the wide range
in hydrologic conditions that occur within the Everglades and Big Cypress
basins.

FLOW THROUGH TAMIAMI CANAL OUTLETS

One of the longest continuous records of discharge in southeastern
Florida is that of the southward flow through the "Tamiami Canal outlets"
beneath the Tamiami Trail between Levee 30, west of Miami, and Monroe,
in Collier County. (See figure 17 for location.) This record is of maximum
importance because: (1) it shows annual changes in southward movement
of water resulting from variations of rainfall within the Everglades and
Big Cypress basins; (2) it shows the volume of water along the Tamiami
Canal between Levee 30 and Monroe, Florida in the Everglades hydrologic
system after all the upstream natural losses and man-imposed diversions
are accounted for; (3) it reflects and permits evaluation of significant
changes in the system to the north that result from diversions, impound-
ments, or water use in upbasin areas, and it may be used in defining the
historic flows toward Everglades National Park.
The discharge through the Tamiami Canal outlets for 1940-69 is
portrayed by the hydrograph on figure 13. The record spans a period of
flows through the Everglades during the last part of the period of drainage
and land reclamation (until 1946), during the period of flood control and
water control (1946-62), and during the beginning of the period of water
management.
As shown by the hydrograph on figure 13, the flow southward
through Tamiami Canal outlets toward the Everglades National Park
fluctuates seasonally and varies greatly from year to year. The annual
fluctuation is exemplified by flood years 1947, 1948, and 1960, as
compared to drought years 1944 and 1961. Not only does the discharge
vary from year to year, as indicated by the annual mean discharge on







BUREAU OF GEOLOGY


YEAR
*----- 1944

-1947

--1959
---1960


Vil.1
M 3 J


EXPLANATION


76.5 cfs

2120 cfs

2380 cfs
2180 cfs


.A S 0. N D JI F M
A S O N D J F M


Figure 12. Hydrographs of monthly mean discharge through the Tamiami
Canal outlets, showing a comparison of the three wettest
runoff years and 1944, one of the driest years of record since
1940




















z
0











U
0.



I-

Li


(hJ


Figure 13. Monthly mean discharge southward toward Everglades National Park through the Tamiami Canal outlets,
Levee 30 to Monroe, Florida 1940-69





































( DISTANCE ALONG TAMIAMI CANAL)
Figure 14. Profiles of maximum, minimum, and average water levels in the Everglades just north of the Tamiami Canal
during 1955, a relatively dry year. Also shown is the altitude of zero overland flow southward






REPORT OF INVESTIGATION NO. 60


figure 13, but the wet and dry seasons may change also from year to year.
Annual monthly peak flows usually occur in September or October, but
two of the more significant monthly mean peaks that occurred out of
phase were the February 1958 peak (2,973 cfs) and the November 1959
peak (4,560 cfs). For all years except 1956 and 1961, discharge through
the Tamiami Canal outlets continued through March of the following
year. The two most significant periods of zero flow were the 114 days
from March 5 to June 26, 1956, and the 189 days from December 6,
1961 to June 12, 1962.
The annual mean discharge in figure 13 indicates there have been
two significant extended dry periods. The first was noted from the begin-
ning of record November 1939 (not shown) to May 1947, and the
second was from April 1961 through mid-1966. In 1947 the peak of
record flow was recorded following one of the driest years, whereas
in 1960 the second highest peak of record followed several years of
above-normal flow. Also in 1961 the discharge was substantially below
normal except for January through March, during which time discharge
was basically runoff from the preceding year. Examining the past
record and the foregoing examples indicates that in the Everglades
area there is very little residual effect from one year to the next. The
main reason for this is that historically about 70 percent of the
rain each year comes normally June through October and the remaining
30 percent falls November through May each year, the period when
evapotranspiration almost always exceeds rainfall. It is during this dry
period each year that surface storage in the Everglades is generally
depleted.
The high and low water levels along the measuring section of the
Tamiami Canal outlets are compared with the effective land-surface
elevations during a dry and wet year on figures 14 and 15. The pro-
files for 1955 (fig. 14) show that only during the period of high water
levels during the wet season did overland flow occur through the
entire measuring section. At times of average conditions in 1955,
flow occurred only through the section between Levee 30 and 40-Mile
Bend. At the lowest water-level condition during the dry season, water
levels were below the land surface, and no flow occurred through any
of the outlets.
The impounding effect of Levee 30 on water west of the levee
and the changes in head across the levee that occurred under the
different conditions are also shown on figure 14. The higher water
levels west of Levee 30 were caused by the flow diverted southward
along the levee system.
In contrast to the conditions during a relatively dry year shown
on figure 14, the water-level profiles on figure 15 for 1960, a wet





































Figure 15. Profiles of maximum, minimum, and average water levels in the Everglades just north of the Tamiami Canal during 1960,
a relatively wet year. Also shown is the altitude of zero overland flow southward and the peak profile of 1947 prior to the
construction of Levee 30






REPORT OF INVESTIGATION NO. 60


year, show that southward flow occurred during the entire year through
the eastern part of the flow section and during all but the minimum or
near minimum conditions through the western part of the flow section.
In order to compare pre-Levee 30 high water-level conditions with con-
ditions after the completion of Levee 30, the maximum profile for
1947 (before levees) is superimposed on the 1960 profiles (fig. 15).

An important feature of the profiles in figures 14 and 15 is the
rise of the effective land surface west of 40-Mile Bend. Although the
maximum elevation west of the 40-Mile Bend site is only slightly more
than 2 feet higher than the elevation at the west toe of Levee 30, the
difference is sufficient to cause most of the flow during wet years to
occur through the eastern part of the section. An analysis of the
distribution of discharge through the Tamiami Canal outlets for 1940-60
showed that for most runoff years when discharge was less than 300,000
acre-feet, the percentage of discharge through the western section
(Monroe to 40-Mile Bend) was greater than that through the eastern
section (40-Mile Bend to Levee 30). However, when the runoff-year
discharge exceeded 725,000 acre-feet, about 70 percent of the discharge
occurred through the eastern section. The relation between runoff-year
100 1- 1 -- 1-- 1- 1--1-1

90- TAMIAMI CANAL OUTLETS


I70-
so




245 g RUNOFF YEAR (APRIL- MARCH)
-- /e49
42 ""
4 4 93


.44
20




0 'b.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
DISCHARGE, MILLIONS OF ACRE-FEET

Figure 16. The relation between the annual discharge through
the Tarniami Canal outlets, Levee 30 to Monroe,
and the percent that flowed through the eastern
section, Levee 30 to 40-Mile Bend






BUREAU OF GEOLOGY


discharge through the Tamiami Canal outlets and the percentage that
flowed through the eastern section, 40-Mile Bend to Levee 30, is shown
on figure 16. Water that flows through the eastern section is from the
Everglades basin, whereas water that flows through the western
section is from the Big Cypress Swamp.

CHANGES IN FLOW THROUGH TAMIAMI CANAL OUTLETS
In order to describe and evaluate the changes in flow through the
Everglades as a result of drainage, water control, and water management
within the drainage basins, the Tamiami Canal outlets were subdivided
into three flow sections, as shown in figure 17. The monthly mean
discharge for the three sections for the period of record is given in
tables 7 to 10, and the Tamiami Canal outlet bridge numbering system
and mileage is given in table 11 in the appendix.
The western section, 40-Mile Bend to Monroe, is the flow from the
Big Cypress Swamp, the only section whose drainage basin has remained
relatively unchanged through the period of record. Therefore, the flow
through that section is used as the index of natural runoff. The middle
section extends from 40-Mile Bend to Levee 67A, and includes the
discharge of the four spillways (S-12A, B, C, and D) at the south end of
Conservation Area 3A, operational after 1962. These spillways control
the direct surface flows into the Everglades National Park. The third or
eastern section extends from Levee 67A to Levee 30. After 1962, the
discharge through this section has been limited to seepage through Levee
29 on the south side of Conservation Area 3B (figs. 1 and 17). The monthly
mean discharge through the three reaches during 1941-69 is shown in
figure 18.

The discharge hydrograph for the reach 40-Mile Bend to Levee 67A
before 1962 shows the normal flow conditions before completion of
Levee 29 and the associated S-12 spillways and completion of Levee 67A
in 1962. After 1962 a distinct change in flow pattern is apparent
by comparison with the index flow section 40-Mile Bend to Monroe, for
the same period. No discharge occurred through S-12 spillways into
the Everglades National Park from Conservation Area 3A during 1963,
and only a small amount was discharged in 1964. However, the flow
through that reach into the Park for 1966 and 1968 was inordinately
large in relation to the annual rainfall and to the flow through the index
section for that year; furthermore, the flow in 1966, 1968 and 1969.
greatly exceeded the prior record flow of 1947 through that section.
Other effects of managing the water in Conservation Area 3A
through the manipulation of S-12 spillway gates, constructed in 1962.
are shown in figure 18 by the hydrograph of the Levee 67A to 40-Mile







































Figure 17. Map showing detail of the Tamiami Canal outlets sub-divided into the three flow
sections (Levee 30 to Levee 67A, Levee 67A to 40-Mile Bend, and 40-Mile Bend to
Monroe, Florida)






BUREAU OF GEOLOGY


Bend section during 1966, 1968, and 1969. The rate of rise and decline
of the discharge after the 1966-68 wet season was greater than it was
for any prior year of record. This sharp decline in 1966 was caused by
closing the spillway gates in November to retard the runoff, thereby
storing water for later release to the National Park. The discharge hydro-
graph of the Levee 67A to 40-Mile Bend section for 1967 shows that
flow was maintained throughout the year, except for a brief period in
January, despite the fact that 1967 was a year of subnormal rainfall,
as indicated by the small discharge through the 40-Mile Bend to Monroe
index flow section. At the end of the dry season of 1967, southeastern
Florida was the only area in Florida that did not experience excessively
low water levels.
The discharge through the section between Levee 30 and Levee 67A
(fig. IS) represents a significant part of the overland flow to eastern
and southeastern Dade County. The discharge before 1962 was predomin-


I i l II lL I iL I I I I 1 i i I I
TAMUUI CANAL OUTLETS 40-MLE BEND TO MONROE

- A '


Figure 18.
Figure 18.


1 I I 11 I I 1 It I 1 I I I
Monthly mean discharge of the Tamiami Canal outlets,
Levee 30 to Monroe, Florida, subdivided into three sections,
1941-69






REPORT OF INVESTIGATION NO. 60 39

antly overland for periods of high and moderate flow; for periods of
low flow, the discharge was chiefly by ground-water flow to the Tamiami
Canal and then through the outlets. After 1962, discharge in this reach
was a combination of seepage through Levee 29 along the south boun-
dary of Conservation Area 3B and ground-water flow to the Tamiami
Canal. The hydrograph shows that during the pre-1962 period, generally
more water flowed through the Levee 30 to Levee 67A section than flowed
through either of the other sections. After Levee 30 was completed in
1953, the additional water that was routed southward by the levee
probably caused the flow to continue for a longer period of time each
year. The decrease in flow recession rate is evident when the recession
rate for 1947-48 and 1948-49 is compared with the rate for 1959-60
and 1960-61, each following abnormally wet rainy seasons. The decrease
in recession rate probably resulted from the southward diversion of
flow by the levee system and the impoundment of water behind the levee.
The marked change in flow pattern in the Levee 30-Levee 67A
flow section is shown by the hydrographs for 1966 on figure 18. During
1966, water that normally would have flowed through the eastern sec-
tion was diverted southward by Levee 67A and impounded in Conservation
Area 3A. The only flow recorded for the Levee 67A-Levee 30 section was
seepage through Levee 29.
Examination of the hydrographs on figure 18 shows that the dis-
tribution of flows through the Tamiami Canal outlets has been altered,
and the greatest flows now occur through the center flow section,
40-Mile Bend to Levee 67A.

Before construction of Levee 29, the section between Levee 30 and
Levee 67A contributed significant quantities of water to south Dade
County. Because water is now being stored in Conservation Area 3B
or diverted to the west by Levee 67A, the contribution to south Dade
County has been altered, and annual peak water levels there have been
reduced.
A method was devised to determine changes in the pattern of flow
through the three sections of the Tamiami Canal outlets and also the
changes in flow in each section during the different periods of con-
struction of the C&SFFCD works. Because the three sections have a related
(although undefined) drainage basin, flow through the 40-Mile Bend
to Monroe section (which is largely unaffected by control works) was
used as a "benchmark" station to determine the changes in the other
two related but controlled sections. To use the 40-Mile Bend to Monroe
section as an index, its cumulative discharge from runoff year to runoff
year was plotted in a straight line by adjusting time, as shown in figure
19. The cumulative discharges of the other two flow sections should







































Figure 19. Cumulative annual discharge showing the effects of construction on each of the
three sections of the Tamiami Canal outlets between Levee 30 and Monroe,
Florida






REPORT OF INVESTIGATION NO. 60


also plot in a straight line on the same time base as long as they are
hydrologically related-that is as long as the hydrologic conditions in
the three sections are not changed. Therefore, any departures from a
straight-line plot, for the two eastern sections, beyond a normal scat-
tering, will show the time and magnitude of the effects that levee con-
struction and other changes have had on the flow.

The effects of the construction of Levee 30 markedly increased
the flow through the section between Levee 30 and Levee 67A, as
shown by the increased slope of the time-adjusted plot (fig. 19). The
increase in the slope indicates an increase in the flow through the sec-
tion. The additional water was diverted southward toward Everglades
National Park and south Dade County by Levee 30 and other levees
east of the three conservation areas, which interrupted the natural east-
ward flow toward the ocean. The magnitude of the change in flow bet-
ween 1953 and 1961 can be estimated for the section by projecting a
straight line from the initially established trend for 1941 to 1952 to
1961 on figure 19 and determining the difference between the values
obtained for 1961. Accumulated discharge would be 3,077,000 acre-
feet rather than the 5,274,000 acre-feet shown. The levees to the
east of the conservation area thus diverted an additional 2,197,000
acre-feet southward. Based on the 1941-52 trend, the natural dis-
charge through the section would have averaged about 146,500 acre-
feet annually rather than 251,100 acre-feet for 1941-61 runoff years.
The additional discharge for the section averaged 245,300 acre-feet
per runoff year between 1953 and 1961, which was a direct result of
the construction of the levee systems. The southward flow for the Levee
30-Levee 67A section for 1953 to 1961 averaged 426,000 acre-feet per
runoff year rather than the average of 180,700 acre-feet per runoff year that
would have occurred for the period if the levee system had not been built.
This was, on the average, 136 percent greater than the flow that would have
occurred if the levee system had not diverted runoff southward.
The magnitude of the change in flow between 1953 and 1961 can
be estimated for the Levee 67A to 40-Mile Bend section by project-
ing a straight line from the initially established trend for 1941 to 1952
to 1961 on figure 19 and by determining the difference in discharge
between the values obtained. Accumulated discharge would be
2,480,000 acre-feet rather than the 2,684,000 acre-feet shown. The
levees at the east side of the conservation areas thus diverted an ad-
ditional 204,000 acre-feet southward. Based on the 1941-52 trend,
the pre-levee natural discharge through Levee 67A to 40-Mile Bend
section of the Tamiami Canal outlets would have averaged 118,100
acre-feet annually rather than 127,800 acre-feet foi 1941-61 runoff
years. The additional discharge for the section averaged 22,920 acre-






BUREAU OF GEOLOGY


feet annually per runoff year for 1953-61 as a direct result of diversion
by the levee systems. The discharge directly to the Everglades National
Park through the Levee 67A to 40-Mile Bend section for 1953 to
1961 averaged 169,000 acre-feet per runoff year rather than 146,100
acre-feet per year if the levee system had not been built an average
of 16 percent greater flow.
The accumulated discharge for the 40-Mile Bend to Monroe
section (the index section) based on 1941-61 record was 4,189,800
acre-feet, or an average 199,500 acre-feet per runoff year.
Levee 29 was constructed in 1962 just north of and parallel to
the Tamiami Canal from 40-Mile Bend to Levee 30, obstructing south-
ward overland flow. After Levee 29 construction, flow through the
Levee 30-Levee 67A section was reduced to seepage through Levee
29, an average of about 66,200 acre-feet per runoff year. Levee 67A,
which separates Conservation Areas 3A and 3B, was completed in
1963, routing considerable water westward through the 40-Mile
Bend-Levee 67A section. Therefore, the annual average seepage dis-
charge of about 66,200 acre-feet in the Levee 30-Levee 67A section
should continue. (See table 9 in the appendix.)
In summary, the flow before 1961 southward toward the Ever-
glades National Park and south Dade County, based on the 1941-61
record, averaged 251,100 acre-feet per runoff year through the Levee
30 to Levee 67A section, 127,800 acre-feet per runoff year through
the Levee 67A to 40-Mile Bend section, and 199,500 acre-feet per
runoff year through the 40-Mile Bend to Monroe section of the Ta-
miami Canal outlets. (See table 4 for comparison of flow between the
calendar year and runoff year for the three sections of the Tamiami
Canal outlets.) The trends of discharge shown on figure 19 indicate
that the average for 1962-68 through the Levee 30 to Levee 67A sec-
tion has been reduced to about 66,200 acre-feet. Although the annual
discharge in the Levee 67A to 40-Mile Bend reach has ranged from
0 to 1.1 million acre-feet, the average for 1962-68 was 341,900 acre-
feet per runoff year, about 214,100 acre-feet greater than the 1941-
61 annual average, and dischage through the 40-Mile Bend to Mon-
roe section has remained about the same.

CONSERVATION AREAS

Three large areas within the Everglades are surrounded by le-
vees and form an important integral part of the water-management
system in south Florida-Conservation Areas 1, 2, and 3A and B
(figure 1). Effective closure of the conservation areas was accomplished
at the end of 1962 except for the west side of Conservation Area 3.







REPORT OF INVESTIGATION NO. 60


Table 4. Total and average discharge of three flow sections of the
Tamiami Canal showing a comparison between runoff and
calendar years for the period 1941-68 (for locations of the
three sections, see figure 17).

Totals Average
n P d (Thousands of Ac-ft) (Thousands of Ac-ft)
Section Period
Runoff Calendar Runoff Calendar
Years a Years Years a Years
Levee 30 to 1941-52 1,439.5 1,422.5 120.0 118.5
Levee 67A 1953-61b 3,834.1 3,881.4 426.0 431.3
1941-61 5,273.6 5,303.9 251.1 252.6
1962-68c 463.1 442.4 66.2 63.2
1941-68 5,736.7 5,746.3 204.9 205.2
Levee 67A to 1941-52 1,162.9 1,169.4 96.9 97.4
40-Mile Bend 1953-61b 1,521.1 1,536.7 169.0 170.7
1941-61 2,684.0 2,706.1 127.8 128.9
1962-68c 2,393.1 2,265.2 341.9 323.6
1941-68 5,077.1 4,971.3 181.3 177.5

40-Mile Bend 1941-52 2,013.3 2,033.8 167.8 169.5
to Monroe 1953-61b 2,176.5 2,187.9 241.8 243.1
1941-61 4,189.8 4,221.7 199.5 201.0
1962.68c 1,303.9 1,293.6 186.3 184.8
1941-68 5,493.7 5,515.3 196.2 197.0

a Runoff year is defined as period April 1-March 31
b After construction of L-30
c After construction of L-29

Conservation Area 3 was considered fully enclosed by July 1967
with the exception of a 7.1-mile stretch of levee between L-28 Inter-
ceptor levee and L-28 tieback levee. Water in the canal system can
flow by gravity or be pumped into the conservation areas, thus delay-
ing runoff from the central Everglades area. During times of intense
rainfall, excess surface waters are pumped to temporary. storage in the
conservation areas, thus reducing the flood-peak water levels east of
the conservation areas, especially urban areas along the Atlantic
Coastal Ridge. Conditions during a wet period, before and after water-
management systems were operational, are shown on figure 20. Dur-
ing dry periods, seepage through levees and regulated releases from
the conservation areas sustain water at higher dry-period levels to the
east for longer periods than could be maintained before the manage-
ment system went into operation.
The three conservation areas occupy 1,345 square miles, near-
ly twice the area of Lake Okeechobee. Although the areas are shallow
reservoirs, large volumes of water can be stored temporarily in them,
thereby delaying runoff from the interior.











BEFORE


EVERGLADES


BEFORE






EFFECTS OF LEVEE SYSTEM ON
RUNOFF FROM A LARGE STORM
TIME INCREASING -4b


LEVEE


COASTAL RIDGE

'""**" ..-^/LC BISCAYNE BAY

4. .q.
0.0' .AP A'
S FRESH WATER SEA WATER











AFTER


COASTAL RIDGE


EVERGLADES
EVERGLADE BORROWBISCAY BAYCANAL
WATER TABLE BISCA YNr BAY

S A


,,* "* ,
FRESH WATER Ar 00 SEA WATER

.A *.. .4 4-

Figure 20. Schematic diagram direction of flow and water levels in a typical west-to-east section, from the Everglades through the
coastal ridge to Biscayne Bay. Conditions during a wet period, before and after water management systems were opera-
tional, as shown


II______ _~ __ _


t






REPORT OF INVESTIGATION NO. 60


RAINFALL AND STORAGE

Rainfall differs in intensity over the three conservation areas (fig.
6) and affects the amount of water available for storage in each of the
areas. Average rainfall over Conservation Areas 1, 2, and 3 is 59, 56,
and 53 inches, respectively.
Most rainfall on the conservation areas evaporates or is transpir-
ed to complete the hydrologic cycle. Consequently, the three conser-
vation areas have nearly gone dry several times since being enclosed.
In dry years more water enters the conservation areas than is discharg-
ed from them through the control structures, as shown by the records
for 1961-64, table 6.
The amount of water temporarily in storage in the combined con-
servation areas as a result of rainfall of a given intensity is shown in
figure 21. The amount of storage expected from each storm of a known
magnitude is indicated in the illustration. A 6-inch rain, for instance,
would add about 430,000 acre-feet, or about 140 billion gallons of
fresh water to storage.

SEEPAGE
Considerable water leaves the conservation areas by seeping
through the levees. Seepage is generally beneficial because it distri-
butes runoff from severe rain storms at uniformly decreasing rates
to the areas east of the conservation areas. The conservation areas
retain fresh water from storms until excess water in the coastal area
can be removed by canals to the ocean; then seepage through the levees
and discharge through the levee control structures help maintain
optimum water levels in the areas east of the conservation areas.
Seepage from Conservation Area 1 eastward through Levee 40,
from October 1962 to December 1963, is shown in figure 22. The
hydrograph of seepage (lower graph) is estimated from a head-discharge
relation from Corps or Engineers discharge measurements and from
the average head of several gages in the area, shown in the upper graph.
The mean eastward seepage for 1963 is estimated to be 109 cfs. This
amounts to 3.7 cfs per mile of levee, or a total of about 78,900 acre-
feet along 29.2 miles of levee.
The seepage from Conservation Area 2 eastward and southward
through levees 35 and 36 is shown in figure 23, and seepage eastward
and southward through levees 29, 30, 33, and 37 of Conservation Area
3A and B is shown in figure 24. The estimated seepage during 1963,
180 cfs to the east for Area 2 and 388 cfs to the east and south for
S Area 3A and B, averages 8.0 cfs and 9.6 cfs per mile, respectively.








BUREAU OF GEOLOGY


I-

I
LJ
U


u.
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I,
z


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I--


-1300



-1200



-1100



-1000



-900



-800 _
J
-J


-700
0

()
z
-600 0

Ca
-J



500



-400



-300




200



-100


Figure 21. Nomograph of rainfall-storage relation in the three conservation areas


- 440


-420


-400


- 380


-360


-340


-320


-300


-280


-260


-240


-220


-200

180


-160


140


-120


100


- 80


60


-40


- 20






REPORT OF INVESTIGATION NO. 60


LW OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.
1962 1963
Figure 22. Estimated seepage eastward from Conservation Area 1
through and under Levee 40. Discharge data furnished by
the U.S. Corps of Engineers

Using the above values of seepage for 22.5 miles of levee, northeast-
ern Broward County received about 130,300 acre-feet of water in 1963
from Conservation Area 2, whereas, for 40.35 miles of levee, southeast-
ern Broward and eastern and southern Dade counties received about
280,900 acre-feet from Conservation Area 3.
The shallow earth materials have low to moderate permeability
in the north and become moderately to highly permeable in the south
along the levees on the east side of the conservation areas, as indicated
by the seepage rates of 3.7 cfs per mile of levee from Area 1, 8.0 cfs
per mile of levee from Area 2, and 9.6 cfs per mile of levee from Area
3. The monthly seepages in table 5 from each of the three conservation
areas were derived from figures 22, 23, and 24. Throughout 1963 and
1964, the total amount of seepage for each year was greater during
November through February, the dry season, than during June through
September, the wet season, because of greater head differential during
the dry season. For each of the 2 years, the dry-season seepage was
178,460 and 280,400 acre-feet; the wet-season seepage was 143,360
and 242,200 acre-feet.






48 BUREAU OF .GEOLOGY











- \
I I -
4






I I
I Estimated-1
i I IIl ll










F~gute 23. Estimated seenage southward and eastward from Conservation Area 2
through levees L and36. Discharge data furnished by the U.S. Corps
a.


OCT NOVH DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.
962 1963
Figure 23. Estimated seepage southward and eastward from Conservation Area 2
through levees L-35 and L-36. Discharge data furnished by the U.S. Corps
of Engineers

A generalized water budget was developed for 1963 and 1964
for the combined water conservation areas using the 1963 seepage values
to determine the amount of the water that was lost by evapotranspiration.
Of the 4 million acre-feet available in 1963, 3.5 million acre-feet (86.8
percent) evaporated and transpired, and 490,200 acre-feet seeped to
the east and south. In 1964, of the 5 million acre-feet available, 3.6 mil-
lion acre-feet (70.5 percent) evaporated and transpired, and 734,500
acre-feet seeped to the east and south.
Major inflow, outflow, rainfall, seepage,, change in storage, and
evapotranspiration for the three conservation areas are shown in table 6.
The discharge data for all the stations in existence during 1958-62 are
shown for comparison with the same type of data for these stations in 1963
and 1964. The evapotranspiration for 1963 and 1964 vas computed by
summation of the inflow, outflow, rainfall, change in storage and the
estimated seepage from table 5. For most average years, about 500,000
acre-feet of fresh water may be expected to seep eastward through the
levee system.
The prime functions of the conservation areas are to store excess
water to reduce flooding of the area east of the levee systems during wet








Table 5 Estimated monthly and annual seepage
and L-29 from L-30 to L-67A.


in acre-feet 1 to the east and south through L-40, L-36, L-35, L-37, L-33, L-30,


Conservation Areas
Month 2 1 2 3A and 3B Totals
193 1 63 1964 1963 1964 1963 196 1963 1964

January 8,300 6,760 9,530 3,070 25,820 30,130 43,650 39,960

February 6,660 7,220 11,110 3,060 25,270 26,660 43,040 36,940
March 7,690 8,610 9,530 5,530 20,910 23,670 38,130 37,810

April 5,650 6,840 11,600 8,630 12,500 19,640 29,750 35,110

May 5,840 7,070 10,140 11,070 10,450 23,060 26,430 41,200

June 5,650 6,540 9,520 13,980 14,880 30,640 30,050 51,160
July 4,920 7,690 10,140 8,610 22,140 35,660 37,200 51,960
Atigust 5,230 7,070 9,530 15,060 20,600 37,510 35,360 59,640.

September 6,840 7,440 6,540 30,050 27,370 41,950 40,750 79,440
October 8,610 9,220 17,830 36,280 47,960 52,260 74,400 97,760

November' 6,840 8,930 15,170 44,330 28,560 48,790 50,570 102,050
December 6,760 7,990 9,840 40,890 24,600 52,570 41,200 101,450
Totals 78,990 91,380 130,480 220,560 281,060 422,540 490,530 734,480

1 One acre-foot equals 43,560 cubic feet.







kiduint Iii aorucIibet ulaowliiiy iiiiiiiuil InIOVenient ol water /1111( thle three combnined c~)Inuervtlhiol ireems,


tSmtion 10S8 1050 1060 1061 10628 1063 1064

S25 i 856,300 557,000 336,300 104,200 188,600 117,200 360,500
S.6 189,400 166,000 184,000 43,200 60,300 61,600 148,300
S S- established i 262,600 136,800 74,400 98,200
S.8 a established I 90,100 146,800
S-9 118,800 117,700 110,600 118,800 35,900 43,700 93,600
S.12 .939,700 .1,044,700 2'.1,163,400 .162,2Q00 4.32,700 4 .65,000 4 -15,400
S.34 -316,100 -215,700 -123,300 -600 0 -14,400 -3,500
S S.38 0 0 0 0 5 established 1 -18,600 .20,700
S-39 -191,500 -200,500 -84,500 -73,400 -21,300 -19,200 -11,900

Rainfall 4,760,200 5,827,600 4,932,400 2,978,400 3,701,400 3,761,700 4,351,000
Subtotal 4,031,500 5,146,900
Note: Water budget not computed for 1958-62 due to construction and Storage Change 6 -43,400 6 -781,900
incomplete data. Negative signs indicate loss from conservation Seepage -490,500 -734,500
area, except for storage change.
Evapotranspiration 7 -3,497,600 7 -3,630,500

1 First complete year of record.
2 Tamiami Canal outlet discharge, Levee 30 to 40-Mile Bend prior to construction of
Levee 29.
Established 2/9/62.
S4 Total includes estimated seepage through Levee 29 between L-67-A and 40-Mile Bend.
SEstablished 7/3/61; assumed discharge to be zero for year. Prior record is zero because
Sflow was restricted by Levee 36.
S Represents an increase in storage in the conservation areas.
7 Evapotranspiration computed from difference between subtotal and storage change -
computed seepage.


'Falrle H. ~enerallaill welur







REPORT OF INVESTIGATION NO. 60 51

7 I I I .\ I -I- l l I -- I I |l


S-r







S0 -IoI I I I I I I I I I I I
o-


z I \


\ 1
\ I '

500 Estimated -I
U o o I \ -

\ Discharge measurement/
/0 A -
3UJ I00


100
IOF

C I-I I I I I I I I I I I
OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT OCT. NOV. DEC.
1962 1963
Figure 24. Estimated seepage southward and eastward from Con-
servation Areas 3A and B through levees L-37, L-33, L-30,
and L-29. Discharge data furnished by the U.S. Corps of
Engineers
periods and to release water during dry periods to minimize the effects
of droughts. Flooding along the urban coastal ridge during the wet years
of 1959 and 1960 would undoubtedly have been much greater had it not
been for the effectiveness of the drainage and flood-control practices of
the C&SFFCD.
In summary, the overall effects of building the eastern levees and
establishing the conservation areas are as follows: The levees prevent the
overland flow of flood water from the Everglades to the urbanized coast-
al areas, thereby reducing flooding there. By impounding excess water
in the conservation areas, runoff is delayed, and part of the excess is avail-
able as direct releases through canals or as-seepage from conservation
areas during the dry season to maintain water at favorable levels in the
coastal areas. -.
During the period of construction of the C&SFFCD system, urbani-
zation expanded into interior areas,. many of which were formerly un-






BUREAU OF GEOLOGY


suitable for habitation because of frequent flooding. Much of this low
land between the coastal ridge and the Everglades was covered by 2 to 3
feet of water for many weeks during 1947. By 1960, only part of the
flood-control works was in operation, but only parts of south Dade County
were significantly flooded from hurricane rainfall. Chances for flood
conditions comparable with those of 1960 have been minimized since
completion of the Flood-control works in south Dade County in the mid
196ffs.
CHANGES IN DISCHARGE FROM THE MAJOR CANALS

During the early stages of land reclamation in south Florida, the
major canals, including the Miami, North New River, Hillsboro, and
West Palm Beach canals, functioned primarily as drains to conduct water
out of the Everglades area. As drainage and reclamation progressed,
water-control structures and additional canals were constructed (fig. 1)
so that discharge from and water levels in the major canals could be con-
trolled and managed.
Adjustments in operation of canals and canal structures to meet
changing needs over the years have changed amount, timing, and distri-
bution of discharge from the primary canals since the early days of drain-
age- Changes in discharge of the major canals constitute one of the prin-
cipal indicators of the effect of water control and water management on
the water resources.
Because the Miami, North New River, Hillsboro and West Palm
Beach canals drain the Everglades and transect the coastal ridge, the an-
C I I I I I I
MIAMI CANAL 47
913

EIC a


1964 2 01940
0----- 644049 -YA A----------------

L5 6 43 41&


M RUNOFF YEAR. APRIL THROUGH MARCH
z3 I I


DISCHARGE, MILLIONS OF ACRE FEET
Figure 25. Generalized relation between annual rainfall at index sta-
tions in the area and discharge to the ocean from the Miami
Canal for runoffyears 1940-64







REPORT OF INVESTIGATION NO. 60 53


nual discharge from each can be used as an indicator of present and past
(because of their long records) hydrologic conditions and effects of water
management.

A general relationship between annual rainfall and the discharge for
a runoff year (April through March) was determined by plotting the aver-
age annual rainfall for all index rain gages against the annual discharge
of the Miami Canal at N. W. 36th Street, Miami, figure 25. The resulting
graph is a rainfall-runoff rating curve that indicates little or no runoff if
annual rainfall is less than 37 inches, assuming a normal distribution pat-
tern within the year.

By subtracting 37 inches from the annual rainfall, the double-mass
curve relating "adjusted" cumulative rainfall at the index station to cumu-
lative discharge of the Miami Canal at N. W. 36th Street for each runoff
year was constructed, figure 26. The relation should plot as a straight line
for periods when there were no major water control or flood control changes
in the drainage basin. Two changes in slope occur, one around 1955 and
the other after 1960, each indicating a significant reduction of discharge
in the Miami Canal. The first major break occurred a few years after the
completion of the eastern levee system (levees 30 and 33) about 15 miles
upstream from the 36th Street control structure, and the completion of
0 II I I I II b IA


o50 1960- /
500 -

In -


SMIAMI CANAL 1955
-J
S/ I EXPLANATION
S300- A 999.100 ACRE-FEET REDUCTION-
p IN DISCHARGE DURING 1956-65
1950 (AVERAGE ABOUT 99,900 ACRE-
W FEET ANNUALLY)

S200- 1947 REDUCTION IN DISCHARGE, 1961-
S- 65 (AVERAGE ABOUT 170.100
SACRE.FEET ANNUALLYi


I 2 3 4 5 6 7 8 9 10 II
CUMULATIVE DISCHARGE. MILLIONS OF ACRE-FEET
Figure 26. Cumulative runoff-year discharge to the ocean from the
Miami Canal related to the adjusted cumulated annual
mean rainfall from the eleven index rain gages. Note the
change in slope beginning 1955 and 1960






BUREAU OF GEOLOGY


the two control structures (S-32 and S-32A) in the Miami Canal (fig. 1),
which regulate flow of the canal. The second break in slope occurred after
1960, when most of the control structures, spillways, and pumping sta-
tions of the C&SFFCD system were operational south of Lake Okeecho-
bee, and Levee 67A, which separated Conservation Area 3A from 3B;
was completed. The separation was made in order to reduce water levels
in Area 3B, thereby minimizing eastward seepage through levees 30 and
33 and seepage southward through the eastern reach of Levee 29.
The two major changes in the slope of the curve indicate reductions
in discharge of water to the ocean. The amount of water that would have
been discharged to the ocean is indicated in the upper right corer of figure
26 and is labeled A and B. The amount of discharge for the 10-year period
"A' (1956-65) was 999,100 acre-feet, averaging about 99,900 acre-feet
per runoff year, and the additional amount for the 5-year period "B"
(1961-65) was 850,700 acre-feet, averaging about 170,000 acre-feet
per runoff year. The total reduction in discharge of Miami Canal for the
10 years 1956-65, as shown in figure 26, was about 1.85 million acre-
feet, or about 185,000 acre-feet for each runoff year.
The annual rainfall (average for the long-term index gages) was
also compared with the combined discharge of the West Palm Beach,
Hillsboro, and North New River canals after adjustments were made to
account for inflow from Lake Okeechobee. The relation is shown in figure
27. A wide scattering in the plottings resulted, as did that for the Miami

ticI


9C WEST PALM BEACH, HILLS8ORO. AND NORTH NEW RIVER CANALS
I47




4 3 I /4 *
SA49



9v I Ni" VrAR APRIL THR(nIGH MARCH


04 0.8 L2 1.6 2.0 2.4 2.8
DISCHARGE. MILLIONS OF ACRE FEET
Figure 27. Generalized relation between the annual rainfall at index
stations in the area and combined discharge to the ocean
from the West Palm Beach, Hillsboro, and North New
River canals, for runoff years 1940-64






I I I I I I I I I I I I I I I I I I

1964V / -
WEST PALM BEACH, HILLSBORO, AND NORTH NEW RIVER CANALS /6./
1960

/ -



400 3


I I / EXPLANATION
SA 1,998,200 ACRE-FEET REDUCTION IN
SI DISCHARGE FOR THE 1953-65 PERIOD
30 I / BASED ON THE 1953-1957 TREND(AVERAG
ABOUT 153,700 ACRE-FEET ANNUALLY)
S1950 B 1,831,600 ACRE-FEET ADDITIONAL REOUCT-
ION IN DISCHARGE FOR PERIOD 1958-65
(AVERAGE ABOUT 229,000 ACRE-FEET
ANNUALLY)



CONSERVATION AREAS EASTERN BOUNDARY LEVEES o
COMPLETED MAY 1953. z


100 WATER MOVEMENT TO OR FROM CONSERVATION
AREAS ABOUT 90 PERCENT CONTROLLED
1957.
01940


5 10 IS 20 25 30 33
CUMULATED ANNUAL DISCHARGE, MILLIONS OF ACRE-FEET
Figure 28. Cumulative runoff-year discharge to the ocean from the West Palm Beach, Hillsboro, and North New River canals related
to adjusted cumulated annual mean rainfall from the eleven index rain gages. Adjustments for inflow to and outflow from
Lake Okeechobee applied to runoff values






BUREAU OF GEOLOGY


Canal in figure 25, and, similarly, the curve indicated that little or no
runoff to the ocean would occur if rainfall was 37 inches or less. As a
matter of interest, an examination of several rainfall-runoff relations for
other discharge stations in southern Florida showed that flow to the ocean
approaches zero when rainfall is about 37 inches, suggesting that for most
years evapotranspiration is at least 37 inches.

