Water Resources of the
Florida Power & Light
Service Area: Availability
FLORIDA POWER & LIGHT
WATER RESOURCES OF THE
FLORIDA POWER & LIGHT
SERVICE AREA: AVAILABILITY
Florida Power & Light
1 INTRODUCTION 1 1
PURPOSE AND SCOPE 1 1
DESCRIPTION OF THE STUDY AREA 1 2
St. Johns River Water
Management District 1 2
South Florida Water
Management District 1 5
Southwest Florida Water
Management District 1 6
Suwannee River Water
Management District 1 8
2 HISTORICAL BACKGROUND 2 1
WATER LAW 2 1
The Prior Appropriation Doctrine 2 1
The Riparian Doctrine 2 2
The Hydrologic Cycle and the Law 2 2
The Reasonable Use Rule 2 3
Florida's Water Resources Acts 2 3
WATER MANAGEMENT IN FLORIDA 2 3
3 WATER MANAGEMENT AND REGULATION 3 1
INTRODUCTION 3 1
WATER MANAGEMENT OBJECTIVES 3 1
WATER MANAGEMENT TOOLS 3 2
Regulation and Control
of Supplies 3 3
Augmentation of Supply 3 8
Population Growth Control 3 12
4 THE HYDROLOGIC SYSTEM 4 1
THE HYDROLOGIC CYCLE 4 1
EVAPOTRANSPIRATION 4 2
PRECIPITATION 4 5
SURFACE WATER 4 6
SURFACE-WATER FEATURES OF THE
STUDY AREA 4 10
ST. JOHNS RIVER WATER MANAGEMENT
DISTRICT 4 10
St. Johns River 4 11
4 SOUTH FLORIDA WATER MANAGEMENT
DISTRICT (SFWMD) 4 11
The Kissimmee Valley Planning
Area 4 12
Kissimmee River 4 13
Indian Prairie-Lake Istokpoga
Planning Area 4 13
Lake Okeechobee Planning Area 4 14
Lake Okeechobee 4 14
St. Lucie Canal 4 14
Caloosahatchee River 4 15
Area (EAA) 4 15
Upper East Coast Planning
Area 4 15
Lower East Coast Planning
Area 4 15
Areas 4 16
Lower West Coast Planning
Area 4 17
SOUTHWEST FLORIDA WATER MANAGEMENT
DISTRICT (SWFWMD) 4 17
Peace River 4 17
Manasota Basin 4 18
SUWANNEE RIVER WATER MANAGEMENT
DISTRICT (SRWMD) 4 19
Suwannee River 4 20
Santa Fe River 4 20
,.St. Marys and Oklawaha Rivers 4 21
GROUND WATER 4 21
:Floridan Aquifer 4 22
Shallow Aquifers 4 23
Saltwater Aquifers 4 24
Underground Disposal 4 24
GROUND-WATER CONDITIONS IN THE
STUDY AREA 4 25
St. Johns River Water Management
District 4 26
South Florida Water Management
District 4 32
..,Southwest Florida Water
Management District 4 37
Suwannee River Water Manage-
ment District (SRWMD) 4 42
5 WATER RESOURCES 5 1
INTRODUCTION 5 1
WATER 5 2
Availability 5 3
Quality 5 4
WATER 5 5
Availability 5 7
Evaluation of Development
Potential 5 7
WATER AVAILABILITY IN THE ST. JOHNS
RIVER WATER MANAGEMENT DISTRICT
(SJRWMD) 5 9
Surface Water 5 9
Ground Water 5 19
Injection Disposal and Saline
Water 5 23
Potential--Area Summaries 5 29
WATER RESOURCES OF THE SOUTH
FLORIDA WATER MANAGEMENT DISTRICT
(SFWMD) 5 40
Surface Water 5 40
Ground Water 5 46
Potential 5 54
WATER RESOURCES OF THE SOUTHWEST
FLORIDA WATER MANAGEMENT DISTRICT
(SWFWMD) 5 65
Surface Water 5 65
Ground Water 5 69
Potential 5 76
WATER RESOURCES OF THE SUWANNEE
RIVER WATER MANAGEMENT DISTRICT
(SRWMD) 5 82
Surface Water 5 82
Ground Water 5 83
Potential 5 87
6 WATER USE AND DEMAND 6 1
INTRODUCTION 6 1
ST. JOHNS RIVER WATER MANAGEMENT
DISTRICT 6 3
Present Water Use 6 3
Future Water Use 6 10
6 SOUTH FLORIDA WATER MANAGEMENT
DISTRICT 6 12
Present Water Use 6 12
Future Water Use 6 16
SOUTHWEST FLORIDA WATER MANAGEMENT
DISTRICT 6 18
Present Water Use 6 18
Future Water Use 6 22
SUWANNEE RIVER WATER MANAGEMENT
DISTRICT 6 24
Present Water Use 6 24
Future Water Use 6 28
7 SUMMARY AND CONCLUSIONS 7 1
MANAGEMENT OF WATER RESOURCES 7 1
The Florida Experience 7 1
Water Management Districts 7 2
Management Philosophy 7 2
FLORIDA WATER RESOURCES 7 3
Hydrologic Cycle and Water
Budget 7- 3
Consumptive Use of Water 7 3
Streams 7 5
Lakes 7 7
Ground Water 7 7
A ANALYSIS OF SURFACE-WATER FLOW DATA A 1
B SURFACE-WATER QUALITY SUMMARIES B 1
C COMPUTATION OF THE REGULATORY LOW
FLOW FOR SELECTED STREAMS IN THE
SOUTHWEST FLORIDA WATER MANAGEMENT
DISTRICT C 1
5-1 Major Lakes of the St. Johns River Water
Management District 5 17
5-2 Water Quality--Floridan Aquifer
St. Johns River Water Management District 5 24
5-3 Water Quality--Shallow Aquifer
St. Johns River Water Management District 5 27
5-4 Water Quality--Floridan Aquifer
South Florida Water Management District 5 50
5-5 Water Quality--Shallow Aquifers
South Florida Water Management District 5 53
5-6 Water Quality--Floridan Aquifer Southwest
Florida Water Management District 5 74
5-7 Water Quality--Shallow Aquifers Southwest
Florida Water Management District 5 75
5-8 Water Quality--Floridan Aquifer
Suwannee River Water Management District 5 88
5-9 Water Quality--Shallow Aquifer
Suwannee River Water Management District 5 89
6-1 Freshwater Use in Florida, 1975 6 2
6-2 Summary of Water Usage for the Study
Area, Present Sources and Present and
Projected Usage 6 4
6-3 St. Johns River Water Management
District Water Usage By County, 1975 6 7
6-4 St. Johns River Water Management
District Present Sources and Present
and Projected Usage 6 9
6-5 South Florida Water Management District
Freshwater Usage By County, 1975 6 13
6-6 South Florida Water Management District
Present Sources and Present and
Projected Usage of Freshwater 6 14
6-7 Southwest Florida Water Management
District Water Usage By County, 1975 6 19
6-8 Southwest Florida Water Management
District, Present Sources and Present
and Projected Usages 6 21
6-9 Suwannee River Water Management
District Water Usage By County, 1975 6 25
6-10 Suwannee River Water Management District
Present Source, Present and Projected
Usage 6 26
7-1 Florida's Freshwater Budget--1975 7 4
7-2 Summary of Freshwater Withdrawn and
Consumed in the State of Florida--1975 7 4
7-3 Estimated 1979 Water Budgets for the
Study Area 7 6
7-4 Surface Runoff in Florida in
Billion Gallons per Day 7 8
1-1 Study area
1-2 Physiographic divisions of Florida
1-3 Physiographic areas of South Florida
4-1 Generalized hydrologic cycle
4-2 Average yearly evaporation rate from free water
4-3 Average annual rainfall (inches)
4-4 Comparative rainfall distribution
4-5 Major streams in Florida
5-1 Development potential of surface waters in the
5-2 Top of Floridan aquifer and areas of possible
active sinkholes, SJRWMD
5-3 Potentiometric surface and recharge areas,
5-4 Total dissolved solids in the upper part of
Floridan aquifer, SJRWMD
5-5 Typical east-west geologic section showing
development of shallow aquifer
5-6 Potential deep-well injection zones, SJRWMD
5-7 Development potential of surface waters in the
5-8 Major canals and water control structures, SFWMD
5-9 Top of Floridan aquifer and areas of possible
active sinkholes, SFWMD
5-10 Main use aquifers and water quality, SFWMD
5-11 Potentiometric surface in the upper part of
Floridan aquifer, SFWMD
5-12 Potential deep-well injection zones, SFWMD
5-13 Ground-water temperature in the Floridan aquifer,
5-14 Development potential of surface waters in the
5-15 Top of Floridan aquifer and areas of possible
active sinkholes, SWFWMD
5-16 Main use aquifers and water quality, SWFWMD
5-17 Potentiometric surface and recharge areas,
5-18 Potential deep well injection zones, SWFWMD
5-19 Ground-water temperature in the Floridan aquifer,
5-20 Development potential of surface waters in the
5-21 Top of Floridan aquifer and areas of possible
active sinkholes, SRWMD
5-22 Potentiometric surface and recharge areas, SRWMD
6-1 Present and projected water use by source and
category for the study area
6-2 Present and projected water use by source and
category for the SJRWMD
6-3 Present and projected water use by source and
category for the SFWMD
6-4 Present and projected water use by source and
category for the study area within the SWFWMD
6-5 Present water use by source and category for the
study area within the SRWMD
ON Chapter 1
PURPOSE AND SCOPE
At the request of Florida Power & Light Company (FPL), CH2M
HILL has prepared this report to provide an evaluation of
the water resources and management in the FPL service area
and, in general, to determine the availability of this water
for present and future use. The objective of this study was
to review all pertinent literature and present, in a concise
form, all data, facts, rules, and laws bearing on the avail-
ability and allocation of water for municipal, agricultural,
industrial, and power generation needs projected through the
year 2020. This study is not intended to be site-specific
but to provide an overview of water resources and water
management philosophy and administration throughout the
The report covers the geographic area shown on Figure 1-1,
which includes all of the St. Johns River Water Management
District, all of the South Florida Water Management District,
and portions of the Southwest Florida and Suwannee River
Water Management Districts. The scope of this study includes
summarization of present and future water demands and water
availability (including regulatory and water quality
constraints) for the study area from the present time to the
Population projections, present water use, and future water
demands were obtained for the most part from the water
management plans developed by each of the districts within
the study area. Where data from the water management
districts were not available, alternate sources were used
and are referenced accordingly.
Also within the scope of this report, the present structure
of water management philosophy and administration in Florida
is explored (as well as the history of the development of
this structure) with regard to physical, philosophical, and
Although this study does present an analysis of the various
factors involved in determining "water availability," one
must remember that the study of each of these elements
separately does not necessarily ensure a full grasp of the
whole. In this report, we have attempted to identify the
most important and relevant aspects of these elements, which
have significant bearing on the development, use, conserva-
tion, and protection of water resources in the State of
DESCRIPTION OF THE STUDY AREA
The study area, which covers approximately 65% of the State
of Florida, is the service area for Florida Power & Light
Company. As mentioned previously, the area includes all of
the St. Johns River and the South Florida Water Management
Districts and portions of the Southwest Florida and Suwannee
River Water Management Districts. Figure 1-1, a map of the
study area, shows the boundaries of the water management
St. Johns River Water Management District
The St. Johns River Water Management District (SJRWMD) is
located in the northeastern part of the State along the east
coast of peninsular Florida. Included within its boundaries
are the entire St. Johns and Nassau River Basins, several
coastal drainage basins, and the Florida portion of the
St. Marys River basin. The area of the District comprises
approximately 21% of the State, and, in 1975, included
approximately 22% of the State's total population.
All or part of 19 counties are located in the SJRWMD. The
main urban centers are Jacksonville, Daytona Beach, and
Orlando (located in Duval, Volusia, and Orange Counties,
respectively) and Cocoa and Melbourne in Brevard County.
Gainesville and Ocala are two other important cities in the
The rolling hill country of the District, along with rich
soils, long growing seasons, and available water, make it
ideally suited to the cattle industry. Horse breeding is
another important industry in the Marion County area. Truck
farming is prevalent throughout the District, and the central
interior portion is part of the citrus-growing area of
Florida. The forest industry is also important in the
northern part of the District.
The topography of the SJRWMD consists of low, nearly level
plains; gently rolling hills; numerous intermittent ponds;
swamps and marshes; many lakes; and a few perennial streams.
As shown on Figure 1-2, there are two major physiographic
divisions within the District, the Coastal Lowlands and the
Central Highlands. The Coastal Lowlands extends inland 20
to 30 miles from the coast. The area consists of alternating
low ridges and swales, generally parallel to the present
coast, which represent relief shorelines. The area has been
further subdivided by White (1970) into the Eastern Valley
(elevation generally below 35 feet), the Atlantic Coastal
Ridge (elevation 40 to 50 feet), and the Crescent City and
Deland Ridges (elevation up to 70 feet).
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The Central Highlands includes high sandy hills (up to
150 feet above sea level) in the northern part of the District
and a relatively low swampy plain in the south. The higher
lands include some areas of karst (sinkhole) topography.
Major subdivisions (White, 1970) include the Northern High-
lands, Trail Ridge, and Duval Upland, the Mount Dora Ridge,
and the Marion Upland (elevations 75 to 150 feet) in the
north and the Osceola Plain (elevation 50 to 90 feet) in the
The area is underlain by 2,500 to 4,000 feet of limestone
and dolomite of Upper Eocene to Paleocene age. Overlying
the limestone in most places in the area is 50 to 200 feet
of Miocene silt, sand, clay, and phosphatic limestone.
Surface deposits consist of older Pleistocene terrace sands
inland and younger Pleistocene sand and shell deposits in
the coastal lowlands.
South Florida Water Management District
The South Florida Water Management District (SFWMD) is
located in the southern part of peninsular Florida. There
are two major river basins within its boundaries: the Kissimmee
River Basin and the Calossahatchee River Basin. The other
major hydrologic feature is Lake Okeechobee and its related
system of distributary canals and conservation storage
areas. Fisheating Creek and Taylor Creek and some small
coastal basins comprise the other smaller hydrological
features of the District. The District encompasses approxi-
mately 31% of the State and contains approximately 39% of
the State's total population.
All or part of 16 counties are located in the SFWMD. The
main urban centers are Miami, Fort Lauderdale, West Palm
Beach, Fort Pierce, and Fort Myers (located in Dade, Broward,
Palm Beach, St. Lucie, and Lee Counties, respectively).
The biggest industry in the SFWMD is tourism. This area
constitutes the largest retail sales market in the State.
Service trades are the next largest business category, with
garment manufacturing and food processing closely following.
Government employment and the construction industry are also
important sources of income in the District. Mineral production
is limited to nonmetallic minerals. Only limestone, sandstone,
and petroleum are mined in economically significant quantities.
Extensive portions of the District are set aside as national
park and other conservation areas.
Where soils are suitable, agricultural production is extensive.
Production of citrus, vegetables, and sugarcane has been
increasing during the past few years. Livestock production,
on the other hand, has declined slightly.
Physiographically, this District is primarily within the
Coastal Lowlands, with the most southerly extension of the
Central Highlands comprising a very small portion of the
northern area of the District (see Figure 1-2). The high-
lands consist of well-drained sand hills, with poorly
developed stream patterns and numerous lakes of various
sizes. Most precipitation sinks directly into the sandy
soil. Elevations in the Central Highlands range from a low
of about 70 feet above mean sea level to around 175 feet.
Within the District, the Coastal Lowlands area has been
further divided into five subareas on the basis of topo-
graphic and ecologic similarities. Physiographic divisions
of the District are shown on Figure 1-3.
Most of the northern area of the District is covered by the
Flatwoods, a nearly level plain characterized by sluggish
surface-water systems and perennially wet swamp resulting
from the high water table. A few small ridges in the
Flatwoods do have well-drained soils. Elevations range from
sea level to as high as 100 feet in the northern portion.
The Atlantic Coastal Ridge, a sandy, sharp crest rarely
exceeding 50 feet in elevation, is located along the east
coast, 1/4 mile to 10 miles west of the Coastal Lagoon. A
limestone foundation underlies this ridge in most areas.
The southern portion of the District, comprised of the
Everglades, Big Cypress Swamp, and the Southern Coastal
Marsh, consists of wetlands and cypress swamps which are
often flooded. Elevations in this area range from sea level
to no more than 30 feet on domes and islands scattered
throughout the swamp.
There are over 1,400 lakes in the SFWMD. The largest is
Lake Okeechobee. Other major lakes are Kissimmee, Istokpoga,
Tohopekaliga, and East Tohopekaliga.
Poorly drained muck soils occur in the low swampy areas of
the SFWMD, but on the ridges, well-drained sandy soils are
found. Forty-five soil series and six unclassified soil
units have been recognized in the District. Many of these
soils are affected by a shallow water table.
Southwest Florida Water Management District
The Southwest Florida Water Management District (SWFWMD) is
located in the southwest portion of peninsular Florida.
Included within its boundaries are the Withlacoochee, Peace,
Myakka, Hillsborough, and the Alafia River Basins. Also
included are the coastal drainage basins between the Myakka
and Alafia Rivers and the Hillsborough and Withlacoochee
Rivers. The District encompasses approximately 17% of the
State and, in 1976, contained 26% of its population.
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All or part of 16 counties are included in the SWFWMD. The
main urban centers are Lakeland, Sarasota, Bradenton, and
the urban areas around Charlotte Harbor (including Port
Charlotte and Punta Gorda).
The main industry in the SWFWMD is phosphate mining. The
production of agricultural commodities, especially citrus,
beef, and vegetables, is very high in this area. Commercial
forest land is extensive; however, many areas formerly
planted in timber have been cleared for grazing. Tourism is
an important industry, especially in the coastal areas.
The topography of this portion of the SWFWMD is characterized
by low, nearly level plains. Gently rolling terrain does
occur in the eastern portion of this area in Polk and Hardee
Counties, which comprise part of the Central Highlands of
the State. The remainder of the area falls within the
physiographic division called the Coastal Lowlands (see
Figure 1-2). There are numerous intermittent ponds, swamps,
and marshes in the area as well as many large to medium-sized
lakes, occurring mostly in Polk County. Small lakes and
streams are found throughout the area. The largest water-
courses are the Peace, Myakka, Braden, and Manatee Rivers
and their tributary systems. Elevations increase gradually
in a northeasterly direction and range from sea level along
the coast to approximately 270 feet in Polk County. Most of
the water in the area is freshwater; however, brackish-to-
salty water can be found in the lower reaches of all water-
courses which flow into the Gulf of Mexico.
The area is characterized geologically by near-surface rocks
and sediments of the following formations: Hawthorn, Tamiami,
Bone Valley, St. Marks, Caloosahatchee, and Anastasia.
High-quality phosphate deposits occur in the Bone Valley
Formation. Deeper-lying formations include the Suwannee
Limestone, the Avon Park Limestone, and the Lake City
Limestone. Parts of these formations are important water
Soil conditions in the area are very complex. This diversity
results in a wide variety of capabilities and limitations
for specific water uses.
Suwannee River Water Management District
The Suwannee River Water Management District (SRWMD) is
located in the north-central portion of the State. Included
within its boundaries are the Suwannee, the Aucilla, and a
portion of the St. Marys River Basins. Also included are
the coastal drainage areas between the Aucilla and Suwannee
Rivers and the Withlacoochee and Suwannee Rivers. The
District encompasses approximately 13% of the State and, in
1975, contained approximately 2% of the State's total
All or part of the 14 counties are included in the SRWMD.
The main urban centers are Lake City, Live Oak, and Starke
(located in Columbia, Suwannee, and Bradford Counties,
The major industries within the District include dairy
farming, truck farming, mining, mineral processing, and
Physiographically, the District includes two major divisions,
the uplands which are subdivided into the Northern Highlands
and the Tallahassee Hills, and the Coastal Lowlands. The
uplands are found in the northern and eastern portions and
comprise approximately half of the District. Also included
within the District are several sand ridges and coastal
swamps. Elevations in the District range from near sea
level along the coast to greater than 200 feet in the upland
The District is underlain by 2,000 to 3,000 feet of limestone
and dolomite of Late Eocene to Paleocene age. Overlying the
limestone in part of the area is up to several hundred feet
of Miocene sand, silt, and clay. Surficial deposits of
Pleistocene to Recent sand and shell deposits are present
throughout the District.
The soils of the SRWMD are generally sandy. They occur as
thick to thin layers over loamy, clayey, or weakly cemented
sandy subsoils. Loamy and organic top soils are common in
the lowlands and marshes. The upland regions are generally
sloping and well drained whereas the lowlands are usually
level and poorly drained.
0I Chapter 2
0E HISTORICAL BACKGROUND
Even though the study area described in Chapter 1 is unique,
blessed with certain natural and manmade resources and
burdened with certain problems, at least one common cause
ties it to other civilizations past and present: the
management of water. Water is essential to human life, to
agriculture, to industry, and to the environment as we know
it. Civilizations can rise and fall simply as a result of
water supply and demand relationships.
Historically, water management has been in response to
excesses or scarcities of water, with the aim of stabilizing
the water supply and demand imbalances. Laws governing the
use of water developed as early as the first agriculturally
based civilizations. The following discussion provides some
historical perspective on the development of water law and,
more specifically, on the development of water management
practices in Florida.
The basis of water law in a particular area generally reflects
the abundance or lack of water in that area. Therefore, the
basic philosophy of water law can generally be divided into
the law of humid regions and the law of arid regions. In
areas of water scarcity, water may be the main object of
real property, with land being only of secondary importance,
whereas in areas of abundant water supply, the rights to the
water are taken for granted and are considered to be an
accessory to the land. Within the United States, rights to
ground water inherent in land ownership vary from state to
state. The English doctrine declares the right of each
landowner to be absolute. American courts have, for the
most part, rejected this absolute ownership doctrine and
adopted a "reasonable use" rule which recognizes the common
rights of owners of land overlying a ground-water reservoir
and protects the water from unreasonable use or waste.
California has gone further and provides that the rights of
landowners to a common ground-water reservoir are correlative
and, if the supply is insufficient for all, each will be
accorded a fair proportion.
The Prior Appropriation Doctrine
In arid regions, the law permits rights to be acquired by
actual use of water and protects these rights against
subsequent appropriations. This is called the doctrine of
prior appropriation and was derived from Moslem law, much of
which originated in the teachings of Mohammed (A.D. 570-632).
These rights were based on actual use and need. The right
of thirst was given the highest priority. The doctrine of
prior appropriation, the basis of water law in most of the
Western United States, is based on beneficial use, as was
Moslem law, and accords rights to actual use: the first in
time is the first in right.
The Riparian Doctrine
In the humid regions of the Eastern United States, a system
of water law called the riparian doctrine developed from the
English common law. Under this system of law, the right to
withdraw water is based on the ownership of riparian land,
or land adjacent to a surface-water body. A riparian owner
could withdraw water for domestic purposes but essentially
could not alter the flow of the stream and thereby deprive
the downstream riparian owners of their full flow of the
stream. In humid areas, until recently, adequate water
supplies were generally available to everyone: the riparian
doctrine, rather than appropriation, was the basis of water
management. In Florida, serious competition for water and
concern over water rights dates from the late 1950's.
The Hydrologic Cycle and the Law
Water in its various stages in the hydrologic cycle represents
a complex system of interrelationships. Our legal system,
however, does not recognize this interdependence and treats
the various stages of the cycle as separate and distinct.
The law has categorized water into four general areas:
(1) surface water in a natural watercourse, (2) diffused
surface water, (3) ground water in distinct underground
streams, and (4) percolating ground water. Each of these
categories is governed by a separate set of rules rather
than in a consistent or unified manner. These separate
rules have come about primarily because the courts found it
easier to deal with conflicts arising over surface waters.
Ground water remained more of a mystery. In the Eastern
States, whenever ground water has been shown to occur in the
form of an underground stream, the water rights associated
with it have followed the riparian system. When the ground
water has been shown to be percolating water, unlimited use
has been permitted.
The categorization of water with respect to its position in
the hydrologic cycle forms a relatively convenient basis for
case law to deal with water conlficts; however, this approach
is a poor basis for water management.
The legal regulation of water use, as currently practiced by
the water management districts, is based on the reasonable
use rule. To some extent, the reasonable use rule probably
conflicts with case law regarding water rights.
The Reasonable Use Rule
Until recently, in the eastern United States, very little
attention has been given to the problem of rights of non-
riparian owners to the use of surface waters since the
abundance of ground water adequately provided for most
municipal, agricultural, mining, power, and other industrial
demands. Today, however, water shortages in coastal areas
have created the need for capturing, storing, and using
excess surface waters where they are available and also
diverting these flows to other areas. In the West, the
doctrine of prior appropriation permitted those who did not
own land bordering a body of water to utilize the water.
Historically, however, in the East the riparian doctrine did
not allow for water to be diverted from a watercourse beyond
the immediately adjacent lands. The riparian owner was
entitled to the full flow of the stream and during times of
surplus water the excess went to waste. Even the riparian
owner could not make use of the excess water beyond his
riparian lands. In time, this riparian concept yielded to a
reasonable use doctrine, and reasonable use diversions were
permitted. However, the basic premise of the reasonable use
doctrine differs strongly with that of the appropriation
doctrine. The riparian owner is still entitled to a certain
minimum flow in the stream. No such provision is considered
under the appropriation system in the West.
Florida's Water Resources Acts
In 1957 Florida passed a water resources law which was
designed to encourage the effective use of excess water by
setting up the means by which permits could be granted to
divert such water beyond riparian (or in the case of ground
water, overlying) lands. With the passage of this law,
Florida was no longer entirely under the riparian doctrine,
and excess flows of surface waters could, by law, be
The Florida Water Resources Act of 1972 (which set up the
present five water management districts with their water-use
permitting authority) further required that water withdrawn
from the ground as well as excess water diverted from streams
be put to "reasonable and beneficial use."
WATER MANAGEMENT IN FLORIDA
In the past, Florida's predominant water problems related to
periodic excesses of water, resulting in flood damage. The
most important of the State's early acts to guard the public
welfare against these flood occurrences was the General
Drainage Act of 1913, which authorized the formation of
single-purpose drainage districts by decree of the circuit
courts of the State.
Until very recently, most of the water resources legislation
in Florida has been enacted in response to severe climatic
events. Disastrous floods in 1947 and 1948 resulted in
legislative action in 1949 creating the Central and Southern
Florida Flood Control District (CSFFCD) to act as a local
sponsor for a Federally funded Corps of Engineers project to
provide flood control facilities for South Florida. Although
the CSFFCD was created to implement a flood control program,
it soon became a more multipurpose district since Florida's
rapidly growing population had created the need for a dif-
ferent perspective on water resource problems.
Water resource problems are now considered to be more complex
and include: (1) providing adequate water supplies for
agriculture, power generation, and industry, as well as
providing adequate municipal supplies, especially in rapidly
growing coastal communities; (2) preventing saltwater intru-
sion in these coastal areas; and (3) protecting water sources
throughout the State from pollution.
In 1961, the legislature created another large-scale multi-
purpose district, the Southwest Florida Water Management
District (SWFWMD). Based on a comprehensive study by the
Corps of Engineers, Congress authorized the Federally
financed Four River Basins Project, with the SWFWMD acting
as the local sponsor. Even though this District was created
primarily in response to the extensive flood damage incurred
in the floods of 1959 and 1960, its multipurpose nature was
envisioned from the beginning.
Until 1968, both the CSFFCD and the SWFWMD had jurisdiction
only over certain surface-water bodies. In 1968, the
Governing Board of the Southwest Florida Water Management
District approved the formation of a ground-water regulatory
district, the first of its kind in the State.
In addition to the CSFFCD and the SWFWMD, special legislation
also created numerous special districts affecting water use
and control, such as mosquito control districts, navigation
districts, water supply districts, and irrigation and soil
conservation districts. Although the formation of such
districts did provide for water management and control in
local areas, there was no statewide policy. As early as
1944, public interest generated the appointment of a citizens
committee to study Florida's freshwater situation. As a
result of this study, a proposed bill was drafted, but it
failed to be enacted by the legislature. However, in 1947,
the legislature did establish the Water Survey and Research
Division of the State Board of Conservation. In 1955, the
legislature dissolved this agency and turned its functions
over to the Florida Geological Survey. In 1955, the Governor
of Florida appointed another citizens water problem study
committee. The work of this committee resulted in enactment
by the legislature of an act which outlined, for the first
time, a water policy for the State of Florida. This act
also created the Florida Water Resources Study Commission.