By subtracting 37 inches from the annual rainfall (average of all
index stations) the double-mass curve relating "adjusted" cumulative
rainfall to cumulative discharge from the West Palm Beach, Hillsboro,
and North New River canals for runoff years 1940 to 1964 was construc-
ted, figure 28.
Similarly, as in the graph for the Miami Canal (fig. 26), the early
points plot as a straight line, and the data for more recent years defined
two changes in slope, which also indicate reductions in discharge to the
ocean. The first change in slope of the curve begins between 1952 and
1953, corresponding to completion of the eastern levees. The second
change begins after 1957, when most of the pumping stations and control
structures were completed, when the agriculture areas were established,
and when Conservation Areas 1 and 2 were enclosed by levees.
The total effects of all the changes in the three canals since 1953
may be summed up in an average and total reduction of discharge to the
ocean. The extended straight line on figure 28 shows what the discharge
would have been for the West Palm Beach, Hillsboro, and North New
River canals if no changes had been made. This projection indicates
that an average of 1,167,000 acre-feet would have been discharged for
each of the 13 years (1953-65), a total discharge of 15,171,000 acre-feet.
The actual total discharge from the three canals to the ocean for the 13-
year period was 11,341,000 acre-feet, or about 872,400 acre-feet per
runoff year. Therefore, the reduction in discharge over the 13 years
was 3,830,000 acre-feet, an average of about 294,600 acre-feet per
rnmoffyear. The total amount of discharge would break down into 1,998,200
acre-feet for the 13-year period "A" (1953-65), averaging 153,700 acre-
feet per year, and an additional reduction in discharge of 1,831,600 acre-
feet for the 8-year period (1958-65), averaging 229,000 acre-feet per
year. This total reduction in discharge would indicate a 25-percent reduc-
tion of the projected discharge to the ocean. The above discharge values
have been adjusted for inflow to and outflow from Lake Okeechobee to
the upper Everglades basin.
In summary, the four major canals, Miami, North New River, Hills-
boro, and West Palm Beach, drain the Everglades and transect the coastal
ridge. The discharge records on the four major canals date back to 1939
before changes by the C&SFFCD projects and can be used to detect






REPORT OF INVESTIGATION NO. 60


changes in hydrologic conditions or effects of water management. One of
the more significant changes noted was the reduction in seaward dis-
charge of fresh water coincident with the completion of levee systems east
of the three conservation areas. The reduction in flow to the ocean began
with the completion of these levees in 1953, resulting in reduction of dis-
charge to the ocean from the Miami Canal of about 185,000 acre-feet per
runoff year for 1956-65 and a reduction of discharge from the North New
River, Hillsboro, and West Palm Beach Canals of about 294,600 acre-
feet per runoff year for 1953-65.
Although the discharge records of the four major canals indicate a
25 percent reduction in annual discharge to the ocean, not all the salvaged
water is available for use. Additional canals have been constructed, such
as the Cutler Drain (C-100); most of the old canals such as Snapper Creek
and Snake Creek canals have been widened, deepened, and provided with
new control structures for flood protection. Consequently, the overall
reduction of fresh-water flow to the ocean in southeastern Florida since
1953 as a result of flood-control and water-management practices is about
20 percent.



WATER LEVEL CHANGES ALONG COASTAL RIDGE AND VICINITY

One principal effect of pre-1945 land-reclamation practices was
the lowering of ground-water levels throughout the coastal ridge and in-
terior areas. Water-level declines resulted from virtually uncontrolled
drainage from the four major canals that traverse the Everglades and the
coastal ridge. The West Palm Beach, Hillsboro, North New River, and
Miami canals conducted large quantities of water from the Everglades
to the ocean. In the coastal ridge area, the canals penetrate the permeable
Biscayne aquifer, and water from the aquifer drains to the canals when
canal levels are lower than the water table. In the early period when drain-
age continued throughout the dry seasons, some areas were overdrained,
allowing sea water to enter the canals and the aquifer and to migrate pro-
gressively inland, as shown by Parker, Ferguson, Love, and others (1955,
figure 169).
The lowest water levels of record occurred in May and June 1945,
the end of a prolonged drought and the end of the period of uncontrolled
drainage. The contour map in figure 29 portrays these conditions in Dade
County (Schroeder and others, 1958, fig. 14). It was during 1945 that
the greatest threat of sea-water contamination of Miami's water supply
system occurred, and remedial steps were taken to control flow in the
major drainage canals before the next dry season. The important features






BUREAU OF GEOLOGY


Figure 29. Map of Dade County showing contours of the low water
levels of record, May-June 1945 (from Schroeder and others,
1958, fig. 14)
of the contour map are the below sea-level elevations throughout the
southeast and southern parts of the county and the low eastward gradient
in the northern part.

Marked changes in hydrology took place during the 15-
year span beginning in 1950. Canals were extended inland for expanded
drainage. New canals were dug through the coastal ridge, and many ex-
tended inland to the eastern levee system to accommodate rapid urbani-
zation. Each new major canal was equipped with a gated control struc-
ture. The improved drainage lowered peak levels during the rainy season,






REPORT OF INVESTIGATION NO. 60 59


Figure 30. Map of Florida's lower east coast showing contours of low-
water conditions in May 1962 (adapted from Sherwood and
Klein, 1963, fig. 9 and McCoy and Sherwood, 1968, fig. 8)






BUREAU OF GEOLOGY


and the timely closing of the control structures at or soon after the rainy
season prevented overdrainage and excessive lowering of water levels,
thereby stabilizing the salt front in the aquifer in most areas. The contour
map in figure 30 shows water levels in southeastern Florida in May 1962,
the end of a prolonged drought that was comparable in intensity -to that
ending June 1945 (fig. 29). A comparison of the two maps shows that
the low levels in south Dade County in May 1962, although below sea
leveL were not as low as in 1945 and that the levels in middle and northern
Dade County were about 1 foot higher in 1962 than in 1945, despite the
fact that water use had multiplied many times during the 17 years.

In 1967 a new system of drainage canals was completed
in south Dade County, an area that had experienced flooding in 1947


Figure 31. Map of part of Dade County showing contours of the high
water conditions of September 1960






REPORT OF INVESTIGATION NO. 60


Figure 32. Map of Florida's lower east coast showing contours of the
High water conditions of June 1968






BUREAU OF GEOLOGY


and 1948, 1954, and 1960. The high-water conditions resulting from two
tropical storms in September 1960 are shown on figure 31. Water-level
peaks exceeded 10.5 feet above mean sea level in the high parts of the
ridge, sheet flow occurred through the transverse glades, and much of
the coastal marsh east of the ridge was flooded.
The flooding in south Dade County brought about a high priority
for completing the drainage system there. That system was nearly com-
pleted by the end of 1968 and is shown in figure 32 in the area south of
Canal 2 (Snapper Creek Canal). The effectiveness of the system in
preventing floods is shown by the water-level contours for June 1968
(fig. 32), which show conditions after rainfall of nearly 16 inches in
May and more than 15 inches at Homestead during the first 20 days of
June 1968. Drainage by the canals resulted in local ground-water mounds
in the intercanal areas rather than a high elongate mound, as was shown
for September 1960. No flooding resulted from the May-June 1968 rain-
fall in Dade County, though the rainfall was greater than that during the
September 1960 storm.


10 II 12 13 14 15 16 17 18 19 20 21
JUNE 1961
4 f I I
WELL S-182














5 6 7 8 9 10 11 12 13 14 15 16
SEPTEMBER 1965
Figure 33. Hydrographs of well S-182 showing water-level recession
rates before and after construction of Canal 1






REPORT OF INVESTIGATION NO. 60


The effects of the new canal system and flood-control practices on
the hydrology of south Dade County were also marked by a change in
the recession rate of water levels. Figure 33 shows selected graphs of
sections of the water level recorded at well S-182, a short distance north
of Canal 1 (see figure 1 for location), to contrast the recession rates before
and after Canal 1 was completed and the salinity control S-21 was ac-
cepted. The graphs show that the rate for part of June 1961 (pre-canal
construction) was about 0.2 foot per day, half the 0.4 foot per day rate
of September 1965.
Long-term records of fluctuations of ground-water levels and general
water-level trends from observation wells provide the most valuable
information to aid in determining changes in water levels caused by
the flood-control and water-control practices. Scattered records of
water levels and reports of general hydrologic conditions in different
areas, as reported by Parker, Ferguson, Love, and others (1955, p. 500-
585), indicate that water levels were near or at the land surface along
much of the coastal ridge area before drainage. Detailed records of water-
level fluctuations since 1940, as reported by Kohout and Hartwell (1967,
p. 25-27, fig. 13), show the adjustment of ground-water levels to water-
control activities in subsequent years and that water levels are generally
several feet below land surface. The records show that in the northern
half of Dade County the yearly water-level peaks were lowered, espec-
ially after 1954, and a small but gradual rise in annual minimum levels
occurred in certain areas.
General changes in water levels and the patterns of fluctuations
along and immediately west of the coastal ridge in Broward County are
shown on figure 34 by the hydrograph of well G-616, near Pompano
Beach. The apparent changes are an increase in the rate of fluctuations


Figure 34. Hydrograph of well G-616 in Broward County






BUREAU OF GEOLOGY


1940 45 1950 55 60 65 1969
Figure 35. Hydrographs of selected observation wells in southern Dade County






REPORT OF INVESTIGATION NO. 60


beginning about 1958 and the lowering of the annual minimum levels.
The first downward trend in minimum water levels began in 1955 and
generally coincides with the completion of the canal system west of
Pompano Beach, which connected with the Pompano Canal (C-14). The
second downward trend in minimum water levels began in 1965, when
the drainage system for a large community northwest of Pompano Beach
was connected to the Pompano Canal.
Inspection and analysis of long-term water-level records in other
parts of the coastal ridge also show changes in trends, in magnitude of
fluctuations, and in recession rates. Figure 35 shows hydrographs of
five observation wells in southern Dade County, wells F-319, S-196,
G-596, G-614, and G-620. Locations of wells are shown in figure 1.
The hydrograph for well F-319, near the coast south of Miami,
shows the marked moderation of the height of annual water-level peaks
since the 1947 record high and-an upward trend of the minimum levels.
These changes in the pattern of fluctuations are a result of water-control
practices in Snapper Creek Canal (C-2). Even during the extreme rain-
fall of September 1960, flooding in the urbanized areas of the Snapper
Creek Canal basin was minimal or nonexistent. The upward trend in
minimum levels is the result of two factors: (1) the ability of the Snapper
Creek Canal and its secondary canal system to pick up ground water
in the interior reach and convey it eastward, thereby maintaining rela-
tively high levels in the coastal reach to combat sea-water intrusion;
(2) improved water-control practices brought about by increased ex-
perience in control-structure operations resulted in a decrease in fresh-
water discharge to the ocean and a slowdown in the recession rate of water
levels.
The hydrograph for well G-596 (fig. 35) west of Levee 31 shows
the changes in water level in the interior areas as a result of the con-
struction of the levee system around the conservation areas, the exten-
sion of Black Creek Canal (C-1) inland to the levee system, and the sub-
sequent flood-control and water-control practices in the area drained
by C-1. The 1952-60 water levels for well G-596 shows a slight rise,
probably in part of a result of construction of the eastern levee system
and the resultant southward diversion of surface flows. The record for
1962-68 shows a distinct downward trend. The annual minimum levels
are as much as 1.0 to 1.5 feet lower than earlier minimums, and the
annual peak levels are as much as 0.5 foot lower than those for the pre-
ceding period. These lowered water levels are significant because they
are the difference between flooding and not flooding in the area, which
has enabled the establishment of new farmlands in the vicinity of Levee
31. The annual magnitude of fluctuations for 1962-68 is considerably






BUREAU OF GEOLOGY


increased from that observed in the earlier period of record. The down-
ward displacement of water levels and the increase in the magnitude of
fluctuations are the result of: (1) below-normal rainfall during part
of the period, particularly 1962-63; (2) the draining effect of the Black
Creek Canal (C-l), which picks up water from the vicinity of well G-596
and conducts it to the coast; (3) completion (1962) of the eastern sec-
tion of Levee 29 along the south boundary of Conservation Area 3B,
which prevented southward overland flow from Conservation Area 3B.
The hydrographs for wells S-196 and G-614 in southern Dade
County indicate a lowering of annual minimum levels during 1962-68;
however the lowering was not so pronounced as that observed in the
vicinity of well G-596. The lowering of ground-water levels in southern
Dade County, as indicated in the hydrographs of wells S-196 and G-
614, may have been the result of the drainage by the Black Creek Canal
(C-1), because those two wells are south of and, in part, downgradient
from the Black Creek Canal (C-l); and lowering of levels owing to drain-
age by C-I will be reflected in the levels in areas to the south. Canals
102 and 103 were operational in 1967, but sufficient time has not
passed to determine the incremental effect that those canals have had on
adjacent ground-water levels.
In the highly permeable aquifer of eastern Dade County, the canal
system has effectively lowered water levels, thereby aiding in the pre-
vention of major flooding. Many of the canals extend long distances
inland to the Everglades and drain areas of relatively high water levels.
Drainage of Everglades water through the canals has resulted in lower-
ing inland water levels and raising levels near the coast. One overall
hydrologic result is a reduction of the water-level gradient throughout
the area east of the levee system.
A complete evaluation of the effects that water management dur-
ing 1962-68 had on hydrologic conditions is beyond the scope of this
report, but indications are that they have been effective in flood con-
trol and water availability and that works in progress will increase its
effectiveness. Owing to a prolonged period of below-average rainfall,
which began after Hurricane Donna in the fall of 1960, surplus water
was not available to manage until 1966, a year of above-normal rain-
falL Sufficient water was retained in the management system after the
1966 rainy season to permit major but gradually reduced releases to
the Everglades National Park throughout the subsequent dry season
and to maintain adequate water levels along the coast.
Flood benefits of the new canal system in south Dade County were
realized at the beginning of the rainy season of 1968, when rain in ex-
cess of 32 inches fell during May and June. Without the canal system,







REPORT OF INVESTIGATION NO. 60


inundation equaling or exceeding 1947-48 and 1960 conditions would
probably have occurred. (Compare figs. 31 and 32 in south Dade County.)

CHANGES IN WELL-FIELD AREAS AND SEA-WATER INTRUSION

A prime objective for water management is to hold additional
water in the conservation areas by reducing flood flow to the ocean.
This should insure that water deliveries to the coastal sections of the


BISCArNE CAUAL



S LITTLE REER CAN4

SLA STN .
, eAMI WAITER

f ___ 36 TH


MIAMI
f^-r l
*i



c


.(
C, /7P1


Figure 36. Maps of the Miami area in eastern Dade County showing
the sea-water encroachment at the base of the Biscayne
aquifer 1904-69 (Parker, Ferguson, Love, andothers, 1955,
p. 589, Kohout, 1961, Leach and Grantham, 1966) updated


CRE EK






BUREAU OF GEOLOGY


Biscayne aquifer are adequate during dry seasons to prevent further
sea-water intrusion and to provide replenishment to well fields by in-
filtration from the canals. If this objective is satisfied, then hydrologic
conditions in inland areas and in the Everglades National Park should
improve.
Sea-water intrusion and its control have been problems in develop-
ing the water resources of southeastern Florida. Parker, Ferguson, Love,
and others (1955, p. 571-711) presented a detailed history of sea-water
intrusion in southeastern Florida. Figure 36 updates their presentation
(1955, fig. 169) of the progressive movement of salt water into the
Biscayne aquifer in the Dade County area. It is apparent that further
intrusion has not been significant since 1962, indicating that adequate
coastal water levels have been maintained in the aquifer. As water
demands increase in the future, however, sea-water intrusion may again
become significant unless more water is furnished from interior storage
areas, especially during dry periods.

The major long-established municipal well fields are located along
the coastal ridge but at sufficient distances from the coast and upstream
from water-control structures to be protected from sea-water intrusion.
Figure 37 shows the locations of and daily pumping rates in the large
municipal well fields in southeastern Florida in late 1970 and their
locations with respect to the area affected by sea-water intrusion. Most
fields are located upstream from the control structures in canals to
facilitate infiltration of fresh water from the canals. Infiltration from
the canals to the well fields minimizes drawdown caused by pumping,
thereby reducing the possibility of inland gradients and salt-water intru-
sion in the vicinity of the well fields.

Because of the critical hydrologic conditions in the vicinity of
the major well fields and the past experiences of sea-water intrusion in
well fields of Miami and Fort Lauderdale, intensive investigations of
large well fields have continued for more than 20 years. Analyses of
hydrologic conditions in well fields before and after water control and
management indicate their effectiveness. -

MIAMI MUNICIPAL WELL FIELDS
The Miami municipal well field, adjacent to the Miami Canal at
Miami Springs (fig. 37) was placed into service in 1925 and yielded
water of low chloride content until April 1939, when wells near the
Miami Canal began to yield salty water (Parker, Ferguson, Love and
others, 1955, p. 691). The source was salty water that had moved up-
stream in the uncontrolled canal to the vicinity of the well field and had
infiltrated laterally through the aquifer. Contamination in the field







REPORT OF INVESTIGATION NO. 60


EXPLANATION

--i
EXTENT OF SEA-WATER INTRUSION
AT BASE OF AQUIFER

MAJOR WELL FIELD PUMPAGE
MILLION GALLONS PER DAY


Figure 37.: Map of Florida's lower, east coast showing the major well
fields and their pumping rates in million gallons per day
near the: end of 1970; and the extent of seawater encroach-
ment at:the:base of the Biscayne arieuer-






BUREAU OF GEOLOGY


Figure 38. Map of the Miami well field showing water levels and
chloride conditions June 29, 1945 during uncontrolled con-
ditions of Miami Canal
remained a problem through 1945. The contour map in figure 38 shows
water-level and chloride conditions in the well field on June 29, 1945,
the end of a prolonged drought. The highest water level in the well-
field area was 0.4 foot above mean sea level, and the hydraulic gradient
was inland and toward the centers of pumping, where water levels were
nearly 3 feet below sea level. The pattern of the choloride lines shows
that tongues of salty water had moved up the uncontrolled Miami Canal
and had infiltrated vertically into the aquifer and laterally toward the
areas of greatest water-level drawdown. Pumpage in the well field at
the time was 30 mgd.
In 1946 a control structure of sheet steel piles was built in the Miami
Canal at N. W. 36th Street to prevent the inland movement of salt water.
During the rainy seasons the control was opened to permit discharge of
surplus water, but after the flood seasons the control was closed to pre-
vent overdrainage and excessive lowering of water levels. As a result,
water levels in the well field were maintained at higher levels during dry
seasons, and the areas contaminated by salt water were gradually fresh-
ened.


I ,






REPORT OF INVESTIGATION NO. 60


Figure 39. Map of the Miami well field showing water levels and
chloride conditions April 7, 1966 during controlled condi-
tions of Miami Canal

Figure 39 is another contour map of the Miami well field area that
shows water-level and chloride conditions during the dry season of
1966, so that comparison can be made with the uncontrolled condition
in 1945. Pumpage in the well field during the dry season of 1966 was
80 mgd, the control structure at N. W. 36th Street was closed, and a
water level of 2 feet above mean sea level was being maintained along
the controlled reach of the canal. The contours show that the canal was
replenishing the well field by downward and lateral infiltration into the
aquifer. A general appraisal shows that as a result of the general rise
in water level at the control structure, pumpage of 80 mgd in 1966 pro-
duced about the same minimum water level in the withdrawal centers
as pumpage of 30 mgd in June 1945. Also, under the 1966 condition,
sea water was not intruding the aquifer. Sea water did intrude in 1945.
In 1968 additional supply wells on the north side of the Miami
Canal were added to the municipal system, thereby increasing the
capacity of the well field from 80 to 130 mgd. Planned modifications





BUREAU OF GEOLOGY


and additions to the northwest will boost the yield of the well field to
more than 200 mgd in the next few years. As long as adequate quantities
of water are available by eastward seepage or by releases from Con-
servation Area 3 into the upper reach of the Miami Canal to maintain
adequate fresh water levels at the 36th Street control structure, the well
field is expected to yield its capacity without significant inland advance
of salt water in the Miami Canal basin. However, the threat of sea-water
intrusion to the well field also persists from the south, from the pre-
sently uncontrolled reach of the Tamiami Canal. If no further lowering
of water levels occurs in the southern part of the well field, the salt
water there should not advance toward the well field. A permanent
control structure, to be provided by a recent (1969) decision, in the
Tamiami Canal near its confluence with the Miami Canal should give
further protection to the well field.
Because the permanence of the well field depends upon replenish-
ment from the inland part of the basin and from the water conservation
areas during drought, management of the water in the Miami Canal
basin during future years will be a key to the protection of the well field.
Water-level contour maps, such as the map of May 1962 (fig 30),
that depict hydrologic conditions in Dade County at the end of pro-
longed droughts, show characteristic low levels and a nearly flat hydrau-
lic gradient in the northern part of the county from the levee eastward
to the coast, about 15 miles. The low gradient is the result of effective
drainage by the primary canals and the extensive network of secondary
canals connected to the Miami and Snake Creek canals, as shown in
figure 30. Water levels are regulated by a single control near the coast
in each of the primary canals.
To minimize flooding in low lying residential areas along the
coastal ridge, it is necessary to reduce water levels in inland areas there-
by reducing the amount of water in aquifer storage available for use
during the dry seasons and partly negating the replenishment bene-
fits of rainfall. For several years this method of water control served
the basic needs of flood control and the stabilization of sea-water intru-
sion; however, the practices have resulted in progressively greater
reliance on water in the conservation areas each year as the source of
aquifer replenishment in the coastal area during dry seasons. The rate
at which municipal needs are increasing suggests that in the near future,
replenishment from the conservation areas by itself might not be ade-
quate to fulfill all demands required to protect the water resources
during prolonged drought.
The Alexander Orr-Southwest well-field complex of Miami was
placed into operation in the early 1950's, when moderate quantities of





REPORT OF INVESTIGATION NO. 60


Figure 40. Maps of the Alexander Orr and Southwest well field areas
of the City of Miami showing water-level conditions March
21, 1951 (A) and May 24, 1962 (B) (from Sherwood and
Leach, 1962, fig. 17 and Sherwood and Klein, 1963, Fig. 8)






BUREAU OF GEOLOGY


water were pumped from a cluster of wells about half a mile north of
the Snapper Creek Canal (Canal 2). Figure 40A shows the small cone
of depression in the water table that formed as a result of moderate pump-
ing of 6.7 mgd (Sherwood and Leach, 1962, fig. 17) on March 21, 1951,
during the dry season. That cluster of wells (Orr well field) served the
growing urban area south of Miami; but, because of rapidly increasing
demands during the late 1950's, additional high-capacity wells south of
the canal and 4 miles west of the original cluster were placed into opera-
tion. The well field to the west, the Southwest well. field, comprised 6
wells each capable of pumping 10 mgd. The Southwest field was the
primary source, and the Orr well field was used as a reserve to make up
peak demands during the tourist season and prolonged droughts. How-
ever, after Klein (1958) indicated that the Orr reserve field could be
pumped at capacity safely on a permanent basis, the bulk of the with-
drawals for the increased demands south of Miami was shifted to the
Orr well field, and the Southwest field was placed on reserve status.
The effect of heavy municipal pumping in the Orr field, 42 mgd, and
in the Southwest field, 28 mgd, near the end of a prolonged drought in
May 1962 is shown in figure 40B (Sherwood and Klein, 1963, fig. 8).

Since 1962 the capacity of the Orr field has been increased to 60
mgd (10 wells), and plans call for maximum withdrawal of about 300
mgd from the Southwest well field. These quantities can be withdrawn
from that area because of the following safety factors related to the
Snapper Creek Canal system: (1) The canal extends westward and
northward connecting with the Tamiami Canal, which, in turn, extends
to Conservation Area 3, thereby assuring a source of replenishment to
the canal for maintaining high levels at the coastal control structure and
for infiltration to the well field; (2) the coastal control structure has been
efficient, and loss of water is minimal during dry seasons (Kohout and
Hartwell, 1967, p. 40-42); and (3) because the spur canal east of the
Orr field (fig. 40) is connected to the Snapper Creek Canal, its water
level is the same as that of the Snapper Creek Canal and, therefore, it
is a source of aquifer replenishment, which minimizes the eastward
expansion of the cone of depression formed by well-field pumping and
stabilizes the movement of salt water in the aquifer between the well
field and the coast. Water-level measurements in the Orr-Southwest
well-field area in dry seasons during 1966-68 indicated that when pump-
ing was increased to 65 mgd the cone was deepened only by about 1 foot.

FORT LAUDERDALE WELL FIELDS
Some of the more marked hydrologic changes over the years have
occurred in the Prospect well-field area of Fort Lauderdale, located
between the Pompano Canal (Canal 14) and the Middle River Canal






REPORT OF INVESTIGATION NO. 60


Figure 41. Map of southeastern Broward County showing water-level
conditions February 15, 1941 (adapted from Sherwood,
1959, fig. 9)


(Canal 13). Sherwood (1959, fig. 9) mapped water levels in eastern
Broward County in 1941 before intensive drainage and urbanization
and before establishment of the Prospect well field. Those early levels
are shown in figure 41 so that comparisons can be made with levels
after development. The Prospect well field was placed in operation






BUREAU OF GEOLOGY


Figure 42. Map of the Oakland Park area of Broward County showing
water-level conditions in the Prospect well field August 7,
1956 (from Sherwood, 1959, fig. 11). The total pumpage for
the Prospect well field was 7 mgd




about 1955 when Fort Lauderdale was experiencing its greatest growth
rate. Figure 42 (Sherwood, 1958, fig. 11) shows the effect that canal
drainage and pumping the original 10 municipal wells at more than 7
mgd had on water levels in that area in 1956. This map, when compared
with that of figure 41 for 1941, and that of figure 43 for 1968, indicates
the large changes in water levels and water-table configuration that
resulted over the years as a result of increases in withdrawals, changes
in the pattern of pumping, and changes in canal systems and control
structures. The pumping rates that produced the cones in figure 43 were
30 mgd from the supply wells and 5 mgd from the rock pit in the western
part of the field.






REPORT OF INVESTIGATION NO. 60


Figure 43. Map of the Oakland Park area of Broward County show-
ing water-level conditions in the Prospect well field April
18, 1968 (map prepared by H. J. McCoy). The Pumpage
from the Prospect well field was 30 mgd and the western
rock pit was 5 mgd


The Prospect well field has had a history of sea-water intrusion
(Sherwood and Grantham, 1966) in its southern part; however, structures
to combat the intrusion are scheduled for completion in the near future.
These structures include a feeder canal (fig. 43), which will connect with
the Middle River Canal upstream from the control structure (Sherwood
and Klein, 1963, fig. 4). The purpose of the connection is to increase
replenishment to the well field, and, because the feeder canal will be
controlled at a point seaward of the well field, water levels in the area
formerly intruded by sea water will be raised, thereby retarding further
inland movement of salt water.
Other municipal well fields of large capacities are shown in figure






BUREAU OF GEOLOGY


37. The map indicates the pumping rate of each of the well fields in
November 1970 and shows the position of each field in relation to the
inland extent of water containing 1,000 mg/1 (milligrams per liter)
chloride near the base of the Biscayne aquifer. In addition, other smaller
municipal well fields and many supplies for individual housing develop-
ments, not shown in figure 37, are scattered throughout the lower east
coast.
The capability of maintaining high water levels along the eastern
perimeter of the Lake Worth Drainage District in eastern Palm Beach
County (fig. 46 for location) during dry seasons through water-control
practices, insures that a dependable source of replenishment will be avail-
able to the shallow aquifers along the urban coastal area and that ground-
water levels sufficient to retard sea-water intrusion can be maintained.
Municipal well fields along the 30-mile coastal strip from Boca Raton
northward to West Palm Beach, therefore, have a built-in system of
ground-water replenishment, whereby the water-control practices that
benefit agriculture in the inland area offer concurrent benefits to the
expanding urban areas. So long as water-management practices in the
area remain effective and the quality of the water that replenishes the
shallow aquifer remains acceptable, the ground-water supplies should
be sufficient for future needs.
A large part of the water released from Conservation Areas 1 and
2 into primary canals in Palm Beach and Broward counties is channeled
into equalizer and lateral canals to maintain water levels for irrigation
in the Lake Worth Drainage District and other agricultural districts
bordering the eastern Everglades. The water-level map in figure 44
(McCoy and Hardee, 1970, fig. 14) shows the effect that maintaining
water levels in canals in the southern part of the Lake Worth Drainage
District (area west of Canal E-3) has on ground water in the Boca Raton
area. On April 12, 1967, near the end of the dry season, the water level
in Canal E-3, was about 10 feet above sea level, and water from the
canal was seeping eastward under a high gradient. The contours show
that the eastward seepage in the southern part of Boca Raton was being
discharged into the uncontrolled reach of the Hillsboro Canal and El
Rio Canal, whereas the seepage in the northern part of the city was being
discharged to the controlled reach of El Rio Canal (above the control
structure), and part of that seepage was being diverted toward the pump-
ing wells in the well field.
The rate of eastward seepage from Canal E-3 depends in part
upon the permeability of the shallow water-bearing materials. The
quantity of seepage can be estimated by the equation: Q=TIL, where Q
is the quantity of seepage, in gallons per day, T is the transmissivity
of the aquifer, in gallons per day per foot, I is the hydraulic gradient,






REPORT OF INVESTIGATION NO. 60


Figure 44. Map of the Boca Raton area showing water-level contours
during the low water conditions of April 12, 1967 (from
McCoy and Hardee, 1970, fig. 14)

in feet per foot, and L is the length of the flow section in feet. McCoy
and Hardee, (1969, p. 25) determined that the transmissivity of the
shallow aquifer west of Boca Raton is about 380,000 gpd/ft. Substi-
tuting that value in the equation and inserting the water-table gradient
that prevailed east of Canal E-3 on April 12, 1967 (7 feet in 11,000
feet) it was determined that the rate of eastward underflow along the
5-mile section between Canal L-38 and Canal L-47 was 6.4 mgd near
the end of the dry season of-1967.






BUREAU OF GEOLOGY


Schroeder and others (1954, p. 11-14) determined that the trans-
missivity of the shallow aquifer in Delray Beach to the north is apprec-
iably less than in the area of Boca Raton, indicating that the ability of
the shallow aquifer to transmit water decreases northward from Boca
Raton. Therefore, eastward seepage from the Lake Worth Drainage
District probably is proportionately less in the north than it is in the
south, and the yield of wells is smaller in the north.
The annual quantity of fresh water discharged to tidewater by the
West Palm Beach Canal represents excess water within the drainage
basin under management operations. Figure 45 graphically relates be-
tween the average discharge to the ocean of the West Palm Beach Canal
and the average rainfall measured at Loxahatchee and the West Palm
Beach Airport. The discharge ranged from about 220 cfs in 1956 to
more than 1500 cfs in 1947 and 1948. It is apparent from the graph of
the discharge, that a reduction of total flow to the ocean occurred after
1955, when Pumping Station 5A began operation. The graph also
shows that the increment of flow brought in by agricultural and drainage
canals and by ground-water inseepage along the 20-mile reach east of
the pumping station constitutes a significant part of the total canal flow.

Even during years of deficient rainfall, such as 1955-56 and 1961-
63, some discharge to the ocean took place. The discharge from the
West Palm Beach Canal also represents a part of the fresh-water poten-
tial of the basin and is the quantity of water that can be used for munici-
pal and other purposes without causing further decrease of fresh water
in storage under present conditions. As water requirements increase
with time, water-management practices will be directed toward incre-
mental decreases in discharge of the West Palm Beach Canal and the
probable increase in utilization of Lake Okeechobee and Conserva-
tion Area 1 for water storage and delay of runoff by backpumping.


THE COURSE AND COMPROMISES OF
FUTURE WATER DEVELOPMENT

Earlier parts of this report describe the sequence and nature of
past water-development works and how each has altered the manner
in which water occurs, moves, is stored and released, is lost to the at-
mosphere, is utilized by man, and is disposed. Increasing water require-
ments will require new works and further changes in hydrologic pat-
terns. As with existing canals, control works, levees, pumps, well fields,
treatment plants, and pipe lines, each new facility will be designed to
improve land use and (or) make greater quantities of water of adequate
quality available in certain areas during drought. Many of the new facil-







REPORT OF INVESTIGATION NO. 60 81


ities, iri addition, will be placed or designed with a new purpose: that
of protecting or enhancing the environment.
The design and location of many of the new facilities will be dif-
ficult. Greater water storage for dry periods often is accomplished only
at some sacrifice to land use. During extreme drought the competition
for water among localities will be more severe. Public demands for
environmental protection will require allocation of water to sustain the
ecology in specified areas. New works interspersed with the older will
certainly add to the complexity of water management.
Successful location, design, and operation of facilities also will
require greater knowledge of the water system on which it is imposed
and will alter it to varying degrees. Hydrologic knowledge gained in
one water system may be utilized beneficially in considering further
works affecting another system.


AVERAGE FOR LOXAHATCHEE
AND WEST PALM BEACH AIRPORT
Un
S100-

o
-J
z. -



0
1941 45 50 55 60 65 1968


2500
o M PICKUP BETWEEN S-5E AND OCEAN
0
) 2000-
mU

a. 1500 = S-5E OPERATION BEGAN 1956
I.--









1941 45 50 55 60 65 1968
Figure 45. Graphs relating rainfall to the discharge of the West Palm
Beach Canal to the ocean, 1941-69. -Alsshown is the pickup
of flow in the canal reach below S-5E from 1956






BUREAU OF GEOLOGY


The primary purpose of this chapter is to relate previous experi-
ence with the hydrologic characteristics of water systems in south Flor-
ida to some of the alternatives for further water-development works.
No recommendations are made by the authors for or against specific
development works. Their only contribution is to report upon the hy-
drology of the present system and to predict the changes that may result
from various types and locations of new works under consideration.
Certain segments or features of actual development plans or pro-
posals for water-development works in particular locations have been
selected to illustrate the probable impact of specific works on water
systems.