The extensive work carried out by the Commission was the
initial foundation for subsequent work which eventually led
to the Florida Water Resources Act of 1972. This Act created
five multipurpose water management districts covering the
entire State. These districts are:
1. The Southwest Florida Water Management District.
2. The Southern Florida Water Management District (formerly
the Central and Southern Florida Flood Control District).
3. The St. Johns River Basin Water Management District.
4. The Northwest Florida Water Management District.
5. The Suwannee River Basin Water Management District.
The Florida Department of Environmental Regulation acts as
the supervisory agency over each of the water management
districts and has the power to review actions of the districts.
In many ways, the Water Resources Act of 1972 patterns the
new water management districts after the organization of the
Southwest Florida Water Management District and its ground-
water regulatory district.
The Water Resources Act did not "grandfather in" existing
water users. Existing users had to apply for a permit and
justify the use as being reasonable and beneficial. Also,
the user had to show that the water was not being diverted
beyond replenishment, that the use was not unduly interfering
with other users, and that the withdrawal was not causing
Each water management district levies ad valorem taxes to
meet its budget and each has the responsibility for estab-
lishing its own rules and regulations for carrying out the
responsibilities delegated to it under the Water Resources
Act of 1972.
II Chapter 3
IU WATER MANAGEMENT AND REGULATION
Second in importance only to the State's human resources,
Florida's water resources are perhaps the State's most
valuable [natural] asset. All segments of Florida's
population, economy, and general welfare are directly
influenced by the waters that lie on, beneath, or
around the State.'
Civilization and water resources are and have always been
intrinsically bound together. The earliest civilizations
arose where water was a dominant element of the environment,
providing both a source of food and a transportation system.
Some of these earliest civilizations failed because their
water supplies failed. Today, water continues to dominate
man's activities; where he builds his factories and cities
is often dictated by the accessibility of water. He then
sometimes proceeds to pollute the water and deplete the
aquifers to such a degree that large amounts of money and
ingenuity must be expended to obtain the water needed to
sustain his activities.
It is important to recognize that the same amount of fresh-
water is now present in the world's ground and surface
reservoirs as was present even before mankind appeared,
about 9 million billion gallons. The water is not used up,
but variations in its availability, sometimes natural and
sometimes man-induced, create a continuing concern over our
Flood or drought, feast or famine, there always seems to be
too much or too little. The aim of water management planning
and regulation is to balance these two extremes to permit
the maximum beneficial use of our water resources while
protecting these resources from needless waste and contamination.
WATER MANAGEMENT OBJECTIVES
The Florida Water Resources Act of 1972, Chapter 373 of the
Florida Statutes, lists the following objectives for water
management throughout the State:
'Florida Water Resources Study Commission. Florida's Water
Resources. Gainesville, Florida. December 1956.
1. To provide for the management of water and related land
2. To promote the conservation, development, and proper
utilization of surface and ground water.
3. To develop and regulate dams, impoundments, reservoirs,
and other works and to promote water storage for bene-
4. To prevent damage from floods, soil erosion, and exces-
5. To preserve natural resources, fish, and wildlife.
6. To promote recreational development, protect public
lands, and assist in maintaining the navigability of
rivers and harbors.
7. To otherwise promote the health, safety, and general
welfare of the people of this State.
The five water management districts established under this
Water Resources Act are comprehensive agencies charged with
the responsibilities of investigating the water resources of
their respective areas, producing management plans, develop-
ing criteria to implement these plans with regulatory processes,
and enforcing these regulations.
The key concept of the 1972 Water Resources Act is "reasonable-
beneficial use," which means "the use of water in such
quantity as is necessary for economic and efficient utiliza-
tion for a purpose and in a manner which is both reasonable
and consistent with the public interest." This concept was
developed by combining the best features of both the prior
appropriation doctrine of western water law and the riparian
doctrine of eastern water law.
WATER MANAGEMENT TOOLS
Management of water resources requires the utilization of
tools to accomplish certain objectives. Water management
tools are of two basic types: those which seek to protect
existing supplies by regulation and control and those which
seek to augment existing supplies through innovative manage-
ment techniques. The implementation of any of these tools
implies the acceptance of a water management philosophy.
Water level regulation and monitoring are tools aimed at the
conservation and control of existing supplies, whereas
augmentation of existing supplies by various means indicates
a philosophy of innovative management. Interbasin importa-
tion or transfer of water implies allocating water from
areas having a surplus of water to enhance the development
of some other desirable locality where water is in limited
supply. The water crop concept is a water allocation tool
which ties water rights to land ownership. Population
growth control is a means of reducing water demand by limiting
development, based on an arbitrary number of service connections
to be allowed.
Regulation and Control of Supplies
The fundamental basis for the regulation and control of
water in Florida is the "reasonable-beneficial use" concept
embodied in the Water Resources Act of 1972. However, there
is, as yet, no universally accepted means of determining
what constitutes reasonable and beneficial use of water. As
a practical matter, it is seldom, if ever, possible to
develop sizeable water supplies without changing, to some
degree, an existing natural hydrologic system. Even when a
proposed water use can be shown to be beneficial, its impact
on the natural system may be deemed unreasonable. An added
complication is that the degree to which a proposed action
may affect the resources is often not clear, and further
clarification is not possible at a feasible cost in time and
The water manager's problems in arriving at a decision
regarding regulation of a ground-water system were summed up
by McGuinness (1969) as follows.
Generally, aquifer systems are complex, replenishment
and natural discharge rates are variable and difficult
to determine, there are existing ground-water develop-
ments that must be considered, there are possible
quality complications resulting from waste disposal or
the presence of inferior water, there are economic or
legal ramifications, and there is not enough information.
Always, there is not enough information.
A similarly complicated situation exists with regard to
surface-water systems. Almost every management decision
requires consideration of a highly complex and often unique
set of technical, social, and economic variables.
To deal with this almost infinitely variable set of condi-
tions, each of the management districts is mandated under
Florida's Administrative Procedures Act to promulgate a set
of rules and regulations defining clearly and concisely the
criteria to be used in allocating and regulating water
supplies. At this time, none of the management districts
have finalized rules and regulations dealing with all aspects
of their regulatory activities.
Management tools which have been or may be used to control
and regulate existing water supplies include allocations
based on "water crop," water level regulation, water quality
monitoring, streamflow regulation, lake level regulation,
and population growth control. The implications and limita-
tions of each of these tools are discussed below.
Water Crop Concept. The water crop concept is an accepted
hydrologic tool for determining "rule of thumb" estimates of
water availability in hydrologically isolated or very large
areas. The concept is one of water availability for
"harvesting." If the average annual evapotranspiration for
a given area is subtracted from the average annual rainfall,
the resultant amount of water is considered to be available
to "harvest" for a particular use. For example, the water
crop in the SWFWMD is determined for regulatory purposes to
be: 52 inches of rainfall minus 39 inches of evapotranspira-
tion, or 13 inches. This translates into 1,000 gallons of
water per acre per day.
When used as a regulatory tool, this concept is satisfactory
only if it is used as a general guide, since factors such as
evapotranspiration and ground-water inflow and outflow may
vary considerably. The water crop calculation given above
assumes a constant evapotranspiration rate, whereas, in
reality the rate may vary widely depending upon the type of
vegetation, the number of surface-water bodies, and the
depth to the water table. In areas where large withdrawals
are made, the lowering of the water table may substantially
reduce the evapotranspiration losses.
Variations in local geology and aquifer productivity must
also be considered: the recovery of the water crop from
some areas would be difficult and costly, whereas in other
areas production in excess of the water crop would be possible
and desirable from a water management standpoint.
Ground-Water Level Regulation. Whenever a well is pumped,
the water level in the aquifer in the vicinity of the well
is lowered. The amount of lowering and the area affected by
pumping depend upon the hydraulic characteristics of the
aquifer and the rate and volume of pumping. The water table
may also be lowered, as may the level of lakes and ponds in
the affected area.
The purpose of ground-water level regulation is to limit
lowering of water levels to values which will not adversely
affect the source of water, the environment, or the rights
of other water users or landowners. In any given situation,
the amount of water level lowering is proportional to the
amount of water withdrawal; therefore, limitations on water
level are, in effect, limitations on water withdrawal and
use. The management districts generally require applicants
for water permits to submit predictions of well level effects
and supporting data for their predictions. In many cases,
installation of appropriate observation wells to confirm the
predicted effect is required as a condition of a water use
Two somewhat different approaches have been used by the
water management districts in establishing regulatory water
The Southwest Florida Water Management District has adopted
rules which specify numerical limits on lowering of water
levels. The rules state that, in order for a water use
permit to be granted, the proposed use:
1. Must not cause the level of the potentiometric surface
under lands not owned, leased, or otherwise controlled
by the applicant to be lowered more than 5 feet.
2. Must not cause the level of the water table under land
not owned, leased, or otherwise controlled by the
applicant to be lowered more than 3 feet.
3. Must not cause the level of the surface of water in any
lake or other impoundment to be lowered more than
1 foot unless the lake or impoundment is wholly owned,
leased, or otherwise controlled by the applicant.
4. Must not cause the potentiometric surface to be lowered
below sea level.
These limitations are arbitrary in that they are not related
to whether the amounts of lowering would or would not prove
detrimental under any particular circumstances. These
limitations, however, are used as guidelines, in the context
of which each use is evaluated by the districts. The SWFWMD
rules provide for exemption from these limits upon presenta-
tion of adequate supporting data by the applicant and a
finding by the District governing board that an exemption is
in the public interest.
The SFWMD has not spelled out specific regulatory limits on
water levels. Instead, this District establishes minimum
levels on a case-by-case basis as appropriate. Although
other factors are considered in setting regulatory water
levels, the SFWMD looks primarily to the prevention of
saltwater intrusion. The criteria used by the SFWMD to
allocate water are presented in a recent paper "Basis of
Staff Review," which is proposed for adoption as a rule in
The District commonly requires predictive modeling of the
effects of water withdrawal and the establishment of a
ground-water level monitoring program as conditions for
granting a permit for large water withdrawals.
Regardless of the initial approach to setting regulatory
water levels, monitoring of actual effects of withdrawal
will probably play a large part in any ongoing water use
Ground-Water Quality Monitoring. Over much of the study
area, water supplies are obtained from aquifers which are in
relatively close proximity to water of inferior quality.
Under some conditions, pumping from wells may induce this
inferior water to move toward the pumping well. The purpose
of ground-water quality monitoring is to detect intrusion of
inferior water in time to allow remedial action. Movement
of inferior water generally occurs in response to a substan-
tial long-term decline in water level, which in turn occurs
in response to overpumping of an aquifer. Remedial actions
to prevent intrusion may include reducing or terminating
water withdrawal, moving the point of withdrawal further
from the coast, or increasing recharge.
The factors influencing the movement of inferior water are
much more complex than those controlling water levels. The
source of inferior water may be a saltwater body or a connate
water below the producing aquifer. Intrusion may occur by
lateral movement of water or by upward seepage. Because of
these complexities, models are less reliable for predicting
the effects of pumping on water quality than for predicting
effects on water levels.
In areas subject to saltwater intrusion, the management
districts generally require, as a condition for granting a
water use permit, that a water quality monitoring program be
initiated by the user. Water quality monitoring programs
have been underway in the coastal areas for many years.
Streamflow Regulation. The Florida Water Resources Act of
1972 (Florida Statutes, Chapter 373) authorizes the five
water management districts in Florida to establish minimum
flow criteria for surface watercourses so that withdrawals
above the minimum flow are not significantly "harmful to the
water resources or ecology of the area."
The SWFWMD is the only water management district located in
the study area which has established a legal definition of
minimum flow for surface waters. The SWFWMD minimum stream-
flow criteria are written as follows.
Unless otherwise deemed appropriate by the Board, the
minimum rates of flow at a given point on a stream or
other watercourse shall be established by the Board for
each month, January through December. Minimum rates of
flow shall be established as follows: For each month,
the five (5) lowest monthly mean discharges for the
preceding twenty (20) years shall be established as
seventy percent (70%) of these values for the four (4)
wettest months and ninety percent (90%) of these values
for the remaining eight (8) months. The determination
shall be based on available data, or in the absence of
such data, it shall be established by reasonable calcula-
tions approved by the Board.2
The SWFWMD minimum flow criteria stated above establish a
minimum flow for each month. There are several drawbacks to
this approach. This computation of monthly minimum flow
does not give a statistical representation of either the
likelihood of flows equal to or below the monthly minimum
flow or the duration of such flows. In addition, the monthly
minimum flow is a cumbersome tool requiring continuous flow
observations. The monthly minimum flow is subject to change
monthly as additional data become available.
An alternative method of regulatory surface-water withdrawal,
taking into account the frequency of occurrence of low flows
and dependable annual flow, is described in Appendix A of
Although the SWFWMD is the only District to define "minimum
flow," both the SWFWMD and the SJRWMD have established
limitations for permitting the consumptive use of surface
waters. The SWFWMD conditions state that a permit will be
denied if the withdrawal would cause the streamflow to be
lowered below the minimum rate of flow or if the withdrawal
would reduce the rate of flow by more than 5% at the time
and point of withdrawal. SJRWMD requires that a water
withdrawal not restrict or alter the rate of flow of a
stream by more than 10% at any time and point of withdrawal.
Both the 5% and 10% constraints are potentially more restric-
tive than minimum flow regulation. The effect of a percentage
limitation will be to prevent full utilization of surface
water during times of high flow.
Lake Level Regulation. Lake level regulation is a water
management tool which falls under the category of conserva-
tion and control of existing supplies. Lakes with adequate
outlet canals and control structures can have high water
levels maintained and still be operated to prevent flooding.
An operations schedule of this nature would produce a maximum
surface-water storage capability, thereby conserving surface
water and raising the ground-water table. From a strictly
water conservation standpoint, this practice would be
desirable; however, long-term high water levels can have
serious detrimental effects ranging from septic tank problems
to disruption of aquatic and terrestrial ecosystems.
Long-term high water levels may produce changes in upland
vegetation, which in turn could result in changes in the
food chain and, thereby, changes in the wildlife. Also,
fish propagation depends upon the fluctuating high and low
2Rules and Regulations of the Southwest Florida Water
Management District, Item 16J-0.15-2.
water levels that result from natural hydroperiods. For
lakes that are used directly as water supply reservoirs,
trade-offs on ecosystem stability are undoubtedly warranted.
For lakes which are not direct water supply sources, these
factors should be weighed carefully along with other criteria,
such as adjacent real estate values and effects of water-level
fluctuations on adjacent groves or crops, before establishing
a lake level regulation schedule.
Within the study area, only three lakes (Lake Okeechobee,
Clear Lake, and Lake Mangonia) are presently used for
municipal water supply. Many lakes in the study area are
used, however, as sources of water for agricultural irrigation.
Industrial and power plant uses of natural lakes in the
study area are not extensive.
Augmentation of Supply
One of the primary goals set forth in the Water Resources
Act of 1972 is "to promote the conservation, development,
and proper utilization of surface and ground water." Augmen-
tation and reuse are among the basic tools available to
accomplish this goal. Augmentation, i.e., adding to the
supply available, includes methods such as surface impoundment
of runoff, artificial recharge of fresh ground-water aquifers,
storage and retrieval of freshwater in deep saline aquifers,
and adding to the available supply by reuse of water.
Surface-Water Impoundment. Detention storage of runoff
during wet-weather periods in natural swamp and overflow
areas and in artificial impoundment areas is a vital step in
water conservation. Drainage of wetlands and flood plains
for development generally requires costly flood protection
measures and may pose a threat to water conservation by
diminishing water storage lands. A surface-water impoundment
may function only to retard rapid runoff and allow percola-
tion to the ground water or it may actually serve as a water
supply reservoir for municipal, industrial, or agricultural
The study area has a distinct seasonal pattern of streamflow
which influences the surface water available for withdrawal
and consumption. The northern part of the study area (Suwannee
and lower St. Johns) is characterized by two wet seasons,
one of which occurs in early spring and the other in mid-summer.
The southern part of the study area has a spring dry period
ending in June and a summer wet period, usually June through
October. With the wide variations in seasonal flows resulting
from these climatic conditions, few streams have dependable
year-round flows available for withdrawal to meet municipal
or other water supply demands. Possible solutions to this
problem include the use of dams or a process called water
scalping. There are, however, a few problems associated
with the use of dams in Florida.
The major obstacle is the lack of natural damsites due to
the relatively flat topography. Other undesirable features
associated with dams are possible flooding of environmentally
sensitive areas and increased evapotranspiration losses due
to the large surface area of the water body associated with
the dam. Water scalping, the other alternative, involves
the diversion of a portion of the peak streamflow to an
offstream storage reservoir whenever the stream discharge is
above a predetermined minimum. This stored water would
subsequently be used to augment water supplies during periods
of low flow.
The major benefits of scalping include (1) water conservation
by means of capture and storage of water from peak flows
which would otherwise be discharged to saltwater, (2) develop-
ment of water supply sources which could not otherwise be
developed due to either relatively low water availability,
low reliability, and/or highly variable streamflow, (3) potential
for increased recharge to aquifers by seepage from the
reservoir, and (4) reduction of flood peaks. Possible
undesirable effects may include (1) flooding of environ-
mentally sensitive lands, (2) increased evapotranspiration
losses from impounded water, and (3) reduced flushing action
in estuaries. Other factors to be considered in designing a
scalping facility include the buildup of total dissolved
solids, determination of the maximum economic size of the
pumping station and reservoirs, seepage losses, permissible
withdrawals, and potential conjuctive uses of the reservoir,
such as municipal use combined with agricultural use, munici-
pal use combined with withdrawal for cooling purposes, or
recreational and fish propagation uses in combination with
agricultural or cooling uses.
Where adequate land is available, surplus water can be
captured essentially where it falls. This is the principle
of the operation of the Everglades Conservation Area as
maintained by the SFWMD. Although evaporative loss from
these areas is high, conservation is still accomplished
since the water retained would otherwise be lost as runoff.
Artificial Recharge. Natural recharge to the artesian
aquifer occurs when the head gradient between the water
table and the potentiometric surface is downward. Surface
water moves downward to the water table, then through the
downward gradient to the artesian aquifer. Artificial
recharge can be accomplished by induced infiltration, spread-
ing, and recharge wells. Induced infiltration is accomplished
by increasing the water table gradient from a source of
recharge by placing wells near a lake or stream. Water
spreading involves the diversion of surface water over
permeable ground where it may infiltrate to the ground
water. Recharge through wells may be desirable if
underground conditions permit. Where a stratum of low
permeability overlies the aquifer and restricts natural
recharge, connector wells may be constructed to recharge the
aquifer by gravity, or water may be pumped under pressure
into injection wells to increase the recharge rate.
There are several advantages in storing water underground.
The cost of recharge may be considerably lower than the cost
of equivalent surface reservoirs, and this reduction in
initial cost may offset the cost of pumping. Underground
storage avoids problems of evaporation and pollution while
also serving as an underground distribution system, eliminating
the need for surface pipelines or canals. A ground-water
reservoir can be operated alone or in conjunction with a
Some limited experiments in artificial recharge and under-
ground storage have been conducted, and the results appear
Deep Aquifer Storage and Retrieval. During wet-weather
periods, vast quantities of water are discharged through
surface-water systems to the sea. If there were a feasible
means of storage, some of this water could be saved for use
during dry-weather periods. Injection, storage, and retrieval
of freshwater in the saline portions of the Floridan aquifer
has the potential for providing large quantities of water
during periods of high demand. Although the capabilities of
this augmentation alternative are not yet fully defined,
environmental impacts appear to be minimal and public response
is favorable. Other advantages include minimal retrieval
costs, prevention of the wasteful use of water, and elimina-
tion of evaporation losses.
Reuse. The one-time reuse of treated wastewater would, in
effect, nearly double any available freshwater supply.
Adequately treated wastewater could be reused for industrial,
agricultural, or municipal purposes. One way to reclaim
wastewater is to treat it by normal biological methods and
then allow the treated water to percolate through soil to
mix with other ground waters, which are subsequently with-
drawn and used. Another method of making water suitable for
recycling is by means of advanced waste treatment, i.e., the
use of other than conventional processes to prepare waste-
water for direct reuse. Municipal use of water adds both
inorganic and organic materials to the water. Normal waste-
water treatment removes most of the readily biologically
degradable organic material but leaves biologically resistant
materials in the effluent. Technological, economic, health-
related, and aesthetic considerations remain to be resolved
before direct reuse of wastewater for municipal supply
Demineralization. In recent years, there has been a rapidly
increasing interest in the development of processes which
convert saline water to freshwater. The cost of demineral-
ization is still relatively high, but new technology is
making it increasingly more competitive with traditional
water resource development. In fact, in some areas,
demineralization is already competitive with other means of
obtaining freshwater and, in many instances, has provided
freshwater to regions which previously had none.
The demineralization process can produce a source of water
which can be used as a sole supply or as a supplemental
supply. For instance, demineralized water could be used as
a supplemental supply during critical or peak periods, or it
could be used for dilution of a water source which had
become too highly mineralized. It could be used simply as
the total supply source or as a backup during conventional
plant breakdowns or aquifer overpumpage. Demineralized
water is also a suitable source of "adjustable" water quality
for nonpotable uses.
Demineralization is a term which actually covers a wide
variety of processes ranging from the treatment of brackish
ground water to the desalting of ocean water. The following
are a few of the many processes for removing salts from
Reverse Osmosis--This process makes use of membranes which
are selectively permeable to water rather than to salts.
Water under high pressure is pushed through the membranes,
leaving the salt behind. There are a number of reverse-
osmosis plants already operating along coastal Florida.
Electrodialysis--Electrodialysis is an electrochemical
process in which ions, under the action of an electrical
potential, move through selectively permeable membranes.
Since the cost of electrodialysis is proportional to the
amount of salt in the water, it is an unsuitable process for
use with seawater but can be used for treating brackish
Distillation--Distillation of seawater is a practice which
has been going on for many years. Water obtained by this
means is expensive; however, there is a possibility that
large dual-purpose plants generating high-pressure steam for
electric power could also produce low-pressure steam for
producing freshwater. If such technology is developed, this
process could become economically competitive, under certain
circumstances, with other methods of demineralization of
water. Solar stills have been used for limited production
of water in areas of abundant sunshine throughout the year,
but large-scale solar still production does not yet appear
Ion Exchangers--Salts can be removed from water through ion
exchangers in a process similar to water softening. The
process is prohibitively expensive for use with seawater but
is well-suited for treating waters with a salt content of
less than 1,000 mg/l.
Freezing--In freezing, the temperature of seawater is grad-
ually lowered until ice crystals are formed. The ice crystals
are essentially pure water and can be separated from the
brine. On the basis of present technology and cost, this
technique is one of the least promising methods for the
demineralization of saline water.
Interbasin Transfer and Importation of Water. The water
supply and demand equation is often unbalanced. Where water
is most needed, it is often least available. Florida's
rapidly developing coastal areas tend to concentrate water
demand in places where freshwater is least available. The
most economical approach to providing freshwater to some
coastal areas is to import it, establish inland well fields,
and pump the water to the consumers. Such import/export
arrangements are a fact of life in many coastal areas where
population far exceeds local available water supply. If the
water demands of an area outstrip even the ability of inland
parts of the same basin to supply the demand, importation of
water from ever-increasing distances becomes necessary. As
the distance increases, other environmental, social, and
economic considerations come into play. Energy requirements
must be considered, environmental effects and the hydrologic
balance must be weighed, and finally the question of the
commitment of the water resources of one area to supply
another must be addressed. Since the withdrawal and diversion
of water from one jurisdiction to another raises important
environmental, political, economic, and philosophic questions,
such transfers are generally discouraged except when no
other alternative is available.
Population Growth Control
The warm climate and attractive environment of Florida have
made it a highly desired place of residence. Visiting
tourists return to live permanently in Florida and increasing
numbers of retirees are flocking to these shores. This high
rate of migration into Florida has resulted in rapid urbaniza-
tion of the coastal areas rather than a uniform growth
throughout the State. The resulting imbalance in the water
supply and demand situation is discussed above under Inter-
basin Transfer and Importation of Water.
Water conservation and reuse, demineralization, and importa-
tion of water have been discussed as means of alleviating
the water supply shortage in highly urban coastal areas.
Another means of balancing the water supply and demand
equation is to limit the growing demand. Population growth
control would be another governmental regulatory activity
aimed at limiting the water demand to that which could be
satisfied by existing or readily available sources. This
regulatory activity would have to be coordinated with local
planning so that the "saturation" population (the maximum
population that could result based on local land use plans
for maximum residential densities) would not outstrip the
available water supply. If projected population densities
did appear to exceed the future available water supply, the
land use plan would have to be changed accordingly.
Residential areas would have to be down-zoned and industrial
growth and agricultural production would also have to be
limited by available water supplies.
Population control regulation obviously has the potential
for making an enormous impact on the local and even the
statewide economy. It could limit industrial growth; it
could create a decline in service trades; and, in all fair-
ness, it could also reduce tourism in order to limit peak
R Chapter 4
THE HYDROLOGIC SYSTEM
Legal, historical, and philosophical factors play an important
part in determining the actual practices associated with
water use, but the most basic factor involved is the water
itself and the physical setting in which it occurs. This
chapter presents a discussion of the hydrologic cycle and
its various components and describes the natural occurrence
of both ground water and surface water in the study area.
THE HYDROLOGIC CYCLE
Virtually all of the water in our environment is continuously
being recycled by forces exerted by the sun's energy and the
earth's gravity. This eternal movement of water, called the
hydrologic cycle, has no real beginning or end, but we
usually think of it as beginning with the waters of the
ocean since they cover about three-fourths of the earth's
surface and with the other surface waters of the earth.
Solar energy acting upon these surface waters draws water,
in the form of vapor, into the atmosphere. This vapor
rises, then collects to form clouds. The vapor in the
clouds will condense to form drops of water which, due to
gravity, fall to the earth in the form of rain, sleet, hail,
Once this water reaches the earth and wets the foliage and
ground, part of it will run off over the surface of the
ground to streams which will carry it back to the oceans.
In highly urbanized areas, a considerable amount of the
rainfall is lost to runoff since paved parking lots, houses,
and buildings allow for little percolation of water into the
soil. In nonurban areas, factors such as soil type, vegeta-
tive cover, slope of the terrain, and water table conditions
govern the rate of runoff.
The water which seeps into the ground may be used by plants
in a process in which the water is transpired back into the
atmosphere or it may percolate further into the ground.
Once it has reached the zone of saturation, the percolating
water is called ground water. Surface water and ground
water are intimately related; changes in one will result in
changes to the other. Springs are composed of surface water
which only moments before was ground water. At times, part
of the flow of rivers comes from the ground water. At other
times, part of the flow of rivers seeps into the ground to
become ground water. Lakes also have an intimate relationship
with ground water; their levels may rise and fall in response
to changes in the ground-water level. These fluctuations
may be due to seasonal changes in rainfall, long-term periods
of drought or flooding, or pumping of ground water or surface
water for irrigation, industry, or municipal water supply.
Figure 4-1 depicts the hydrologic cycle and shows the inter-
relationships of water in the various phases of the cycle.
The total amount of water in the cycle is believed to have
remained constant for the past 1/2-billion years; however,
over limited areas, the amount of water in any particular
part of the cycle may at certain times vary significantly.
The study of these interactions and variations is the science
Some of the water that seeps into the ground and some of the
water in surface-water bodies is used by plants in a process
called transpiration. In this process, water is taken from
the ground by the root system of plants and transpired into
the atmosphere through the leaves. The depth from which
plants will take up ground water varies with the species of
plant and type of soil, ranging from a few feet for ordinary
grasses to 50 feet or more for certain types of desert
Transpiration varies seasonally. It is low during the fall
and winter and high during the growing season. Evaporation
also varies seasonally and is dependent on such factors as
humidity, cloud cover, solar radiation, wind movement, and
air temperature. Figure 4-2 shows the average yearly evapo-
ration rate from free water surfaces in the study area.
Water lost to the atmosphere through solar energy or plant
use is often thought of jointly and called evapotranspiration.
Areas covered by vegetation and with a water table contin-
uously at or near ground surface can produce annual
evapotranspiration losses which are higher than the average
annual rainfall at the same location. Under the same condi-
tions, evapotranspiration losses will also significantly
exceed evaporation from free water surfaces.
A lowering of the water table decreases the rate of
evapotranspiration. From experiments in Belle Glade, south-
east of Lake Okeechobee, where the water table ranges from
ground level to an average of about 2 feet below, annual
evapotranspiration from sawgrass land was determined to be
approximately 60 inches (Clayton, et al. 1942). In an area
south of Miami, evapotranspiration from pineland and grass-
land which had a lower water table was estimated at
approximately 35 inches per year (Parker, et al. 1955).