DEVELOPMENTAL PLANS

Several plans of improvement for drainage and enhancement of
the water resource through careful management have been proposed
from time to time.

IMPLEMENTATION OF AREA B AND EAST
COAST BACKPUMPING PLANS

The plan by the Corps of Engineers (1958) for development of Area
B, the area east of the levee system in northern Dade and southern
Broward Counties (fig. 46), is basically a flood-control plan. Nonethe-
less, the plan for Area B ". will have considerable potential for
conservation of fresh water," (Kohout and Hartwell, 1967, p. 59). Back-
pumping to the conservation areas a part of the plan would reduce
canal discharge to the ocean. Some hydrologic effects of backpumping,
disregarding the quality of the backpumped water, would be as follows:
(1) reduction in amount and duration of wet-period discharge to the
ocean; (2) lowering of peak levels and an equalization of water levels
east of the levee system; (3) reduction of total runoff to the ocean; (4)
delay in water-level recession in the conservation areas; (5) early clos-
ing of coastal control structures; (6) ability to maintain proper water
levels at coastal structures for longer periods to retard sea-water intru-
sion; and (7) utilization of the aquifer system as a water-storage reser-
voir. Kohout and Hartwell (1967 p. 42) suggested the use of supple-
mental pumps (100-400 cfs capacity) at the west and east sides of Area
B and control structures in canals at the east side of Area B for flexi-
bility of water control during periods of intermediate water-level con-
ditions. They further suggested that when Conservation Area 3 is dry,
the east-side pumps would help maintain levels along the urban coast
by pumping seaward from the Area B canals.








REPORT OF INVESTIGATION NO. 60


-' u





4 -J


C-2

SIso Pmnpingstatio
30 .A




0 5 10bUE
I I I L


Figure 46. Map of southeastern Florida showing locations of the Area
A, Area B, and southwest Dade area in relation to the Cen-
tral and Southern Florida Flood Control District works






BUREAU OF GEOLOGY


During prolonged drought after urbanization is completed, it may
be necessary to pump water from aquifer storage west of the levee
system into the Area B canals to furnish water to the coastal area.
Possibly, pumping from aquifer storage west of Levee 30 could re-
place pumping from the east end of the Area B canals. The capacity
of the pumps would be adequate to sustain proper water levels at the
coastal control structures, most importantly the structures in the Snake
Creek, Miami, and the Snapper Creek canals. The quantities would
be equivalent to the normal losses by seepage around each structure
along the controlled easterly reach of each of these canals, about 40-
50 efs per canal, plus the quantities diverted from the canals by well
field withdrawals.

CONVEYANCE CANALS TO SOUTH DADE COUNTY
An area of perennial water deficiency is the south Dade County
area, where water levels approach or decline below sea level by the end


Figure 47. Map of the southern tip of Florida showing contours of
water-level conditions in May 1962, a near record low-
water condition






REPORT OF INVESTIGATION NO. 60


of each dry season, as shown in figure 47. The south Dade area is pro-
bably the most water deficient area in dry periods because it is at the
southern tip of the hydrologic system and is the most difficult area to
replenish. The plan proposed by the Corps of Engineers (1968) to
replenish south Dade County by means of conveyance canals connect-
ed to Conservation Area 3 would, if effected, reduce the rate of water-
level recession. Any water that can be shunted southward during pro-
longed drought will slow, or possibly stop, the recession in water levels,
even though evapotranspiration will increase. Hartwell and others
(1963) estimated that in May 1962, a near-record low-water period,
evapotranspiration within a 275-square-mile area of low water levels
in south Dade County was about 790 cfs (1,580 acre-feet per day).
The Corps of Engineers has indicated that a total of 1,400 cfs
(2,800 acre-feet per day) might be available for dry-season distribu-
tion to the south Dade area and the Everglades National Park and to
the eastern part of Dade County.
Replenishment from Conservation Area 3 through conveyance
canals to the south would be needed only during dry periods. Part of
the replenishment at other times might be lost to the ocean through
automatic operation of coastal control structures in the south Dade
canals. One proposed conveyance-canal route is southward along the
eastern boundary of the Everglades National Park and then eastward
to the Levee 31 Canal, where water would be distributed northward,
eastward, and southward. (See fig. 1.) An alternate route might be
directly southward through the Levee 31 Canal, a part being diverted
eastward and part southward.
Water carried southward through the Levee 31 Canal would be
delivered directly to critical areas the coast of south Dade County
and the southern panhandle of the National Park. Because of the long
distance involved in moving water from the north end of Levee 31
Canal to the panhandle area, pumping facilities may be required to
assure replenishment to the southern terminus of the canal system.
Replenishment to the southern terminus also would raise water levels
in the U.S. Navy's Key West well field near Florida City. (See fig. 37
for location.)
Recharging the aquifer in south Dade appears to be of high pri-
ority. Therefore, early investigations may be warranted to determine
the effect that releases of water into the Levee 31 Canal might have on
canal levels and on ground-water levels to the south and southeast. If
results show that levels can be maintained in south Dade, consideration
could be given to utilizing the method eadh year until the subsequent
rainy season begins. Included also might be the possibility of ground-






BUREAU DF GEOLOGY


water pumping from Conservation Area 3B to Levee 31 canal when
low-water conditions in the South are prolonged.

SOUTHWEST DADE PLAN OF IMPROVEMENT
The southwest Dade plan of improvement (Corps of Engineers,
1963) proposes to pump water at 15 inches per month from the area
between Levee 31 and the eastern boundary of Everglades National
Park. (See fig. 46.) As a result of the pumping, water levels would be
lowered below the land surface far enough to permit preparation of
fields for farming by early November of each year. Under present con-
ditions most of that area normally remains inundated or swampy
through December.
Hull and Galliher (1970, fig. 8) showed that, even during low-
water conditions, water levels in the northern part of the southwest
Dade area are 4-6 feet above msl; and, therefore, that this area serves
as the source of part of the water replenishment for southeastern and
southern Dade County. Because the plan is designed to lower peak water
levels in the southwest Dade area, the lowering also would affect levels
in areas downgradient, to the east and the south.
Actually the improvement plan would accelerate runoff from the
southwest Dade area, in turn accelerating recession of water levels in
adjacent areas. Implementation of the completed south Dade flood-
control plan has already lowered peak levels in the lower east coastal and
southern parts of the county. Any additional lowering occasioned by
implementing the improvement plan would then be superimposed on
the previous lowering, thus facilitating the possibility of salt-water
encroachment.
Because the Southwest Dade plan is designed specifically to en-
hance agriculture, fertilizers and pesticides will be involved. Through
years of operation, pesticides could build up in the soils. As the plan
calls for pumping the excess water westward into the Everglades
National Park, the Park officials may choose to reject the excess water
if it proved to be detrimental to wildlife. No other outlet for the excess
water is provided for in the plan. On the other hand, if the pesticide con-
tent of the water proved to be harmless to wildlife, the Park officials
might accept the excess water as part of the annual release from the
water-conservation system. Then part of the water from the conser-
vation areas normally earmarked for discharge to the Park could be re-
tained in the Conservation Area 3 for later use.
Land-use studies in southeastern Florida have shown that much
land made suitable for agriculture through improved drainage has been
later converted to urban use. If this were to happen in Southwest Dade,







REPORT OF INVESTIGATION NO. 60


year-round flood protection, of course, would be required. The hydrolo-
gic effects of such urbanization would be an accelerated lowering of
levels to the east and south and an increase in seepage through and
under the levees southward from Conservation Area 3. A pre-urbanization
alternative to improved drainage would be filling the land to higher
elevations and installing related secondary and tertiary control structures
in canals to delay runoff.

LOWER EAST COAST AGRICULTURAL AREAS

The Central and Southern Florida Flood Control District is committed
to provide flood protection to the agricultural lands along the lower
east coast of Dade County, where the land surface is generally at an
altitude below 3 feet. Ground-water levels there must be maintained
below the land surface to prevent crop damage during the growing
season, which starts in October. The optimum canal level at the coastal
structures in canals 1, 102, and 103 is 1.4 feet above msl during the
growing season. In order to maintain that level during the early part of
the growing season, when water levels are usually high, the automatic
gates in the structures open and close repeatedly, depending upon the
rate of ground-water flow to the lower reaches. The operations for flood
and salinity control, which are necessary along the coast, constitute a
drain on the water resources of the interior, and the repeated operations
are decreased in frequency as water levels in the interior decline.

Continued growth in population suggests that agriculture along
the lower east coast may be gradually phased out in favor of urban
use of land. To accommodate urban expansion, the lower east coast
properties would have to be raised to elevations adequate for protection
against tidal inundations. At that time, the optimum water levels at the
coastal control structures could be raised to levels corresponding to
those in canals in urban areas to the north, 2.5 to 3 feet above msl. The
controls would be used to remove flood peaks, but they could be closed
earlier and kept closed during the entire dry season. As a result, much
of the water presently being lost during the early months of the dry season
could be retained in the Biscayne aquifer.

Raising ground-water levels behind control structures along the
coast will result in a decrease in water-table gradient within the control-
led sections of the Biscayne aquifer. In turn, this will moderate the
lowering of levels in the interior and thus reduce seepage southward
and southeastward from Conservation Area 3. An increase in levels along
the coast also could result in a seaward movement of the salt front in
the aquifer.






BUREAU OF GEOLOGY


With the demands for water increasing at unprecedented rates,
strict water management will be necessary to protect the water resource.
In the particular area of coastal Dade County, agriculture does not
seem to be hydrologically compatible with urban development. In other
agricultural areas, for example the Lake Worth Drainage District and
adjacent agricultural districts in Palm Beach and Broward Counties,
water control is beneficial because it insures that water levels will be
maintained at high levels, thereby furnishing constant replenishment
to the urban coastal strip.

ALTERNATIVES FOR FURTHER WATER DEVELOPMENT

Analysis of the hydrologic effects of water-develoment plans and
operation of the water-management system indicates that management
and control might be improved in the future. Accomplishing the improve-
ments involves operations, proposed plans for development works, and
long-range goals.
Experience in the operation of works shows that the levees and
the system of primary and secondary canals can adequately protect
most urban areas from flooding. As indicated previously, however, a
few areas in northern Broward and Palm Beach Counties are subject
to inundation locally during sustained heavy rainfall because of the low
permeability of the shallow sediments.

A major objective of water-resources planning agencies is to
conserve water resources, primarily by reducing or delaying runoff to
the ocean. Gradual reduction of canal discharge to the ocean is feasible
and can be accomplished in some places (1) by adjustments in timing
of control-structure operations, (2) by adding secondary control
structures-a feature that would also reduce the depth of water and
the time it remains in canals locally, (3) by raising optimum water-control
elevations in selected canals, and (4) by implementing plans for back-
pumping excess water into conservation areas. Net usable supplies
may also be increased by raising design levels in the surface reservoirs,
such as Lake Okeechobee and the conservation areas, without increasing
evapotranspiration.

REDUCTION OF LOSSES TO THE OCEAN
As urbanization continues, increased water requirements can be
met in part with water salvaged by reducing canal discharge to the
ocean, either by earlier control closings or by fewer releases of water
to the ocean. Whether such changes in control operations are possible
can be determined by monitoring and analysis of the results of the






REPORT OF INVESTIGATION NO. 60


operations and by review of past operations. Adjustments can then be
made in operations for optimum results.
The most vulnerable area in southeastern Florida during drought
is southern Dade County, because it is remote from any major surface
source of fresh-water replenishment. Therefore, careful water-manage-
ment practices will be required there to assure ample water for all
users during drought. A second vulnerable area is northern Dade County,
particularly the Miami Canal area, where sufficient water must be
retained to replenish the Miami well field and to maintain canal levels
to prevent encroachment of sea water into the Biscayne aquifer. Any
method that would delay the runoff from those two areas, such as
raising the optimum water levels at coastal and secondary control
structures in major canals at or before the end of the rainy season
would increase the water resource.
Increased flexibility in controlling runoff would, on a long-term
basis, reduce losses to the ocean and, hence, will probably become a
part of overall water-management plans. Flexibility can be gained in
several ways. A few ways that might be applicable, depending on location,
are as follows:
(1) Installation of additional secondary control structures: Such
structures might, to advantage, be placed on Snake Creek Canal, Miami
Canal, Snapper Canal, or Bird Road Canal. Of these, Snake Creek (C-9)
and Miami Canals (C-6) are equipped only with coastal salinity control
structures, so that the base level of their inland reaches is the same as
the coastal control; under these conditions, steep groundwater gradients
inland induce large water pickup to canals, causing water to move east-
ward to the coastal salinity control structures. Stepped-up levels by use
of secondary structures in both canals to raise water levels in inland
reaches would reduce hydraulic gradients to canals in inland reaches.
This reduction would delay runoff from upstream reaches and would
retain significant quantities of water in upbasin storage, over and above
quantities stored in canals and the aquifer upgradient from the single struc-
tures at the coast. The quantities salvaged would be the water retained
in the aquifer resulting from the higher level maintained behind the
secondary control structures plus the water contributed from Conser-
vation Area 3B and vicinity to the canal discharge that is lost in urban
flood protection under current operating conditions.
If secondary structures were to be placed on the two canals they
might be located-from a water-conservation standpoint-9 to 11
miles downstream from Levee 33 in the Snake Creek Canal and 7 to 8
miles downstream from the levee system in the Miami Canal. Those
locations may not be feasible physically, however, because of low
land elevations in parts of the canal reaches upgradient from these






BUREAU OF GEOLOGY


suggested sites. By installation of the secondary control structure in the
Miami Canal, water could be released as needed to replenish the Miami
well field and to maintain adequate levels in the canal at the 36th Street
control structure.
If a secondary control structure were to be constructed in the
Snapper Creek Canal, say, downstream from its confluence with the Bird
Road Canal (2 miles south of the Tamiami Canal), or in the Bird Road
Canal near its outlet, runoff from the interior part of the basin would
be delayed. Adjustments in control operations would permit releases to
replenish the Alexander Orr and Southwest well fields of Miami and to
maintain levels at the salinity-control structure near the coast. These
suggested controls should be effective because the Bird Road Canal and its
connections with the Tamiami Canal at 132nd Avenue and 157th Avenue
contribute a large percentage of the flow in the Snapper Creek Canal during
the dry season.
(2) Installation of tertiary controls. For example, if the Black
Creek Canal (Canal 1) could be regulated near its confluence with the
Levee 31 Canal, seepage into the northern reach of the Levee 31 Canal
would be reduced. Simultaneous with this, the reduced contribution
to the downstream reaches of the Black Creek Canal would result in
fewer operations of the automatic coastal structure (S-21) during
dry seasons.
(3) If a decision is made to construct a boat lock in the Miami
River downstream from the existing N.W. 36th street structure pro-
tective procedures could be devised to prevent excessive loss of water
from boat locks and to retard sea-water intrusion. Boggess (1970, fig. 7)
sampled water containing 250 mg/1 chloride at the bottom of the Caloo-
sahatchee River channel about 11 miles upstream from boat lock S-79
near Fort Myers at the end of the dry season of 1968. The source of
chloride was slugs of salty water from the tidal reach of the river that
moved upstream as a result of lockages.
Under conditions of inland low water and frequent boat lockages,
slugs of salt water could migrate upstream in the Miami Canal into
the area of influence of the Miami well field. Because the well field
depends heavily upon the Miami Canal for its replenishment, salt water
in the canal upstream from the 36th Street structure for an extended
period of time could be extremely damaging.
On the Tamiami Canal, where a boat lock is scheduled for
construction near its confluence with the Miami Canal, protective
devices and careful scheduling of lockages should assist in suppressing
sea-water intrusion. The main purpose of the lock on Tamiami Canal
would be to reduce the threat of salt-water intrusion on the south flank
of the Miami well field by retaining more fresh water in that part of the
Tamiami Canal basin than is being retained currently. That reach of the







REPORT OF INVESTIGATION NO. 60


canal through the basin has been uncontrolled in the past, and at times
salt water has moved inland to the downstream side of the control
structure at N.W. 67th Avenue. The effect of this lock, as far as
prevention of sea-water intrusion is concerned, would be negated if it
is not operated carefully. If restrictions on lockages cannot be imposed,
the control near 67th Avenue would need to be retained. If the control at
67th Avenue is abandoned and replaced by the downstream lock and
no lockage restrictions are imposed, water could be diverted southward
from the Miami Canal basin. Water levels in the vicinity of Miami's
municipal well field, thus, could decline excessively.
(4) Canal discharge to the ocean could be reduced by decreasing
the number of automatic operations of coastal control structures. At
the beginning of the growing season, October or early November,
particularly in the low coastal agricultural areas of south Dade County,
some discharge is necessary to keep water levels low enough to prepare
fields and to prevent crop damage by flooding. Water-level data indicate
that discharge may continue for several weeks into the dry season.
For example, continuous data collected in 1968 at coastal control structure
S-21 in Canal 1 show that the control was opened several times each day
during January 1 through mid-April, the dry season. The openings were
in response to the pickup of ground water from the interior part of the
Canal 1 basin. A large contribution of discharge to the coastal reach in
Canal 1 is the result of seepage around the secondary control structure
near U.S. Highway 1.
Decreasing the number of automatic operations would be easier
if seepage could be decreased. One way in which seepage could be
decreased would be to install an impermeable liner along the canal
upstream from the structure or possibly a grout curtain flanking the
structure.
Water-level contours prepared by Flood Control District person-
nel show that the bulk of the seepage occurs within 200-300 feet
upstream from the structure. Hence, an impermeable canal liner or
grout curtain there would lengthen the flow lines in the vicinity of the
structure, thereby decreasing the gradient. The resulting decrease in
the number of automatic operations at the coastal control structure
would delay the recession of water levels in the basin.
Consideration also might be given to impermeable canal liners up-
stream from other secondary control structures. The resulting water
levels in the upper reach would approximate those before canal con-
struction, but the peak levels would be reduced by operation of the
structures.
(5) Lowering ground-water levels unduly could be avoided to
minimize further loss. In past years, lowering water levels adjacent to






BUREAU OF GEOLOGY


the west edge of the coastal ridge has given strong impetus to the inland
expansion of urbanization. Adequate drainage made it possible to build
on areas of low altitude, thereby lowering the cost of preparing the
land for housing. Were it not for the effective drainage by the canal
systems and water diverted from the urban areas by the levees, much of
the area immediately west of the coastal ridge would have required
filling to raise land elevations which would have added to the cost of
the housing units. However, once the drainage system is in operation,
the houses built, and a residence environment established, floods, of
course, must be prevented. A result of urban expansion was the lower-.
ing of water levels along the ridge and the east edge of the Everglades.
It is to be expected that as expansion continues, pressure will be exerted
to continue with this pattern of drainage and water-level lowering.
To minimize further loss of water, particularly in inland areas where
water levels are normally high, minimum allowable land-surface
altitudes could be established at the highest levels practicable, perhaps in
combination with raising the altitude of the land by filling and back-
pumping excess water to conservation-area storage.
Locally, where land altitude is low, as in the Miami, the Little River
and the Biscayne Canal basins and parts of southern Broward County,
the rainy seasons are chronically troublesome because these areas are
prone to flooding. As some of the houses in those low areas were built
before the establishment of minimum elevation standards, below
which construction is not considered advisable, the control structures
must be operated in such a way that these older houses are protected.
Water levels in much of the basin areas, thus, are lower than they need
be, consistent with effective management practice.

MAINTAINING WATER QUALITY
Two major problems of water quality confront the water-manage-
ment agencies of southeastern Florida. One problem, long standing
contamination resulting from sea-water intrusion, will continue to
threaten water resources as water needs increase. The protection of all
well fields from sea-water intrusion is essential. The other problem,
pollution, is emerging and may become a great threat as urbanization
continues, with its concurrent demand for water and waste-water systems.
Fort Lauderdale plans to increase withdrawals from its Prospect
well field between the Pompano Canal and the Middle River Canal. This
well field's history of sea-water intrusion is well known (Sherwood, 1959,
p. 26). Because of intrusion, any further expansion would be safer in the
southern part of the well field, in the vicinity of the Middle River Canal
and west of the salinity-control structure, S-36. There, the upper part of
the aquifer is permeable, facilitating artificial recharge from the canal







REPORT OF INVESTIGATION NO. 60


by infiltration of fresh water when the wells are pumped. By developing
this part of the field, drawdown would be minimized as a result of
infiltration from the canal, and the possibility of further sea-water
intrusion would be reduced. Sufficient water for induced recharge to
the well field from the Middle River Canal would probably be available
were the canal to be extended into Conservation Area 2. By so extending
the canal to Area 2, not only would a supplemental supply from Conser-
vation Area 2 be available, but the canal would tap, and partly drain,
shallow ground-water bodies in the intervening reach.
The capacity of Fort Lauderdale's Dixie well field between the
North New River Canal and the Plantation Canal (C-12), is small. Be-
cause of its proximity to the uncontrolled salt-water reach of the North
New River Canal, heavy pumping of the field would lower water levels
between the well field and the canal during the dry season and would
induce recharge of salt water. Extension of a connector canal from the
controlled reach of the Middle River Canal to the Plantation Canal
would raise the stage in both canals and, as a result, would raise ground-
water levels in the northern part of the Dixie well field. The fresh-
water recharge would permit greater withdrawal of water.
The southern part of the Dixie well field, however, will continue
to be subject to sea-water intrusion from the North New River Canal
during extreme drought, and, therefore, increased withdrawals in that
part of the field is not likely. Grantham and Sherwood (1968, fig. 15)
show that the chloride content of water in the North New River Canal
increases markedly below the salinity-control structure (Sewell Lock)
when discharge through the structure declines below 50 cfs for several
weeks. Because water-management practices in the future will tend to
reduce discharge to the ocean, water below the structure for long periods
would have high chloride content. This would increase the threat of
intrusion of salt water into the shallow aquifer underlying the southern
part of the well field. A control structure placed in the canal downstream
from the area of influence of the well field might, however, tend to
alleviate the threat.
The problem of sea-water intrusion in the Hollywood Canal basin
(C-10) in southern Broward County will intensify as the area continues
to be drained and pumping increases from the Hollywood municipal
well field. Municipal wells in the Dania well field in the vicinity of the
canal have begun to show salt-water contamination from the canal, and
plans are underway to move the field farther from the canal. Saltwater
contamination also may threaten the Hollywood well field adjacent to
the Hollywood Canal, about 3 miles upstream from its confluence with
Canal 11. Drainage by the Hollywood Canal is uncontrolled, water levels
are perennially low, and, thus, the possibility of salt-water intrusion






BUREAU OF GEOLOGY


would be enhanced by major increases in withdrawals from Dania and
Hollywood municipal well fields.
The western spur of the Hollywood Canal is being extended inland
to improve local drainage for additional housing. The spur is to be
controlled, but the structure will prevent only the westward movement
of salt water in the channel. Because the spur canal will be dead-
ended and will have no perennial source of replenishment, a head of
fresh water cannot be maintained on the upstream side of the control
structure during the dry season to prevent salt-water intrusion into the
aquifer. A connection between the upstream end of the spur canal with
one of the primary canals, possibly the Snake Creek Canal, would
furnish a source of replenishment to the controlled reach of the spur,
thereby raising and maintaining a higher water level in the area. A
secondary control structure may be required along the connecting
canal. General resultant benefits would be stabilizing of the salt front
in the aquifer and raising average water levels in the Hollywood well
field, where withdrawals are steadily increasing.
A rapidly developing problem in the urbanizing areas and probably
the most critical problem to be faced in the future is the disposal of
sewage, storm runoff, and other wastes. Agencies involved in waste
disposal and pollution control seem oriented at the present time toward
discharge of treated wastes to ocean outfalls, but, as discharge to the
ocean involves the outflow of the resource from the area of potential
use, the orientation may change in the future.
If anticipated large future water demands (table 3) are to be
satisfied, it may become necessary to retain increasing quantities of
storm runoff and properly treated sewage instead of discharging
them to the ocean.
At the end of 1968 nearly 400 million gallons per month of partly
treated effluent was being discharged into the controlled reaches of
four major canals in Dade County. The effluent represents recharge to
the system because it not only enters the aquifer for reuse but helps
in maintaining water levels at the coastal control structures, thereby
aiding the control of sea-water intrusion into the aquifer. In the future,
the effluent will be treated to meet water quality standards for potable
water supplies, particularly during dry seasons, because then canals
do not discharge to the ocean, and controlled reaches of major canals
are the source of recharge to municipal well fields and other water
supplies along the coastal ridge.
Before sewer systems are installed in areas presently served by
septic tanks, the impact of this alternative on the total available fresh-
water supply should be evaluated. The largest concentration of septic







REPORT OF INVESTIGATION NO. 60


tanks in southeast Florida is in Dade County, where large areas have
been served by septic tanks for years. Suburban developments in
Broward and Palm Beach Counties have, of necessity, relied chiefly upon
treatment plants rather than septic tanks because in many areas water
levels were near the land surface, and the permeability of the shallow
sediments is lower than in Dade County.
Other potential pollutants to the water resource are mainly related
to application of fertilizers and pesticides for agricultural activities
and sanitary landfills. The urban lower east coast differs from many
urban areas in that it comprises scattered centers of populations, and
there are few massive paved areas to restrict infiltration of rainfall to
the aquifer. Residents take pride in the appearance of their homes, and
each home has a well-kept lawn and shrubbery requiring continuous
maintenance. So the city dweller regularly uses fertilizers and pesticides
and irrigates at regular intervals. A variety of fertilizers and pesticides,
therefore, may infiltrate to the aquifer. Water in many of the canals
and the water-storage areas represents, in part, drainage from agricul-
tural lands, including pastures and dairies. The drainage water probably
contains organisms and dissolved chemicals derived from the agricultural
operations, and the situation is unevaluated but potentially
hazardous.

Pesticide and nutrient buildups, generally in nontoxic concentra-
tions, are beginning to appear in some of the canal water, surface-water
bodies, and bottom sediments in Palm Beach and Broward Counties and
in the Everglades National Park. Fortunately, excessive buildup seems to
be minimized by the annual flushing each rainy season. With implemen-
tation of water-conservation plans and reduction of discharge through
canals to the ocean, however, further buildup could be expected in the
controlled canal reaches and in the major water-storage areas.

Of special interest would be the canals, streams, or lakes from which
a few of the municipalities obtain water supplies, such as West Palm Beach
from Clear Lake, immediately inland from the city, and Ft. Myers (on
the Gulf Coast) from the controlled reach of the Caloosahatchee River.
Each source has a potential problem of pesticides, nutrients, and build-
up of dissolved minerals. Urbanization is expanding inland from West
Palm Beach and soon could envelop Clear Lake unless zoning laws prevent
it. If residences were to surround the lake, runoff water could carry
undesirable amounts of nutrients into the lake. Although there is some
mixing of water within the lake, relative stagnation would be expected
during prolonged drought, and pollutants may accumulate to excess
periodically. Monitoring hazardous water constituents not only in
urban areas but also in major canals that traverse agricultural areas and






BUREAU OF GEOLOGY


urban areas and which contribute water to well fields could serve as
an early-warning system.

Contaminants leached from sanitary landfills pose a lesser problem
to potable water supplies at the present time than pesticides and nutrients
because the landfills are small, widely scattered, and are generally some
distance from well fields. No information is available concerning the
occurrence of pollutants in the Biscayne aquifer caused by leaching of
landfills, but the variety of materials deposited in landfills is great
and represents a potential hazard.

SUMMARY

During the early years of development in southeastern Florida,
emphasis was placed on drainage and flood-control works to accommo-
date rapid urbanization and also agriculture. The installation and oper-
ation of these works to prevent flooding lowered water levels in large
areas by facilitating the rapid removal of water from inland areas. By
1962, most of the major works of a complex system of canals, levees,
pump stations, control structures, and water-conservation areas was
completed. As a result, large quantities of water were discharged through
canals to the ocean. The severe drought of 1961-65, together with
increasing water demands and a renewed threat of sea-water intrusion,
shifted the emphasis to curtailment of canal discharge to the ocean and
increased management of water resources.

The hydrology of southeastern Florida was affected significantly
before 1945, when land drainage and reclamation was a principal
objective. The prime effect was a lowering of water levels along the
coastal ridge and in the interior as a result of: (1) completion of several
coastal drainage canals along the urbanizing coastal ridge to provide dry
land for housing developments; (2) completion of the West Palm Beach,
the Hillsboro, the North New River, and the Miami canals, which inter-
cepted or diverted water from the Everglades to the ocean; (3) construc-
tion of the levee on the south shore of Lake Okeechobee, which prevented
southward spillage from the lake during the hurricane season.

Adequate hydrologic data for the early 1900's are lacking, but
estimates indicate that water levels were lowered generally 5 or 6 feet
throughout southeastern Florida as a result of uncontrolled drainage. An
adverse hydrologic effect was intrusion of sea water into canals and the
shallow Biscayne aquifer along the coast. Sea-water intrusion contamin-
ated Miami's main well field in the Hialeah-Miami .Springs area during
the drought in 1945.






REPORT OF INVESTIGATION NO. 60


The initial work of the Central and Southern Florida Flood Control
District, established in 1949 after the disastrous flood of 1947, was the
construction in 1953 of the levee system along the east edge of the conser-
vation areas, which prevented the eastward flow of flood water from the
Everglades. Construction continued on an intermittent basis through
1962. By then, the three water conservation areas were enclosed by
levees except the west part of Conservation Area 3. Most major canals
were equipped with modern gated control structures, the system of
interior pumping stations and spillways was built and became operation-
al, and large agricultural acreage was opened south of Lake Okeechobee.
The period 1946-62 was one of water control as well as flood con-
trol. The water-control practices were an attempt to prevent further
damage to water resources caused by the earlier uncontrolled drainage.
Flood control was of higher priority because urban areas were expanding
inland, and drainage systems had to be improved. Control structures were
built in all major canals to allow the expeditious discharge of large
quantities of water during the rainy season and to retain fresh water in
the canals and aquifer upgradient from controls during the dry season.
The control structures also effectively halted the intrusion of sea water
despite the fact that water use by municipalities and for irrigation
increased several fold during 1946-62.
Analysis of data collected during the flood-control and water-control
phase (1946-62) shows that hydrologic conditions were more favor-
able than during the period of land reclamation. Personnel guiding the
operations became increasingly cognizant of the different water-condi-
tion requirements of the several interests, and operations became
more efficient. The increased need for water conservation, particularly
the reduction of canal discharge to the ocean, became apparent after
the occurrence of regionally low water levels during 1955-56 and 1961-
65. The ability of the system to cope with flood problems was demon-
strated during the extremely wet years of 1957-60, when no appreciable
flooding occurred. The exception was in southern Dade County, where
the system was inadequate for Hurricane Donna in 1960. Flood control
in south Dade County has since been provided.
The major effects upon the hydrology during 1946-62 were:
(1) A southward diversion of some of the flows that previously had
moved eastward through the transverse glades by construction of
the east coast levee system.
(2) A marked reduction in discharge to the ocean by the West Palm
Beach, the Hillsboro, and the North New River canals. The first reduction
occurred in 1953 with the completion of the eastern levee- system. The
second reduction occurred in 1958, when most of the pumping stations






BUREAU OF GEOLOGY


and spillways in the conservation areas were completed. The total
reduction in discharge to the ocean from the three canals was about
294,600 acre-feet per year, or an average salvage of 25 percent of
previous total flow to the ocean.
(3) Modification of flow through the Everglades after enclosure of
Conservation Areas 1 and 2 and completion of the protective system of
levees encircling the agricultural areas southeast of Lake Okeechobee.
Establishment of Conservation Areas 1 and 2 and the Everglades agricul-
tural area has modified the natural Everglades drainage basin.
(4) Initially, a large decrease in coastal canal discharge occurred,
as compared with pre-1946, as a result of operation of coastal control
structures; subsequently, the discharge gradually increased in Dade
County and part of Broward County as a result of expanded urbanization
and the need to drain land for housing in inland areas. Overall, discharge
decreased as compared with the earlier period.
(5) Delay in recession of water levels during the dry season in
conservation areas as a result of pumping part of the surplus water
salvaged by decreased canal discharge into conservation areas.
(6) Increase in gradient between the conservation areas and areas
immediately east of the levee system as a result of lowering peak levels
in urban areas. Increased reliance was placed on the conservation areas
for replenishment of ground water in urban areas during the dry season.
(7) An increase in the rate of recession of water levels along the
coastal ridge and vicinity after the rainy seasons, as a result of improved
canal systems and their inland extension to the levees.
(8) Lowering of annual peak water levels for flood protection on the
coastal ridge and vicinity, as a result of regulated openings of con-
trol structures in the improved canal system, which permitted rapid
discharge to the sea.
(9) Raising of annual low water levels along the coast, chiefly in
areas adjacent to control structures, as a result of closed control struc-
tures and ground-water pickup by canals from inland reaches.
(10) Decrease in water-table gradient throughout the coastal ridge
and vicinity.
(11) Stabilization of the salt front in the aquifer, as a result of the
rise in minimum water levels along the coast, enabled large increases
in municipal withdrawals without further threat of salt-water intrusion.
By the end of 1962, Conservation Area 3 was enclosed on the south
side, and, for the first time, flow through most of the Everglades could
be regulated. The enclosure marked the beginning of the capability for






REPORT OF INVESTIGATION NO. 60


nearly complete management of the water resources within the flood-
control project from Lake Okeechobee southward.
The year 1962 also marked the beginning of a system of controlled
canals in south Dade County designed to protect that area from recur-
rence of floods of the magnitude of those of 1947-48 and 1960. The
canal system was nearly completed and operational by the end of 1967.
The most pronounced effects of the south Dade canals were the lower-
ing of annual peak water levels and faster water-level recession after
storms except in coastal areas. The movement of water from the inland
area to the coast through the canals raised levels along the coast and
helped prevent seawater intrusion.
Water management since 1962 has been highly effective, and works
in progress, particularly those related to water conservation, should
increase its effectiveness. Owing to a prolonged period of low rainfall,
which began after Hurricane Donna in the fall of 1960, surplus water
was not available to manage until 1966, a year of above-normal rain-
fall. Sufficient water was retained in the flood-control system during
the months following that rainy season to permit both major releases
to the Everglades National Park throughout the subsequent dry season
and maintenance of adequate water levels along the coast. The southeast
coast was the only area in Florida that did not have critically low water
levels during the nearly rainless winter and spring of 1966-67.
The new canal system in south Dade County was dramatically
tested at the beginning of the rainy season of 1968 when flooding was
avoided despite more than 32 inches of rain which fell during May and
part of June. Heavy flood damage might have resulted without the
new canal system.
Water management should become even more effective with the
completion of canals capable of moving excess water from Lake Okeecho-
bee through the conservation areas to the south end of the system and
to the Everglades National Park. Raising the level of Lake Okeechobee
in future years would increase the water supply to provide for more
demand. In addition, implementing plans for backpumping of excess
water to the conservation areas would further increase the quantity of
water available, but not necessarily its quality.






BUREAU OF GEOLOGY


REFERENCES


Appel, C. A.
1969 (and Klein) Hydrologic data related to establishment of a
pumping station in the Everglades National Park, Florida:
U. S. Geol. Survey open-file report.

Cohen, P.
1968 (Frankee, O. L. and Foxworthy, B. L.) An atlas of Long Is-
land's water resource: New York Water Resources Commis-
sion, Bull. 62.

Hartwell, J. H.
196:3 (Klein, Howard, and Joyner, B. F.) Preliminary evaluation
of hydrologic situation in Everglades National Park: U. S.
Geol. Survey open-file report.

Klein, Howard
1958 Expansion of permanent water-supply facilities for the City
of Miami, Florida: U. S. Geol. Survey open-file report.

Klein, Howard
1961 (and Sherwood, C. B.) Hydrologic conditions in the vicinity
of Levee 30, Northern Dade County, Florida: Florida Geol.
Survey, Rept. Inv. 24, pt. 1.

Kohout, F. A.
1964 (and Leach, S. D.) Salt-water movement caused by control-
dam operation in the Snake Creek Canal, Miami, Florida:
Florida Geol. Survey, Rept. Inv. 24, pt. 4.