Generalized hydrologic c,
ic cycle. FIGURE 4-1.
FIGURE 4-2. Average yearly evaporation rate from free water surfaces, inches.
The U.S. National Weather Service, formerly the U.S. Weather
Bureau, is the primary source of rainfall records for the
study area; however, extensive additional unpublished data
are also available from various federal, state, municipal,
and private sources.
The published data contain several interesting facts. For
instance, rainfall conditions in the study area are quite
varied, both in annual amounts and seasonal distribution,
despite the fact that the topography varies only slightly.
Average annual rainfall based on a 25-year period varies
from station to station across the state, with averages as
high as 66 inches to as low as 45 inches. Some locations,
such as the Florida Keys, average less than 40 inches of
rainfall annually. The average annual rainfall in Florida
is shown on Figure 4-3.
The area of highest annual rainfall in the study area occurs
in the lower east coast of the peninsula, where annual
rainfalls exceeding 100 inches have been measured.
The distribution of precipitation within a given year is
quite uneven, and changes in seasonal distribution are also
significant from one section of the study area to another,
showing a transition from north to south. In southern
Georgia, there are two high points of rainfall during the
year, one occurring in late winter and the other in mid-summer.
In peninsular Florida, there are two very striking aspects
of the rainfall pattern. First, the summer rainfall is very
dominant, generally with more than one-half of the annual
rainfall occurring from June through September, and second,
the abrupt start and end of the rainy season. The extreme
northern part of the study area exhibits a rainfall pattern
similar to both south Georgia and peninsular Florida, with a
high winter rainfall and a more predominant high in the
summer months. Figure 4-4 shows comparative rainfall distri-
butions for different climatological regions of the study
Most of the summer rainfall in the study area results from
local air mass shower or thundershower activity of short
duration. Large amounts of rainfall during these short
storms are not uncommon. Most gaging stations in the study
area have experienced 2-hour rainfall totals in excess of
3 inches. In the northern part of the study area, precipi-
tation may result from summer thundershowers as well as from
winter and early spring storms caused by interaction of
warm, moist tropical air masses and colder air masses from
the northern interior of the continent. Tropical storms,
which of course can bring excessive amounts of rainfall over
relatively large areas, have been experienced from time to
time throughout the study area.
The study area contains many complex surface-water systems
made up of streams, lakes, springs, marshes, and swamps.
Surface-water and ground-water flows are influenced by pre-
cipitation, topography, vegetation, geology, and man's
alterations to the natural system. Lakes, streams, springs,
and swamps can go from the extreme of flooding to the extreme
of complete dryness due to natural and/or manmade conditions.
Streams in Florida are considered to be major streams when
they have an average flow of at least 1,000 cfs. There are
10 major streams in Florida, as shown on Figure 4-5. Within
the study area, there are seven major streams: Suwannee,
Oklawaha, Caloosahatchee, Santa Fe, Kissimmee, St. Johns,
and Peace Rivers. South of Lake Okeechobee, streams are for
the most part poorly developed and most drainage is through
a system of canals.
The area to the south of Lake Okeechobee is also the only
major portion of the state which does not have well-defined
lakes, being covered by freshwater marshes and swamps. The
lack of well-defined lakes in this area and the abundance of
lakes in the central part of the state is due to the geo-
morphology of the state.
The entire peninsula is underlain at various depths by
porous limestone in which ground water has formed subterranean
cavities. When the strata overlying the limestone are
relatively thin, they may collapse into the cavities.
Sinkholes are formed and a lake may develop if the limestone
is overlain by adequate surficial deposits to form a lake
There are other ways in which a lake may be formed. Large
lakes, such as Okeechobee, Kissimmee, and Istokpoga, are
believed to have been created by receding seas which, in the
past, covered the area. Other large lakes, such as those in
north Florida, were formed by streambeds abandoned by
Hydrologically, lakes in Florida fall into one of three
categories: perched lakes, water-table lakes, or artesian
lakes. Perched lakes are "perched" above the water table
and have an impervious layer of material on the bottom of
the lake. If this layer is disturbed, the lake will be
lowered or, possibly, may dry up altogether. Water-table
lakes are very common in Florida. The level of these lakes
fluctuate with the water table. When the water table is
higher than the water level in the lake, water flows into
the lake; when it is lower, water flows out. Artesian, or
sinkhole, lakes are sustained by springs or water coming
from a direct connection with the artesian aquifer. Since
the pressure in the aquifer may fluctuate, the level of an
artesian lake will also fluctuate accordingly.
60 56 -
C OF OF
N- Q=O 50
FIGURE 4-3. Average annual rainfall, inches.
G E 0 R G I A A-i ro
ak_ o a lle aInternational Airport
-Lake City AvarabwA-riare=-53.36 inches
"- -- -t I-- A-6-verageAnnual = 51.01 inches '
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A re Annual = 49.90 inches
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,. _-., _..- ,.1 AverageAnnual. 5 A a .4 9 incce:
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Scale in Miles
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A L T I,
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-- .- "I Belle Glade ExperimentLStaltmo
SAverage Annual = 58.47 inches
1- y *21 -,-
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F M I
nual =36.76 inches
M J I -
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- - -
Springs result from a natural overflow of the ground-water
system. Springs in Florida are of two basic types: artesian
springs and nonartesian springs. Artesian springs result
when the hydrostatic pressure in the artesian aquifer forces
water upward to the earth's surface through openings in the
confining bed of the aquifer. Nonartesian springs occur
when percolating water reaches an impervious bed and runs
laterally along the bed until it intersects the earth's
surface, where the water then flows out as a spring. Springs
with an average flow of 100 cfs or more are classed as first
magnitude springs. There are seven first magnitude springs
in the study area, having a combined average daily flow of
1,863 cfs (1,200 mgd).
SURFACE-WATER FEATURES OF THE STUDY AREA
In the following sections of this chapter, surface-water
features of the study area are described. Descriptions are
arranged by water management districts. Districts are
further subdivided into hydrologically similar units for
purposes of discussion. The reader should recognize that
these subdivisions do not reflect, except as noted, formal
political or planning units of the districts.
ST. JOHNS RIVER WATER MANAGEMENT DISTRICT
The St. Johns River Water Management District (SJRWMD) is
comprised of three major drainage basins and several coastal
basins. The major river basins are the St. Johns River
Basin, the Nassau River Basin, and the Florida portion of
the St. Marys River Basin. The St. Johns Basin is further
divided into the.Upper and Lower St. Johns River Basins and
the Oklawaha River Basin.
The coastal basins are designated as the Upper, Middle, and
Lower Coastal Basins. Of the 12,400 square miles in the
SJRWMD, about 9,400 square miles are drained directly by the
St. Johns River and its tributaries. Surface-water features
comprise approximately 9% of the total land area encompassed
by the SJRWMD.
One-third of the lakes in Florida are found in the St. Johns
River Water Management District. The 2,750 lakes in the
District have a total surface area of approximately 420,000
acres and range in size from less than 1 acre to about
70 square miles. Most of the large lakes in the District
are actually wide reaches of the St. Johns River.
Lake Apopka (47.6 square miles) is the largest lake in the
District that is not part of the main stem of the St. Johns
St. Johns River
The St. Johns River, the third largest river in Florida, has
its headwaters in western Indian River County at an elevation
of about 25 feet (msl) and meanders northward parallel to
the coast for 318 miles before discharging into the Atlantic
Ocean near Jacksonville. The St. Johns River is the largest
river in Florida deriving its flow totally from within the
State. Near the mouth of the St. Johns River and upstream
for approximately 100 miles, streamflow is affected by ocean
tides. During each tidal cycle, large quantities of saltwater
enter the St. Johns River and then reverse direction and
flow back to the ocean. It has been estimated that the
average upstream and downstream discharge from the St. Johns
River at Jacksonville is 40,536 and 46,419 cfs, respectively
(Anderson and Goolsby 1973).
The drainage boundaries of the upper reaches of the St. Johns
Basin are poorly defined due to the flat topography. From
the headwaters in western Indian River County, a marshy area
extends northward about 40 miles, bordered by a sandy prairie
which is often inundated by floodwaters. This area has been
altered by numerous drainage and irrigation canals. The
St. Johns River becomes more channelized near Lake Hellen
Blazes in Brevard County. From Lake Hellen Blazes to Lake
Harney, the river channel passes through flat marshy areas
ranging in width from 1 to 7 miles.
From Lake Harney to the mouth of the Oklawaha' River, the
St. Johns River is a wide, well-defined channel forming a
transition between the saline waters of the tidally in-
fluenced lower St. Johns and the freshwater from the upper
reaches. In the lower reaches of the St. Johns River from
the Oklawaha River to the mouth east of Jacksonville, the
channel, about 1 mile wide, flows along a flood plain which
may exceed 10 miles in width. Due to the tidal action in
this portion of the river, freshwater discharge volumes,
which are difficult to determine, are computed by subtracting
upstream flows from downstream flows. The average computed
discharge at Palatka is 6,999 cfs for a drainage area of
7,094 square miles.
SOUTH FLORIDA WATER MANAGEMENT DISTRICT (SFWMD)
The SFWMD encompasses approximately 17,000 square miles and
16 counties in south Florida. The District is generally
divided into three major topographic areas: the Flatwoods
and Highlands Ridge in Orange, Osceola, Polk, Highlands, and
Okeechobee Counties; the coastal ridges bordering the Atlanti
Ocean and the Gulf of Mexico; and the swamps and wet prairies
of the southern interior. The District comprises about 31%
of the land area of Florida, and contains about 39% of the
For water management and planning purposes, the district is
divided into six planning units, referred to as planning
areas: (1) the Kissimmee Valley, (2) Indian Prairie-Lake
Istokpoga Area, (3) Lake Okeechobee, (4) Upper East Coast,
(5) Lower East Coast, and (6) Lower West Coast. The planning
areas are relatively coherent hydrologic units with respect
to both surface and ground water. The Everglades Conservation
Areas, located at the eastern edge of the Everglades, are a
unique feature of the District, acting as shallow storage
reservoirs to distribute water to the Everglades National
Park and the canal network along the lower east coast.
Most of the watersheds in the SFWMD have been extensively
modified by man in an effort to control floods and to manage
the water resources of the area.
The Kissimmee River, the major hydrologic feature in the
northern portion of the District, originates in the Central
Highlands portion of Florida. The Kissimmee River is regulated
by control structures along its length before discharging to
Lake Okeechobee, the largest freshwater lake in Florida.
Lake Okeechobee receives flow along its northern edge and
discharges through control structures in the St. Lucie Canal
to the Atlantic Ocean, the Caloosahatchee River to the Gulf
of Mexico, and canals into the Everglades Agricultural Area.
Excess flows from the Agricultural Area are released into
the Everglades Conservation Areas or to the Atlantic Ocean.
The Conservation Areas primarily provide flood control for
the Atlantic coastal areas and store'water for discharge to
the Everglades National Park. Much of the water transferred
throughout the SFWMD has its source near the headwaters or
along the length of the Kissimmee River and its tributaries.
The Kissimmee Valley Planning Area
The Kissimmee Valley area combines the upper and lower
Kissimmee River Basins, drains 2,470 square miles in Orange,
Osceola, Polk, Highlands, and Okeechobee Counties, and is
the primary contributor of water to Lake Okeechobee.
The upper Kissimmee River Basin is an area of 1,750 square
miles drained predominantly by lakes and connecting canals.
The major lakes in the Basin, East Lake Tohopekaliga, Lake
Tohopekaliga, and Cypress Lake, are interconnected, as are
Lakes Hatchineha, Hart, Mary Jane, Myrtle, Alligator, Gentry,
and Kissimmee, with lake and canal water levels regulated by
nine control structures. The upper Kissimmee River Basin
has an estimated storage potential of 1.4 million acre-feet
(measured at the Lake Kissimmee outlet).
The lower Kissimmee River Basin encompasses 742 square miles
between the outlets from Lake Kissimmee and Lake Okeechobee.
The lower Kissimmee River Basin contains the Kissimmee
River, originally a meandering stream about 90 miles long.
The Kissimmee River has been channelized and is regulated by
five control structures located between Lakes Kissimmee and
Okeechobee. At a stream gaging station located 16 miles
upstream of Lake Okeechobee, the Kissimmee River now dis-
charges about 1,382 cfs annually. Under natural conditions,
before channelization and diversion of a portion of the
river flow to Lake Istokpoga, mean annual flow was 2,188 cfs
at this point. Under flood flow conditions, the Kissimmee
River sometimes receives flow diverted back from the Lake
Istokpoga watershed through the Istokpoga Canal.
Channelization of the Kissimmee River has resulted in the
elimination of a meandering streambed, and thus channel flow
distances and times have been reduced. The channelization
has also resulted in the drainage of adjacent river swamps
and the elimination of natural water storage areas. These
changes tend to reduce the river's natural purification
capacity and thus alter the water quality as well as the
time distribution of waters discharged downstream.
Indian Prairie-Lake Istokpoga Planning Area
The Indian Prairie-Lake Istokpoga watershed in northeast
Glades and southeast Highlands Counties drains approximately
650 square miles, with discharge to Lake Okeechobee. Lake
Istokpoga has a surface area of 43 square miles and a storage
area receiving input from Arbuckle and Josephine Creeks and
diversions from the Kissimmee River. Excess water in Lake
Istokpoga may be discharged through the Istokpoga Canal to
the Kissimmee River and through canal C-41A across the
Istokpoga Marsh to Lake Okeechobee. Canals C-41, Harney
Pond Canal, and C-40, Indian Prairie Canal, receive flow
from the upper reaches of Canal C-41A to irrigate the
Istokpoga-Indian Prairie area and to provide drainage to
Lake Okeechobee. These flows are regulated by the SFWMD.
Arbuckle Creek begins at the Crooked Lake outlet and connects
Reed Lake and Lake Arbuckle, and runs southward to Lake
Josephine Creek, beginning at the north end of Lake Placid,
drains 143 square miles to the west of Lake Istokpoga.
Canal C-41A, the primary outlet from Lake Istokpoga, flows
across the Istokpoga Marsh and discharges to the Kissimmee
River 8.5 miles upstream from Lake Okeechobee. Canal C-41A
connects with Canal C-40, Indian Prairie Canal. Flow in
Canal C-41A is regulated at Lake Istokpoga (S-68) at its
junction with the Kissimmee River (S-84), and at its junction
with Canal C-41.