Kohout, F. A.
1967 (and Hartwell, J. H.) Hydrologic effects of Area B flood con-
trol plan on urbanization of Dade County, Florida: Florida
Geol. Survey, Rept. Inv. 47.

Leach, S. D.
1966 (and Grantham, R. G.) Salt-water study of the Miami River
and its tributaries, Dade County, Florida: Florida Geol.
Survey, Rept. Inv. 45.

Leach, S. D.
1963 (and Sherwood, C. B.) Hydrologic studies in the Snake Creek
Canal area, Dade County, Florida: Florida Geol. Survey,
Rept. Inv. 24, pt. 3.


100







REPORT OF INVESTIGATION NO. 60


Matson, George C.
1913 (and Sanford, Samuel) Geology and ground waters of Florida:
U. S. Geol. Survey Water-Supply Paper 319.

McCoy, H. J.
1970 (and Hardee, Jack) Ground-water resources of the lower
Hillsboro Canal area, southeastern Florida: Bur. Geol. Flor-
ida Dept. Nat. Resources, Rept. Inv. 55.

McCoy, H. J.
1969 (and Sherwood, C. B.) Water in Broward County, Florida:
Florida Bur. Geol., Map Series No. 29.

Parker, G. G.
1955 (Ferguson, G. E., Love, S. K., and others) Water resources
of southeastern Florida, with special reference to the geology
and ground water of the Miami area: U. S. Geol. Survey
Water-Supply Paper 1255.

Sanford, Samuel
1909 Topography and geology of southern Florida: Florida Geol.
Survey 2nd ann. rept.

Schroeder, M. C.
1954 (Milliken, D. L. and Love, S. K.) Water resources of Palm
Beach County, Florida: Florida Geol. Survey Rept. Inv. 13.

Schroeder, M. C.
1958 (Klein, Howard and Hoy, N. D.) Biscayne aquifer of Dade
and Broward counties, Florida: Florida Geol. Survey Rept.
Inv. 17.

Searcy, J. K.
1960 (Hardison, C. H. and Langbein, W. B.) Doublemass curves:
U. S. Geol. Survey Water-Supply Paper 1541-B.

Sherwood, C. B.
1959 Ground-water resources of the Oakland Park area of eastern
Broward County, Florida: Florida Geol. Survey Rept. Inv.
20, 40p.
Sherwood, C. B.
1962 (and Leach, S.D.) Hydrologic studies in the Snapper Creek
Canal area, Dade County, Florida: Florida Geol. Survey
Rept. Inv. 24, pt. 2.


101





BUREAU OF GEOLOGY


Sherwood, C. B.
1963 (and Klein, Howard) Surface and ground-water relation in a
highly permeable environment: Internat. Assoc. Sci. Hydrol-
ogy, Pub. No. 63, Symposium Surface Waters, p. 454-468.

Stringfield, V. T.
1933 Ground-water in the Lake Okeechobee area, Florida: Florida
Geol. Survey Rept. Inv. 2.

1936 Artesian water in the Florida Peninsula: U. S. Geol. Survey
Water-Supply Paper 773-C.

The Division of Water Survey and Research, Tallahassee, Florida
1954 Summary of observed rainfall on Florida to 31 December
1952: Water Survey and Research Paper 11.

U. S. Department of Commerce, Weather Bureau
1964 Climatic summary of the United States supplement for
1951 through 1960: Climatography of the United States
86-6.


102.









BUREAU OF GEOLOGY


APPENDIX


104









Table 7. Control structures in the area of investigation maintained and operated by the Central and Southern Florida Flood
Control District.





Structure Number Date Accepted Remarks

S-2 2-1-57 Pumping station above the fork in the North New River Canal and Hillsboro Canal and 3 miles north of South
Bay, Palm Beach County. The structure has four vertical lift pumps to discharge water into Lake Okeechobee.
Also, at the same site is Hurricane Gate Structure No, 4 which at times discharges water either to or from
the lake by gravity. Daily water levels and discharge measured by the U.S.G.S. since February 1957.
S-3 10-26-59 Pumping station in the Miami Canal at Lake Okeechobee and 0.4 miles upstream from U.S. Highway 27 in
Lake Harbor, Palm Beach County. The structure has three vertical lift pumps, to discharge water from the
Miami Canal to Lake Okeechobee. Also at same site is Hurricane Gate Structure No. 3 which at times discharges
water to or from the lake by gravity. Daily water levels and discharge measured by the U.S.G.S. since October
1957,
S-5A 5-21-55 Pumping station is in Levee 7 and 6 miles west along U.S. Highway 441 from Loxahatchee, Palm Beach
County (see fig. 14 for detail). The structure has 6 horizontal pumps to discharge water from the West Palm
Beach Canal to Conservation Area No. 1. Diversion to Conservation Area No. 1 at same site (see S-5A-S). Daily
water levels and discharge measured by the U.S.G.S. since October 1957. *

S-5A-E 4-15-54 The control structure is in West Palm Beach Canal, 6 miles west along U.S. Highway 441 from Loxahatchee, Palm
Beach County. The structure has two vertical lift gated concrete culverts to discharge water down the West H
Palm Beach Canal from the S-5 complex. Daily water levels and discharge have been measured by the U.S.G.S
since October 1957.
S-5A-S 4-15-54 The control structure is in Levee 40 borrow canal, 6 miles west along U.S. Highway 441 from Loxahatchee, Palm
Beach County. The structure has two bays with vertical lift gates to discharge water through Levee 7 from the Z
S-5 complex to Conservation Area No, 1, Diversion to Conservation Area at same site (see S-5A). Daily water
levels and discharge measured by the U.S.G.S. since October 1957.
S-5A-W 4-15-68 The control structure is in West Palm Beach Canal, 6 miles west along U.S. Highway 441 from Loxahatchee,
Palm Beach County. The structure has two vertical lift gated concrete culverts to discharge water downstream
in the West Palm Beach Canal by gravity. Also may reverse when the downstream water level is high and the
,upstream is drawn down by S-SA pumping. Daily water levels and discharge is measured by the U.S.G.S. since
October 1957.


S-6 4-25-57 Pumping station in the Hillsboro Canal at junction between levees 6 and 7 and about 23 miles southeast from
Belle Glade, Palm Beach County. The structure has three vertical lift pumps to discharge water from the
Hlillsboro Canal to Conservation Area No, 1. Daily water levels and discharge measured by the U.S.G.S. since
October 1957.







Table 7-Continued


Structure Number Date Accepted lIemarks

S-7 1-15-it0 I'lPipinig station in the N1irth New itiver :;anil at junction between levers 5 and fi, on the lIroward-Palm Beach
(Co.ulty line iandc on U.S. Ilighwa)y 27 bhoult 25 inihil south, isutllhrust of South liny, I'alm Beach County. The
structure has three horizontal pumps to discharge water from North New River Canal ta Coinservmation Area
No. 2A. Also, the structure is equipped with a vertical lilt gated control which can discharge water in either
direction to or from the Conservation Area bhy gravity. Daily water levels and discharge measured by the
C:SFIFCD.
S-8 2-9-62 Pumping station in the Miamin Cmanil .t junction between le vees .I and 5 and the Broward-lPaln Beach
County line about 20 miles south of Lake IIrlor. Palm Be-ach County. The structure has four horizontal lift
pumps to discharge water from the Miami Canal to Conservation Area No. 3A. The structure is also equipped w
with a vertical lift gated control that Ihavs into the Conservation Area by gravity, but may reverse if C
conditions dictate. Daily water levels and discharge measured by the U.S.G.S. since March 1962.

S-9 8-9-57 Pumping station is in the South New River Canal C- 11) at the junction between levees 33 and 37, half a mile
west of U.S. Highway 27 and about 13 miles west of Davie, Broward Coubty. The structure has three vertical C
lift pumps to discharge water from South New River Canal west to Conservation Area No 3A. Daily water level
and discharge measured by the U.S.G.S. since October 1957. O
ert
S-10-A,BC Three control structures along Levee 39 between S-6 and S-39 in Palm Beach County. The gated controls
discharge water from Conservation Area No. I to Conservation Area No. 2A. Water levels and discharge
measured by C&SFFCD.
S-I1-A.B.C Three control structures in U.S. Highway 27 and along Levee 38 and between S-34 and 26-Mile Bend in 0
Broward County. The structures each have -I bays with vertical lift gates to control the flow from Conservation r
Area No 2A. to Conservation Area No. 3A. Water levels and discharge measured by CkSFFCD.
S-12-A,B,C,D -Four control structures in Levee 29-U.S. Highway 41 (Tamiami Trail) and located between Levee 67A and 40-
Mile Bend, Dade County. The structures each have 6 bays with vertical lift gates to control the discharge
from Conservation Area No. 3A to the Everglades National Park. Daily water levels and discharge measured by
the U.S.G.S. since October 1963, water levels at S-12-A and S-12-D collected by the Corps of Engineers. Prior
records of Tamiami Canal Outlets, Miami to Monroe, Florida, collected by U.S.G.S. since November 1939.
S-12-E The control structure is in Levee 29 and U. S. Highway 41 at junction of Levee 67A west of Miami, Dade
County. The structure has four vertical lift gated bays to discharge water from Conservation Area No. 3B to the
Everglades National Park. Daily water levels and discharge contained in the discharge station Tamiami Canal
Outlets, Levee 30 to Levee 67A, near Miami, Florida. Prior records of Tamiami Canal Outlets, Miami to Monroe,
Florida, collected by U.S.G.S. since November 1939.
S-13 11-1-54 Pumping station is in the South New River Canal (C-11) just west of U.S. Highway 441 and 1.5 miles east of
Davie, Broward County. The structure has three vertical lift pumps to discharge water downstream in C-li to
the sea. The structure also has an automatic operated vertical lift gated control to discharge water by gravity
to the sea. The downstream side of the structure is effected by tide. Daily water levels and discharge measured
by the U.S.G.S. since March 1957.









Table 7-Continued


Structure Number

S-13-A


S-14


S-18C

S-20-G


S-21


5-22


S-24


Date Accepted

11-15-56


1-31-63



4-15-66

7-12-66

12-8-61


6-15-56



10-15-52


10-15-52


7-12-63


S-24-A


S-24-B


S-27



S-28


4-26-62


Remarks

The control structure is in the South New River Canal (C-11) 4.5 miles upstream from 5-13. The structure has
four vertical lift gated corrugated steel culverts in an earthen structure to control of the flow downstream in
C-ll. Water levels collected by C&SFFCD.
The control structure is in Levee 29 and U.S. Highway 41 at 40-Mile Bend, about I40 miles west of Miami,
Florida, Dade County. The structure has two vertical lift gated culverts to discharge water from Big Cypress
Swamp to the Everglades National Park. Daily water levels and discharge is contained in the discharge station
40-Mile Bend to Monroe by the U.S.G.S. since October 1963 and prior records of Tamiami Canal Outlets, Miami
to Monroe, Florida, collected by U.S.G.S. since November 1939.
The salinity control structure is in Canal 111 about 10 miles south of Homestead, Dade County. The structure
has vertical lift gates to control the flow in C-l 11.
The control structure is in Levee 31 (east) about 7 miles east of Homestead, Dade County. Discharge is to
Biscayne Bay. Downstream side of control is effected by tide.
The salinity control structure is on Black Creek Canal 4C-1) and on Levee 31 (east) and 3.% miles east of
Goulds, Dade County. The structure is controlled by automatic vertical lift gates to discharge water from C-I to
Biscayne Bay. Daily upstream water levels collected by the U.S.G.S. since March 1957.
The control structure is in Snapper Creek Canal (C-2), 2% miles south of South Miami, Dade County. The
structure has two bays controlled by vertical lift gates to discharge water downstream in C-2 to Biscayne Bay.
Daily water levels and discharge measured by the U.S.G.S. since February 1959. Prior records of water
levels collected by U.S.G.S. at same site.
The structure is in U. S. Highway 41 east of Levee 30. The structure is a single gated culvert to discharge
water from L-30 borrow canal and Tamiami Canal to the south through Highway to the L-31 (north) borrow
canal. Twice monthly staff gage readings by the U.S.G.S.
The structure is in Levee 31 (north) 2% miles south of U. S. Highway 41 and Tamiami Canal. The structure
has two culverts controlled by vertical lift gates to discharge water between L-31 (X) borrow canal and the
Everglades to the west.
The structure is the Levee 30 borrow canal, 2% miles north of U. S. Highway 41 and Tamiami Canal. The
structure is gated culverts to control the flow of water southward in the borrow canal.
The structure is in Little River Canal (C-7). 1.2 miles upstream from mouth at Biscayne Bay. The structure
has automatic vertical lift gates to control the discharge of water downstream in C-7 to Biscayne Bay. Daily
water levels and discharge measured by the U.S.G.S. since November 1959. Prior records of water levels
collected at a site upstream by the U.S.G.S.
The structure is in Biscayne Canal (C-8), 1 mile upstream from the mouth at Biscayne Bay and located in
Miami, Dade County. The control has two bays with automatic vertical lift gates to control the discharge
in C-8 to Biscayne Bay. Downstream side of control is tidal. Daily upstream water levels and discharge mea-
sured by the U.S.G.S. since April 1962. Prior records of water levels collected at a site upstream by the U.S.G.S.







Table 7-Continued



Structure Number Dale Accepted Remarks

S-20 12-11-53 The structure is in Snake Creek Canal (C-.), 0,1 mile upstream from mouth at Biscayne Bay and in North
Miami Beach, Dade County. The structure has four bays with vertical lift gates to control the discharge from
C-0 to the Bay. Daily upstream water levels and discharge measured by the U.S.G.S. since January 1959. Prior
records of water levels collected at site upstream by the L.S.G.S.
S-30 11-23.60 The control structure is in the western end of the Snake Creek Canal WC-9), 100 feet east of U. S. Highway
27 and 13.5 miles northwest of Hialeah, Dade County, Daily water levels and discharge measured by the
U.S.G.S. since May 1963.
S-31 7-12-63 The control structure is in the Miami Canal between the junction between levees 30 and 33 and 15 miles
northwest of Hialeah, Dade County. The structure has vertical gates to control the discharge of water from
Conservation Area No. 3B to the Miami Canal.
S-32 9-15-52 The control structure is in the Levee 33 borrow canal and 15 miles northwest of Hialeah, Dade County. The
structure has two bays with vertical gates to control the discharge from Levee 33 borrow canal to the Miami
Canal.
S-32-A 9-15-52 The control structure is in the Levee 30 borrow canal and 15 miles northwest of Hialeah, Dade County. The
structure is a gated culvert to control the flow to the north in the borrow canal and to the Miami Canal.
S-33 11-1-54 The salinity control structure is in the Plantation Road Canal (C-12), half a mile east of U.S. Highway 441
and 4 miles west of Fort Lauderdale, Broward County. The structure has two bays with vertical gates to
control the flow downstream in C-12. Daily water levels collected by the C&SFFCD and daily discharge
measured by the U.S.G.S. since October 1961.
S-34 9-15-52 The control structure is in the North New River Canal and Levee 35 and 18 miles west of Fort Lauderdale,
Broward County. The structure has two culverts with vertical gates to discharge water from Conservation
Area No. 2B to the North New River Canal. Daily water levels and discharge measured by the C&SFFCD.
S-36 11-1-54 The salinity control structure is located in the Middle River Canal (C-13) and 1.5 miles east of U.S. Highway
441 and 5 miles west of Fort Lauderdale, Broward County. The structure has two bays with vertical lift
gates to control the flow in C-13. Daily water levels collected by C&SFFCD and discharge measured by the
U.S.G.S. since March 1962.
S-37-A 8-9-61 The salinity control structure is located in Canal 14, east of State Highway 811 and 3 miles southwest of
Pompano Beach, Broward County. The structure has four bays with vertical automatic gates to control the
flow in C-14 which discharges into tide water at the Intracoastal Waterway. Daily upstream water levels and
discharge measured by the U.S.G.S. since April 1962.


5-37-B 8-9-61


The control structure is in Canal 14, 2 miles south of the Pompano Canal and 4 miles southwest of Pompano
Beach, Broward County. The structure is a gated control in the C-14 to discharge water downstream.









Table 7-Continued



Structure Number Date Accepted Remarks

S-38 7-3-61 The control structure is in Levee 36 and 12 miles west of Pompano Beach, Broward County. The structure
has two culverts that have vertical lift gates to discharge water from Conservation Area No. 2A to the Pom-
pano Canal (C-14) and the borrow canals. Daily water level collected above the structure by the Corps of
Engineers and below the structure by the C&SFFCD. Daily discharge in C-14 by the U.S.G.S. since April
1962.

S-39 9-15-52 The control structure is in the Hillsboro Canal, 6.2 miles upstream from U.S. Highway 441 and 12 miles west :
of Deerfield Beach, Broward County. The structure has one bay with a radial gale to control the discharge -
from Conservation Area No. I to the Hillsboro Canal. Daily water levels and discharge measured by the
C&SFFCD.

S-40 1-15-65 The salinity control structure is in C-15 and at Delray Beach, Palm Beach County. The structure is to control
the discharge from C-15 to the Intracoastal Waterway. Z

S-41 9-17-65 Thesalinity control structure is in the Boynton Canal (C-16) downstream from U. S. Highway 1 and at Boyn- J
ton Beach, Palm Beach County. The structure is controlled to discharge water from C-16 to the Intracoastal CI
Waterway.
S-44 4-9-58 The salinity control structure is in Canal 17 north of West Palm Beach, Palm Beach County. The Structure is
controlled to discharge water from C-17 to the Intracoastal Waterway.
S-46 11-1-58 The control structure in the southwest fork of the Loxahatchee River (C-18) just downstream from State
Highway 706 and 3 miles west of Jupiter, Palm Beach County. The structure has three bays with fixed
crest and vertical lift gates to control the flow down C-18 to the Loxahatchee River, Z
S-48 3-20-62 The control structure in Canal 23 downstream from the Sunshine State Parkway and west of Stuart, Martin Z
County. The structure controls the discharge from C-23 to St. Lucie River.
S-49 7-8-60 The control structure in Canal 24, west of the Sunshine State Parkway and 10 miles northwest of Stuart, St.
Lucie County. The structure controls the flow down C-24 and to the St. Lucie River.
S-50 6-12-61 The control structure in Canal 25 at Fort Pierce, St. Lucie County. The structure controls the flow down
C-25 to the Intracoastal Waterway.
S-76 11-13-53 The control structure is in Levee 8 borrow canal and northwest of Canal Point, Palm Beach County. The
structure controls the flow in the L-8 Canal to and from Lake Okeechobee.
S-118 2-10-66 The salinity control structure in Canal 100, about 14 miles northeast of Home.stead, Dade County. The Structure
controls the flow from C-100 to Biscayne Bay.
S-121 12-15-65 The control structure is in Canal 100C and about 6 miles southwest of Miami, Dade County. The structure
controls the discharge from Snapper Creek Canal (C-2) to C-100 C. 0







Table 7-Continued


Structure Number

S-122

S-124


S-151


Date Accepted

5-17-.65

6.21.06

6-21-66

7-27-62


Riemrks

The control structure in Canal 100 3, about 13 miles south of Miami, Dade County, The structure controls the
discharge from C-100U to C-1,
The control structure in the Levee 35A borrow canal, 12 miles west of Fort Lauderdale, Broward County,
The structure controls the discharge from L-35A borrow canal south to the North New River Canal,
The control structure in Canal 42, 9 miles west of Fort Lauderdale, Broward County, The structure controls
the discharge from C-42 south to the North New River Canal.
The control structure in the Miami Canal about 24 miles northwest of Miami, Dade County, The structure
controls the discharge from Conservation Areas No, 3A to No. 3B,,


0

Note: Some of the more important additional structures operated by the C&SFFCD are listed below,
1. The West Palm Beach control structure located on the WPB Canal under U. S. Highway 1 discharges water from WPB Canal to the Intracoastal
i iWaterway through' five bays that are controlled by stop logs and a boat lock that has a vertical lift gate. Daily water levels and discharge measured by
,the U.S.G.S. since November 1939.
S2. The Hillsbbro, Canal lock and control near Deerfield Beach, Broward County. The structure controls the flow of water down the Hillsboro Canal to
the Intracoastal Waterway. Daily water levels and discharge measured by the' US.G.S. since July 1947,
3. The lock and control on the North New River Canal near Fort Lauderdale. The structure controls the flow in the canal by the use of stop logs in the
Says. The boat lock 'has been abandoned for several years. Daily watei levels and discharge measured by U.S.G.S. since November 1939 (discharge'
measurements only May to September 1913).
4. The control'with a boat lift in the Miami Canal at N. W, 36th Street, Miami, Dade County.. The salinity structure controls the rate of flow down the
Miami Canal by removing sheet steel pilings called needles, Daily water levels and discharge measured by U.S.G.S, since February 1959, Daily water
levels and discharge measured at site upstream (near Hialeah Water Plant) from January 1940 through February 1959.
5. Hurricane Gate Structure No, 5 located at Canal Point, Palm Beach County. This structure controls flow between Lake Okeechobee and the West
Palm Beach Canal which at times can flow in either direction, Daily water levels and discharge measured by US.G.S. since November 1939,
















Table 8. Discharge through the Tamiami Canal outlets east of Levee 30, in acre-feet 1


Year, Jan Feb
1939.' 7 -
1940 3660, 3600
'1941 1050' 5660
'1942 3810 4000
1943 1290 666
1944,' 4300 1280
1945, 1350 222
:1946 3070 1890
147' 1840 '1560
1948 6390 3110
1949 2830 722.
1950 246' 0
,1951 533 167
1952 1050 778
Avg 2420 1820
High 6390 5660
Low 246 0


Annual
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
4710 4630 -
4490 2870 1430 2350 2400 3040 5260 4920 5900 6050 45970
6890 5950 2770 1190 1050 2280 3210 5840 5470 4300 45660
4060 1190 738 2620 6460 4180 5590 3500 1730 1910 39790
492 595 369 1010 2710 2210 4460 5410 4280 4180 27670
861 298 1290 774 1110 1290 595 1230 2080 1110 16220
0 0 0 0 369 615 1550 6030 5770 3750 19660
1110 536 492 60 0 1720 2620 2890 2020 2830 19240
1720 1550 738 1840 -1350 9160 17730 31670 13920 10450 90830
369 60 61 0 0 -61 0 15430 10830 7750, 43940
246 60 -61 298 0 492 893 2580 714 1050 9820
0 0 0 0 246 123 417 184 893 369 2480
0 0 0 0 0 123 595 1480 1790 2520 7210
123 0 0 357 (Discontinued) -
1570, 1010 600 810 1080 2100 3580 6760 4620 3920'. 30290
6890 5950 2770 2620 6460 9160 17730, 31670 13920 10450 119670
0 0 -61 0 -1350 -61 0 184 714 369 41


0


0









0
z
z
p


1 Includes all the flow to the south through bridges 60-62, from November 1939 through June 1952 when
the station was discontinued; also the eastward flow in the Tamiami Canal through the control structure in Dade-
Broward Levee from November 1939 to October 1949.







Table 0 Discharge through the Tamlami Canal outlets between Levee 30 and Levee 07A, in acre-feet'


Year
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
S1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
Avg
High
Low


Jan
3600
7440
1840
0
1840
0
3200
1050
57060
11680
5350
799
2640
20110
75940
39230
2090
184
83750
16230
99240
74220
0
3570
3330
7680
9280
3420
8180
9440
18420
99240
0


Feb
1730
15328
222
0
0
0
0
56
19440
3110
1000
555
1500
21220
25660
16440
288
56
108700
6110
58960
39430
0
1610
1250
5150
6570
2760
4840
6110
11630
108700
0


I Includes all the flow southward beneath 19 bridges from bridge 41 to 59. The flow in this section has
been limited to seepage through Levee 29 immediately north of the Tamiami Canal since 1963.


MXar
61
7440
61
0
0
0
0
0
1720
0
307
0
0
5960
11930
2090
0
123
93580
4610
34800
12910
0
1350
373
4480
4450
1180
2680
5160
6510
93580
0


Apr
-
0
11840
238
0
0
0
0
0
0
0
0
0
0
119
1670
0
0
0
88420
1490
11310
595
0
0
-46
1240
2730
499
739
3600
4150
88420
-46


May
61
2830
0
307
246
0
123
61
61
0
0
0
0
61
2340
0
0
5900
59580
615
4180
0
0
0
-161
113
1450
0
2960
6130
2900
59580
-161


Jun Jul Aug Sep
0 615 1040 11310
357 6210 6330 6550
11130 9280 6400 7620
0 184 1290 6550
0 369 1840 476
0 0 14 22700
119 123 615 8390
3810 13400 32710 45640
0 184 0 8690
60 309 1660 14220
0 61 61 1550
0 0 61 3450
0 3070 2210 5590
60 307 6890 1480
22430 38310 55770 76110
1070 2090 11740 37840
0 0 430 1070
238 1540 7320 39750
74260 74150 36580 37840
19760 99060 123300 112000
4880 5230 11190 80090
357 738 1780 1430
1250 2100 4120 8210
0 1350 4920 15650
2540 1800 3500 4650
-22 -34 97 2060
8720 15580 13460 8770
742 1130 1930 2550
15210 16920 16500 13310
10520 7460 12280 10360
5920 10060 12210 19870
74260 99060 123300 112000
-22 -34 0 476


O()c Nov
27070
12360 0520
9100 6600
3630 0
6330 4400
709 833
23860 21720
3810 3750
222800 143800
148400 91700
31850 26480
8420 94600
13100 16900
33940 46950
115500 147300
95550 74880
35110 19760
21520 15290
140600 101700
37140 26000
111000 131300
186500 177800
492 0
12240 6780
4540 3570
6840 8070
7240 10390
9540 7080
14030 13550
19920 15440

46110 38970
222800 177800
492 0


Annual
)De Total
5660 -
6030 46420
3630 83660
0 40480
3870 22930
0 6400
8480 77030
1840 21970
33630 496960
46300 373620
9350 98780
2400 28610
13340 48200
27980 123880
115200 319010
66650 547160 C
9100 174470
3500 44180 0
62230 359640
20780 740780
131600 757080
132900 807080
0 131950 0
5840 40840
2490 39050 0
10490 42640 0
9200 47590 -4
4390 92020
11450 53240
10280 126980

25290 199740
132900 1391640
0 705









Table 10. Discharge through the Tamiami Canal outlets between Levee 67A and 40-Mile Bend, in acre-feet'


Year
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954'
1955,
'1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
Avg
High
Low


Jan

4610
4300
2830
0
1780
123
3010
2090
16420
11680
5160
3320
1480
8420
17890
6700
0
0
25580
1910
32040
25020
0
0
0
2260
1320
9130
9350
15850


7080 4850 6660 6100 6100 14820 28600 31940 32760 36460 20750
32040 32660 85450 91850 97230 178400 214000 269100 182400 159900 84200
0 0 0 0 0 0 0 0 0 0 0


1 Includes all the flow southward through 12 bridges from bridge 29 to 40. The flow in the section has been
regulated by and measured at S-12 structures A, B, C, and D since 1963.


Feb
1780
12140
666
0
403
0
111
1670
3970
0
0
1330
1040
6000
4610
1220
0
0
32660
555
18520
11050
0
0
0
0
5780
7760
7630
26620


Mar
123
5600
615
0
0
0
0
553
61
0
0
0
0
1110
1600
0
0
0
30130
184
7440
799
0
0
0
0
43490
16310
6240
85450


Apr
179
10290
298
0
0
0
0
60
0
0
0
0
0
0
60
0
0
0
19700
0
3210
0
0
0
56
93
41750
10640
4830
91850


May Jun Jul Aug Sep Oct Nov
11900
123 60 0 6330 22610 14700 5710
3070 2140 12240 9350 6130 8240 8450
984 14820 6400 1350 1250 799 0
0 119 2890 3380 15350 11500 4400
0 0 615 3810 417 2090 2260
0 0 676 7320 24810 27920 17910
123 357 1230 3870 11130 12850 6310
0 6190 32830 39480 41770 125600 64090
0 0 0 861 15830 109100 43320
0 2080 6270 10640 21240 38370 18680
0 0 1660 861 8390 29640 10650
0 0 676 3380 5830 12850 12910
0 238 5600 8240 11360 31910 22550
0 0 2090 8610 30470 51530 50280
1230 20710 21890 21950 33320 31050 22490
0 179 1600 4490 13630 8060 4220
0 0 0 246 4820 18820 7080
369 0 1720 5900 20940 47650 27730
23980 29040 32340 14630 9760 9350 2800
799 15000 38610 40890 44210 49930 60520
123 4460 2950 12670 70450 107400 84200
0 0 922 3870 1670 861 0
0 1190 3260 2770 6720 9410 1070
0 0 0 0 0 0 0
811 2530 1570 0 0 0 0
0 0 0 728 3460 5720 21700
42360 67770 200300 242500 165600 159900 35690
6380 7750 17720 33440 29520 18490 16380
5430 91520 248000 269100 179700 113500 59330
97230 178400 214000 197400 182400 -


Annual
Dec Total
5660 -
4240 60460
5230 87180
0 30010
3500 41220
246 11620
7500 86260
6270 45260
30560 344890
15500 205060
7690 116650
3870 60230
6460 46760
11810 94230
32340 190850
14140 190940
799 40900
123 31090
14390 118700
2640 232610
55030 307640
36280 379740
0 44190
0 24420
0 0
0 4970
2980 36940
0 1006460
7860 181380
16370 1011000

9720 205840
55030 1482260
0 0


0




C,


0


z
z
0
2;


0J







Table 11, Discharge through the Tamlami Canal outlets between 40.OMile Ulund und Monroe, Florida, In acre.feot,

Annual
Jan Feb Mar Apr .Mi y Jun Jul Aug Sep Oct Nov Dec Total


1039
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953'
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965'
1966
1967,
1968
1969,
Avg
High
Lowv


1720
6890
4430
123
1170
676
799
861
13840
2890
1600
2090
369
6030
8360
1660
1230
0
36090
2150
13710
5720
0
430
11760
3470
3180
1560
2640
4920
4680
36090
0


944
13800
833
0
863
666
0
278
2700
389
444
500
2590
4830
1610
0
460
56
23820
1560
4140
1780
0
2000
2700
2100
3940
885
1390
2440
2590,
23820
0


123
11250
984
0
18.1
246
0
3440
738
0
123
246
246
615
1170
0
0
492
31600
1600
1230
246
0
430
944
1080
1260
194
975
2900
2080
31600
0


60
10350
298
179
0
0
0
893
357
0
60
298
60
536
1130
0
0
119
14940
714
6310
0
0
0
631
210
351
20
193
7170
1500
14940
0


184 3510 7750 19060 41360
3600 5770 35290 27120 25170
492 51650 8920 2830 16000
984 1070 4180 17710 43260
0 893 3630 11870 0340
0 238 10020 17950 43380
0 2380 4490 6030 25050
184 18030 40950 56200 72300
61 595 3630 8920 45340
0 2020 20110 26190 35640
61 417 4920 7010 34570
0 0 10270 22750 18330
0 476 11680 21400 33740
184 2020 20480 30380 64620
7750 50400 48580 33260 47360
0 7560 10390 6460 21060
0 60 6150 15370 26420
4860 11730 25760 35110 43910
44390 46240 47040 34860 23440
6330 61350 49800 39540 62720
369 10590 24720 41010 141700
61 1250 18850 23550 10410
0 22020 16110 16290 42840
369 4050 3320 3690 17850
198 8880 10920 28280 15800
131 1120 15760 20890 30420
131 25590 124300 92190 62580
0 24370 30400 17810 8010
6880 80130 62450 37200 30290
35840 89890 80030 53470 41810
3770 17810 25300 25810 37840
44390 89890 124300 92190 141700
0 0 3320 2830 8010


-- 6010
18820 2920
20540 21480
3690 298
23800 5530
11250 5890
30460 12730
24600 11840
147900 67890
164600 24100
68010 26960
75880 12910
32100 22970
67940 36890
75630 37430
40090 13210
3140 655
46120 5180
58900 19220
7190 2080
84610 79500
153000 77950
2090 298
44460 19930
51130 4340
21930 20670
35140 24330
37490 7510
36690 8320
30410 18340

49090 19910
153000 77950
2090 298


3260 -
861 97310
7560 188910
0 01020
3010 99850
799 45890
3140 125510
3750 78940
95370 504300
5530 270410
3810 186020
4430 142420
5600 115150
9960 185350
21150 263900
5780 258700
430 51360
246 101240
8240 208400
1600 313290
43350 433220
20840 495570
0 62260
4670 166320
1290! 88900
7350 130060
4900 139550
1820 360340
4110 132370
5200 276100

9270 193540
95370 925240
0 16550


0




0
0

Ic


I Includes the flow southward through 29 bridges from bridge 96 to 117 and bridge 22 to 28. The. flow from
this section of the Tamiami Canal outlets has been the least affected by regulation and remains almost in a natural
state. Flow in the regulated sections of the Tamiami Canal outlets has been compared with the flow in the 40-Mile
Bend to Monroe segment to determine the effects of regulation.






REPORT OF INVESTIGATION NO. 60 115


TABLE 12. Tamiami Canal outlet bridges numbering system and mileage from Mon-
roe, Florida east to Dade-Broward Levee. I


Bridge
Numbers
Old New
Monroe, Fla.
124 96
125 97
126 98
127 99
128 100
129 101
130 102
131 103
132 104
133 105
134 106
135 107
136 108
137 109
138 110
139 111
140 112
141 113
142 114
143 115


Bridge
Numbers Mile-
Old New age
144 116 14.0
145 117 14.9
146 22 15.9
147 23 17.0
148 24 17.9
149 25 18.5
150 26 18.7
151 27 19.2
152 28 19.9
40 mi-bend 20.1
153 29 20.4
154 30 21.2
155 31 2;.2
156 32 22.9
157 33 23.3
158 34 23.8
159 35 24.7
160 36 25.7
161 37 26.7
162 38 27.7
163 39 28.7


Mile-
age
0
0
0.8
1.8
3.3
4.3
5.4
5.8
6.4
6.9
7.2
7.7
8.7
9.2
9.7
10.4
10.9
11.5
12.0
12.8
13.5


Bridge
Numbers Mile-
Old New age
164 40 29.7
Levee 67A 29.9
165 41 30.0
166 4-2 30,8
167 43 31.6
168 44 32.2
169 45 32.7
170 46 33.4
171 47 33.8
172 48 34.5
173 49 35.2
174 50 35.5
175 51 38.0
176 52 36.6
177 53 36.7
178 54 37.2
179 55 37.7
180 56 38.2
181 57 39.0
182 58 39.6
183 59 40.1
Lever 30 40.9
184 60 41.0
185 61 41.8
186 62 43.8
D-B Levee 43.9


1 The Tamiami Canal outlet bridges were renumbered as indicated above in
August 1942. All the old wooden bridges (40 to 62) were replaced by smooth concrete
culverts between August 1952 and January 1953, and on all the remaining bridges, 96
to 117 and 22 to 39, the wooden decking was replaced by concrete in 1963. The dis-
tance between any two bridges may be computed from the difference in mileage figures
as indicated. Monroe, Florida used as a starting point from west to east for all mileage.




Hydrologic effects of water control and management of southeastern Florida ( FGS: Report of investigations 60 )
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 Material Information
Title: Hydrologic effects of water control and management of southeastern Florida ( FGS: Report of investigations 60 )
Series Title: ( FGS: Report of investigations 60 )
Physical Description: 115 p. : illus., maps. ; 23 cm.
Language: English
Creator: Leach, Stanley D
Klein, Howard ( joint author )
Hampton, E. R. ( joint author )
Geological Survey (U.S.)
Publisher: State of Florida, Bureau of Geology
Place of Publication: Tallahassee
Publication Date: 1972
 Subjects
Subjects / Keywords: Water-supply -- Florida   ( lcsh )
Hydrology -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by S. D. Leach, Howard Klein, and E. R. Hampton.
Bibliography: Bibliography: p. 100-102.
General Note: "Prepared by the U.S. Geological Survey in cooperation with the Central and Southern Florida Flood Control District, the Bureau of Geology, Florida Department of Natural Resources, and other state, local and Federal agencies."
Funding: Digitized as a collaborative project with the Florida Geological Survey, Florida Department of Environmental Protection.
 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 - 000835586
notis - AED1262
lccn - 72611037
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Table of Contents
    Title Page
        Page i
        Page ii
    Transmittal letter
        Page iii
        Page iv
    Contents
        Page v
        Page vi
        Page vii
        Page viii
        Page ix
        Page x
    Abstract
        Page 1
        Page 2
        Page 3
    Introduction
        Page 4
        Page 3
        Page 5
    Introduction
        Page 6
        Page 7
    Geographic and geologic setting
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
    Water control and management
        Page 22
        Page 23
        Page 24
        Page 21
    Hydrologic effects of water control and management
        Page 25
        Page 26
        Page 24
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
    Course and compromises of future water development
        Page 81
        Page 82
        Page 80
    Developmental plans
        Page 83
        Page 82
        Page 84
        Page 85
        Page 86
        Page 87
        Page 88
    Alternatives for future water development
        Page 89
        Page 90
        Page 91
        Page 92
        Page 93
        Page 88
        Page 94
        Page 95
    Summary
        Page 96
        Page 97
        Page 98
        Page 99
    References
        Page 100
        Page 101
        Page 102
        Page 103
    Appendix
        Page 104
        Page 105
        Page 106
        Page 107
        Page 108
        Page 109
        Page 110
        Page 111
        Page 112
        Page 113
        Page 114
        Page 115
    Copyright
        Copyright
Full Text







STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Randolph Hodges, Executive Director




DIVISION OF INTERIOR RESOURCES
Robert 0. Vernon, Director




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




Report of Investigations No. 60


HYDROLOGIC EFFECTS OF WATER CONTROL AND
MANAGEMENT OF SOUTHEASTERN FLORIDA




By
S.D. Leach, Howard Klein, and E.R. Hampton
U.S. Geological Survey



Prepared by the
U.S. GEOLOGICAL SURVEY
in cooperation with the
CENTRAL AND SOUTHERN FLORIDA FLOOD CONTROL DISTRICT,
the
BUREAU OF GEOLOGY
FLORIDA DEPARTMENT OF NATURAL RESOURCES,
and
OTHER STATE, LOCAL AND FEDERAL AGENCIES


TALLAHASSEE, FLORIDA
1972










DEPARTMENT
OF
NATURAL RESOURCES




REUBIN O'D. ASKEW
Governor


RICHARD (DICK) STONE
Secretary of State




THOMAS D. O'MALLEY
Treasurer




FLOYD T. CHRISTIAN
Commissioner of Education


ROBERT L. SHEVIN
Attorney General




FRED 0. DICKINSON, JR.
Comptroller




DOYLE CONNER
Commissioner of Agriculture


W. RANDOLPH HODGES
Executive Director










LETTER OF TRANSMITTAL


Bureau of Geology
Tallahassee
December 7, 1971


Honorable Reubin O'D. Askew, Chairman
Department of Natural Resources
Tallahassee, Florida

Dear Governor Askew:


Since about the turn of the century the natural hydrologic regimen in
southeastern Florida has been modified by man. The higher, dryer land was
the first to be utilized and progressively more of the lower, wetter lands have
been utilized through water control and management.

This report very adequately portrays the effects of this management
n the hydrology of southeastern Florida, and it is a significant contribution
to an understanding of the water resources in this part of Florida.



Respectfully yours,



Charles W. Hendry, Chief
Bureau of Geology

















































Completed manuscript received
November 23, 1971
Printed for the Florida Department of Natural Resources
Division of Interior Resources
Bureau of Geology
by News-Journal Corporation
Daytona Beach, Florida

Tallahassee
1972










CONTENTS


A b stract ............ ........... ......... .. .. ....... ..
Introduction ........................................................
Purpose and scope .................................................
Acknow ledgm ents ..................................................
Previous investigations ..............................................
Geographic and geologic setting ........................................
Physiography and drainage ..........................................
Climate ...........................................................
G eology ............ ...........................
Population distribution and water-use trends .............................
Population .......................................................
W ater use .......................................................
M u n icip al .... ................................................
A agricultural ..................................................
W ater control and management ........................................
History of water-control works ........................................
Water-management practices and problems ..............................
Hydrologic effects of water control and management ................. .....
Flow through the Everglades ................................... ....
Rate of overland flow .............................................
Flow through Tamiami Canal outlets ................................
Changes in flow through Tamiami Canal outlets ....................
Conservation areas ...............................................


Rainfall and storage .................................
Seep age ..........................................
Changes in discharge from the major canals ...............
Water-level changes along the coastal ridge and vicinity .......
Changes in well-field areas and sea-water intrusion .........
M iami municipal well fields ..........................
Fort Lauderdale well fields ...........................
The course and compromises of future water development ......
Developmental plans ................ ..................
Implementation of Area B and east coast backpumping plans
Conveyance canals to south Dade County .................
Southwest Dade plan of improvement ....................


Lower east coast agricultural areas .......
Alternatives for further water development .
Reduction of losses to the ocean ..........
Maintaining water quality ...............
Sum m ary ..............................
References ..............................
Appendix ........... '. ................


Page
1
3
5
5
6
7
7
8
15
15
17
18
18
20
21
21
23
24
25
25
29
36
42
45
45
52
57
67
68
74
80
82
82
84
86
88
88
88
92
96
100
104


. . . .



. . .

. . .





. . .
. . .


. . .

. .......


. . . ..

. . . . .
. . .









ILLUSTRATIONS


Figure
1. Map showing the Central and Southern Florida Flood
Control project structures and hydrologic features
in southeastern Florida, 1968 ..........................
"2 Physiographic provinces of southern Florida .............
3. Graph of maximum, minimum, and average annual rain-
faill of the eleven long-term index rain gages in
southeast Florida, 1940-65 ...................
4. Map of annual rainfall in the area of investigation
for 1956, a relatively dry year, using U.S. Weather
Bureau data ........................................
5. Map of annual rainfall in the area of investigation
for 1947, one of the wettest years of record, using
U.S. W weather Bureau data ............................
6- Map showing deviation from the annual average rainfall
at 24 U.S. Weather Bureau gages, 1941-60. The
records of several rain gages located outside the
area were also used to aid in determining the shape
of the isohvetal lines .................................
7. Map of Florida's lower east coast showing the con-
figurations of the natural drainageways (transverse
glades) and locations of major canals through the
coastal ridge .......................................
8. Comparison in population trends in Dade, Broward, and
Palm Beach counties of Florida's southeast coast ..........
9. Comparison of city of Miami municipal fresh-water
supply and Dade County population over the years ........
10. Relation between the Tamiami Canal outlets' dis-
charge and the average distance a particle of
water would travel in the Everglades in a day ............
11. Accumulation of the average monthly distance
traveled by a particle of water in the Everglades,
based on flow in the measuring section north of
the Tamiami Canal .................................
12. Hydrographs of monthly mean discharge through the
Tamiami Canal outlets, showing a comparison of
the three wettest runoff years and 1944, one of
the driest years of record since 1940 ..................
13. Monthly mean discharge southward toward Everglades
National Park through the Tamiami Canal outlets,
Levee 30 to Monroe, Florida, 1940-69 .................
14. Profiles of maximum, minimum, and average water
levels in the Everglades just north of the Tamiami
Canal during 1955, a relatively dry year. Also shown
is the altitude of zero overland flow southward ...........


I5. Profiles of maximum, minimum, and average water
levels in the Everglades just north of the Tamiami
Canal during 1960, a relatively wet year. Also
shown is the altitude of zero overland flow south-
ward and the peak profile of 1947 prior to the construction of Levee 30 ....


Page



. . . ... 4
. . . ... 7


............. 10


............. 12


............. 13





............. 14




.............. 16

. . . 17

. . ..... 19



. . . ... 27




.............. 28




. . . ... 30



.. . . ... 31




. . . . 32









ILLUSTRATIONS-continued


Figure
16. The relation between the annual discharge through the
Tamiami Canal outlets, Levee 30 to Monroe, and the
percent that flowed through the eastern section,
Levee 30 to 40-Mile Bend .........................
17. Map showing detail of the Tamiami Canal outlets sub-
divided into the three flow sections (Levee 30 to
Levee 67A, Levee 67A to 40-Mile Bend, and 40-Mile Bend
to M onroe, Florida) ................................
18. Monthly mean discharge of the Tamiami Canal outlets,
Levee 30 to Monroe, Florida, subdivided into three
sections, 1941-69. ................................
19. Cumulative annual discharge showing the effects of
construction on each of the three sections of the
Tamiami Canal outlets between Levee 30 and Monroe,
F lorida ..........................................
20. Schematic diagram showing direction of flow and
water levels in a typical west-to-east section,
from the Everglades through the coastal ridge
to Biscayne Bay. Conditions during a wet


Page



............ 35



............ 37


............ 38



............ 40


period, before and after water-management
systems were operational, as shown ..................................
21. Nomograph of rainfall-storage relation in the three
conservation areas ................................................
22. Estimated seepage eastward from Conservation Area 1
through and under Levee 40. Discharge data furnished
by the U.S. Corps of Engineers .....................................
23. Estimated seepage southward and eastward from
Conservation Area 2 through levees L-35 and L-36.
Discharge data furnished by the U.S. Corps of Engineers ...............
24. Estimated seepage southward and eastward from
Conservation Areas 3A and B through levees L-37,
L-33, L-30, and L-29. Discharge data furnished
by the U.S. Corps of Engineers ......................................
25. Generalized relation between annual rainfall at
index stations in the area and discharge to the
ocean from the Miami Canal for runoff years 1940-64 ....................
26. Cumulative runoff-year discharge to the ocean from
the Miami Canal related to the adjusted cumulated
annual mean rainfall from the eleven index rain gages.
Note the change in slope beginning 1955 and 1960 .....................
27. Generalized relation between the annual rainfall at
index stations in the area and combined discharge
to the ocean from the West Palm Beach, Hillsboro,
and North New River canals, for runoff years 1940-64 ..................
28. Cumulative runoff-year discharge to the ocean from
the West Palm Beach, Hillsboro, and North New
River canals related to adjusted cumulated
annual mean rainfall from the eleven index rain
gages. Adjustments for inflow to and outflow
from Lake Okeechobee applied to runoff values .........................








ILLUSTRATIONS-continued


Figure
29. Map of Dade County showing contours of the low-water
levels of record. May-June 1945 (from Schroeder
and others. 1958. fig. 14) ............................
30. Map of Florida's lower east coast showing contours of
row-water conditions in May 1962 (adapted from
Sht-rwood and Klein, 1963. fig. 9 and McCoy and
Sherwood, 1968, fig. 8) .............................
1t. Map of part of Dade County showing contours of the
high-water conditions of September 1960 ................
32- Map of Florida's lower east coast showing contours
of the high-water conditions of June 1968 ................
3:3. Hyvdrographs of well S-182 showing water-level
recession rates before and after construction of Canal I ....
34. Hydrograph of well G-616 in Broward County ............
35. Hydrographs of selected observation wells in southern
Dude County .......................................
36. Maps of the Miami area in eastern Dade County showing
the sea-water encroachment at the base of the
Biscayne aquifer 1904-69 (Parker, Ferguson, Love,
and others. 1955, p. 589, Kohout, 1961, Leach and
Grantham. 1966) updated ...........................
37. Map of Florida's lower east coast showing the major
well fields, their pumping rates near the
end of 1970, and the extent of sea-water
encroachment at the base of the Biscayne
aquifer .................................. ... ..
38. Map of the Miami well field showing water levels and
chloride conditions June 29, 1945 during uncontrol-
led conditions of Miami Canal ........................
39. Map of the Miami well field showing water levels
and chloride conditions April 7, 1966 during
controlled conditions of Miami Canal ..................
40. Maps of the Alexander Orr and Southwest well-field
areas of the city of Miami showing water-level
conditions March 21, 1951 (A) and May 24, 1962 (B)
(from Sherwood and Leach, 1962, fig. 17 and
Sherwood and Klein, 1963, fig. 8) .....................
41. Map of southeastern Broward County showing water-
level conditions February 15, 1941 (adapted
from Sherwood, 1959, fig. 9) .........................
42. Map of the Oakland Park area of Broward County show-
ing water-level conditions in the Prospect well
field August 7, 1956 (from Sherwood, 1959, fig. 11).
The total pumpage for the Prospect well field was 7 mgd ..
4:3. Map of the Oakland Park area of Broward County show-
ing water-level conditions in the Prospect well
field April 18, 1968 (map prepared by H. J. McCoy).
The pumpage for the Prospect well field was 30 mgd


and the western rock pit was 5 mgd ......... .......................


Page


........... 58



..... ...... 59

... ..... 60

. . . 61

. . . 62
. . .... 63

.. .... ..... 64





............ 67





............ 69


........ .... 70



. . .. 71





.. .......... 73


............. 75



. . . .. 76








ILLUSTRATIONS--continued

Figure Page
44. Map of the Boca Baton area showing water-level
contours during the low-water conditions of April 12,
1967 (from McCoy and Hardee, 1970, fig, 14) ........................ 79
45, Graphs relating rainfall to the discharge of the
West Palm Beach Canal to the ocean, 1941-69. Also
shown is the pickup of flow in the canal reach
below S-5E from 1956. ....................................... 81
46. Map of southeastern Florida showing locations of
the Area A, Area B, and southwest Dade area in
relation to the Central and Southern Florida
Flood Control District works....................... ............... 83
47. Map of the southern tip of Florida showing contours
of water level conditions in May 1962, a near-
record low-water condition. ............ ........................ 84








TABLES


Table


Page


1. Annual rainfall, in inches for the eleven long-term index
rain gages in the area of investigation for 1940-65. Also
tabulated are the annual averages for all stations and the
highest. lowest, and average values at each gage .......................
2. Pumpage by the three largest supply systems in Florida's
low er east coast ..................................................
3. Population for the three largest counties of Florida's
lower southeast coast and the amount of fresh water (in
1,000 Ac-ft per year) pumped and consumed for municipal,
industrial, and agricultural uses in 1965, and as estimated
for the year 2000 .................................................
4. Total and average discharge of three flow sections of the
Tamiami Canal showing a comparison between runoff and
calendar years for the period 1941-68 (for locations of the
three sections, see figure 17) .......................................
5. Estimated monthly and annual seepage in acre-feet to the
east and south through L-40, L-36, L-35, L-37, L-33, L-30
and L-29 from L-30 to L-67A .......................................
6. Generalized water budget in acre-feet showing annual move-
ment of water in the three combined conservation areas ................
7. Control structures in the area of investigation maintained
and operated by the Central and Southern Florida Flood
Control-District ..................................................
8. Discharge through the Tamiami Canal outlets east of Levee
:30, in acre-feet. .................................................
9. Discharge through the Tamiami Canal outlets between Levee 30
and Levee 67A, in acre-feet ........................................
10. Discharge through the Tamiami Canal outlets between Levee 67A
and 40-Mile Bend, in acre-feet .....................................
11. Discharge through the Tamiami Canal outlets between 40-Mile
Bend and Monroe, Florida, in acre-feet ...............................
12- Tamiami Canal outlet bridges numbering system and mileage
from Monroe, Florida east to Dade-Broward Levee .......................


105

111

112

113

114

115







HYDROLOGIC EFFECTS OF WATER CONTROL
AND MANAGEMENT IN
SOUTHEASTERN FLORIDA


By
S. D. Leach, Howard Klein, and E. R. Hampton


ABSTRACT

Most of the land in southeastern Florida presently utilized for urban,
suburban, and agricultural purposes was inundated all or much of the time
under natural predevelopmental conditions. Early settlement was on the
higher ground, where flooding during the rainy season was less probable.
Major urban expansion in the 1900's occurred in the vicinity of Miami, Fort
Lauderdale, and West Palm Beach. Drainage canals were extended inland
along natural drainageways, and through transverse glades. Urban areas
expanded westward on land formerly inundated or used for agriculture,
displacing agriculture to land farther inland to the east edge of the Ever-
glades.
The hydrologic regimen of the Lake Okeechobee-Everglades area has
undergone continuous modification since settlement began late in the nine-
teenth century. Before drainage and land reclamation in the northern part
of the Everglades, water levels in Lake Okeechobee and those in the Ever-
glades adjacent to the lake were about the same during periods of high wa-
ter; overflow occurred first at two low places when water stages reached 15
feet outflow along the south shore became general at a stage of about 18
feet. Modification of overland flow in the Everglades began when drainage
canals and levees were built around Lake Okeechobee beginning in 1881.
Most of the excavation for major drainage canals along the lower east coast
was completed by 1932 canals were either uncontrolled or inadequately
controlled, and continuous drainage resulted in lowered ground-water levels
and sea-water intrusion into the Biscayne aquifer in the Miami area. After
the 1943-45 drought, major canals through the coastal ridge were equipped
with control structures, which prevented overdrainage during dry periods
and prevented additional or reduced existent sea-water intrusion.
Extensive flooding which followed the heavy rains of 1947 demon-
strated the need to improve the water-control systems. The 1947 flooding
led to the establishment in 1949 of the Central and Southern Florida Flood
Control District, whose functions were to furnish flood protection to urban
and agricultural lands during rainy seasons and to provide facilities for
conserving water for alleviation of the effects of drought. Work on new
water-control facilities in collaboration with the U. S. Army Corps of En-






BUREAU OF GEOLOGY


gineers proceeded during the 1950's; water Conservation Areas 1 and 2
were enclosed by levees in Palm Beach and Broward counties, and a large
area southeast of Lake Okeechobee was made useable for agriculture by
the system of levees, canals, and pumping stations. By the end of 1962,
water Conservation Area 3 was enclosed on the south side and for the
first time, surface flow in the Everglades north of the Everglades National
Park could be fully controlled. Conservation Area 3 was considered fully
enclosed by July 1967 except for a 7.1 mile stretch of levee between L-28
interceptor levee and the L-28 tieback levee on the west side. Additional
changes and modifications in the water-management structures are
planned for construction as needed.
The prime effect of the water-control works in south Florida has been
to facilitate the flow of water out of the Everglades by means of the canal
system, thereby changing the spatial and temporal distribution of runoff
from the Everglades. Prior to 1961, flow southward toward the Everglades
National Park and south Dade County through the Tamiami Canal outlets,
based on the 1941-61 record, averaged 252,600 acre-feet per year through
the Levee 30 to Levee 67A section, 128,900 acre-feet per year through the
Levee 67A to 40-Mile Bend section, and 201,000 acre-feet per year through
the 40-Mile Bend to Monroe section. During 1962-68, average annual
discharge through the Levee 30 to Levee 67A section was reduced to about
63.200 acre-feet, the discharge through the Levee 67A to 40-Mile Bend
section increased to about 323,600 acre-feet, and the discharge in the 40-
Mile Bend to Monroe section remained about the same. Adjustments in
operation of canals and control structures to meet changing needs have
changed the amount, timing, and distribution of seaward discharge of the
Miami, North New River, Hillsboro, and West Palm Beach canals which
drain the Everglades and transect the coastal ridges. Reduction i4n flow to
the ocean began with completion of the levee systems east of the three
conservation areas in 1953. Discharge to the ocean through Miami Canal
was reduced an average of 185,000 acre-feet per run-off year for 1956-65,
and combined discharge from North New River, Hillsboro, and West Palm
Beach canals was reduced about 294,600 acre-feet per runoff year for
19.53-65, from the average discharge of 1940-52. Overall reduction of fresh
water flow to the ocean since 1953 as a result of flood and water-control
measures is about 20 percent of the fresh water that otherwise would have
been discharged to the ocean in southeastern Florida.
Before drainage, water levels were near or at land surface along much
of the coastal ridge area. One principal effect of pre-1945 land-reclama-
tion practices was the lowering of ground-water levels throughout the
coastal ridge and interior areas. Overdrainage of many coastal areas al-
lowed sea-water intrusion of canals and the Biscayne aquifer, the source
of nearly all potable water in the area. The overdrainage has been arrested
and. since 1954, water levels have tended to stabilize in most of Dade






REPORT OF INVESTIGATION NO. 60


County. Yearly peak water levels are considerably lower than in pre-flood-
control times, and yearly low water levels are higher than in pre-manage-
ment tirries. Thus, during 1945, after a prolonged drought, salty water moved
up the Miami Canal and intruded the Biscayne aquifer in the vicinity of the
Miami well field, when water was being withdrawn at 30 mgd (million
gallons per day). In 1966, in a similar dry season, water was being with-
drawn at 80 mgd; minimum water levels near the center of the field were
about the same as in 1945, but sea-water intrusion was controlled. The
improved conditions of well-field production and salinity control are re-
sults of salinity barriers in canals and replenishment of water in well-field
areas from canals. Similar conditions prevail at other near-shore well
fields in the southeast Florida area.
Additional improvements in the hydrologic situation in places in
southeast Florida can be achieved by applying existing hydrologic manage-
ment practices to smaller, specific areas of need, generally by installing
additional salinity and water-control structures at key places in canals and
by carefully manipulating these to maintain ground water at the maximum
levels that allow flood protection to urban and suburban areas. Manage-
ment practices of this sort will aid prevention of sea-water intrusion during
dry periods and allow increased withdrawals of potable water from well
fields. Continuous replenishment of water in well fields will be from ca-
nals in the dry season, requiring careful attention to the overall quality of
water in the canals.


INTRODUCTION

Southeastern Florida is considered in this report to include that part
of the State, from the northern shore of Lake Okeechobee and the mouth
of the St. Lucie Canal southward to the tip of Florida and from the east
coast westward to about the middle of Hendry and Collier Counties (fig.
1). This-area is one of rapid urban expansion, where increasing quantities
of water are needed to satisfy growing requirements for municipal and
industrial supplies and other uses. The region could not have urbanized
.were it not for programs, started in the early 1900's, aimed initially toward
land reclamation, later toward flood control and water control, and finally
toward water management. Implementation of these programs has caused
major hydrologic changes throughout southeastern Florida. These changes
were characterized by modification in rates and duration of fresh-water
runoff, impoundment of water in water-storage areas, diversion of water
from historical flow patterns, adjustment in water-level gradients and
ranges in fluctuations, and changes in water quality. The area of south
Florida affected by drainage and reclamation encompasses about 5,800
square miles and is shown on figure 1. Included in the area of investiga-







BUREAU OF GEOLOGY


Pcd doi.m


1 e u" 9"0 15 0 I u s


I Figure 1. Map showing the Central and Southern Florida Flood
Control project structures and hydrologic features in
southeastern Florida, 1968






REPORT OF INVESTIGATION NO. 60


County. Yearly peak water levels are considerably lower than in pre-flood-
control times, and yearly low water levels are higher than in pre-manage-
ment tirries. Thus, during 1945, after a prolonged drought, salty water moved
up the Miami Canal and intruded the Biscayne aquifer in the vicinity of the
Miami well field, when water was being withdrawn at 30 mgd (million
gallons per day). In 1966, in a similar dry season, water was being with-
drawn at 80 mgd; minimum water levels near the center of the field were
about the same as in 1945, but sea-water intrusion was controlled. The
improved conditions of well-field production and salinity control are re-
sults of salinity barriers in canals and replenishment of water in well-field
areas from canals. Similar conditions prevail at other near-shore well
fields in the southeast Florida area.
Additional improvements in the hydrologic situation in places in
southeast Florida can be achieved by applying existing hydrologic manage-
ment practices to smaller, specific areas of need, generally by installing
additional salinity and water-control structures at key places in canals and
by carefully manipulating these to maintain ground water at the maximum
levels that allow flood protection to urban and suburban areas. Manage-
ment practices of this sort will aid prevention of sea-water intrusion during
dry periods and allow increased withdrawals of potable water from well
fields. Continuous replenishment of water in well fields will be from ca-
nals in the dry season, requiring careful attention to the overall quality of
water in the canals.


INTRODUCTION

Southeastern Florida is considered in this report to include that part
of the State, from the northern shore of Lake Okeechobee and the mouth
of the St. Lucie Canal southward to the tip of Florida and from the east
coast westward to about the middle of Hendry and Collier Counties (fig.
1). This-area is one of rapid urban expansion, where increasing quantities
of water are needed to satisfy growing requirements for municipal and
industrial supplies and other uses. The region could not have urbanized
.were it not for programs, started in the early 1900's, aimed initially toward
land reclamation, later toward flood control and water control, and finally
toward water management. Implementation of these programs has caused
major hydrologic changes throughout southeastern Florida. These changes
were characterized by modification in rates and duration of fresh-water
runoff, impoundment of water in water-storage areas, diversion of water
from historical flow patterns, adjustment in water-level gradients and
ranges in fluctuations, and changes in water quality. The area of south
Florida affected by drainage and reclamation encompasses about 5,800
square miles and is shown on figure 1. Included in the area of investiga-






REPORT OF INVESTIGATION NO. 60 5

tion, which is coexistent with southeastern Florida as defined above, are
project structures and other control features of the Central and Southern
Florida Flood Control District (C&SFFCD).

PURPOSE AND SCOPE

This report was prepared by the U.S. Geological Survey in cooperation
principally with the Central and Southern Florida Flood Control District
(C&SFFCD) as part of the statewide program of water resource evalua-
tion. In addition, the Bureau of Geology, Florida Department of Natural
Resources, Broward, Dade, and Palm Beach counties, the cities of Fort
Lauderdale, Miami Beach, and West Palm Beach, the Miami Department of
Water and Sewers, the National Park Service, and the U.S. Navy extended
financial support for the report. All of these agencies are interested in the
hydrologic effects of drainage and reclamation of southeast Florida.
Although the results of several water-related investigations have been
published, the total hydrologic effects of drainage and reclamation have not
been clearly portrayed. The purpose of this report is to describe and evalua-
te from the mass of hydrologic information the effects that man's activities
have had on the hydrology of southeast Florida. Analysis of the data col-
lected, together with an evaluation of the effects of water management pro-
vide answers to such questions as:
1. What gross effects have the works of the C&SFFCD had on the
hydrologic regimen of southeast Florida?
2. What are the climatic conditions in the southeast Florida area today,
and how do they compare with conditions in the past?
3. Will the present and proposed flood-control system be adequate to
prevent flooding and to halt sea-water intrusion into the Biscayne
aquifer in coastal areas and to provide water to meet the demands
of the growing population and other demands?
In the process of answering the above questions, the history of the
construction of C&SFFCD works was compiled, the seepage beneath var-
ious levees was determined, a generalized water budget was estimated for
the conservation areas, and projection of water needs by the year 2000
have been made.

ACKNOWLEDGMENTS

Thanks are given to William V. Storch, Director, Engineering Di-
vision, and Robert L. Taylor, Chief of the Hydrology and Hydraulics
Branch, C&SFFCD; F.D.R. Park, Water Control Engineer, Dade County
Department of Public Works; Garrett Sloan, Director of the Miami De-
partment of Water and Sewers; J. Stanley Weedon,Water Control Engi-





BUREAU OF GEOLOGY


neer, Broward County; John G. Simmons, Director of Utilities, West Palm
Beach; and Frank Nix, Hydraulic Engineer, Everglades National Park,
for furnishing hydrologic data, and other information. Thanks are also
given to the Corps of Army Engineers, Jacksonville, for furnishing dis-
charge information on seepage through levees. The authors are indebted
to D. F. Tucker, the Florida District Cartographer, for the many useful
suggestions concerning the layout of the illustrations. This report was
prepared under the general supervision of C. S. Conover, District Chief,
Florida District.

PREVIOUS INVESTIGATIONS

Information concerning the water resources and geology of southeast-
ern Florida is contained in many published reports. Three of the earlier
reports that provided the authors with background material are: Matson and
Sanford's 1913 report and those of Stringfield in 1933 and 1936.
A comprehensive report on the geohydrologic environment of south
Florida based on data collected through 1946 by Parker, Ferguson, Love,
and others (1955) provided much background material for establishing the
hydrologic setting for the early years during the Everglades Drainage
District period, established in 1905, and was used as an aid in determin-
ing the effects of changes by the Central and Southern Florida Flood Con-
trol District. Several other reports bear on the hydrology of the southeast
Florida area. Reports by Schroeder, Klein, and Hoy (1958); Sherwood
and Klein (1963); and Sherwood (1959) provide considerable back-
ground information on the Biscayne aquifer and the geology. Reports by
Klein (1959) and Appel and Klein (1969) 'on fresh-water supplies pro-
vided information on the effects of pumping from the highly permeable
Biscayne aquifer.
Reports by Sherwood and Leach (1962), Leach and Sherwood (1963),
Kohout and Leach (1964), and Leach and Grantham (1966) provide back-
ground information on canal hydrology, sea-water intrusion, and the
interconnection between the aquifer and the canals.
Information on seepage through levees was presented by Klein and
Sherwood (1961) and a general background on hydrology in segments of
the study area were provided by Hartwell, Klein, and Joyner (1963) and
Kohout and Hartwell (1967).






REPORT OF INVESTIGATION NO. 60


GEOGRAPHIC AND GEOLOGIC SETTING


PHYSIOGRAPHY AND DRAINAGE


Southeastern Florida generally is flat and low-lying. It has been divid-
ed into the Atlantic coastal ridge, sandy flatlands, the Everglades, the Big
Cypress Swamp, and the mangrove and coastal glades topographic-ecologic
(physiographic) provinces as shown on figure 2. The report area includes
all of south Florida generally east of the Big Cypress Swamp-Everglades


Figure 2. Physiographic provinces of southern Florida






REPORT OF INVESTIGATION NO. 60


GEOGRAPHIC AND GEOLOGIC SETTING


PHYSIOGRAPHY AND DRAINAGE


Southeastern Florida generally is flat and low-lying. It has been divid-
ed into the Atlantic coastal ridge, sandy flatlands, the Everglades, the Big
Cypress Swamp, and the mangrove and coastal glades topographic-ecologic
(physiographic) provinces as shown on figure 2. The report area includes
all of south Florida generally east of the Big Cypress Swamp-Everglades


Figure 2. Physiographic provinces of southern Florida







BUREAU OF GEOLOGY


boundary shown on figure 2. A more comprehensive description of the
physiographic areas shown on figure 2 is given by Parker, Ferguson, Love,
and others (195.5, p. 141-155).
The Atlantic coastal ridge is about 5 miles wide, ranges from about 8
to 24 feet above mean sea level, and occupies about 600 square miles. It is
breached in many places south of Boca Raton by transverse glades most
which are sites of canals. The sandy flatlands province is between the
Atlantic coastal ridge and the Everglades, and in the report area it slopes
gently southward. Altitudes range from about 20 feet adjacent to Lake
Okeechobee to about 6 feet near Miami. It occupies about 1,200 square
miles of the report area. The Everglades is slightly lower than the sandy
flatlands; it is a seasonally inundated 4,000-square-mile area of organic
soils covered predominantly by sawgrass marsh and broken by elongate
treet islands." The Everglades area ranges in altitude from about 14 feet
near Lake Okeechobee to about sea level near Florida Bay. The man-
grove and coastal glades are mostly tidal flatlands subject to inundation
during high tide, particularly when winds are from the southwest. They
)occutpy an area of about 1,100 square miles. They are not a part of the
fresh-water system described in this report.
Natural drainage in the report area was generally southward within
the Everglades and eastward from the Everglades across the sandy flatlands
and through the Atlantic coastal ridge via transverse glades. Present-day
drainage through the transverse glades is largely by way of canals.


CLIMATE


The climate of south Florida is subtropical. Average daily temperatures
range from about S2 F in the summer to about 68 F in the winter.
Rainfall was determined from the records of 11 National Weather Ser-
vice (L .S. Weather Bureau) gages selected as index stations because of their
long continuous operation (since. 1940) and their adequate distribution.
Missing record for a particular index station was estimated from one or
more of the nearby stations. Table 1 lists the long-term index rain gages,
the annual total rainfall for each, the average rainfall for the period of
record foir each, and the annual average for all gages. Also shown is high
and low annual rainfall for each gage.
The annual rainfall in southeastern Florida occurs in distinct cycles.
The rainy season, normally June through October, contributes about 70 per-
cent. or about 41 inches of the 59-inch annual total, based on the 20-year
average of the index gages. The remaining 18 inches is distributed through-
out the other seven months.









Table 1. Annual rainfall, in inches, for the eleven long-term index rain gages in the area of investigation for 1940-65. Also tabu-
lated are the annual averages for all stations and the highest, lowest, and average values at each gage.












1940 54.9-1 59.,12 64.28 70.75 6-1.28 70.37 6.1.28 66.22 58.98 6-1.28 69.30 64.28
1941 63.53 70.2:3 65.37 55.01 57.37 7647 7-1.00 63.34 6.1.79 6.7-1 72.88 66.16
1942 65.82 51.51 0 .5,4 5 5.3.05 615.39 6:3.31 6.3.25 68.87 58.5.1 54,-1.3 69.47 61.74
1944 5.12 40.56 -14.75 -13.09 39.29 51.15 57.51 .19 -15.68 41.60 -11.42 45.21
1945 50.65 53.02 60.31 51.99 .10.98 54.28 .54.12 -12.28 5-1.75 53.55 62.69 .52.60
19-16 7.94 6.1.86 2.23 -17.70 55.4 6.1.27 0. 53 54.9:3 1.0 .16.67 61.47 58.01
1947 84.68 88.11 106.08 102.36 78.25 9.1.07 97.20 78.39 7:3,11 82.76 105.22 90.02
1948 62.98 -19.24 7-1.945 70.87 73.03 70.67 1.50 78.87 58.59 58.47 63.627 65.71
1949 53.5203 43.529 8.97 47.3875 6-1.86 5.32 527.1 62.1- 52.15 589.26 .51.67 61.08
1950 51.053 36.8 60.91 5.399 52.0398 55.96 58.57 -19.17 -1.865 56.96 51.92 52.560
1951 62.18 56.22 -13.72 :37.3-1 55.-141 -15.6-1 6-1.9.5 8.7 -7. 9 .6 3921 52.843 48.017
195472 57.75 5883.26 106.21 102.36 53.35 8.07 970.-18 .18.9-1 5573.11 82.76 150.87 590.302
194853 62.31 6849.13 7.80 76.75 70.82 703.99 80. 65.187 -1.359 583.-19 71.62 69.96
1954 .5.1 5.29 68.972.2 85.80 7-1.09 67.732 78.2391 62.26 70.08 -19.99 73.21 617.9308
1955 51.0 46.892 35.8 -1159.32 5 50 52.59 -576 -1.47 44.8 -16.196 37.31.92 524.543
1956 39.5185 .12.07 293.702 :39.235 47.0- -15.37 13.93 :37.0 7.968 2.9721 5238.10 4-0.48
1957 71.26 69.91 69.21 72.15 (7.5335 58.22 7.73 70.87.9 61.9 8.22 62.9 0 .87 53.31
1958 62.310 68.1367 6721.41 7.75 75.28 7:3.00 80.132 51.49 60.3 59.33 671.18 66.35
1959 72.99 70.15 8172.62 79.70 89.90 87.09 9785.63 89. 87.78 6749.99 78.6-1 81.20

1960 69.50 5:3.55 72.0-1 00.4-8 68.8.1 82.12 77.7-1 70.26 60.90 7:3.91 66.77 68.74
1961 40.85 -19.28 -10.2:3 35.5.1 41.10 .15.75 36.6-1 .41.70 -3.76 -14.1,05 :37.76 -11.51
1962 61.51 -17.72 -11.92 56.11 50.67 55..5 55.70 12.27 51.59 56,06 -48.56 51.61
1963 -19.87 -11.10 -16.615 59.3-1 5-14.9-1 62.65 -15.29 -16,08 54.6:3 62.11 53.31 52.39
1964 45.13 60.26 4.17.67 66.99 69.67 61.09 59.46 60.20 62.2:3 55.28 79.30 60.606
1965 55.56 61.83 55.99 59.76 60.8-1 -146.30 58.23 58,40 40.57 -19.-19 58.20 55.02
Average 58.07 56.03 59.32 59.58 60.32 62.81 6(4.1:3 58.15 55.91 57.15 60.35 59.26
High 84-1.68 88.11 106.08 102.36 89.90 94.07 97.20 8').33 87.78 82.76 105.22 90.02
Low 39.5.5 36.69 29.02 35.54 39.29 -15.37 :36.6.1 :,7.00 40.57 39.21 :37.31 -10.-48








































Figure 3. Graph of maximum, minimum, and average annual rainfall of the eleven long-term index gages in southeast Florida, 1940-65







REPORT OF INVESTIGATION NO. 60


The extremes in annual rainfall for 11 long-term index stations (table 1)
range from 106 inches in 1947 to 29 inches in 1956. Both extremes were
at the station 5 miles west of Dania in Broward County. The maximum
and minimum rainfall recorded each year at any one of the 11 stations is
shown in figure 3, along with a bar graph to show the average by year of
the 11 stations. Extremes in rainfall range from about 19 inches greater
than the yearly average of the 11 stations to about 18 inches less than the
yearly average of the 11.