Lake Okeechobee Planning Area
The Lake Okeechobee Planning Area includes Lake Okeechobee
(with a surface area of 740 square miles within the levee
system), the Everglades Agricultural Area, 1,082 square
miles located south of the lake, and that portion of the
Caloosahatchee River Basin between the eastern boundary of
Lee County and Lake Okeechobee.
Lake Okeechobee is the second largest freshwater lake in the
United States and is the heart of the water supply network
in the south Florida. It is fed from the north predominantly
by the Kissimmee River, Fisheating Creek, and the Indian
Prairie Canal. East of the Kissimmee River Basin is Taylor
Creek watershed, which drains approximately 260 square
miles. All flows entering the lake are regulated by control
structures except that from Fisheating Creek.
Lake Okeechobee, with a storage capacity of approximately
4.7 million acre-feet (1,525 billion gallons), serves as a
balancing reservoir, receiving inflow mainly from the north
and discharging flows to the east through the St. Lucie
Canal (C-44), to the west through the Caloosahatchee River
(C-43), and to the Everglades Agricultural Area to the south
via the West Palm Beach, Hillsboro, North New River, and
Outflow from the lake is controlled by pumping, gravity
flow, and impoundment levees to maintain a lake surface
elevation between 15.5 and 17.5 feet (msl). Lake Okeechobee
serves as a supply reservoir for the Caloosahatchee River
and the St. Lucie Canal Basins as needed, but is also used
to maintain canal levels in southeast Florida to retard
saltwater intrusion, to argument municipal supplies during
sustained droughts, and to assist in recharge of municipal
St. Lucie Canal
The St. Lucie Canal, running from the east edge of Lake
Okeechobee easterly to the south fork of the St. Lucie
River, discharges a major portion of the lake outflow to the
Atlantic Ocean at Stuart, Florida, along with runoff from an
additional 1,322 square miles, excluding Lake Okeechobee.
The canal is flow-regulated by navigation locks both at Lake
Okeechobee and at a location about 25 miles downstream from
the lake. The St. Lucie Canal discharges an average of
1,100 cfs of runoff to the Atlantic Ocean. However, these
flows occur only when the stage of Lake Okeechobee is high.
On the average, the St. Lucie Canal floodgates are closed
70% of the time. An undetermined amount of water is pumped
by landowners from the canal for irrigation purposes.
The easterly portion of the Caloosahatchee River flows from
a hurricane gate at Lake Okeechobee at Moore Haven, Florida,
along southern Glades and northwestern Hendry Counties
toward the Gulf of Mexico west of Fort Myers, Florida. The
river is controlled at Ortona (15 miles downstream from
Moore Haven) and at Ogla, about 15 miles east of Fort Myers,
by navigational locks. The Caloosahatchee River, Lake
Okeechobee, and the St. Lucie Canal together form the Cross-
State Okeechobee Waterway, a navigable channel and lock
network extending from Fort Myers to Stuart.
Everglades Agricultural Area (EAA)
The Everglades Agricultural Area includes about 1,085 square
miles located south of Lake Okeechobee. The entire area is
enclosed and crossed by a network of levees, pumping stations,
and water control structures which are used to distribute
water throughout the area for irrigation. The principal
canals through the area, the West Palm Beach, Hillsboro,
North New River, and Miami Canals deliver water from Lake
Okeechobee to the area as required. Excess flows from the
Agricultural Area are released either to the Atlantic Ocean
or to the Everglades Conservation Areas for eventual dis-
charge to the Everglades National Park.
Upper East Coast Planning Area
The Upper East Coast Planning Area encompasses the St. Lucie
County agricultural area and is drained entirely by three
major canals (C-23, C-24, and C-25) which rely on runoff
from within the area as their only source of supply. The
area, including St. Lucie County, the eastern portion of
Okeechobee County and most of Martin County, is predominantly
agricultural. Unlike most of the District, the surface
waters of this District are entirely dependent on canal
storage and inseepage from ground water.
Discharges from canals C-23, C-24, and C-25 are regulated by
downstream structures to maintain canal levels between 20.0
and 22.8 feet (msl). Whenever canal stages drop below
14.0 feet (msl), withdrawal from the canals is stopped.
Lower East Coast Planning Area
The Lower East Coast Planning Area extends from southern
Martin County southward to, and including, Dade County; and
from the easterly portion of the Everglades National Park
(east of Big Cypress Swamp) and the Everglades Conservation
Areas eastward to the Atlantic Coastal Ridge and the Atlantic
Water control in the Lower East Coast Planning Area is
provided by a system of 25 major canals with downstream
control structures to inhibit saltwater intrusion. Many of
these canals are connected to the Conservation Areas which
serve as water supply sources.
The Lower East Coast Planning Area is separated from the
Conservation Areas and the Everglades by a levee extending
from Lake Okeechobee in southwest Martin County southward to
Homestead in Dade County. The levee, constructed to prevent
overland flooding, forms the easterly perimeter of the
Everglades Conservation Area.
Four of the major canals in the area, the West Palm Beach,
Hillsboro, North New River, and Miami Canals, share Lake
Okeechobee as their primary source of water supply and
discharge to the Atlantic Ocean at West Palm Beach, Boca
Raton, Ft. Lauderdale, and Miami. The portion of the Tamiami
Canal in the Lower Coastal Planning Area is the easterly
continuation of the main drainage canal for the Everglades
National Park and the Big Cypress Swamp. This easterly
portion of the Tamiami Canal, located east of the 40-mile
bend, primarily drains the Everglades and the westerly
portion of the Big Cypress Swamp. During wet periods, most
of the flow in the canal originates in the Everglades;
during dry periods, the Big Cypress Swamp contributes most
of the canal flow.
Everglades Conservation Areas
Everglades Conservation Areas 1, 2, 3A, and 3B, which have a
combined drainage area of 1,345 square miles, lie south and
east of the Everglades Agricultural Area. The purpose of
these Conservation Areas is to control the rate of runoff
from the central Everglades, to provide flood control for
the coastal areas, and to supply a monthly minimum allotment
of water to the Everglades National Park as required by
Congress (315,000 acre-feet per year).
The Conservation Areas act as shallow storage reservoirs
receiving flow from the Everglades Agricultural Area, either
by pumping or by gravity flow. Canal levels in the area are
regulated to maintain satisfactory levels for both environ-
mental and hydrologic reasons.
Since 1953, freshwater discharge to the ocean has been
reduced due to the implementation of recent water management
techniques. The primary effect of water control has been to
facilitate flows into and out of the Everglades and to alter
the distribution of runoff from the area.
Lower West Coast Planning Area
The Lower West Coast Planning Area is divided into two
watersheds, the Coastal and the Big Cypress, located princi-
pally in Collier, Lee, and southern Charlotte Counties and
draining about 3,400 square miles. The 1,420-square-mile
coastal watershed is drained to the Gulf of Mexico by the
Caloosahatchee River and its tributaries and also by numerous
small coastal streams. The 2,000-square-mile watershed of
the Big Cypress is a swampy area which becomes a coastal
marsh along the southwestern edge. Drainage from the Big
Cypress Swamp is generally southwesterly, through the Golden
Gate Canal network and through the Okaloachoochee Slough,
the Baron River and Turner River Canals, and through the
Tamiami Canal in the central area. Flow measurements con-
ducted by Klien and others (1970) indicate a southward flow
of about 1,900 cfs from the central undeveloped portion of
the watershed during a period of high water levels in November
1969. In the western portion of the watershed, flows were
660 cfs and 400 cfs southward and westward, respectively.
Because of the diffuse nature of surface-water flow in the
Big Cypress (i.e., absence of defined river systems),
surface-water supply development potential is extremely
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT (SWFWMD)
The portion of the Southwest Florida Water Management District
within the study area includes Polk, Hardee, DeSoto, Sarasota,
and Manatee Counties and part of Charlotte County. There
are numerous intermittent ponds, swamps, and marshes in the
area as well as many large to medium-sized lakes, located
mostly in Polk County. The major streams are the Peace,
Myakka, Braden and Manatee Rivers and their tributary systems.
Waters in the study area are generally low in chlorides and
dissolved solids and relatively high in nutrient concentrations.
The Peace River drains about 2,480 square miles in DeSoto,
Hardee, Polk, and Charlotte Counties. From its headwaters
in north-central Polk County, the Peace River flows southerly
for approximately 105 miles to the Gulf of Mexico at Charlotte
Harbor. Three USGS gaging stations on the Peace River, at
Bartow, Zolfo Springs, and Arcadia, have continuous flow
records for more than 30 years. The Peace River at Zolfo
Springs has a drainage area of 826 square miles and an
average discharge of 720 cfs. The maximum and minimum
discharges recorded at the Zolfo Springs station are
26,300 cfs and 39 cfs. At Arcadia the drainage area is
1,367 square miles, with an average discharge of 1,216 cfs.
The maximum and minimum discharges recorded at the Arcadia
station are 36,200 cfs and 37 cfs. The estimated average
flow at the mouth of the river is approximately 2,400 cfs.
The river forms a tidal estuary at its outlet and is thus
subject to various mixtures of freshwater and saltwater in
its lower reaches. The upstream extent of the tidal mixing
zone varies with flow conditions and will be greatest during
periods of low freshwater inflow.
Water quality in the Peace River and its upper tributaries
is characterized by high nutrient concentrations. The very
high phosphorus levels are due to phosphate mining activities,
natural runoff from phosphate-rich formations, effluent
discharge from wastewater treatment plants, citrus packing
plants, and other industrial plants. In addition, the river
and its upper tributaries have been subject to pollution by
spills from phosphate mining areas in Polk County, as well
as to pollution from agricultural runoff containing pesticides
and fertilizers. As a result, the Peace River has a high
fertility, causing frequent and massive algal blooms during
warm weather and low streamflow conditions. Nutrient con-
centrations steadily decrease at stations downstream, as a
result of dilution due to the increased flow volume.
The Manasota Basin in west-central Florida encompasses both
Manatee and Sarasota Counties. The two major streams in the
Basin, the Myakka and Manatee Rivers, and their tributaries
drain about 585 square miles and discharge to Charlotte
Harbor, Tampa Bay, and the Gulf of Mexico.
Myakka River. The Myakka River, the largest stream in the
Basin, rises in the marshes of southeastern Manatee County
and flows southerly for 54 miles to Charlotte Harbor and the
Gulf of Mexico with an average discharge at its mouth of
A USGS continuous recording station is located on the Myakka
River about 14 miles southeast of Sarasota and 36 miles
upstream from the mouth. The drainage area at the gaging
station covers approximately 235 square miles, and the
average annual flow is 261 cfs. The maximum discharge
recorded at this station was 8,670 cfs. Periods with no
flow for many days have occurred during several years. The
longest period of no flow that has been recorded at this
station was 133 days in 1950. These low-flow or no-flow
conditions in the stream for the period March through May
result from drainage of the water table aquifer and the
combined effects of storage and increasing evapotranspiration
in both Myakka Lake and the surrounding marshlands. Because
of observed long periods of low flow, the Myakka River
offers little potential for development as a large water
The mean monthly concentration of dissolved solids is about
100 mg/l. However, during periods of low flow, April through
June, dissolved solids concentrations in the river increase
High nutrient levels in the river periodically cause algae
and aquatic weed problems. Objectionable quality character-
istics that occasionally occur during periods of high runoff
are dissolved iron concentrations of about 0.3 mg/l and high
turbidity. Saltwater in this river extends at times well
into Sarasota County above Deer Prairie Creek.
Water in the upper reaches of the Myakka River is calcium
bicarbonate in type and low in mineral content (100 mg/l)
during periods of high flow. During low flow, the river is
sodium chloride in type and highly mineralized from water
flowing from irrigation wells.
Big Slough. The Big Slough, also know as the Myakkahatchee
Creek, is a tributary to the Myakka River in its lower
reaches. Big Slough rises in southeast Manatee County and
flows southerly into the Myakka River near the Sarasota/
Charlotte County line. Water quality is similar to that of
the Myakka River.
Manatee River. The Manatee River rises in eastern Manatee
County and flows westerly to the Gulf of Mexico, draining
about 350 square miles at its mouth with an annual streamflow
estimated to be about 460 cfs. The Braden River is the
major tributary to the Manatee River.
Data obtained at water quality stations upstream from Bradenton
on the Manatee River indicate low chlorides and dissolved
solids, averaging about 10 and 100 mg/l, respectively.
However, high nutrient levels cause occasional algae and
weed problems in the slow-moving reaches of the river during
low flows and warm weather.
Little Manatee River. The Little Manatee River rises in
western Hillsborough County and drains about 150 square
miles in Hillsborough and Manatee Counties. Except for a
short section in northern Manatee County, the main stream of
the Little Manatee is outside the study area.
Total dissolved solids concentration in the stream reach
within the study area is normally less than 100 mg/l, and
nutrient levels are low.
SUWANNEE RIVER WATER MANAGEMENT DISTRICT (SRWMD)
That portion of the Suwannee River Water Management District
within the study area is comprised of Suwannee, Columbia,
Union, and Bradford Counties and a small portion of Baker
County. The principal streams in this eastern portion of
the District are the Suwannee and Santa Fe Rivers. Stream
flow data and water quality data for these streams are
presented in Appendixes A and B, respectively.
The headwaters of the Suwannee River, the second largest
stream in Florida, are at an elevation of 120 feet (msl) in
the Okefenokee Swamp in southern Georgia. The river flows
to the Gulf of Mexico, draining an area of 9,900 square
miles, 4,200 square miles of which are in Florida. Numerous
springs, four of which (Troy, Ichatucknee, Fannin, and
Manatee) are magnitude springs, discharge a total of 770 cfs
to the Suwannee River.
At Benton, Florida, about 6 miles south of the Florida-Georgia
state line, where the river has a drainage area of 2,090 square
miles, streamflow observed during 1977 averaged about 2,200 cfs,
with maximum and minimum flows of 10,500 and 5.0 cfs. The
average discharge for 52 years of record at White Springs,
Florida, about 25 miles further downstream, is 1,879 cfs.
The maximum and minimum flows for the period of record are
38,100 (1973) and 4.8 cfs (1931). At Branford, about 96 miles
downstream from White Springs and 10 miles upstream from the
Santa Fe River, the average streamflow increases to 6,994 cfs
for 46 years of record. The drainage area at this point
covers 7,800 square miles, of which 4,170 square miles are
drained by the Withlacoochee and Alapaha Rivers, tributaries
to the Suwannee River.