Rainfall patterns for a dry year, 1956, and a wet year, 1947, are shown
in figures 4 and 5. A comparison of the figures shows the wide range in
rainfall between the dry year and the wet year. The isohyetal lines of rain-
tall for 1956 shown on figure 4 used data from 33 rain gages for which
records for the year were complete. The 1956 year is a typical dry year as
compared with other dry years except for the wet cell near the intersection
of the Miami and North New River canals. In 1956, the coastal and interior
areas received about the same amount of rainfall.

The isohyetal lines of rainfall for 1947, shown in figure 5, used data
from 47 rain gages for which records for the year were complete. In 1947
a hurricane in September and one in October crossed south Florida and
yielded much of the excessive rainfall along the coast. In other years of
above-normal rainfall, the data show that the coastal ridge generally
receives more rainfall than the interior.

The deviation from the 1941-60 average rainfall (57.34 inches) for the
24 rain gages that have complete records is shown in figure 6. Several rain
gages outside the area were also used to aid in determining the shape of the
isohyetal lines. These lines show the deviation from the average of all 24
gages and indicate that the coastal ridge annually receives several inches
more rainfall than the Everglades.

A further examination of figure 6 reveals that Lake Okeechobee receiv-
ed on the average about 7 inches less per year than the average of the 24
rain gages. Also, the rainfall deviation has a gradient over the lake from
near average along the southeastern shore (zero isohyetal) to 11 inches
below average (-11 isohyetal) along the northeastern shore.

The figure shows a wide variation in rainfall over the three water con-
servation areas. Rainfall averaged about 2 inches per year above the 57-
inch 24-gage average in Conservation Area 1, 1 inch below the average in
Conservation Area 2 and about 4 inches below the average in Conservation
Area 3.







12 BUREAU OF GEOLOGY


EXPLANATION


Figure 4. Map of annual rainfall in the area of investigation for 1956,
a relatively dry year, using U.S. Weather Bureau data








REPORT OF INVESTIGATION NO. 60


BIG CYPRESS


EXPLANATION


Figure 5. Map of annual rainfall in the area of investigation for 1947,
one of the wettest.years of record, using U.S. Weather Bureau
data
























































%J




4...Sbim ddeviatio IN I
two o $~ 7.34 ke

25 Vale Is deviatio lrea Ifte


Rein pin h h
-
afSSn 20.a ~rl


"k Flo0 wM rf.in, I


Figure 6. Map showing deviation from the annual average rainfall at
24 U.S. Weather Bureau gages, 1941-60. The records of sev-
eral rain gages located outside the area were also used to aid in
determining the shape of the isohyetal lines


BUREAU OF GEOLOGY


0 a O.IL
d::






REPORT OF INVESTIGATION NO. 60


GEOLOGY
Sedimentary deposits, mostly sand and limestone, underlie south-
ern Florida. The geologic units of particular importance to the water
resources of the area are the highly permeable limestone and sandstone
units that compose the Biscayne aquifer and the younger deposits of
sand that underlie beach and dune ridges and some terraces.

The Biscayne aquifer underlies most of Dade County, central and
eastern Broward County, and southeastern Palm Beach County; it ranges in
thickness from a few feet in the central parts of the Everglades to more
than 250 feet in coastal Broward County. The aquifer yields all the fresh
ground water used in the three counties, except for eastern and north-
eastern Palm Beach County, where supplies are obtained from sedi-
ments of lower permeability.

The rocks that compose the Biscayne aquifer of southern Florida
overlie a thick sequence of relatively impermeable clayey materials
which in turn overlie the permeable limestone formations of the Floridan
aquifer. Beneath much of southern Florida, the Floridan aquifer contains
water under sufficient artesian pressure to flow at the surface, but the
water generally contains dissolved constituents in excess of the limits
recommended for drinking water by the U.S. Public Health Service (1962).

A comprehensive description and discussion of the geology of
southern Florida is presented by Parker, Ferguson, Love, and others
(1955).



POPULATION DISTRIBUTION AND WATER USE TRENDS


Early settlement in southeastern Florida was on the higher ground
of the Atlantic coastal ridge (figure 2) because flooding during the rainy
season was less probable there. The areas of major urban expansion were
in the vicinity of Miami, Ft. Lauderdale, and West Palm Beach. As drainage
canals were extended inland and improved, water levels were lowered
sufficiently to permit construction along the transverse glades, the
natural drainageways that traverse the coastal ridge, and in areas
immediately west of the coastal ridge. Figure 7 shows that alignments of
several of the major canals generally follow the natural drainageways
through the coastal ridge. As drainage progressed, urban areas expanded
to the west along the drainageways on lands formerly used for agricul-
ture, displacing agricultural lands farther inland to the eastern edge of
the Everglades.







BUREAU OF GEOLOGY


Figure 7. Map of Florida's lower east coast showing the configurations
of the natural drainageways (transverse glades) and locations
of major canals through the coastal ridge







REPORT OF INVESTIGATION NO. 60


POPULATION

The region is one of extremely rapid growth in population and
economy since 1940. Local planning agencies estimate that the growth


Figure 8, --Comparisonin population trends in Dade, Broward, -and
PalmBeach counties of Florida's southeast coast






BUREAU OF GEOLOGY


rate will continue. The following tabulation shows combined population
increases for Dade, Broward, and Palm Beach Counties:

1940......................... 390,000
1950......................... 695,000
1960........................ 1,500,000
1965........................ 1,870,000
1970........................ 2,217,000

By the year 2000 the population of the three counties is expected to
approach 4.2 million. Figure 8 shows the long-term rate of population
growth in three counties of Florida's lower east coast. In addition many
tourists visit the lower east coast each year. The major influx has been
during the winter, but in recent years summer tourism has increased
substantially.

WATER USE
MUNICIPAL
Rapid population increases and the periodic influx of millions of
tourists have created major fluctuating stresses on municipal water-
supply systems. The municipal systems have succeeded in meeting these
demands by planning 10 to 15 years in advance of current needs. For-
tunately, the water resources of the region have been adequate despite
local problems of contamination by sea-water intrusion and seasonal
droughts. Pumpage figures in table 2 show rates of increase in municipal
water use for the three largest supply systems-Miami, Fort Lauderdale,
and West Palm Beach. All municipal supplies are obtained from ground-
water sources except that for West Palm Beach, which obtains its supply
from lakes immediately inland from the coast.


Table 2 Pumpage by the three largest supply systems in Florida's lower east coast
Average day Peak day Average
City Year million million for year
gallons gallons 1000 Ac/ft
Miami 1960 96.8 137.8 108.4
1965 131.1 173.7 146.8
1970 153.1 212.0 171.5
Fort Lauderdale 1960 20.0 35.6 22.4
1965 28.6 46.9 32.0
1970 40.7 60.2 45.6
West Palm Beach 1960 11.7 14.6 13.1
1965 13.9 18.2 15.6
1970 17.0 29.3 19.0







REPORT OF INVESTIGATION NO. 60


The Department of Water and Sewers of the city of Miami estimates
that by 1980 its daily pumpage during the peak of the tourist season
(January-March) will be about 250 mgd (million gallons per day). The
Department serves Miami, Miami Beach, Hialeah, Coral Gables, and some
nearby communities. In addition, many other smaller municipalities
such as North Miami, North Miami Beach, Hollywood, Pompano Beach,
Boca Raton, and Lake Worth operate separate municipal systems which
show comparable increases in withdrawal rates. The graph in figure 9


0 2


DADE COUNTY POPULATION,


8 10 12 14
HUNDRED THOUSANDS


Figure 9. Comparison of city of Miami municipal fresh-water supply
and Dade County population over the years.







BUREAU OF GEOLOGY


relates Dade County population growth to the increase in pumping by the
city of Miami. The steepening of the curve indicates the per capital use of
water in the county has increased over the years.


AGRICULTURAL

Agriculture is the largest user of water in Dade, Broward, and Palm
Beach counties. In addition to pumping more water for irrigation than
all other users combined, agricultural users consumed about six times
more water than the other users in 1965. The supplemental water pump-
ed for irrigation is withdrawn directly from canals and from the Biscayne
aquifer. As noted in table 3, irrigation use is projected to increase nearly
two and a half times by the year 2000.

The fresh-water demand for the year 2000 for Dade, Broward, and
Palm Beach Counties, the three largest counties of Florida's lower east
Table 3. Population for the three largest counties of Florida's lower
southeast coast and the amount of fresh water (in 1000 Ac-ft
per year) pumped and consumed for municipal, industrial, and
agricultural uses in 1965, and as estimated for the year 2000.
WATER USE 1965 2
County Popula- Municipal Industrial Agriculture
tion' Pumped Consumed Pumped Consumed Pumped Consumed
Broward 480,000 83 21 3.3 0.1 95 40
Duade 1,100,000 225 22 8.5 4.6 214 86
Palm Beach 290,000 43 8.5 6.3 1.1 654 262
Totals 1,870,000 351 51.5 18.1 5.8 963 388

WATER USE 2000 4
County Popula- Municipal Industrial Agriculture
tion3
Pumped Consumed Pumped Consumed Pumped Consumed
Broward 1,370,000 237 60 9.4 0.3 271 114
Dude 1,970,000 403 39 15 8.2 383 154
Palm Beach 910,000 135 27 20 3.4 2,050 822
Totals 4,250,000 775 126 44.4 11.9 2,704 1,090
Adapted from Florida Development Commission data.
2 Written communication on Water Use 1965, R. W. Pride.
County population projections developed by the Florida Social Sci-
ences Advisory Committee (total occupants less tourists).
4 The 2000 year water-use estimates are based on water use in 1965
and population projections.






REPORT OF INVESTIGATION NO. 60


coast, was estimated on the basis of a comparison of the total amount
of fresh water pumped and consumed in 1965 (table 3), assuming that
per capital use will remain constant and the ratio between water pumped
and watei consumed also will remain constant. Estimates for the year
2000 show that Dade, Broward, and Palm Beach Counties will pump
3,523,000 and consume 1,230,000 acre-feet of fresh water annually. The
consumptive use of water in the year 2000 will be 782,600 acre-feet
more than the 445,300 acre-feet consumed by the three counties in 1965.
Water consumed is water removed from the local hydrologic system and
no longer immediately available for man's use. This increased consump-
tion equals about 700 mgd, or about one and three quarter times the
consumption in 1965 for all uses. Most of this additional consumption
of water occurs during the dry season each year.


WATER CONTROL AND MANAGEMENT


HISTORY OF WATER CONTROL WORKS


The hydrologic regime of the Lake Okeechobee-Everglades area has
undergone continuous modification since settlement began late in the
nineteenth century.

The northern part of the Everglades immediately south of Lake
Okeechobee was covered by a thick layer of peat that supported dense
vegetation, chiefly sawgrass. During the rainy seasons and for several
months afterward, water stood above the surface at varying depths,
and large losses by evapotranspiration resulted (Parker, Ferguson, Love,
and others, 1955, p. 333). Overland flow through the dense vegetation
was nearly imperceptible and resembled flow through a permeable
aquifer, rather than the surface flow of a wide river. In the southern part
of the Everglades, the soil is thin, rocks crop out in many places, and
vegetation is less dense; consequently, overland flow there is more rapid.
Under natural conditions, most of the water in a particular area of the
upper (northern) Everglades was derived from rain on that area or
inflow from the area immediately to the north.

In the northern part of the Everglades, before land was drained and
reclaimed, water levels in Lake Okeechobee and those in the Everglades
adjacent to the lake were the same during periods of high water. When
water stages in the area reached about 15 feet, overflow probably occur-
red first at two low places: part of the water flowed westward into the
headwaters of the Caloosahatchee River and part southward -into the






BUREAU OF GEOLOGY


Everglades in a narrow reach. Outflow along the south shore became
general at a water stage of about 18 feet and "sizeable volumes of water
moved slowly in flat, broad sloughs toward tidewater" (Parker, Ferguson,
Love, and others, 19.55, p. 332).
Modification of the overland flow in the Everglades began when
drainage canals and levees were built around Lake Okeechobee. Deepen-
ing of the natural flood channel from Lake Okeechobee to the Caloosa-
hatchee River was an early venture. Drainage operations began in July
1882, and by early 1883 a shallow canal connected the Caloosahatchee
River to Lake Okeechobee (Parker, Ferguson, Love, and others, 1955, p.
328).
Land drainage and reclamation in the Everglades during 1905 under
the Everglades Drainage District began with the construction of two
dredges on the banks of New River where Ft. Lauderdale now stands.
The dredges were used to excavate four major channels from Lake Okee-
chobee to the Atlantic Ocean, and by 1913, the North New River Canal
was open from Ft. Lauderdale to Lake Okeechobee. The Miami Canal
was open except for the lower 6-mile section that was completed by May
I. 1913, the Hillsboro Canal was completed except for a 5-mile section,
and the West Palm Beach Canal was under construction. The above four
canals were completed and fully operational by 1921; they extended
from the southeast shore of the lake across the Everglades and coastal
ridge to the ocean. Hurricane gates were constructed at the lake ends of
the canals. The gates were closed during hurricanes to minimize water
damage to nearby agricultural land in reclaimed parts of the Everglades
from the storm tides generated in the lake. The gates were also closed
when the water level of the lake was higher than that of the drainage ca-
nals adjacent to the lake.

Construction of the St. Lucie Canal began in 1916, and water
first flowed through the canal in 1924. During 1935-46, the St. Lucie
Canal was the main controlled outlet for the regulation of the water level
of the lake.
Construction of a low muck levee on the south and east sides of Lake
Okeechobee was begun in 1921 and completed in 1924. This levee was
overtopped and breached in 1926 and 1928 by hurricane-driven storm
surge. A second, higher earth levee was constructed between 1924 and
1938 on the east, south, and west sides of the lake. The total length of
this levee was 85 miles, and the top elevations ranged from 34 to 38
feet.
As new land southward and eastward from Lake Okeechobee and
along the east edge of the Everglades in Palm Beach, Broward, and Dade
counties was used for agriculture, greater areas came under water control,






REPORT OF INVESTIGATION NO. 60


and drainage facilities were improved through efforts of several drainage
districts. These lands were effectively drained, and flood waters were dis-
posed of rapidly. Thus a large part of the overland flow from the Ever-
glades was diverted through the canal systems to the ocean.
Most of the excavation for major drainage canals along the lower
east coast was completed by 1932. The canals were either uncontrolled
or inadequately controlled, and the continuous drainage to the ocean
during dry seasons resulted in intrusion of sea water into the Biscayne
aquifer, which threatened municipal water supplies in Miami. After the
1943-45 drought, the major canals through the coastal ridge were equip-
ped with salinity-control structures, which could be opened to discharge
flood water during the rainy season and closed to prevent overdrainage
of fresh water from the Biscayne aquifer and consequent salt-water
encroachment during dry periods.
The heavy rains of 1947 resulted in extensive flooding of the uiban
and agricultural areas of southeast Florida, which demonstrated the need
for improvement in the water-control systems. As a result, more effective
programs to handle flood waters were developed, which led to the
establishment in 1949 of the C&SFFCD, whose functions were to furnish
flood protection to urban and agricultural lands during rainy seasons and
to provide facilities for conserving water for alleviation of the effects of
drought and for control of salt-water encroachment.

Work on the C&SFFCD facilities in collaboration with the U.S. Army
Corps of Engineers proceeded on an intermittent basis during the 1950's.
Water Conservation Areas 1 and 2 were enclosed by levees in Palm Beach
and Broward Counties, and a large area southeast of Lake Okeechobee was
zoned for agriculture and made useable by the system of levees, canals,
and pumping stations (fig. 1).

WATER MANAGEMENT PRACTICES AND PROBLEMS


Water control to protect agricultural areas from flooding was either
by gravity flow or by pumping from canals toward Lake Okeechobee and
by pumping into the water conservation areas. Water flowed southward by
gravity through canals and control structures or was pumped to Conserva-
tion Area 3 where it moved slowly southward toward the Everglades
National Park. Also, that part of the water in Conservation Area 1 which
was in excess of the regulation level was diverted to Conservation Area 2,
and the excess in Conservation Area 2 was moved to Area 3 through
spillways. Establishment of the levees and water conservation areas
in the Everglades and the beginning of reductions in the flow of canals






BUREAU OF GEOLOGY


to the ocean were the first compensating steps toward reverting toward
the original drainage patterns and water conditions in the Everglades.
By the end of 1962, Conservation Area 3 was enclosed on the south
side, and, for the first time, the surface flow in the Everglades north
of the Everglades National Park could be fully controlled. Conserva-
tion Area 3 was considered fully enclosed by July 1967 except for a
7.1-mile stretch of levee between the L-28 Interceptor levee and the L-28
tieback levee on the west side. According to plans, additional changes and
modifications in water-management structures are to be constructed as
needed. A list and description of the various control structures built or
operated by the C&SFFCD through 1969 is given in table 7 in the ap-
pendix.

During 1946 to 1962 and concurrent with the construction of the
flood-control works in the Everglades area, the urban east coast was
undergoing accelerated economic development. Housing expanded west-
ward from the coastal ridge in Palm Beach, Broward, and Dade Counties,
resulting in new urban areas requiring drainage and protection against
flooding.
The need to conserve fresh water, particularly the reduction of
discharge of surplus water to the ocean, was emphasized by the regionally
low water levels during the droughts of 1955-56 and 1961-65. The ability
of the system to cope with flood problems was demonstrated during the
extremely wet years of 1957-60, when no appreciable flooding occurred
in the areas protected by drainage works. Extensive damage did occur in
southern Dade County, where the drainage system was not improved to
cope with rainfall of the intensity that accompanied Hurricane Donna in
1960. The south Dade flood-control plan has since been implemented, and
the works are nearly complete.


HYDROLOGIC EFFECTS OF WATER CONTROL
AND MANAGEMENT

The prime effect of the early water-control works in south Florida
has been to increase the flow of water out of the Everglades through
canals. Because the source of much of the flow in the canals in southeast-
ern Florida is from Lake Okeechobee and the Everglades, any changes
in the hydrology caused by impoundment of water or diversion of water
from normal courses in the Everglades will be reflected in the discharge
of those canals. In order to evaluate the effects that changes in water-
control and flood-control practices have brought about, the rainfall-runoff
relation for the primary canals that traverse the Everglades was examined,
and the annual discharges of fresh water to the ocean were analyzed.






REPORT OF INVESTIGATION NO. 60


coast, was estimated on the basis of a comparison of the total amount
of fresh water pumped and consumed in 1965 (table 3), assuming that
per capital use will remain constant and the ratio between water pumped
and watei consumed also will remain constant. Estimates for the year
2000 show that Dade, Broward, and Palm Beach Counties will pump
3,523,000 and consume 1,230,000 acre-feet of fresh water annually. The
consumptive use of water in the year 2000 will be 782,600 acre-feet
more than the 445,300 acre-feet consumed by the three counties in 1965.
Water consumed is water removed from the local hydrologic system and
no longer immediately available for man's use. This increased consump-
tion equals about 700 mgd, or about one and three quarter times the
consumption in 1965 for all uses. Most of this additional consumption
of water occurs during the dry season each year.


WATER CONTROL AND MANAGEMENT


HISTORY OF WATER CONTROL WORKS


The hydrologic regime of the Lake Okeechobee-Everglades area has
undergone continuous modification since settlement began late in the
nineteenth century.

The northern part of the Everglades immediately south of Lake
Okeechobee was covered by a thick layer of peat that supported dense
vegetation, chiefly sawgrass. During the rainy seasons and for several
months afterward, water stood above the surface at varying depths,
and large losses by evapotranspiration resulted (Parker, Ferguson, Love,
and others, 1955, p. 333). Overland flow through the dense vegetation
was nearly imperceptible and resembled flow through a permeable
aquifer, rather than the surface flow of a wide river. In the southern part
of the Everglades, the soil is thin, rocks crop out in many places, and
vegetation is less dense; consequently, overland flow there is more rapid.
Under natural conditions, most of the water in a particular area of the
upper (northern) Everglades was derived from rain on that area or
inflow from the area immediately to the north.

In the northern part of the Everglades, before land was drained and
reclaimed, water levels in Lake Okeechobee and those in the Everglades
adjacent to the lake were the same during periods of high water. When
water stages in the area reached about 15 feet, overflow probably occur-
red first at two low places: part of the water flowed westward into the
headwaters of the Caloosahatchee River and part southward -into the






REPORT OF INVESTIGATION NO. 60


The history of the development of well fields in the Biscayne aquifer,
the relation of reduced water levels to sea-water intrusion, and the rela-
tion of municipal well fields along the Atlantic Coastal Ridge to present
day water-management practices indicate the extent that natural hydro-
logic conditions have been altered by water-management practices.


FLOW THROUGH THE EVERGLADES

Before attempts were made to reclaim lands for agriculture south-
east of Lake Okeechobee, flow through the Everglades area was moslty
southward toward the Gulf of Mexico and Florida Bay, and, during the
peak period of the rainy season, to the Atlantic Ocean through the
transverse glades (fig. 7). Only during extremely wet years, did water
in Lake Okeechobee overflow southward. The extent that the Everglades
drainage basin changed from year to year depended upon the amount and
distribution of rainfall during each year. During wet years, the effective
drainage basin for the Everglades probably extended to or beyond Lake
Okeechobee. On the other hand, during dry years and dry seasons, the
effective drainage area of the Everglades was greatly reduced and did
not include Lake Okeechobee.

RATE OF OVERLAND FLOW

A number of previous workers in the Everglades area have observed
that water flows slowly southward out of Lake Okeechobee into the Ever-
glades. Bogart and Ferguson (p. 332, in Parker, Ferguson, Love, and others,
1955), stated, "overflow of the south shore became general at stages of
17 to 18 feet, and sizable volumes of water moved slowly in flat, broad
sloughs toward tidewater. The largest slough (known as the Everglades)
extends as a grassy marsh, 35 to 50 miles wide, from south and southeast
shores of the lake to the end of the Florida peninsula, 100 miles to the
south...." On page 333, the above authors state "In its natural state, only
a minor part of the rainfall and the overland flow from Lake Okeechobee
left the Everglades as surface drainage. Overland flow was extremely
slow because land slopes generally averaged about 0.2 ft. per mile, and
interconnecting natural drainage channels were extremely shallow and
were choked with vegetation. During and after the rainy season, water
stood at varying depths over the surface of the organic soils. These con-
ditions naturally led to large losses through evaporation and trans-
piration."
It is of more than academic interest, therefore, to determine the
natural rate of overland flow through the Everglades and the distance






BUREAU OF GEOLOGY


water moves in the basin within a runoff year (April 1-March 31). To
determine the rate of overland flow, an east-west section was selected
immediately north of the Tamiami Canal and extending from Levee 30
westward to Monroe in Collier County (fig. 1). The section was selected
because of the availability of semimonthly discharge information from
1940 for the outlets along the Tamiami Canal. Overland flow at this section
is probably greater than elsewhere in the Everglades because vegetation
is less dense near the Tamiami Trail than it is to the north and evapotrans-
piration is less there than it is to the south. The discharge information
incorporates several prolonged droughts such as 1944-46, 1950-52,
1955-56, and 1961-65 and the extremely wet years 1947-48, 1958-60.
Examination of the discharge records showed that southward flow
occurred as soon as water was only slightly above the general land
surface of the Everglades. Elevations along the measuring section at which
flows occurred initially are referred to as the effective land surface.
Effective land surface elevations were determined from each of the
water-level gages along the Tamiami Canal. To determine the cross section-
al area for the different flow sections, the water depth above the effective
land surface was ascertained from the profile gage readings along the
Tamiami Canal; the water depth was then multiplied by the length of sec-
tion represented by each gage. This section extends from halfway between
two gages. past a given gage, and halfway to the next gage. By using the
basic equationQ=VA, where Q is discharge through the canal outlets in
cubic feet per second and A is the area of flow section in square feet, V,
the velocity of water movement in feet per second, can be determined
and then converted to feet per day. It is assumed that flow is evenly dis-
tributed within each section, as defined above, and that the discharge
measured through the Tamiami Canal outlets represents the flow in the
nearby section.

Discharge data for 1960, which show a wide range of discharges,
and random discharge data from other years were used to determine the
rate of flow through the Everglades and the adjoining section of the Big
Cypress Swamp. The maximum rates of southward water movement at
the Tamiami Canal section were computed to be 1,550 feet per day during
October 1947 and 1,480 feet per day during September 1960. The average
velocity for the 1960 runoff year (defined as April 1 through March 31)
was about 860 feet per day. The minimum rate of southward overland
movement is zero, when water levels decline below land surface. Figure
10 shows the relationship between the rate of water movement, in feet
per day, and the total instantaneous flow through the Tamiami Canal
outlets. The monthly cumulative distances of water movement, based on
the curve in figure 10, for three wet years and one dry year are shown in
figure 11. The distances shown indicate that even during the excessively






BUREAU OF GEOLOGY


to the ocean were the first compensating steps toward reverting toward
the original drainage patterns and water conditions in the Everglades.
By the end of 1962, Conservation Area 3 was enclosed on the south
side, and, for the first time, the surface flow in the Everglades north
of the Everglades National Park could be fully controlled. Conserva-
tion Area 3 was considered fully enclosed by July 1967 except for a
7.1-mile stretch of levee between the L-28 Interceptor levee and the L-28
tieback levee on the west side. According to plans, additional changes and
modifications in water-management structures are to be constructed as
needed. A list and description of the various control structures built or
operated by the C&SFFCD through 1969 is given in table 7 in the ap-
pendix.

During 1946 to 1962 and concurrent with the construction of the
flood-control works in the Everglades area, the urban east coast was
undergoing accelerated economic development. Housing expanded west-
ward from the coastal ridge in Palm Beach, Broward, and Dade Counties,
resulting in new urban areas requiring drainage and protection against
flooding.
The need to conserve fresh water, particularly the reduction of
discharge of surplus water to the ocean, was emphasized by the regionally
low water levels during the droughts of 1955-56 and 1961-65. The ability
of the system to cope with flood problems was demonstrated during the
extremely wet years of 1957-60, when no appreciable flooding occurred
in the areas protected by drainage works. Extensive damage did occur in
southern Dade County, where the drainage system was not improved to
cope with rainfall of the intensity that accompanied Hurricane Donna in
1960. The south Dade flood-control plan has since been implemented, and
the works are nearly complete.


HYDROLOGIC EFFECTS OF WATER CONTROL
AND MANAGEMENT

The prime effect of the early water-control works in south Florida
has been to increase the flow of water out of the Everglades through
canals. Because the source of much of the flow in the canals in southeast-
ern Florida is from Lake Okeechobee and the Everglades, any changes
in the hydrology caused by impoundment of water or diversion of water
from normal courses in the Everglades will be reflected in the discharge
of those canals. In order to evaluate the effects that changes in water-
control and flood-control practices have brought about, the rainfall-runoff
relation for the primary canals that traverse the Everglades was examined,
and the annual discharges of fresh water to the ocean were analyzed.















0
a
z
0

U.

w
CL

W

u

U



<
LU






9
U
5n
is


-0 200 400 600 800 1000 1200 1400 1600 1700
DISTANCE TRAVELED, FEET PER DAY
Figure 10. Relation between the Tamiami Canal outlets' discharge and the average distance a particle of water would travel in the -4
Everglades in a day








BUREAU OF GEOLOGY


EXPLANATION
RUNOFF YEAR DISTANCE


......... 1944
-1947
---1959


6.5 miles
42.5 miles
50.3 miles
45.2 miles


NOTE: RUNOFF YEAR (APRIL-MARCH)


Figure 11. Accumulation of the average monthly distance traveled by a
particle of water in the Everglades, based on flow in the
measuring section north of the Tamiami Canal






REPORT OF INVESTIGATION NO. 60


wet years 1947, 1959, and 1960, water from the vicinity of Lake Okeecho-
bee probably did not reach as far south as the Tamiami Canal, because
Lake Okeechobee is more than 60 miles to the north. Although it is unlikely
that water in the northern part of the basin ever reached the Tamiami
Canal, the upbasin water supplies are important because they maintain
gradients that sustain the slow southward flow through the Everglades.
The graphs in figure 11 show that the total estimated distance that
water traveled in the Everglades during a runoff year was greatest during
1959, the year of greatest total flow. However, the peak flow through the
Tamiami Canal outlets for the 1959 runoff year was only about half the
peak flow for 1947 or 1960, as shown in figure 12. Comparison of the
graph for 1944, a dry year, to those for wet years shows the wide range
in hydrologic conditions that occur within the Everglades and Big Cypress
basins.

FLOW THROUGH TAMIAMI CANAL OUTLETS

One of the longest continuous records of discharge in southeastern
Florida is that of the southward flow through the "Tamiami Canal outlets"
beneath the Tamiami Trail between Levee 30, west of Miami, and Monroe,
in Collier County. (See figure 17 for location.) This record is of maximum
importance because: (1) it shows annual changes in southward movement
of water resulting from variations of rainfall within the Everglades and
Big Cypress basins; (2) it shows the volume of water along the Tamiami
Canal between Levee 30 and Monroe, Florida in the Everglades hydrologic
system after all the upstream natural losses and man-imposed diversions
are accounted for; (3) it reflects and permits evaluation of significant
changes in the system to the north that result from diversions, impound-
ments, or water use in upbasin areas, and it may be used in defining the
historic flows toward Everglades National Park.
The discharge through the Tamiami Canal outlets for 1940-69 is
portrayed by the hydrograph on figure 13. The record spans a period of
flows through the Everglades during the last part of the period of drainage
and land reclamation (until 1946), during the period of flood control and
water control (1946-62), and during the beginning of the period of water
management.
As shown by the hydrograph on figure 13, the flow southward
through Tamiami Canal outlets toward the Everglades National Park
fluctuates seasonally and varies greatly from year to year. The annual
fluctuation is exemplified by flood years 1947, 1948, and 1960, as
compared to drought years 1944 and 1961. Not only does the discharge
vary from year to year, as indicated by the annual mean discharge on







BUREAU OF GEOLOGY


YEAR
.....* 1944

-1947

--1959
---1960


M 3 J


EXPLANATION


76.5 cfs

2120 cfs

2380 cfs
2180 cfs


A S O N D J F M


Figure 12. Hydrographs of monthly mean discharge through the Tamiami
Canal outlets, showing a comparison of the three wettest
runoff years and 1944, one of the driest years of record since
1940


















z
0

on







U

W
0

T
0.


Figure 13. Monthly mean discharge southward toward Everglades National Park through the Tamiami Canal outlets,
Levee 30 to Monroe, Florida 1940-69





































( DISTANCE ALONG TAMIAMI CANAL )
Figure 14. Profiles of maximum, minimum, and average water levels in the Everglades just north of the Tamiami Canal
during 1955, a relatively dry year. Also shown is the altitude of zero overland flow southward






REPORT OF INVESTIGATION NO. 60


figure 13, but the wet and dry seasons may change also from year to year.
Annual monthly peak flows usually occur in September or October, but
two of the more significant monthly mean peaks that occurred out of
phase were the February 1958 peak (2,973 cfs) and the November 1959
peak (4,560 cfs). For all years except 1956 and 1961, discharge through
the Tamiami Canal outlets continued through March of the following
year. The two most significant periods of zero flow were the 114 days
from March 5 to June 26, 1956, and the 189 days from December 6,
1961 to June 12, 1962.
The annual mean discharge in figure 13 indicates there have been
two significant extended dry periods. The first was noted from the begin-
ning of record November 1939 (not shown) to May 1947, and the
second was from April 1961 through mid-1966. In 1947 the peak of
record flow was recorded following one of the driest years, whereas
in 1960 the second highest peak of record followed several years of
above-normal flow. Also in 1961 the discharge was substantially below
normal except for January through March, during which time discharge
was basically runoff from the preceding year. Examining the past
record and the foregoing examples indicates that in the Everglades
area there is very little residual effect from one year to the next. The
main reason for this is that historically about 70 percent of the
rain each year comes normally June through October and the remaining
30 percent falls November through May each year, the period when
evapotranspiration almost always exceeds rainfall. It is during this dry
period each year that surface storage in the Everglades is generally
depleted.
The high and low water levels along the measuring section of the
Tamiami Canal outlets are compared with the effective land-surface
elevations during a dry and wet year on figures 14 and 15. The pro-
files for 1955 (fig. 14) show that only during the period of high water
levels during the wet season did overland flow occur through the
entire measuring section. At times of average conditions in 1955,
flow occurred only through the section between Levee 30 and 40-Mile
Bend. At the lowest water-level condition during the dry season, water
levels were below the land surface, and no flow occurred through any
of the outlets.
The impounding effect of Levee 30 on water west of the levee
and the changes in head across the levee that occurred under the
different conditions are also shown on figure 14. The higher water
levels west of Levee 30 were caused by the flow diverted southward
along the levee system.
In contrast to the conditions during a relatively dry year shown
on figure 14, the water-level profiles on figure 15 for 1960, a wet





































Figure 15. Profiles of maximum, minimum, and average water levels in the Everglades just north of the Tamiami Canal during 1960,
a relatively wet year. Also shown is the altitude of zero overland flow southward and the peak profile of 1947 prior to the
construction of Levee 30






REPORT OF INVESTIGATION NO. 60


year, show that southward flow occurred during the entire year through
the eastern part of the flow section and during all but the minimum or
near minimum conditions through the western part of the flow section.
In order to compare pre-Levee 30 high water-level conditions with con-
ditions after the completion of Levee 30, the maximum profile for
1947 (before levees) is superimposed on the 1960 profiles (fig. 15).

An important feature of the profiles in figures 14 and 15 is the
rise of the effective land surface west of 40-Mile Bend. Although the
maximum elevation west of the 40-Mile Bend site is only slightly more
than 2 feet higher than the elevation at the west toe of Levee 30, the
difference is sufficient to cause most of the flow during wet years to
occur through the eastern part of the section. An analysis of the
distribution of discharge through the Tamiami Canal outlets for 1940-60
showed that for most runoff years when discharge was less than 300,000
acre-feet, the percentage of discharge through the western section
(Monroe to 40-Mile Bend) was greater than that through the eastern
section (40-Mile Bend to Levee 30). However, when the runoff-year
discharge exceeded 725,000 acre-feet, about 70 percent of the discharge
occurred through the eastern section. The relation between runoff-year
100 1- 1 -- 1-- 1- 1--1-1

90- TAMIAMI CANAL OUTLETS


c c ,S 57 59

?0- 4448------







49.2 0.4 0.6 0.8 1.0 1.2 1.4 1. 1.8 20
SDSCHARGE RUNOFF ACRE- APFEETRIL- MARCH)
/ e49













Figure 16. The relation between the annual discharge through
section, Levee 30 to 40-Mile Bend
50-











section, Levee 30 to 40-Mile Bend






BUREAU OF GEOLOGY


discharge through the Tamiami Canal outlets and the percentage that
flowed through the eastern section, 40-Mile Bend to Levee 30, is shown
on figure 16. Water that flows through the eastern section is from the
Everglades basin, whereas water that flows through the western
section is from the Big Cypress Swamp.

CHANGES IN FLOW THROUGH TAMIAMI CANAL OUTLETS
In order to describe and evaluate the changes in flow through the
Everglades as a result of drainage, water control, and water management
within the drainage basins, the Tamiami Canal outlets were subdivided
into three flow sections, as shown in figure 17. The monthly mean
discharge for the three sections for the period of record is given in
tables 7 to 10, and the Tamiami Canal outlet bridge numbering system
and mileage is given in table 11 in the appendix.
The western section, 40-Mile Bend to Monroe, is the flow from the
Big Cypress Swamp, the only section whose drainage basin has remained
relatively unchanged through the period of record. Therefore, the flow
through that section is used as the index of natural runoff. The middle
section extends from 40-Mile Bend to Levee 67A, and includes the
discharge of the four spillways (S-12A, B, C, and D) at the south end of
Conservation Area 3A, operational after 1962. These spillways control
the direct surface flows into the Everglades National Park. The third or
eastern section extends from Levee 67A to Levee 30. After 1962, the
discharge through this section has been limited to seepage through Levee
29 on the south side of Conservation Area 3B (figs. 1 and 17). The monthly
mean discharge through the three reaches during 1941-69 is shown in
figure 18.

The discharge hydrograph for the reach 40-Mile Bend to Levee 67A
before 1962 shows the normal flow conditions before completion of
Levee 29 and the associated S-12 spillways and completion of Levee 67A
in 1962. After 1962 a distinct change in flow pattern is apparent
by comparison with the index flow section 40-Mile Bend to Monroe, for
the same period. No discharge occurred through S-12 spillways into
the Everglades National Park from Conservation Area 3A during 1963,
and only a small amount was discharged in 1964. However, the flow
through that reach into the Park for 1966 and 1968 was inordinately
large in relation to the annual rainfall and to the flow through the index
section for that year; furthermore, the flow in 1966, 1968 and 1969-
greatly exceeded the prior record flow of 1947 through that section.
Other effects of managing the water in Conservation Area 3A
through the manipulation of S-12 spillway gates, constructed in 1962.
are shown in figure 18 by the hydrograph of the Levee 67A to 40-Mile






































Figure 17. Map showing detail of the Tamiami Canal outlets sub-divided into the three flow
sections (Levee 30 to Levee 67A, Levee 67A to 40-Mile Bend, and 40-Mile Bend to
Monroe, Florida)






BUREAU OF GEOLOGY


Bend section during 1966, 1968, and 1969. The rate of rise and decline
of the discharge after the 1966-68 wet season was greater than it was
for any prior year of record. This sharp decline in 1966 was caused by
closing the spillway gates in November to retard the runoff, thereby
storing water for later release to the National Park. The discharge hydro-
graph of the Levee 67A to 40-Mile Bend section for 1967 shows that
flow was maintained throughout the year, except for a brief period in
January, despite the fact that 1967 was a year of subnormal rainfall,
as indicated by the small discharge through the 40-Mile Bend to Monroe
index flow section. At the end of the dry season of 1967, southeastern
Florida was the only area in Florida that did not experience excessively
low water levels.
The discharge through the section between Levee 30 and Levee 67A
(fig. 18) represents a significant part of the overland flow to eastern
and southeastern Dade County. The discharge before 1962 was predomin-


i l I i i I i I I I I 1 i i I I
TAMUUI CANAL OUTLETS 40-MLE BEND TO MONROE

- A '


Figure 18.


1 I II I 1 I 119 I I
Monthly mean discharge of the Tamiami Canal outlets,
Levee 30 to Monroe, Florida, subdivided into three sections,
1941-69






REPORT OF INVESTIGATION NO. 60 39

antly overland for periods of high and moderate flow; for periods of
low flow, the discharge was chiefly by ground-water flow to the Tamiami
Canal and then through the outlets. After 1962, discharge in this reach
was a combination of seepage through Levee 29 along the south boun-
dary of Conservation Area 3B and ground-water flow to the Tamiami
Canal. The hydrograph shows that during the pre-1962 period, generally
more water flowed through the Levee 30 to Levee 67A section than flowed
through either of the other sections. After Levee 30 was completed in
1953, the additional water that was routed southward by the levee
probably caused the flow to continue for a longer period of time each
year. The decrease in flow recession rate is evident when the recession
rate for 1947-48 and 1948-49 is compared with the rate for 1959-60
and 1960-61, each following abnormally wet rainy seasons. The decrease
in recession rate probably resulted from the southward diversion of
flow by the levee system and the impoundment of water behind the levee.
The marked change in flow pattern in the Levee 30-Levee 67A
flow section is shown by the hydrographs for 1966 on figure 18. During
1966, water that normally would have flowed through the eastern sec-
tion was diverted southward by Levee 67A and impounded in Conservation
Area 3A. The only flow recorded for the Levee 67A-Levee 30 section was
seepage through Levee 29.
Examination of the hydrographs on figure 18 shows that the dis-
tribution of flows through the Tamiami Canal outlets has been altered,
and the greatest flows now occur through the center flow section,
40-Mile Bend to Levee 67A.

Before construction of Levee 29, the section between Levee 30 and
Levee 67A contributed significant quantities of water to south Dade
County. Because water is now being stored in Conservation Area 3B
or diverted to the west by Levee 67A, the contribution to south Dade
County has been altered, and annual peak water levels there have been
reduced.
A method was devised to determine changes in the pattern of flow
through the three sections of the Tamiami Canal outlets and also the
changes in flow in each section during the different periods of con-
struction of the C&SFFCD works. Because the three sections have a related
(although undefined) drainage basin, flow through the 40-Mile Bend
to Monroe section (which is largely unaffected by control works) was
used as a "benchmark" station to determine the changes in the other
two related but controlled sections. To use the 40-Mile Bend to Monroe
section as an index, its cumulative discharge from runoff year to runoff
year was plotted in a straight line by adjusting time, as shown in figure
19. The cumulative discharges of the other two flow sections should







































Figure 19. Cumulative annual discharge showing the effects of construction on each of the
three sections of the Tamiami Canal outlets between Levee 30 and Monroe,
Florida






REPORT OF INVESTIGATION NO. 60


also plot in a straight line on the same time base as long as they are
hydrologically related-that is as long as the hydrologic conditions in
the three sections are not changed. Therefore, any departures from a
straight-line plot, for the two eastern sections, beyond a normal scat-
tering, will show the time and magnitude of the effects that levee con-
struction and other changes have had on the flow.

The effects of the construction of Levee 30 markedly increased
the flow through the section between Levee 30 and Levee 67A, as
shown by the increased slope of the time-adjusted plot (fig. 19). The
increase in the slope indicates an increase in the flow through the sec-
tion. The additional water was diverted southward toward Everglades
National Park and south Dade County by Levee 30 and other levees
east of the three conservation areas, which interrupted the natural east-
ward flow toward the ocean. The magnitude of the change in flow bet-
ween 1953 and 1961 can be estimated for the section by projecting a
straight line from the initially established trend for 1941 to 1952 to
1961 on figure 19 and determining the difference between the values
obtained for 1961. Accumulated discharge would be 3,077,000 acre-
feet rather than the 5,274,000 acre-feet shown. The levees to the
east of the conservation area thus diverted an additional 2,197,000
acre-feet southward. Based on the 1941-52 trend, the natural dis-
charge through the section would have averaged about 146,500 acre-
feet annually rather than 251,100 acre-feet for 1941-61 runoff years.
The additional discharge for the section averaged 245,300 acre-feet
per runoff year between 1953 and 1961, which was a direct result of
the construction of the levee systems. The southward flow for the Levee
30-Levee 67A section for 1953 to 1961 averaged 426,000 acre-feet per
runoff year rather than the average of 180,700 acre-feet per runoff year that
would have occurred for the period if the levee system had not been built.
This was, on the average, 136 percent greater than the flow that would have
occurred if the levee system had not diverted runoff southward.
The magnitude of the change in flow between 1953 and 1961 can
be estimated for the Levee 67A to 40-Mile Bend section by project-
ing a straight line from the initially established trend for 1941 to 1952
to 1961 on figure 19 and by determining the difference in discharge
between the values obtained. Accumulated discharge would be
2,480,000 acre-feet rather than the 2,684,000 acre-feet shown. The
levees at the east side of the conservation areas thus diverted an ad-
ditional 204,000 acre-feet southward. Based on the 1941-52 trend,
the pre-levee natural discharge through Levee 67A to 40-Mile Bend
section of the Tamiami Canal outlets would have averaged 118,100
acre-feet annually rather than 127,800 acre-feet foi 1941-61 runoff
years. The additional discharge for the section averaged 22,920 acre-






BUREAU OF GEOLOGY


feet annually per runoff year for 1953-61 as a direct result of diversion
by the levee systems. The discharge directly to the Everglades National
Park through the Levee 67A to 40-Mile Bend section for 1953 to
1961 averaged 169,000 acre-feet per runoff year rather than 146,100
acre-feet per year if the levee system had not been built an average
of 16 percent greater flow.
The accumulated discharge for the 40-Mile Bend to Monroe
section (the index section) based on 1941-61 record was 4,189,800
acre-feet, or an average 199,500 acre-feet per runoff year.
Levee 29 was constructed in 1962 just north of and parallel to
the Tamiami Canal from 40-Mile Bend to Levee 30, obstructing south-
ward overland flow. After Levee 29 construction, flow through the
Levee 30-Levee 67A section was reduced to seepage through Levee
29, an average of about 66,200 acre-feet per runoff year. Levee 67A,
which separates Conservation Areas 3A and 3B, was completed in
1963, routing considerable water westward through the 40-Mile
Bend-Levee 67A section. Therefore, the annual average seepage dis-
charge of about 66,200 acre-feet in the Levee 30-Levee 67A section
should continue. (See table 9 in the appendix.)
In summary, the flow before 1961 southward toward the Ever-
glades National Park and south Dade County, based on the 1941-61
record, averaged 251,100 acre-feet per runoff year through the Levee
30 to Levee 67A section, 127,800 acre-feet per runoff year through
the Levee 67A to 40-Mile Bend section, and 199,500 acre-feet per
runoff year through the 40-Mile Bend to Monroe section of the Ta-
miami Canal outlets. (See table 4 for comparison of flow between the
calendar year and runoff year for the three sections of the Tamiami
Canal outlets.) The trends of discharge shown on figure 19 indicate
that the average for 1962-68 through the Levee 30 to Levee 67A sec-
tion has been reduced to about 66,200 acre-feet. Although the annual
discharge in the Levee 67A to 40-Mile Bend reach has ranged from
0 to 1.1 million acre-feet, the average for 1962-68 was 341,900 acre-
feet per runoff year, about 214,100 acre-feet greater than the 1941-
61 annual average, and dischage through the 40-Mile Bend to Mon-
roe section has remained about the same.

CONSERVATION AREAS

Three large areas within the Everglades are surrounded by le-
vees and form an important integral part of the water-management
system in south Florida-Conservation Areas 1, 2, and 3A and B
(figure 1). Effective closure of the conservation areas was accomplished
at the end of 1962 except for the west side of Conservation Area 3.






REPORT OF INVESTIGATION NO. 60


Table 4. Total and average discharge of three flow sections of the
Tamiami Canal showing a comparison between runoff and
calendar years for the period 1941-68 (for locations of the
three sections, see figure 17).

Totals Average
Section Period (Thousands of Ac-ft) (Thousands of Ac-ft)
Runoff Calendar Runoff Calendar
Years a Years Years a Years
Levee 30 to 1941-52 1,439.5 1,422.5 120.0 118.5
Levee 67A 1953-61b 3,834.1 3,881.4 426.0 431.3
1941-61 5,273.6 5,303.9 251.1 252.6
1962-68c 463.1 442.4 66.2 63.2
1941-68 5,736.7 5,746.3 204.9 205.2
Levee 67A to 1941-52 1,162.9 1,169.4 96.9 97.4
40-Mile Bend 1953-61b 1,521.1 1,536.7 169.0 170.7
1941-61 2,684.0 2,706.1 127.8 128.9
1962-68c 2,393.1 2,265.2 341.9 323.6
1941-68 5,077.1 4,971.3 181.3 177.5

40-Mile Bend 1941-52 2,013.3 2,033.8 167.8 169.5
to Monroe 1953-61b 2,176.5 2,187.9 241.8 243.1
1941-61 4,189.8 4,221.7 199.5 201.0
1962.68c 1,303.9 1,293.6 186.3 184.8
1941-68 5,493.7 5,515.3 196.2 197.0

a Runoff year is defined as period April 1-March 31
b After construction of L-30
c After construction of L-29

Conservation Area 3 was considered fully enclosed by July 1967
with the exception of a 7.1-mile stretch of levee between L-28 Inter-
ceptor levee and L-28 tieback levee. Water in the canal system can
flow by gravity or be pumped into the conservation areas, thus delay-
ing runoff from the central Everglades area. During times of intense
rainfall, excess surface waters are pumped to temporary. storage in the
conservation areas, thus reducing the flood-peak water levels east of
the conservation areas, especially urban areas along the Atlantic
Coastal Ridge. Conditions during a wet period, before and after water-
management systems were operational, are shown on figure 20. Dur-
ing dry periods, seepage through levees and regulated releases from
the conservation areas sustain water at higher dry-period levels to the
east for longer periods than could be maintained before the manage-
ment system went into operation.
The three conservation areas occupy 1,345 square miles, near-
ly twice the area of Lake Okeechobee. Although the areas are shallow
reservoirs, large volumes of water can be stored temporarily in them,
thereby delaying runoff from the interior.










BEFORE


EVERGLADES


BEFORE





EFFECTS OF LEVEE SYSTEM ON
RUNOFF FROM A LARGE STORM
TIME INCREASING -4b


LEVEE


COASTAL RIDGE

8iSCAYNE BAY


0.'1, AP ** A'
*" FRESH WATER SEA WATER










AFTER


COASTAL RIDGE


EVERGLADES BRO CAA
.. ... ,WAB.ROW__. .TER TABLE BISCAYNr BAY


.4 "4. -. A
4. FRESH WATER 0 SEA WATER
A4 *. R



Figure 20. Schematic diagram direction of flow and water levels in a typical west-to-east section, from the Everglades through the
coastal ridge to Biscayne Bay. Conditions during a wet period, before and after water management systems were opera-
tional, as shown


t






REPORT OF INVESTIGATION NO. 60


RAINFALL AND STORAGE

Rainfall differs in intensity over the three conservation areas (fig.
6) and affects the amount of water available for storage in each of the
areas. Average rainfall over Conservation Areas 1, 2, and 3 is 59, 56,
and 53 inches, respectively.
Most rainfall on the conservation areas evaporates or is transpir-
ed to complete the hydrologic cycle. Consequently, the three conser-
vation areas have nearly gone dry several times since being enclosed.
In dry years more water enters the conservation areas than is discharg-
ed from them through the control structures, as shown by the records
for 1961-64, table 6.
The amount of water temporarily in storage in the combined con-
servation areas as a result of rainfall of a given intensity is shown in
figure 21. The amount of storage expected from each storm of a known
magnitude is indicated in the illustration. A 6-inch rain, for instance,
would add about 430,000 acre-feet, or about 140 billion gallons of
fresh water to storage.

SEEPAGE
Considerable water leaves the conservation areas by seeping
through the levees. Seepage is generally beneficial because it distri-
butes runoff from severe rain storms at uniformly decreasing rates
to the areas east of the conservation areas. The conservation areas
retain fresh water from storms until excess water in the coastal area
can be removed by canals to the ocean; then seepage through the levees
and discharge through the levee control structures help maintain
optimum water levels in the areas east of the conservation areas.
Seepage from Conservation Area 1 eastward through Levee 40,
from October 1962 to December 1963, is shown in figure 22. The
hydrograph of seepage (lower graph) is estimated from a head-discharge
relation from Corps ot Engineers discharge measurements and from
the average head of several gages in the area, shown in the upper graph.
The mean eastward seepage for 1963 is estimated to be 109 cfs. This
amounts to 3.7 cfs per mile of levee, or a total of about 78,900 acre-
feet along 29.2 miles of levee.
The seepage from Conservation Area 2 eastward and southward
through levees 35 and 36 is shown in figure 23, and seepage eastward
and southward through levees 29, 30, 33, and 37 of Conservation Area
3A and B is shown in figure 24. The estimated seepage during 1963,
180 cfs to the east for Area 2 and 388 cfs to the east and south for
Area 3A and B, averages 8.0 cfs and 9.6 cfs per mile, respectively.








BUREAU OF GEOLOGY


I-
fW







I
LJ
U


IL.
0


Z
z
:0
0
z

I--


-1300



-1200



-1100



-1000



-900


(/n
z
-800 _
.J
-J


-700
0

U)
z
-600 0

Ca
-J


-500



-400



-300



-200



-100


Figure 21. Nomograph of rainfall-storage relation in the three conservation areas


- 440


-420

-400


- 380


-360


-340


-320

-300

-280


-260


-240


-220


- 200

-180

-160


-140

-120


-100


- 80


-60

- 40


- 20






REPORT OF INVESTIGATION NO. 60


W OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.
1962 1963
Figure 22. Estimated seepage eastward from Conservation Area 1
through and under Levee 40. Discharge data furnished by
the U.S. Corps of Engineers

Using the above values of seepage for 22.5 miles of levee, northeast-
ern Broward County received about 130,300 acre-feet of water in 1963
from Conservation Area 2, whereas, for 40.35 miles of levee, southeast-
ern Broward and eastern and southern Dade counties received about
280,900 acre-feet from Conservation Area 3.
The shallow earth materials have low to moderate permeability
in the north and become moderately to highly permeable in the south
along the levees on the east side of the conservation areas, as indicated
by the seepage rates of 3.7 cfs per mile of levee from Area 1, 8.0 cfs
per mile of levee from Area 2, and 9.6 cfs per mile of levee from Area
3. The monthly seepages in table 5 from each of the three conservation
areas were derived from figures 22, 23, and 24. Throughout 1963 and
1964, the total amount of seepage for each year was greater during
November through February, the dry season, than during June through
September, the wet season, because of greater head differential during
the dry season. For each of the 2 years, the dry-season seepage was
178,460 and 280,400 acre-feet; the wet-season seepage was 143,360
and 242,200 acre-feet.






48 BUREAU OF .GEOLOGY








I I-





L I -
t 4



4 "1

SI CONSERVATION AREA 2 I

i I IIl ll

e 23. Estimated sewage southward and eastward from Conservation Area 2

through levees L-35 andDischarge measuremnta furnished by the U.S. Corps

a.


OCT NOVH DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.
962 1963
Figure 23. Estimated seepage southward and eastward from Conservation Area 2
through levees L-35 and L-36. Discharge data furnished by the U.S. Corps
of Engineers

A generalized water budget was developed for 1963 and 1964
for the combined water conservation areas using the 1963 seepage values
to determineduce flamount of the water that was lost by evapotranspiration.
Of the 4 million acre-feet available in 1963, 3.5 million acre-feet (86.8
percent) evaporated and transpired, and 490,200 acre-feet seeped to
the east and south. In 1964, of the 5 million acre-feet available, 3.6 mil-
lon acre-feet (70.5 percent) evaporated and transpired, and 734,500
acre-feet seeped to the east and south.
Major inflow, outflow, rainfall, seepage,,, change in storage, and
evapotranspiration for the three conservation areas are shown in table 6.
The discharge data for all the stations in existence during 1958-62 are
shown for comparison with the same type of data for these stations in 1963
and 1964. The evapotranspiration for 1963 and 1964 Was computed by
summation of the inflow, outflow, rainfall, change in storage and the
estimated seepage from table 5. For most average years, about 500,000
acre-feet of fresh water may be expected to seep eastward through the
levee system
The prime functions of the conservation areas are to store excess
water to reduce flooding of the area east of the levee systems during wet








Table 5 Estimated monthly and annual seepage
and L-29 from L-30 to L-67A.


in acre-feet 1 to the east and south through L-40, L-36, L-35, L-37, L-33, L-30,


Conservation Areas
Month 1 2 3A and 3B Totals
1963 1964 1963 1964 1963 1964 1963 1964

January 8,300 6,760 9,530 3,070 25,820 30,130 43,650 39,960

February 6,660 7,220 11,110 3,060 25,270 26,660 43,040 36,940
March 7,690 8,610 9,530 5,530 20,910 23,670 38,130 37,810

April 5,650 6,840 11,600 8,630 12,500 19,640 29,750 35,110

May 5,840 7,070 10,140 11,070 10,450 23,060 26,430 41,200

June 5,650 6,540 9,520 13,980 14,880 30,640 30,050 51,160
July 4,920 7,690 10,140 8,610 22,140 35,660 37,200 51,960

SAigust 5,230 7,070 9,530 15,060 20,600 37,510 35,360 59,640.

September 6,840 7,440 6,540 30,050 27,370 41,950 40,750 79,440
October 8,610 9,220 17,830 36,280 47,960 52,260 74,400 97,760

November' 6,840 8,930 15,170 44,330 28,560 48,790 50,570 102,050
December 6,760 7,990 9,840 40,890 24,600 52,570 41,200 101,450
Totals 78,990 91,380 130,480 220,560 281,060 422,540 490,530 734,480

1 One acre-foot equals 43,560 cubic feet.







kiadiuit Iii aIoru~Ii1et ulaowliii~ iiiiiiiuil inovenient ol water 1111(1 the three combined c~)I1uervilhioll imreem~,


Station 1958 1950 1960 1061 1062 1063 1964

2S5 856,300 557,000 336,300 104,2X00 188,600 117,200 360,500
S.6 189,400 166,000 184,000 43,200 60,300 61,600 148,300
S S- established 1 262,600 136,800 74,400 98,200
S-8 a established I 90,100 146,800
S-9 1 118,800 117,700 110,600 118,800 35,900 43,700 93,600
S.12 .939,700 2 .1,044,700 2'.1,163,400 *.162,200 4.32,700 4 .65,000 4 -15,400
S.34 -316,100 -215,700 -123,300 -600 0 -14,400 -3,500
E S.38 0 0 0 0 5 established 1 -18,600 .-20,700
S-39 -191,500 -200,500 -84,500 -73,400 -21,300 -19,200 -11,900

Rainfall 4,760,200 5,827,600 4,932,400 2,978,400 3,701,400 3,761,700 4,351,000
Subtotal 4,031,500 5,146,900
Note: Water budget not computed for 1958-62 due to construction and Storage Change 6 -43,400 6 -781,900
incomplete data, Negative signs indicate loss from conservation Seepage -490,500 -734,500
area, except for storage change.
Evapotranspiration 7 -3,497,600 7 -3,630,500

I First complete year of record.
2 Tamiami Canal outlet discharge, Levee 30 to 40-Mile Bend prior to construction of
Levee 29.
Established 2/9/62.
4 Total includes estimated seepage through Levee 29 between L-67-A and 40-Mile Bend.
Est ablished 7/3/61; assumed discharge to be zero for year. Prior record is zero because
flow was restricted by Levee 36.
6 Represents an increase in storage in the conservation areas.
7 Evapotranspiration computed from difference between subtotal and storage change -
computed seepage.






REPORT OF INVESTIGATION NO. 60 51

7 I I I .\ I -I- l l I -- I I |l


S-r











700 I \ -
900

S\ CONSERVATION AREA 3A AND 3B I \

\ I
500 -- Estimated -I \
o- \ o- \ I \-e

ad L 9 \ Discharge measurement/ i /
300 -



2oC nd De \ANI FB Mi A M t eec
100

OCT. NOV. DEC.d JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT OCT. NOV. DEC.
1962 1963
Figure 24. Estimated seepage southward and eastward from Con-
servation Areas 3A and B through levees L-37, L-33, L-30,
and L-29. Discharge data furnished by the U.S. Corps of
Engineers
periods and to release water during dry periods to minimize the effects
of droughts. Flooding along the urban coastal ridge during the wet years
of 1959 and 1960 would undoubtedly have been much greater had it not
been for the effectiveness of the drainage and flood-control practices of
the C&SFFCD.
In summary, the overall effects of building the eastern levees and
establishing the conservation areas are as follows: The levees prevent the
overland flow of flood water from the Everglades to the urbanized coast-
al areas, thereby reducing flooding there. By impounding excess water
in the conservation areas, runoff is delayed, and part of the excess is avail-
able as direct releases through canals or as -seepage from conservation
areas during the dry season to maintain water at favorable levels in the
coastal areas. -
During the -period of construction of the C&SFFCD system, urbani-
zation expanded into interior areas,. many of which were formerly un-






BUREAU OF GEOLOGY


suitable for habitation because of frequent flooding. Much of this low
land between the coastal ridge and the Everglades was covered by 2 to 3
feet of water for many weeks during 1947. By 1960, only part of the
flood-control works was in operation, but only parts of south Dade County
were significantly flooded from hurricane rainfall. Chances for flood
conditions comparable with those of 1960 have been minimized since
completion of the Flood-control works in south Dade County in the mid
196ffs.
CHANGES IN DISCHARGE FROM THE MAJOR CANALS

During the early stages of land reclamation in south Florida, the
major canals, including the Miami, North New River, Hillsboro, and
West Palm Beach canals, functioned primarily as drains to conduct water
out of the Everglades area. As drainage and reclamation progressed,
water-control structures and additional canals were constructed (fig. 1)
so that discharge from and water levels in the major canals could be con-
trolled and managed.
Adjustments in operation of canals and canal structures to meet
changing needs over the years have changed amount, timing, and distri-
bution of discharge from the primary canals since the early days of drain-
age- Changes in discharge of the major canals constitute one of the prin-
cipal indicators of the effect of water control and water management on
the water resources.
Because the Miami, North New River, Hillsboro and West Palm
Beach canals drain the Everglades and transect the coastal ridge, the an-
C I I I I I I
MIAMI CANAL 47
913

EIC a


1964 1 42 0 1940

U YA AG *44 4 1&


M RUNOFF YEAR. APRIL THROUGH MARCH


DISCHARGE, MILLIONS OF ACRE FEET
Figure 25. Generalized relation between annual rainfall at index sta-
tions in the area and discharge to the ocean from the Miami
Canal for runoff years 1940-64







REPORT OF INVESTIGATION NO. 60 53


nual discharge from each can be used as an indicator of present and past
(because of their long records) hydrologic conditions and effects of water
management.

A general relationship between annual rainfall and the discharge for
a runoff year (April through March) was determined by plotting the aver-
age annual rainfall for all index rain gages against the annual discharge
of the Miami Canal at N. W. 36th Street, Miami, figure 25. The resulting
graph is a rainfall-runoff rating curve that indicates little or no runoff if
annual rainfall is less than 37 inches, assuming a normal distribution pat-
tern within the year.

By subtracting 37 inches from the annual rainfall, the double-mass
curve relating "adjusted" cumulative rainfall at the index station to cumu-
lative discharge of the Miami Canal at N. W. 36th Street for each runoff
year was constructed, figure 26. The relation should plot as a straight line
for periods when there were no major water control or flood control changes
in the drainage basin. Two changes in slope occur, one around 1955 and
the other after 1960, each indicating a significant reduction of discharge
in the Miami Canal. The first major break occurred a few years after the
completion of the eastern levee system (levees 30 and 33) about 15 miles
upstream from the 36th Street control structure, and the completion of
So0 II I I I I I b IA


50 1960 /
500 -

In -


MIAMI CANAL '1955
-J
< S EXPLANATION
S300 -A 999.100 ACRE-FEET REDUCTION-
p IN DISCHARGE DURING 1956-65
1950 (AVERAGE ABOUT 99,900 ACRE-
W FEET ANNUALLY)
Sa8 850,700 ACRE-FEET ADDITIONAL
= 200-1947 REDUCTION IN DISCHARGE, 1961.
S- 65 (AVERAGE ABOUT 170.100
SACRE.FFFT ANNUALLYi


I 2 3 4 5 6 7 8 9 10 II
CUMULATIVE DISCHARGE, MILLIONS OF ACRE-FEET
Figure 26. Cumulative runoff-year discharge to the ocean from the
Miami Canal related to the adjusted cumulated annual
mean rainfall from the eleven index rain gages. Note the
change in slope beginning 1955 and 1960






BUREAU OF GEOLOGY


the two control structures (S-32 and S-32A) in the Miami Canal (fig. 1),
which regulate flow of the canal. The second break in slope occurred after
1960, when most of the control structures, spillways, and pumping sta-
tions of the C&SFFCD system were operational south of Lake Okeecho-
bee, and Levee 67A, which separated Conservation Area 3A from 3B,
was completed. The separation was made in order to reduce water levels
in Area 3B, thereby minimizing eastward seepage through levees 30 and
33 and seepage southward through the eastern reach of Levee 29.
The two major changes in the slope of the curve indicate reductions
in discharge of water to the ocean. The amount of water that would have
been discharged to the ocean is indicated in the upper right comer of figure
26 and is labeled A and B. The amount of discharge for the 10-year period
"A' (1956-65) was 999,100 acre-feet, averaging about 99,900 acre-feet
per runoff year, and the additional amount for the 5-year period "B"
(1961-65) was 850,700 acre-feet, averaging about 170,000 acre-feet
per runoff year. The total reduction in discharge of Miami Canal for the
10 years 1956-65, as shown in figure 26, was about 1.85 million acre-
feet, or about 185,000 acre-feet for each runoff year.
The annual rainfall (average for the long-term index gages) was
also compared with the combined discharge of the West Palm Beach,
Hillsboro, and North New River canals after adjustments were made to
account for inflow from Lake Okeechobee. The relation is shown in figure
27. A wide scattering in the plottings resulted, as did that for the Miami

iI I


9C WEST PALM BEACH, HILLS8ORO, AND NORTH NEW RIVER CANALS
47



Sa &4____1__________ -------_ ------ ---
S4599


I RIINI" YVAR APRIL THR02GH MARCH


0.4 0.8 L2 1.6 2.0 2.4 2.8
DISCHARGE, MILLIONS OF ACRE FEET
Figure 27. Generalized relation between the annual rainfall at index
stations in the area and combined discharge to the ocean
from the West Palm Beach, Hillsboro, and North New
River canals, for runoff years 1940-64






I I I I I I I I I I I I I I I I I I

1964 /
WEST PALM BEACH, HILLSBORO, AND NORTH NEW RIVER CANALS /64./ _
1960

/



400 3


/ EXPLANATION
/ A 1,998,200 ACRE-FEET REDUCTION IN
J I DISCHARGE FOR THE 1953-65 PERIOD I
3 I / BASED ON THE 1953-1957 TREND(AVERAGE
I ABOUT 153,700 ACRE-FEET ANNUALLY)
S1950 B 1,831,600 ACRE-FEET ADDITIONAL REDUCT-
SyION IN DISCHARGE FOR PERIOD 1958-65
(AVERAGE ABOUT 229,000 ACRE-FEET
ANNUALLY )



CONSERVATION AREAS EASTERN BOUNDARY LEVEES
COMPLETED MAY 1953.


100 WATER MOVEMENT TO OR FROM CONSERVATION
AREAS ABOUT 90 PERCENT CONTROLLED
1957.
01940


5 10 IS 20 25 30 33
CUMULATED ANNUAL DISCHARGE, MILLIONS OF ACRE-FEET
Figure 28. Cumulative runoff-year discharge to the ocean from the West Palm Beach, Hillsboro, and North New River canals related
to adjusted cumulated annual mean rainfall from the eleven index rain gages. Adjustments for inflow to and outflow from
Lake Okeechobee applied to runoff values






BUREAU OF GEOLOGY


Canal in figure 25, and, similarly, the curve indicated that little or no
runoff to the ocean would occur if rainfall was 37 inches or less. As a
matter of interest, an examination of several rainfall-runoff relations for
other discharge stations in southern Florida showed that flow to the ocean
approaches zero when rainfall is about 37 inches, suggesting that for most
years evapotranspiration is at least 37 inches.

By subtracting 37 inches from the annual rainfall (average of all
index stations) the double-mass curve relating "adjusted" cumulative
rainfall to cumulative discharge from the West Palm Beach, Hillsboro,
and North New River canals for runoff years 1940 to 1964 was construc-
ted, figure 28.
Similarly, as in the graph for the Miami Canal (fig. 26), the early
points plot as a straight line, and the data for more recent years defined
two changes in slope, which also indicate reductions in discharge to the
ocean. The first change in slope of the curve begins between 1952 and
1953, corresponding to completion of the eastern levees. The second
change begins after 1957, when most of the pumping stations and control
structures were completed, when the agriculture areas were established,
and when Conservation Areas 1 and 2 were enclosed by levees.
The total effects of all the changes in the three canals since 1953
may be summed up in an average and total reduction of discharge to the
ocean- The extended straight line on figure 28 shows what the discharge
would have been for the West Palm Beach, Hillsboro, and North New
River canals if no changes had been made. This projection indicates
that an average of 1,167,000 acre-feet would have been discharged for
each of the 13 years (1953-65), a total discharge of 15,171,000 acre-feet.
The actual total discharge from the three canals to the ocean for the 13-
year period was 11,341,000 acre-feet, or about 872,400 acre-feet per
runoff year. Therefore, the reduction in discharge over the 13 years
was 3,830,000 acre-feet, an average of about 294,600 acre-feet per
runoffyear. The total amount of discharge would break down into 1,998,200
acre-feet for the 13-year period "A" (1953-65), averaging 153,700 acre-
feet per year, and an additional reduction in discharge of 1,831,600 acre-
feet for the 8-year period (1958-65), averaging 229,000 acre-feet per
year. This total reduction in discharge would indicate a 25-percent reduc-
tion of the projected discharge to the ocean. The above discharge values
have been adjusted for inflow to and outflow from Lake Okeechobee to
the upper Everglades basin.
In summary, the four major canals, Miami, North New River, Hills-
boro, and West Palm Beach, drain the Everglades and transect the coastal
ridge. The discharge records on the four major canals date back to 1939
before changes by the C&SFFCD projects and can be used to detect






REPORT OF INVESTIGATION NO. 60


changes in hydrologic conditions or effects of water management. One of
the more significant changes noted was the reduction in seaward dis-
charge of fresh water coincident with the completion of levee systems east
of the three conservation areas. The reduction in flow to the ocean began
with the completion of these levees in 1953, resulting in reduction of dis-
charge to the ocean from the Miami Canal of about 185,000 acre-feet per
runoff year for 1956-65 and a reduction of discharge from the North New
River, Hillsboro, and West Palm Beach Canals of about 294,600 acre-
feet per runoff year for 1953-65.
Although the discharge records of the four major canals indicate a
25 percent reduction in annual discharge to the ocean, not all the salvaged
water is available for use. Additional canals have been constructed, such
as the Cutler Drain (C-100); most of the old canals such as Snapper Creek
and Snake Creek canals have been widened, deepened, and provided with
new control structures for flood protection. Consequently, the overall
reduction of fresh-water flow to the ocean in southeastern Florida since
1953 as a result of flood-control and water-management practices is about
20 percent.



WATER LEVEL CHANGES ALONG COASTAL RIDGE AND VICINITY

One principal effect of pre-1945 land-reclamation practices was
the lowering of ground-water levels throughout the coastal ridge and in-
terior areas. Water-level declines resulted from virtually uncontrolled
drainage from the four major canals that traverse the Everglades and the
coastal ridge. The West Palm Beach, Hillsboro, North New River, and
Miami canals conducted large quantities of water from the Everglades
to the ocean. In the coastal ridge area, the canals penetrate the permeable
Biscayne aquifer, and water from the aquifer drains to the canals when
canal levels are lower than the water table. In the early period when drain-
age continued throughout the dry seasons, some areas were overdrained,
allowing sea water to enter the canals and the aquifer and to migrate pro-
gressively inland, as shown by Parker, Ferguson, Love, and others (1955,
figure 169).
The lowest water levels of record occurred in May and June 1945,
the end of a prolonged drought and the end of the period of uncontrolled
drainage. The contour map in figure 29 portrays these conditions in Dade
County (Schroeder and others, 1958, fig. 14). It was during 1945 that
the greatest threat of sea-water contamination of Miami's water supply
system occurred, and remedial steps were taken to control flow in the
major drainage canals before the next dry season. The important features






BUREAU OF GEOLOGY


Figure 29. Map of Dade County showing contours of the low water
levels of record, May-June 1945 (from Schroeder and others,
1958, fig. 14)
of the contour map are the below sea-level elevations throughout the
southeast and southern parts of the county and the low eastward gradient
in the northern part.