The most downstream gaging station on the Suwannee River is
near Wilcox, Florida, about 33 miles upstream from the mouth
and 42 miles downstream of the gage at Branford. With
37 years of record, the average, maximum, and minimum flows
recorded are 10,624 cfs, 84,700 cfs (1948), and 3,270 cfs
(1957), respectively. However, flows are generally affected
by tide when the discharge is less than 17,500 cfs.
Santa Fe River
The Santa Fe River, a tributary to the Suwannee River, is
about 70 miles long, has an average slope of 1.9 ft/mi, and
drains 1,380 square miles. At its confluence with the
Suwannee River, its average flow is approximately 2,300 cfs.
The flow of the Santa Fe River is primarily from spring-fed
tributary streams, New River, Swift Creek, and Olustee
Creek, and from Santa Fe Lake and Lakes Sampson and Butler.
The Santa Fe River flows underground approximately 9 miles
east of High Springs, Florida, and reappears about 3 miles
downstream. From the point of its emergence to its confluence
with the Suwannee River, this reach of the Santa Fe is fed
by numerous springs in or near the river channel. The base
flow in the lower reaches of the Santa Fe Basin is greater
than one and one-half times the average rainfall.
There are two primary streamflow gaging stations on the
Santa Fe River, one at Worthington Springs, and one near
Fort White. Streamflows measured at the Worthington Springs
site, 51 miles upstream from its mouth, result from runoff
from about 575 square miles. The average discharge for
46 years of record is 442 cfs at this point, with measured
maximum and minimum flows of 20,000 cfs (1964) and 0.5 cfs
(1955). At maximum flows some water is diverted from Santa Fe
Lake into the Oklawaha River via the Lochloosa Canal.
At the Fort White gaging station, approximately 18 miles
from the confluence of the Santa Fe and Suwannee Rivers, the
upstream drainage area is 1,017 square miles. The average
streamflow observed during 47 years of gage operation is
1,631 cfs. Maximum and minimum flows are 17,000 cfs (1964)
and 609 cfs (1957).
St. Marys and Oklawaha Rivers
The St. Marys River and the Oklawaha River, a tributary of
the St. Johns River, drain small areas along the eastern
edges of the SRWMD. In southwest Baker County, the St. Marys
River drains about 2 square miles of an area located approxi-
mately 12 miles east of Lake City. The Oklawaha River
drains about 85 square miles in eastern Levy County and
western Alachua and Marion Counties. Surface drainage of
the Oklawaha River Basin in this area is generally poorly
defined with surface runoff channeled either directly into
the ground or through sinkholes into underlying aquifers.
The Oklawaha River receives diversion flows from Santa Fe
Lake via Lochloosa Canal during periods of high lake stage,
with eventual discharge to the St. Johns River and the
Ground water is defined as all of the water contained in the
pore spaces in the rocks and sediments in the zone of saturation
beneath the surface and is free to move about under the
influence of gravity. Practically all ground water is
derived from precipitation which percolates through the soil
and is stored in the underlying aquifers. A phase of the
hydrologic cycle, the ground-water body is a reservoir for
the long-term storage of water which it is relatively safe
from evaporation and pollution. When this reservoir is
sufficiently large, it comprises a source of water which is
not effected as much as surface sources by short-term climatic
variations and has multiple uses.
The availability of ground water in an area is largely
determined by a combination of climate and geology. In
order for ground water to contribute significantly to the
total water resources of an area, three conditions must be
1. Precipitation must exceed runoff and moisture-holding
capacity of the soil so that some water is available to
percolate through the soil to recharge underlying
2. The underlying strata must have sufficient thickness
and permeability to form a ground-water reservoir which
is large enough to be economically and practically
3. The soil and rocks must not contain soluble minerals or
native water whose presence will degrade the water
quality to the extent that it would be unusable.
Because of the high annual rainfall and high permeability of
its aquifers, Florida is one of the richest states in ground-
water resources. Average annual rainfall is almost 54 inches.
Most of the state is covered by sandy, relatively permeable
soils, underlain by permeable shell or limestone strata.
The land is relatively flat, with a maximum elevation of
only about 350 feet above sea level. The combination of
high rainfall, permeable soils, and low relief contribute to
a high rate of recharge. Several extensive and highly
permeable aquifers underly the state and act as ground-water
The dominant feature of the ground-water system in Florida
is the section of tertiary limestone and dolomite strata
which underly the whole state. Solution of the carbonate
rocks by circulating ground water has produced a number of
zones of high permeability within these strata. The saturated,
permeable parts of the tertiary carbonate start are referred
to as the Floridan aquifer, one of the most productive
aquifers in the world and the aquifer used most in the
central and northern parts of the state. In the southern
part of the state, the aquifer contains only brackish water
and is used extensively for irrigation and other nondrinking
Although the Floridan aquifer is highly productive throughout
the area, it is not uniformly productive throughout its
thickness. Alternating strata of variable thickness of
limestone, dolostone, and dolomitic limestone separate the
aquifer into distinct zones. These strata vary widely in
permeability. The limestone and some of the dolomite lime-
stones have a chalky texture and consequently have low
permeabilities. The dolostone units tend to be the most
permeable and produce the highest yielding wells. Although
the rock comprising these units may itself appear almost
impermeable, the dolostone strata are typically fractured
and cavernous, which accounts for their high permeability.
Other zones of permeability tend to occur near the contact
between geologic formations where solution of the limestone
was concentrated in the past.
These individual permeable zones frequently function as
separate aquifers, at least over limited areas, with the
intervening chalky limestones acting as effective confining
beds. In most parts of the study area, several such zones
The Floridan aquifer is recharged by rainfall in the center
part of the peninsula, mostly where the land elevation is
above 100 feet. In south Florida and along both coasts, the
aquifer is overlain by relatively impermeable materials
which confine the water under artesian pressure. The top of
the aquifer ranges from about 150 feet above sea level in
parts of north and central Florida to approximately 1,000 feet
below sea level in the southern peninsula.
Water in the Floridan aquifer tends to be relatively high in
dissolved solids because the carbonate rocks comprising the
aquifer are somewhat soluble in water. The least mineralized
water is found in central Florida, where the aquifer recharge
rate is highest. Mineralization in the aquifer increases
generally to the south, toward both coasts, and with depth.
Sources of increasing mineralization include mixing with
connate saltwater, mixing with intruding saltwater from the
sea, and contact with soluble minerals, mostly gypsum and
salt, at the base of the aquifer.
Ground water can be obtained from aquifers more shallow than
the Floridan aquifer at most locations in Florida. These
shallow aquifers occur in the surfical sands, as shell and
calcareous sandstone beds, and in limestone strata above the
Floridan aquifer confining beds.
In areas where the Floridan aquifer contains freshwater,
these shallow aquifers are commonly used for economic reasons,
if only a relatively small supply of water is needed.
The shallow aquifers are of prime importance, however, in
south Florida and in coastal areas where the deeper artesian
water is nonpotable.
With the exception of the Biscayne aquifer on the southeast
coast (Dade, Broward, and Palm Beach Counties), the shallow
aquifers generally have not been recognized and named as
discrete hydrologic units beyond limited local areas.
Locally, they are designated informally as "Upper Hawthorn
aquifer," "Sandstone aquifer," upper artesian aquifer, upper
shell, "lower shell," etc. Some of these aquifers occur in
roughly linear shell and sand bodies, probably related to
Pleistocene shorelines, and are therefore of relatively
limited areal extent. Others occur in later Miocene strata
of sandy limestone, shell, and calcareous sandstone and
change character over short distances, making it difficult
to recognize the aquifers over large areas.
The lone exception to the relatively limited extent of the
shallow aquifers is the Biscayne aquifer of southeast Florida.
This aquifer consists of a wedge-shaped body, 200 to 300
feet thick near the coast and thinning inland to 5 to 10 feet
at the edge of the Everglades. The aquifer consists of
solution-riddled sandy and oolitic limestones of late Miocene
to Pleistocene age. It begins practically at land surface
and is covered in most places by a thin sandy soil. The
combination of high rainfall, rapid percolation, and the
soluble nature of the rock has created an aquifer which is
generally recognized as the most productive in the state,
possibly in the world, in relation to its surface area.
Deep-lying aquifers containing saltwater underly the Floridan
aquifer at depths ranging from 2,000 to 4,000 feet. These
aquifers consist principally of limestone and dolomite of
Lower Eocene to Upper Cretaceous age. The water-producing
zones underlying the southern one-third of the peninsula are
typically fractured and cavernous, a circumstance which has
led to application of the name "Boulder Zone" to the strata.
Because of its cavernous nature, the Boulder Zone is extremely
transmissive and has produced some of the highest well
yields recorded in the United States.
The principal use of these saltwater aquifers at present is
as a receiving zone for the disposal of municipal and industrial
wastewater. A potential future use is as a source of cooling
water, particularly along the southeast coast where the high
yield per well and constant low temperature of the water are
especially desirable characteristics. In this area, the
water temperature ranges from about 750 F to a recorded low
of 590 F.
Underground disposal of municipal and industrial wastewater
and storm runoff is a viable geotechnical solution to some
of Florida's wastewater disposal problems.
The ability of underground formations to accept and store
vast quantities of water at relatively low cost in a large
part of the state is an advantage that Florida shares with
few other areas. Careful application of this natural advantage
can solve some of the state's water problems while at the
same time maintaining water quality standards.
One potentially beneficial aspect of underground disposal
which is presently being studied is the possibility of
recovery and resue of the injected freshwater at some future
time. Preliminary studies have indicated that recovery of a
significant portion of the injected water is feasible under
The geologic conditions required for successful underground
disposal occur only in certain areas of the state. As far
as is known, the deep, highly transmissive saltwater zones,
known collectively as the Boulder Zone, are present only in
the southern part of the peninsula, generally south of a
line from Melbourne on the east coast to near Venice on the
The only known potential receiving zones for large quantities
of effluent in the northern part of the peninsula are much
shallower zones, 1,000 to 2,000 feet in depth, at the base
of the Floridan aquifer system.
In central Florida, from near Lakeland north, all of the
known highly transmissive zones contain freshwater; therefore,
deep-well disposal of secondary treated municipal effluent
will probably prove infeasible. Underground disposal of
municipal effluent in this area will probably be feasible
only in the freshwater zone. This will require advanced
waste treatment of the effluent, as is being done in
GROUND-WATER CONDITIONS IN THE STUDY AREA
Ground water conditions are highly variable from place to
place within the study area. In the northern part of the
area, the Floridan aquifer generally contains potable water
and is the main use aquifer for all water uses.
In the southern part of the area, and along both the east
and west coasts, the Floridan aquifer contains nonpotable
water. In these areas, a variety of shallow aquifers supply
potable water, while the Floridan aquifer is used extensively
for nonpotable water supply, principally irrigation.
In a few areas, principally the extreme southeastern and
southwestern coastal counties, water from the Floridan is to
brackish even for irrigation purposes. In these areas
shallow aquifers are the main use aquifers for all uses.
The following sections of the chapter provide a synopsis of
ground-water conditions within each water management district
in the study area.
St. Johns River Water Management District
Ground water in the St. Johns River Water Management District
is obtained from two aquifer systems: the Floridan aquifer
and overlying shallow aquifers.
The Floridan aquifer underlies the whole District at a depth
ranging generally from less than 50 feet to over 400 feet
and is the main use aquifer over most of the District.
Practically all potable ground water used in the northern
two-thirds of the District is obtained from the Floridan
aquifer. In the southern one-third of the District this
aquifer contains brackish water, which is used extensively
for irrigation and other nondrinking purposes.
The shallow aquifers, both artesian and nonartesian, occur
throughout the District, generally at depths of 30 to 100 feet.
The shallow aquifers do not constitute a single regional
aquifer system. Near the coast they occur as generally
linear bodies of permeable beds of shell or sand more or
less surrounded by relatively less productive strata. In
inland areas they occur as lenticular shell or sand beds of
variable productivity and various depths. The shallow
aquifers are utilized mainly in the areas where the Floridan
aquifer contains nonpotable water or when only a small
supply of water is needed. Practically all drinking water
for coastal cities from St. Augustine southward is obtained
from shallow aquifers.
Floridan Aquifer. The Floridan aquifer is at or near ground
surface in the west-central part of the District (Alachua
and Marion Counties) and lies at a depth of 100 to 150 feet
below ground in the central coastal counties (Flagler,
Volusia, and northern Brevard). From here, the top of the
aquifer slopes to the northeast and southeast to a maximum
depth of about 450 feet in Nassau and Duval Counties in the
north and Indian River County in the south. The aquifer is
comprised entirely of carbonate rocks, limestone, and dolomitic
limestone, mostly of Eocene age.
Over most of the District, the aquifer is overlain by low-
permeability sediments which confine the water under artesian
pressure. Because the confining beds are absent in parts of
Alachua and Marion Counties the Floridan aquifer in these
areas is essentially a water table aquifer.
The Floridan aquifer is recharged principally by precipitation
(rainfall) from the District and adjacent areas. Recharge
occurs wherever the potentiometric surface is lower than the
water table. The rate of recharge is highest where the
confining beds overlying the Floridan aquifer are absent,
relatively thin, or breached by sinkholes. Potentiometric
surface highs centered in southwestern Clay County, northern
Polk County, and central Volusia County are indicators of a
high rate of recharge in those areas. A high recharge rate
in parts of Alachua and Marion Counties is not accompanied
by a potentiometric surface high because the aquifer is
extremely transmissive and is under water table conditions.
The total recharge to the Floridan aquifer in the District
is estimated to be 1,110 mgd. This estimate is based on an
estimate of "surplus water" made by R. E. Dohrenwend
(Dohrenwend, 1976). In addition to recharge within the
District's boundaries, it is estimated that the SJRWMD
receives about 60 mgd as underflow from outside the District.
Discharge from the Floridan aquifer occurs principally as
pumpage from wells, springflow, and underflow to the Atlantic
Ocean. A relatively small amount of water is also discharged
by seepage to overlying aquifers and by evapotranspiration
where the aquifer is near the surface.
Spring discharge, including flow from offshore springs, is
estimated to amount to about 950-mgd, about 800 mgd of which
is freshwater. The largest spring alone, Silver Springs, in
Marion County, discharges an average of 530 mgd of freshwater.