Marked changes in hydrology took place during the 15-
year span beginning in 1950. Canals were extended inland for expanded
drainage. New canals were dug through the coastal ridge, and many ex-
tended inland to the eastern levee system to accommodate rapid urbani-
zation. Each new major canal was equipped with a gated control struc-
ture. The improved drainage lowered peak levels during the rainy season,






REPORT OF INVESTIGATION NO. 60 59


Figure 30. Map of Florida's lower east coast showing contours of low-
water conditions in May 1962 (adapted from Sherwood and
Klein, 1963, fig. 9 and McCoy and Sherwood, 1968, fig. 8)






BUREAU OF GEOLOGY


and the timely closing of the control structures at or soon after the rainy
season prevented overdrainage and excessive lowering of water levels,
thereby stabilizing the salt front in the aquifer in most areas. The contour
map in figure 30 shows water levels in southeastern Florida in May 1962,
the end of a prolonged drought that was comparable in intensity -to that
ending June 1945 (fig. 29). A comparison of the two maps shows that
the low levels in south Dade County in May 1962, although below sea
level were not as low as in 1945 and that the levels in middle and northern
Dade County were about 1 foot higher in 1962 than in 1945, despite the
fact that water use had multiplied many times during the 17 years.

In 1967 a new system of drainage canals was completed
in south Dade County, an area that had experienced flooding in 1947


Figure 31. Map of part of Dade County showing contours of the high
water conditions of September 1960






REPORT OF INVESTIGATION NO. 60


Figure 32. Map of Florida's lower east coast showing contours of the
high water conditions of June 1968






BUREAU OF GEOLOGY


and 1948, 1954, and 1960. The high-water conditions resulting from two
tropical storms in September 1960 are shown on figure 31. Water-level
peaks exceeded 10.5 feet above mean sea level in the high parts of the
ridge, sheet flow occurred through the transverse glades, and much of
the coastal marsh east of the ridge was flooded.
The flooding in south Dade County brought about a high priority
for completing the drainage system there. That system was nearly com-
pleted by the end of 1968 and is shown in figure 32 in the area south of
Canal 2 (Snapper Creek Canal). The effectiveness of the system in
preventing floods is shown by the water-level contours for June 1968
(fig. 32), which show conditions after rainfall of nearly 16 inches in
May and more than 15 inches at Homestead during the first 20 days of
June 1968. Drainage by the canals resulted in local ground-water mounds
in the intercanal areas rather than a high elongate mound, as was shown
for September 1960. No flooding resulted from the May-June 1968 rain-
fall in Dade County, though the rainfall was greater than that during the
September 1960 storm.


10 II 12 13 14 15 16 17 18 19 20 21
JUNE 1961
4 f I I
WELL S-182














5 6 7 8 9 10 II 12 13 14 15 16
SEPTEMBER 1965
Figure 33. Hydrographs of well S-182 showing water-level recession
rates before and after construction of Canal 1






REPORT OF INVESTIGATION NO. 60


The effects of the new canal system and flood-control practices on
the hydrology of south Dade County were also marked by a change in
the recession rate of water levels. Figure 33 shows selected graphs of
sections of the water level recorded at well S-182, a short distance north
of Canal 1 (see figure I for location), to contrast the recession rates before
and after Canal 1 was completed and the salinity control S-21 was ac-
cepted. The graphs show that the rate for part of June 1961 (pre-canal
construction) was about 0.2 foot per day, half the 0.4 foot per day rate
of September 1965.
Long-term records of fluctuations of ground-water levels and general
water-level trends from observation wells provide the most valuable
information to aid in determining changes in water levels caused by
the flood-control and water-control practices. Scattered records of
water levels and reports of general hydrologic conditions in different
areas, as reported by Parker, Ferguson, Love, and others (1955, p. 500-
585), indicate that water levels were near or at the land surface along
much of the coastal ridge area before drainage. Detailed records of water-
level fluctuations since 1940, as reported by Kohout and Hartwell (1967,
p. 25-27, fig. 13), show the adjustment of ground-water levels to water-
control activities in subsequent years and that water levels are generally
several feet below land surface. The records show that in the northern
half of Dade County the yearly water-level peaks were lowered, espec-
ially after 1954, and a small but gradual rise in annual minimum levels
occurred in certain areas.
General changes in water levels and the patterns of fluctuations
along and immediately west of the coastal ridge in Broward County are
shown on figure 34 by the hydrograph of well G-616, near Pompano
Beach. The apparent changes are an increase in the rate of fluctuations


Figure 34. Hydrograph of well G-616 in Broward County






BUREAU OF GEOLOGY


1940 45 1950 55 60 65 1969
Figure 35. Hydrographs of selected observation wells in southern Dade County






REPORT OF INVESTIGATION NO. 60


beginning about 1958 and the lowering of the annual minimum levels.
The first downward trend in minimum water levels began in 1955 and
generally coincides with the completion of the canal system west of
Pompano Beach, which connected with the Pompano Canal (C-14). The
second downward trend in minimum water levels began in 1965, when
the drainage system for a large community northwest of Pompano Beach
was connected to the Pompano Canal.
Inspection and analysis of long-term water-level records in other
parts of the coastal ridge also show changes in trends, in magnitude of
fluctuations, and in recession rates. Figure 35 shows hydrographs of
five observation wells in southern Dade County, wells F-319, S-196,
G-596, G-614, and G-620. Locations of wells are shown in figure 1.
The hydrograph for well F-319, near the coast south of Miami,
shows the marked moderation of the height of annual water-level peaks
since the 1947 record high and-an upward trend of the minimum levels.
These changes in the pattern of fluctuations are a result of water-control
practices in Snapper Creek Canal (C-2). Even during the extreme rain-
fall of September 1960, flooding in the urbanized areas of the Snapper
Creek Canal basin was minimal or nonexistent. The upward trend in
minimum levels is the result of two factors: (1) the ability of the Snapper
Creek Canal and its secondary canal system to pick up ground water
in the interior reach and convey it eastward, thereby maintaining rela-
tively high levels in the coastal reach to combat sea-water intrusion;
(2) improved water-control practices brought about by increased ex-
perience in control-structure operations resulted in a decrease in fresh-
water discharge to the ocean and a slowdown in the recession rate of water
levels.
The hydrograph for well G-596 (fig. 35) west of Levee 31 shows
the changes in water level in the interior areas as a result of the con-
struction of the levee system around the conservation areas, the exten-
sion of Black Creek Canal (C-1) inland to the levee system, and the sub-
sequent flood-control and water-control practices in the area drained
by C-1. The 1952-60 water levels for well G-596 shows a slight rise,
probably in part of a result of construction of the eastern levee system
and the resultant southward diversion of surface flows. The record for
1962-68 shows a distinct downward trend. The annual minimum levels
are as much as 1.0 to 1.5 feet lower than earlier minimums, and the
annual peak levels are as much as 0.5 foot lower than those for the pre-
ceding period. These lowered water levels are significant because they
are the difference between flooding and not flooding in the area, which
has enabled the establishment of new farmlands in the vicinity of Levee
31. The annual magnitude of fluctuations for 1962-68 is considerably






BUREAU OF GEOLOGY


increased from that observed in the earlier period of record. The down-
ward displacement of water levels and the increase in the magnitude of
fluctuations are the result of: (1) below-normal rainfall during part
of the period, particularly 1962-63; (2) the draining effect of the Black
Creek Canal (C-1), which picks up water from the vicinity of well G-596
and conducts it to the coast; (3) completion (1962) of the eastern sec-
tion of Levee 29 along the south boundary of Conservation Area 3B,
which prevented southward overland flow from Conservation Area 3B.
The hydrographs for wells S-196 and G-614 in southern Dade
County indicate a lowering of annual minimum levels during 1962-68;
however the lowering was not so pronounced as that observed in the
vicinity of well G-596. The lowering of ground-water levels in southern
Dade County, as indicated in the hydrographs of wells S-196 and G-
614, may have been the result of the drainage by the Black Creek Canal
(C-i), because those two wells are south of and, in part, downgradient
from the Black Creek Canal (C-1); and lowering of levels owing to drain-
age by C-I will be reflected in the levels in areas to the south. Canals
102 and 103 were operational in 1967, but sufficient time has not
passed to determine the incremental effect that those canals have had on
adjacent ground-water levels.
In the highly permeable aquifer of eastern Dade County, the canal
system has effectively lowered water levels, thereby aiding in the pre-
vention of major flooding. Many of the canals extend long distances
inland to the Everglades and drain areas of relatively high water levels.
Drainage of Everglades water through the canals has resulted in lower-
ing inland water levels and raising levels near the coast. One overall
hydrologic result is a reduction of the water-level gradient throughout
the area east of the levee system.
A complete evaluation of the effects that water management dur-
ing 1962-68 had on hydrologic conditions is beyond the scope of this
report, but indications are that they have been effective in flood con-
trol and water availability and that works in progress will increase its
effectiveness. Owing to a prolonged period of below-average rainfall,
which began after Hurricane Donna in the fall of 1960, surplus water
was not available to manage until 1966, a year of above-normal rain-
falL Sufficient water was retained in the management system after the
1966 rainy season to permit major but gradually reduced releases to
the Everglades National Park throughout the subsequent dry season
and to maintain adequate water levels along the coast.
Flood benefits of the new canal system in south Dade County were
realized at the beginning of the rainy season of 1968, when rain in ex-
cess of 32 inches fell during May and June. Without the canal system,







REPORT OF INVESTIGATION NO. 60


inundation equaling or exceeding 1947-48 and 1960 conditions would
probably have occurred. (Compare figs. 31 and 32 in south Dade County.)

CHANGES IN WELL-FIELD AREAS AND SEA-WATER INTRUSION

A prime objective for water management is to hold additional
water in the conservation areas by reducing flood flow to the ocean.
This should insure that water deliveries to the coastal sections of the


BISCArNE CUL


0
LITTLE RWlER CAN41

a LA STN
M, eAMI WAIER

p 36NTH


551M


MIAM


. .(


Figure 36. Maps of the Miami area in eastern Dade County showing
the sea-water encroachment at the base of the Biscayne
aquifer 1904-69 (Parker, Ferguson, Love, and others, 1955,
p. 589, Kohout, 1961, Leach and Grantham, 1966) updated


CRE EK






BUREAU OF GEOLOGY


Biscayne aquifer are adequate during dry seasons to prevent further
sea-water intrusion and to provide replenishment to well fields by in-
filtration from the canals. If this objective is satisfied, then hydrologic
conditions in inland areas and in the Everglades National Park should
improve.
Sea-water intrusion and its control have been problems in develop-
ing the water resources of southeastern Florida. Parker, Ferguson, Love,
and others (1955, p. 571-711) presented a detailed history of sea-water
intrusion in southeastern Florida. Figure 36 updates their presentation
(1955, fig. 169) of the progressive movement of salt water into the
Biscayne aquifer in the Dade County area. It is apparent that further
intrusion has not been significant since 1962, indicating that adequate
coastal water levels have been maintained in the aquifer. As water
demands increase in the future, however, sea-water intrusion may again
become significant unless more water is furnished from interior storage
areas, especially during dry periods.

The major long-established municipal well fields are located along
the coastal ridge but at sufficient distances from the coast and upstream
from water-control structures to be protected from sea-water intrusion.
Figure 37 shows the locations of and daily pumping rates in the large
municipal well fields in southeastern Florida in late 1970 and their
locations with respect to the area affected by sea-water intrusion. Most
fields are located upstream from the control structures in canals to
facilitate infiltration of fresh water from the canals. Infiltration from
the canals to the well fields minimizes drawdown caused by pumping,
thereby reducing the possibility of inland gradients and salt-water intru-
sion in the vicinity of the well fields.

Because of the critical hydrologic conditions in the vicinity of
the major well fields and the past experiences of sea-water intrusion in
well fields of Miami and Fort Lauderdale, intensive investigations of
large well fields have continued for more than 20 years. Analyses of
hydrologic conditions in well fields before and after water control and
management indicate their effectiveness. -

MIAMI MUNICIPAL WELL FIELDS
The Miami municipal well field, adjacent to the Miami Canal at
Miami Springs (fig. 37) was placed into service in 1925 and yielded
water of low chloride content until April 1939, when wells near the
Miami Canal began to yield salty water (Parker, Ferguson, Love and
others, 1955, p. 691). The source was salty water that had moved up-
stream in the uncontrolled canal to the vicinity of the well field and had
infiltrated laterally through the aquifer. Contamination in the field







REPORT OF INVESTIGATION NO. 60


EXPLANATION
E--i
EXTENT OF SEA-WATER INTRUSION
AT BASE OF AQUIFER

MAJOR WELL FIELD PUMPAGE
MILLION GALLONS PER DAY


Figure 37. Map of Florida's lower, east coast .showing the major1 well
fields and their pumping rates in million gallons per day
Near the: end of 1970; and the extent of seawater encroach-
ment at4the:baseof the Biscayne aqiufer






BUREAU OF GEOLOGY


Figure 38. Map of the Miami well field showing water levels and
chloride conditions June 29, 1945 during uncontrolled con-
ditions of Miami Canal
remained a problem through 1945. The contour map in figure 38 shows
water-level and chloride conditions in the well field on June 29, 1945,
the end of a prolonged drought. The highest water level in the well-
field area was 0.4 foot above mean sea level, and the hydraulic gradient
was inland and toward the centers of pumping, where water levels were
nearly 3 feet below sea level. The pattern of the choloride lines shows
that tongues of salty water had moved up the uncontrolled Miami Canal
and had infiltrated vertically into the aquifer and laterally toward the
areas of greatest water-level drawdown. Pumpage in the well field at
the time was 30 mgd.
In 1946 a control structure of sheet steel piles was built in the Miami
Canal at N. W. 36th Street to prevent the inland movement of salt water.
During the rainy seasons the control was opened to permit discharge of
surplus water, but after the flood seasons the control was closed to pre-
vent overdrainage and excessive lowering of water levels. As a result,
water levels in the well field were maintained at higher levels during dry
seasons, and the areas contaminated by salt water were gradually fresh-
ened.


I .,






REPORT OF INVESTIGATION NO. 60


Figure 39. Map of the Miami well field showing water levels and
chloride conditions April 7, 1966 during controlled condi-
tions of Miami Canal

Figure 39 is another contour map of the Miami well field area that
shows water-level and chloride conditions during the dry season of
1966, so that comparison can be made with the uncontrolled condition
in 1945. Pumpage in the well field during the dry season of 1966 was
80 mgd, the control structure at N. W. 36th Street was closed, and a
water level of 2 feet above mean sea level was being maintained along
the controlled reach of the canal. The contours show that the canal was
replenishing the well field by downward and lateral infiltration into the
aquifer. A general appraisal shows that as a result of the general rise
in water level at the control structure, pumpage of 80 mgd in 1966 pro-
duced about the same minimum water level in the withdrawal centers
as pumpage of 30 mgd in June 1945. Also, under the 1966 condition,
sea water was not intruding the aquifer. Sea water did intrude in 1945.
In 1968 additional supply wells on the north side of the Miami
Canal were added to the municipal system, thereby increasing the
capacity of the well field from 80 to 130 mgd. Planned modifications





BUREAU OF GEOLOGY


and additions to the northwest will boost the yield of the well field to
more than 200 mgd in the next few years. As long as adequate quantities
of water are available by eastward seepage or by releases from Con-
servation Area 3 into the upper reach of the Miami Canal to maintain
adequate fresh water levels at the 36th Street control structure, the well
field is expected to yield its capacity without significant inland advance
of salt water in the Miami Canal basin. However, the threat of sea-water
intrusion to the well field also persists from the south, from the pre-
sently uncontrolled reach of the Tamiami Canal. If no further lowering
of water levels occurs in the southern part of the well field, the salt
water there should not advance toward the well field. A permanent
control structure, to be provided by a recent (1969) decision, in the
Tamiami Canal near its confluence with the Miami Canal should give
further protection to the well field.
Because the permanence of the well field depends upon replenish-
ment from the inland part of the basin and from the water conservation
areas during drought, management of the water in the Miami Canal
basin during future years will be a key to the protection of the well field.
Water-level contour maps, such as the map of May 1962 (fig 30),
that depict hydrologic conditions in Dade County at the end of pro-
longed droughts, show characteristic low levels and a nearly flat hydrau-
lic gradient in the northern part of the county from the levee eastward
to the coast, about 15 miles. The low gradient is the result of effective
drainage by the primary canals and the extensive network of secondary
canals connected to the Miami and Snake Creek canals, as shown in
figure 30. Water levels are regulated by a single control near the coast
in each of the primary canals.
To minimize flooding in low lying residential areas along the
coastal ridge, it is necessary to reduce water levels in inland areas there-
by reducing the amount of water in aquifer storage available for use
during the dry seasons and partly negating the replenishment bene-
fits of rainfall. For several years this method of water control served
the basic needs of flood control and the stabilization of sea-water intru-
sion; however, the practices have resulted in progressively greater
reliance on water in the conservation areas each year as the source of
aquifer replenishment in the coastal area during dry seasons. The rate
at which municipal needs are increasing suggests that in the near future,
replenishment from the conservation areas by itself might not be ade-
quate to fulfill all demands required to protect the water resources
during prolonged drought.
The Alexander Orr-Southwest well-field complex of Miami was
placed into operation in the early 1950's, when moderate quantities of





REPORT OF INVESTIGATION NO. 60


Figure 40. Maps of the Alexander Orr and Southwest well field areas
of the City of Miami showing water-level conditions March
21, 1951 (A) and May 24, 1962 (B) (from Sherwood and
Leach, 1962, fig. 17 and Sherwood and Klein, 1963, Fig. 8)






BUREAU OF GEOLOGY


water were pumped from a cluster of wells about half a mile north of
the Snapper Creek Canal (Canal 2). Figure 40A shows the small cone
of depression in the water table that formed as a result of moderate pump-
ing of 6.7 mgd (Sherwood and Leach, 1962, fig. 17) on March 21, 1951,
during the dry season. That cluster of wells (Orr well field) served the
growing urban area south of Miami; but, because of rapidly increasing
demands during the late 1950's, additional high-capacity wells south of
the canal and 4 miles west of the original cluster were placed into opera-
tion. The well field to the west, the Southwest well. field, comprised 6
wells each capable of pumping 10 mgd. The Southwest field was the
primary source, and the Orr well field was used as a reserve to make up
peak demands during the tourist season and prolonged droughts. How-
ever, after Klein (1958) indicated that the Orr reserve field could be
pumped at capacity safely on a permanent basis, the bulk of the with-
drawals for the increased demands south of Miami was shifted to the
Orr well field, and the Southwest field was placed on reserve status.
The effect of heavy municipal pumping in the Orr field, 42 mgd, and
in the Southwest field, 28 mgd, near the end of a prolonged drought in
May 1962 is shown in figure 40B (Sherwood and Klein, 1963, fig. 8).

Since 1962 the capacity of the Orr field has been increased to 60
mgd (10 wells), and plans call for maximum withdrawal of about 300
mgd from the Southwest well field. These quantities can be withdrawn
from that area because of the following safety factors related to the
Snapper Creek Canal system: (1) The canal extends westward and
northward connecting with the Tamiami Canal, which, in turn, extends
to Conservation Area 3, thereby assuring a source of replenishment to
the canal for maintaining high levels at the coastal control structure and
for infiltration to the well field; (2) the coastal control structure has been
efficient, and loss of water is minimal during dry seasons (Kohout and
Hartwell, 1967, p. 40-42); and (3) because the spur canal east of the
Orr field (fig. 40) is connected to the Snapper Creek Canal, its water
level is the same as that of the Snapper Creek Canal and, therefore, it
is a source of aquifer replenishment, which minimizes the eastward
expansion of the cone of depression formed by well-field pumping and
stabilizes the movement of salt water in the aquifer between the well
field and the coast. Water-level measurements in the Orr-Southwest
well-field area in dry seasons during 1966-68 indicated that when pump-
ing was increased to 65 mgd the cone was deepened only by about 1 foot.

FORT LAUDERDALE WELL FIELDS
Some of the more marked hydrologic changes over the years have
occurred in the Prospect well-field area of Fort Lauderdale, located
between the Pompano Canal (Canal 14) and the Middle River Canal






REPORT OF INVESTIGATION NO. 60


Figure 41. Map of southeastern Broward County showing water-level
conditions February 15, 1941 (adapted from Sherwood,
1959, fig. 9)


(Canal 13). Sherwood (1959, fig. 9) mapped water levels in eastern
Broward County in 1941 before intensive drainage and urbanization
and before establishment of the Prospect well field. Those early levels
are shown in figure 41 so that comparisons can be made with levels
after development. The Prospect well field was placed in operation






BUREAU OF GEOLOGY


Figure 42. Map of the Oakland Park area of Broward County showing
water-level conditions in the Prospect well field August 7,
1956 (from Sherwood, 1959, fig. 11). The total pumpage for
the Prospect well field was 7 mgd




about 1955 when Fort Lauderdale was experiencing its greatest growth
rate. Figure 42 (Sherwood, 1958, fig. 11) shows the effect that canal
drainage and pumping the original 10 municipal wells at more than 7
mgd had on water levels in that area in 1956. This map, when compared
with that of figure 41 for 1941, and that of figure 43 for 1968, indicates
the large changes in water levels and water-table configuration that
resulted over the years as a result of increases in withdrawals, changes
in the pattern of pumping, and changes in canal systems and control
structures. The pumping rates that produced the cones in figure 43 were
30 mgd from the supply wells and 5 mgd from the rock pit in the western
part of the field.






REPORT OF INVESTIGATION NO. 60


Figure 43. Map of the Oakland Park area of Broward County show-
ing water-level conditions in the Prospect well field April
18, 1968 (map prepared by H. J. McCoy). The Pumpage
from the Prospect well field was 30 mgd and the western
rock pit was 5 mgd


The Prospect well field has had a history of sea-water intrusion
(Sherwood and Grantham, 1966) in its southern part; however, structures
to combat the intrusion are scheduled for completion in the near future.
These structures include a feeder canal (fig. 43), which will connect with
the Middle River Canal upstream from the control structure (Sherwood
and Klein, 1963, fig. 4). The purpose of the connection is to increase
replenishment to the well field, and, because the feeder canal will be
controlled at a point seaward of the well field, water levels in the area
formerly intruded by sea water will be raised, thereby retarding further
inland movement of salt water.
Other municipal well fields of large capacities are shown in figure






BUREAU OF GEOLOGY


37. The map indicates the pumping rate of each of the well fields in
November 1970 and shows the position of each field in relation to the
inland extent of water containing 1,000 mg/1 (milligrams per liter)
chloride near the base of the Biscayne aquifer. In addition, other smaller
municipal well fields and many supplies for individual housing develop-
ments, not shown in figure 37, are scattered throughout the lower east
coast.
The capability of maintaining high water levels along the eastern
perimeter of the Lake Worth Drainage District in eastern Palm Beach
County (fig. 46 for location) during dry seasons through water-control
practices, insures that a dependable source of replenishment will be avail-
able to the shallow aquifers along the urban coastal area and that ground-
water levels sufficient to retard sea-water intrusion can be maintained.
Municipal well fields along the 30-mile coastal strip from Boca Raton
northward to West Palm Beach, therefore, have a built-in system of
ground-water replenishment, whereby the water-control practices that
benefit agriculture in the inland area offer concurrent benefits to the
expanding urban areas. So long as water-management practices in the
area remain effective and the quality of the water that replenishes the
shallow aquifer remains acceptable, the ground-water supplies should
be sufficient for future needs.
A large part of the water released from Conservation Areas 1 and
2 into primary canals in Palm Beach and Broward counties is channeled
into equalizer and lateral canals to maintain water levels for irrigation
in the Lake Worth Drainage District and other agricultural districts
bordering the eastern Everglades. The water-level map in figure 44
(McCoy and Hardee, 1970, fig. 14) shows the effect that maintaining
water levels in canals in the southern part of the Lake Worth Drainage
District (area west of Canal E-3) has on ground water in the Boca Raton
area. On April 12, 1967, near the end of the dry season, the water level
in Canal E-3, was about 10 feet above sea level, and water from the
canal was seeping eastward under a high gradient. The contours show
that the eastward seepage in the southern part of Boca Raton was being
discharged into the uncontrolled reach of the Hillsboro Canal and El
Rio Canal, whereas the seepage in the northern part of the city was being
discharged to the controlled reach of El Rio Canal (above the control
structure), and part of that seepage was being diverted toward the pump-
ing wells in the well field.
The rate of eastward seepage from Canal E-3 depends in part
upon the permeability of the shallow water-bearing materials. The
quantity of seepage can be estimated by the equation: Q=TIL, where Q
is the quantity of seepage, in gallons per day, T is the transmissivity
of the aquifer, in gallons per day per foot,- I is the hydraulic gradient,






REPORT OF INVESTIGATION NO. 60


Figure 44. Map of the Boca Raton area showing water-level contours
during the low water conditions of April 12, 1967 (from
McCoy and Hardee, 1970, fig. 14)

in feet per foot, and L is the length of the flow section in feet. McCoy
and Hardee, (1969, p. 25) determined that the transmissivity of the
shallow aquifer west of Boca Raton is about 380,000 gpd/ft. Substi-
tuting that value in the equation and inserting the water-table gradient
that prevailed east of Canal E-3 on April 12, 1967 (7 feet in 11,000
feet) it was determined that the rate of eastward underflow along the
5-mile section between Canal L-38 and Canal L-47 was 6.4 mgd near
the end of the dry season of-1967.






BUREAU OF GEOLOGY


Schroeder and others (1954, p. 11-14) determined that the trans-
missivity of the shallow aquifer in Delray Beach to the north is apprec-
iably less than in the area of Boca Raton, indicating that the ability of
the shallow aquifer to transmit water decreases northward from Boca
Raton. Therefore, eastward seepage from the Lake Worth Drainage
District probably is proportionately less in the north than it is in the
south, and the yield of wells is smaller in the north.
The annual quantity of fresh water discharged to tidewater by the
West Palm Beach Canal represents excess water within the drainage
basin under management operations. Figure 45 graphically relates be-
tween the average discharge to the ocean of the West Palm Beach Canal
and the average rainfall measured at Loxahatchee and the West Palm
Beach Airport. The discharge ranged from about 220 cfs in 1956 to
more than 1500 cfs in 1947 and 1948. It is apparent from the graph of
the discharge, that a reduction of total flow to the ocean occurred after
1955, when Pumping Station 5A began operation. The graph also
shows that the increment of flow brought in by agricultural and drainage
canals and by ground-water inseepage along the 20-mile reach east of
the pumping station constitutes a significant part of the total canal flow.

Even during years of deficient rainfall, such as 1955-56 and 1961-
63, some discharge to the ocean took place. The discharge from the
West Palm Beach Canal also represents a part of the fresh-water poten-
tial of the basin and is the quantity of water that can be used for munici-
pal and other purposes without causing further decrease of fresh water
in storage under present conditions. As water requirements increase
with time, water-management practices will be directed toward incre-
mental decreases in discharge of the West Palm Beach Canal and the
probable increase in utilization of Lake Okeechobee and Conserva-
tion Area 1 for water storage and delay of runoff by backpumping.


THE COURSE AND COMPROMISES OF
FUTURE WATER DEVELOPMENT

Earlier parts of this report describe the sequence and nature of
past water-development works and how each has altered the manner
in which water occurs, moves, is stored and released, is lost to the at-
mosphere, is utilized by man, and is disposed. Increasing water require-
ments will require new works and further changes in hydrologic pat-
terns. As with existing canals, control works, levees, pumps, well fields,
treatment plants, and pipe lines, each new facility will be designed to
improve land use and (or) make greater quantities of water of adequate
quality available in certain areas during drought. Many of the new facil-






REPORT OF INVESTIGATION NO. 60 81


ities, iri addition, will be placed or designed with a new purpose: that
of protecting or enhancing the environment.
The design and loca-ion of many of the new facilities will be dif-
ficult. Greater water storage for dry periods often is accomplished only
at some sacrifice to land use. During extreme drought the competition
for water among localities will be more severe. Public demands for
environmental protection will require allocation of water to sustain the
ecology in specified areas. New works interspersed with the older will
certainly add to the complexity of water management.
Successful location, design, and operation of facilities also will
require greater knowledge of the water system on which it is imposed
and will alter it to varying degrees. Hydrologic knowledge gained in
one water system may be utilized beneficially in considering further
works affecting another system.


AVERAGE FOR LOXAHATCHEE
AND WEST PALM BEACH AIRPORT
Un
z
100-

J
z. -



0
1941 45 50 55 60 65 1968


2500
oz PICKUP BETWEEN S-SE AND OCEAN
0
) 2000-
mU



U. -70









Figure 45. Graphs relating rainfall to the discharge of the West Palm
Beach Canal to the ocean, 1941-69. Also shown is the pickup
of flow in the canal reach below S-5E from 1956
of flow in the can al reach below S-5E from 1956






BUREAU OF GEOLOGY


The primary purpose of this chapter is to relate previous experi-
ence with the hydrologic characteristics of water systems in south Flor-
ida to some of the alternatives for further water-development works.
No recommendations are made by the authors for or against specific
development works. Their only contribution is to report upon the hy-
drology of the present system and to predict the changes that may result
from various types and locations of new works under consideration.
Certain segments or features of actual development plans or pro-
posals for water-development works in particular locations have been
selected to illustrate the probable impact of specific works on water
systems.

DEVELOPMENTAL PLANS

Several plans of improvement for drainage and enhancement of
the water resource through careful management have been proposed
from time to time.

IMPLEMENTATION OF AREA B AND EAST
COAST BACKPUMPING PLANS

The plan by the Corps of Engineers (1958) for development of Area
B, the area east of the levee system in northern Dade and southern
Broward Counties (fig. 46), is basically a flood-control plan. Nonethe-
less, the plan for Area B ". will have considerable potential for
conservation of fresh water," (Kohout and Hartwell, 1967, p. 59). Back-
pumping to the conservation areas a part of the plan would reduce
canal discharge to the ocean. Some hydrologic effects of backpumping,
disregarding the quality of the backpumped water, would be as follows:
(1) reduction in amount and duration of wet-period discharge to the
ocean; (2) lowering of peak levels and an equalization of water levels
east of the levee system; (3) reduction of total runoff to the ocean; (4)
delay in water-level recession in the conservation areas; (5) early clos-
ing of coastal control structures; (6) ability to maintain proper water
levels at coastal structures for longer periods to retaid sea-water intru-
sion; and (7) utilization of the aquifer system as a water-storage reser-
voir. Kohout and Hartwell (1967 p. 42) suggested the use of supple-
mental pumps (100-400 cfs capacity) at the west and east sides of Area
B and control structures in canals at the east side of Area B for flexi-
bility of water control during periods of intermediate water-level con-
ditions. They further suggested that when Conservation Area 3 is dry,
the east-side pumps would help maintain levels along the urban coast
by pumping seaward from the Area B canals.






BUREAU OF GEOLOGY


Schroeder and others (1954, p. 11-14) determined that the trans-
missivity of the shallow aquifer in Delray Beach to the north is apprec-
iably less than in the area of Boca Raton, indicating that the ability of
the shallow aquifer to transmit water decreases northward from Boca
Raton. Therefore, eastward seepage from the Lake Worth Drainage
District probably is proportionately less in the north than it is in the
south, and the yield of wells is smaller in the north.
The annual quantity of fresh water discharged to tidewater by the
West Palm Beach Canal represents excess water within the drainage
basin under management operations. Figure 45 graphically relates be-
tween the average discharge to the ocean of the West Palm Beach Canal
and the average rainfall measured at Loxahatchee and the West Palm
Beach Airport. The discharge ranged from about 220 cfs in 1956 to
more than 1500 cfs in 1947 and 1948. It is apparent from the graph of
the discharge, that a reduction of total flow to the ocean occurred after
1955, when Pumping Station 5A began operation. The graph also
shows that the increment of flow brought in by agricultural and drainage
canals and by ground-water inseepage along the 20-mile reach east of
the pumping station constitutes a significant part of the total canal flow.

Even during years of deficient rainfall, such as 1955-56 and 1961-
63, some discharge to the ocean took place. The discharge from the
West Palm Beach Canal also represents a part of the fresh-water poten-
tial of the basin and is the quantity of water that can be used for munici-
pal and other purposes without causing further decrease of fresh water
in storage under present conditions. As water requirements increase
with time, water-management practices will be directed toward incre-
mental decreases in discharge of the West Palm Beach Canal and the
probable increase in utilization of Lake Okeechobee and Conserva-
tion Area 1 for water storage and delay of runoff by backpumping.


THE COURSE AND COMPROMISES OF
FUTURE WATER DEVELOPMENT

Earlier parts of this report describe the sequence and nature of
past water-development works and how each has altered the manner
in which water occurs, moves, is stored and released, is lost to the at-
mosphere, is utilized by man, and is disposed. Increasing water require-
ments will require new works and further changes in hydrologic pat-
terns. As with existing canals, control works, levees, pumps, well fields,
treatment plants, and pipe lines, each new facility will be designed to
improve land use and (or) make greater quantities of water of adequate
quality available in certain areas during drought. Many of the new facil-








REPORT OF INVESTIGATION NO. 60


-'3 ~3
4. -



4 -J

6


C-2
L-30
S-J Pumping station

19a .



0 5 10 WLCS
I I I


Figure 46. Map of southeastern Florida showing locations of the Area
A, Area B, and southwest Dade area in relation to the Cen-
tral and Southern Florida Flood Control District works






BUREAU OF GEOLOGY


The primary purpose of this chapter is to relate previous experi-
ence with the hydrologic characteristics of water systems in south Flor-
ida to some of the alternatives for further water-development works.
No recommendations are made by the authors for or against specific
development works. Their only contribution is to report upon the hy-
drology of the present system and to predict the changes that may result
from various types and locations of new works under consideration.
Certain segments or features of actual development plans or pro-
posals for water-development works in particular locations have been
selected to illustrate the probable impact of specific works on water
systems.

DEVELOPMENTAL PLANS

Several plans of improvement for drainage and enhancement of
the water resource through careful management have been proposed
from time to time.

IMPLEMENTATION OF AREA B AND EAST
COAST BACKPUMPING PLANS

The plan by the Corps of Engineers (1958) for development of Area
B, the area east of the levee system in northern Dade and southern
Broward Counties (fig. 46), is basically a flood-control plan. Nonethe-
less, the plan for Area B ". will have considerable potential for
conservation of fresh water," (Kohout and Hartwell, 1967, p. 59). Back-
pumping to the conservation areas a part of the plan would reduce
canal discharge to the ocean. Some hydrologic effects of backpumping,
disregarding the quality of the backpumped water, would be as follows:
(1) reduction in amount and duration of wet-period discharge to the
ocean; (2) lowering of peak levels and an equalization of water levels
east of the levee system; (3) reduction of total runoff to the ocean; (4)
delay in water-level recession in the conservation areas; (5) early clos-
ing of coastal control structures; (6) ability to maintain proper water
levels at coastal structures for longer periods to retaid sea-water intru-
sion; and (7) utilization of the aquifer system as a water-storage reser-
voir. Kohout and Hartwell (1967 p. 42) suggested the use of supple-
mental pumps (100-400 cfs capacity) at the west and east sides of Area
B and control structures in canals at the east side of Area B for flexi-
bility of water control during periods of intermediate water-level con-
ditions. They further suggested that when Conservation Area 3 is dry,
the east-side pumps would help maintain levels along the urban coast
by pumping seaward from the Area B canals.






BUREAU OF GEOLOGY


During prolonged drought after urbanization is completed, it may
be necessary to pump water from aquifer storage west of the levee
system into the Area B canals to furnish water to the coastal area.
Possibly, pumping from aquifer storage west of Levee 30 could re-
place pumping from the east end of the Area B canals. The capacity
of the pumps would be adequate to sustain proper water levels at the
coastal control structures, most importantly the structures in the Snake
Creek, Miami, and the Snapper Creek canals. The quantities would
be equivalent to the normal losses by seepage around each structure
along the controlled easterly reach of each of these canals, about 40-
50 efs per canal, plus the quantities diverted from the canals by well
field withdrawals.

CONVEYANCE CANALS TO SOUTH DADE COUNTY
An area of perennial water deficiency is the south Dade County
area, where water levels approach or decline below sea level by the end


Figure 47. Map of the southern tip of Florida showing contours of
water-level conditions in May 1962, a near record low-
water condition