Other major springs (average discharge greater than 30 mgd)
include Rock and Wekiva Springs in Orange County, Salt and
Silver Glen Springs in Marion County, and Blue Springs in
Volusia County. Many of the springs in the District are
located along the St. Johns River, where their occurrence
may be due in part by fractures or faults in the limestone
of the Floridan aquifer. One fairly large offshore spring
has been documented. This spring, located about 2 miles
offshore from Crescent Beach in St. Johns County, discharges
saltwater at a rate estimated at 20 to 30 mgd.
Estimated pumpage from wells in the District is 700 mgd,
about 75% of which is freshwater. The remaining 25% is
nonpotable water used for irrigation.
Areas of ground-water discharge are indicated on the
potentiometric surface map as potentiometric lows. Heavy
pumpage for industrial use in the eastern part of Nassau
County has depressed the potentiometric surface as much as
120 below sea level over a small area and to sea level or
lower over an area of about 30 square miles. Use of artesian
water for irrigation causes seasonal depression of the
potentiometric surface in St. Johns, Flagler, and Indian
River Counties, as well as in other areas of intensive
agricultural water use.
A series of depressions in the potentiometric surface along
the St. Johns River is due to spring discharge. The generally
low (below 20-foot elevation) potentiometric surface in the
central part of the District is also due to spring discharge,
including discharge to offshore springs and seeps.
A comparison of potentiometric surface maps dating from 1961
with the most recent maps shows that, overall, water levels
in the Floridan aquifer have changed only slightly, if at
all, during that period. However, in areas of heavy water
use, substantial declines have occurred. Water level declines
of over 5 feet and up to 50 feet have occurred in Nassau and
Duval Counties. Smaller declines, ranging from 5 to 15 feet,
have occurred in parts of Putnam, Flagler, St. Johns, Orange,
and Seminole Counties. The decline in water levels in
Nassau and Duval Counties results from a combined increase
in industrial and public water supply demand. Increased
irrigation use accounts for much of the water level decline
in Flagler, Putnam, and St. Johns Counties. Increased
public demand is responsible for most of the decline in
Orange and Seminole Counties.
Water levels in the aquifer normally fluctuate several feet
in response to changes in recharge and discharge. Over most
of the District, water levels recover each wet season to
about the same levels as in previous years.
In certain areas, falling water levels in the aquifer, as
described above, indicate that water is being withdrawn from
the aquifer faster than it can be replenished by recharge.
This circumstance is of concern to water managers for the
1. Saltwater intrusion--Declining artesian pressure increases
the tendency for saltwater to move up into previously
freshwater aquifers. Near the coast, intrusion of
saltwater from the ocean is a possible consequence.
2. Sinkhole collapse--Much of the District is subject to
sinkhole activity. There is some suggestion that the
frequency of sinkhole occurrence increases when the
potentiometric surface is lowered substantially.
3. Power cost--The cost of producing water rises as more
power is required to lift it from greater depth.
Water quality in the Floridan aquifer is highly variable,
both with depth and location, in the District. Potable
water is present in the aquifer to a depth of 1,500 feet to
2,000 feet in south Lake County, northern Polk County, and
western Orange and Osceola Counties. Potable water is
present to a depth of 1,000 feet or more over most of the
area from northern Clay and St. Johns County northward,
reaching a maximum of about 2,000 feet in southwestern Duval
County. With the exception of a small area in central
Volusia County, the potable water zone is less than 500 feet
thick over the remainder of the District. Over about 40% of
the District, including most of a 20- to 30-mile-wide strip
along the coast from St. Johns County southward, the Floridan
aquifer contains only nonpotable water.
The concentration of dissolved solids is lowest in recharge
areas and highest in areas of ground-water discharge. In
the recharge areas and for some distance downgradient, the
principal chemical constituents in the ground water are
calcium, magnesium, and bicarbonate derived from solution of
the carbonate rocks which comprise the aquifer. Sodium,
chloride, and sulfate are the principal constituents contri-
buting to the increase in TDS away from the recharge areas.
In addition to the major constituents, water from the aquifer
generally contains dissolved iron, fluoride, and hydrogen
sulfide gas. Dissolved iron is highly variable, but is
generally below the 0.3-mg/l level considered objectionable.
Fluoride likewise is below the level considered significant
in drinking water. Hydrogen sulfide is typically present in
high enough concentrations to give the water a characteristic
odor and taste. Removal of this gas by aeration has caused
some local problems due to the resultant emission of sulfur
Over most of the District, chemical quality of water in the
aquifer has not changed appreciably for at least the last
30 years. However, increased mineralization of water from
the aquifer has been recognized in three areas: eastern
Orange County, the agricultural areas of Flagler, Putnam,
and St. Johns Counties, and the heavily industrialized area
near Fernandina Beach in Nassau County.
In eastern Orange County, the increase was in response to
pumping from a well field to supply the City of Cocoa and
other users in Brevard County. Poor quality water present
in the aquifer along the St. Johns River a few miles to the
east has moved toward the well field and has been detected
in the easternmost wells of the well field. Ground-water
monitoring in the well field over the last 10 years indicates
that water quality has now stablized, probably as a result
of installing new wells farther west.
Total dissolved solids content increases periodically in
irrigation water from the aquifer in the agricultural areas
of Flagler, Putnam, and St. Johns Counties. The increase is
in response to heavy withdrawal of water during the growing
season. TDS concentrations decrease to about their former
levels when withdrawals diminish.
The increase in mineralization of ground water in the
Fernandina Beach area is in response to heavy water use by
pulp and paper industries. In this case, it appears that
some of the affected wells were actually drilled into zones
containing saltwater. Initially, these wells produced an
acceptable mixture of water from several zones. As more
users tapped the upper low-TDS zones, the water produced
from the multizone wells contained an increasingly greater
proportion of high-TDS water from the deeper zones. This
situation was apparently resolved by plugging back some
wells to a shallower depth and by reducing water withdrawals.
Shallow Aquifers. Shallow aquifers in the District occur in
predominantly sandy or shelly materials, depending on location.
In the interior Central Highlands region, the shallow aquifer
is comprised of the 50- to 150-foot-thick strata of sand and
occasional sandy limestone which generally overlies the
limestone of the Floridan aquifer or the clay aquiclude.
Except in the northernmost part of this area, the aquifer is
practically unused; most water supplies are obtained from
the Floridan aquifer. The most significant function of the
aquifer is to store and transmit water to the underlying
In a 20- to 30-mile-wide strip along the coast (the Atlantic
Coastal Lowlands), the aquifer is comprised mostly of shell,
sand, and occasional calcareous sandstone strata. In much
of this area, the shallow aquifer is the only source of
potable ground water.
Although referred to here as a single aquifer, the shallow
aquifer system is actually comprised of many separate aquifers
which occur within the sediments overlying the impermeable
clay and silt aquiclude capping the Floridan aquifer.
Several distinct "shallow aquifers," containing water under
both water table and artesian conditions, may occur in the
The permeability of the sediments comprising the shallow
aquifers in the coastal area varies greatly from place to
place. In some places, relatively thick layers of clean,
broken shells are present which can yield large supplies of
water to wells. In other places, sediments comprising the
aquifer contain a high proportion of fine material (silt and
clay), and therefore are capable of-supplying only a very
limited amount of water.
The shell beds, the desired objective when attempting to
develop a large water supply from the shallow aquifer,
appear to be related to the position of ancient shorelines.
They tend to occur as generally linear bodies nearly parallel
to the present shoreline. Sometimes, but not always, they
occur in conjuction with an obvious topographic ridge. The
shell beds tend to be most productive near the coast and
become thinner, less permeable, and less productive inland.
For this reason, the development of large supplies of fresh
ground water from this aquifer may be difficult in the
inland sections of some coastal counties in the District.
However, there are still large areas where very little is
known about the shallow aquifers.
Rainfall within the District boundaries provides practically
all recharge of the shallow aquifers. In a few areas,
infiltration of irrigation water withdrawn from the Floridan
aquifer provides locally significant recharge. Likewise,
Floridan aquifer water flowing from springs recharges the
shallow aquifer along the spring runs.
Recharge to the shallow aquifers is estimated to be about
3,100 mgd over the District. Recharge is unevenly distributed,
being highest where the soil is sandy and the water table is
relatively deep. Thus, most of the recharge to this aquifer
occurs in the Central Highlands area and on the elevated
coastal ridges. Over much of the District, the water table
is perennially near the surface and no recharge can take
Discharge from the shallow aquifer is by evapotranspiration,
withdrawal from wells, and seepage to surface-water bodies.
Most of the water recharging the shallow aquifers in the
Central Highlands and bordering areas eventually reaches the
Because the more productive parts of the shallow aquifer are
composed of calcium carbonate (shells), water in this aquifer
tends to be high in hardness, although somewhat less mineralized
than water from the Floridan aquifer. The principal differences
in quality between the shallow aquifer and Floridan aquifer
are the highly variable iron content and general absence of
hydrogen sulfide in the shallow aquifer.
Near the coast and along the Intracoastal Waterway and the
Indian River, the shallow aquifer contains saltwater. Some
saltwater intrusion has been reported in Flagler, Volusia,
and Indian River Counties but apparently is not extensive.
The application of brackish Floridan aquifer water for
irrigation has increased the mineral content of shallow
aquifer water over a large area in Flagler, Putnam, and
St. Johns Counties, in Indian River County, and possibly
other areas not recognized or reported. Increases of 200 to
400 milligrams per liter, almost doubling the normal concen-
tration, have occurred in these areas.
Saline Water Aquifers. A saltwater aquifer is defined, in
this report, as an aquifer containing more than 10,000
milligrams per liter (mg/l) of total dissolved solids.
Saltwater aquifers in the District occur both as zones near
the base of the Floridan aquifer system and as distinct
aquifers below the Floridan. Only a few wells have penetrated
these aquifers and relatively little is known about them.
Potential uses of the saltwater aquifers include effluent
disposal, cooling water supply, and desalination supplies.
Test wells have been drilled to investigate the feasibility
of deep-well injection disposal into saltwater aquifers near
Palatka in St. Johns County, near Gainesville in Alachua
County, near Orlando in Orange County, and near Vero Beach
in Indian River County. An exploratory well drilled by the
USGS near Jacksonville penetrated a saltwater aquifer at a
depth of about 2,400 feet. Thirty-nine oil exploratory
wells drilled in the District also provide some data on the
Only the Vero Beach and Palatka wells confirmed the presence
of suitable receiving aquifers for underground disposal of
relatively large volumes of effluent.
The Vero Beach well encountered the "Boulder Zone" at
2,400 feet in depth and had a specific injectivity (volume
of fluid which the aquifer will accept per foot of rise in
pressure) of about 500 gpm/ft.
The Palatka well encountered several saltwater-bearing zones
below 800 feet to a total depth of 1,812 feet. The most
transmissive zones occurred between 1,480 feet and 1,560 feet
in depth. The specific injectivity of the Palatka well was
found to be about 50 gpm/ft, an order of magnitude lower
than at Vero Beach.
No capable high-capacity receiving zones were found in the
Orlando and Gainesville wells, which were, respectively,
6,193 feet and 3,400 feet in depth. No injection tests were
run in the Jacksonville well; however, hydrogeologic data
suggest that the saltwater-bearing zones penetrated there
would have relatively small capacity as receiving zones.
South Florida Water Management District
Ground water in the South Florida Water Management District
is obtained from the Floridan aquifer and several shallow
aquifer systems. In the portion of the District north of
Lake Okeechobee potable water supplies are obtained primarily
from the Floridan aquifer, which also provides a large
quanity of nonpotable irrigation water in portions of Charlotte,
Lee, Collier, Glades, Hendry, Martin, and St. Lucie Counties.
Potable supplies in the area south of Lake Okeechobee are
obtained from shallow aquifers, both confined and unconfined.
The Biscayne aquifer, a shallow, unconfined aquifer, is the
primary source of water for Dade and Broward Counties.
Floridan Aquifer. The Floridan aquifer as a hydrologic unit
underlies the entire District. The elevation of the top of
the aquifer is near sea level in northern Polk County and
dips generally toward the south, southeast, and southwest.
Over most of the District the top of the aquifer is at a
depth of 500 to 800 feet. As defined here, the top of the
aquifer is defined as the first permeable limestone below
the clay and marl of the Hawthorn Formation.
The aquifer is composed of limestones, dolomitic limestones,
and dolomites of middle Eocene to early Miocene Age and
includes the following formations: Lake City Limestone,
Avon Park Limestone, Ocala Limestone, Suwannee Limestone,
and Tampa Limestone. Water is contained within the pore
spaces, solution channels, fractures, and cavities of these
sediments. The transmissivity of a given section of the
aquifer depends greatly on the number of these features
intersected but is commonly very high.
The base of the Floridan aquifer is usually assumed to coin-
cide with the top of the Oldsmar Limestone of early Eocene
Age. This top occurs at approximately 1,500 feet below sea
level at the northern extreme of the District. It dips
gently southward where it reaches a depth of approximately
2,500 feet below sea level just south of Lake Okeechobee and
remains more or less at that elevation to the tip of the
Potable water is present to a depth of about 2,000 feet
below sea level in northern Polk, northwestern Osceola, and
southwestern Orange Counties. It is found to progressively
shallower depths to the east and south until its depth
coincides with the top of the aquifer at approximately
500 feet below sea level in northern Glades and Okeechobee
Except in the northern part of the District, where sinkholes
and artesian lakes are abundent, the aquifer is under artesian
pressure. From the northern edge of Lake Okeechobee southward,
the potentiometric surface is above the land surface and
wells completed in the Floridan aquifer usually flow at the
The shape of the potentiometric surface is relatively flat
south of Osceola County, with a gradual slope (less than
10 feet/mile) toward the southeast, south, and southwest. A
high exists in southern Hendry County and portions of the
counties adjacent to it. In central Polk County, the potentio-
metric surface .rises markedly in response to the high recharge
in that area to more than 120 feet above sea level. The
average elevation for most of the District is 40 to 50 feet.
Recharge to the Floridan aquifer occurs primarily in the
highland ridges of the District's northern portion. The
greatest amount takes place in the area around central Polk,
western Orange, and northwestern Highlands Counties. In
these areas the confining beds are relatively thin and
braced by sinkholes, this condition contributes to the high
rate of recharge. Moderate recharge occurs throughout
central Osceola County and southwestern Highlands County.
Estimated recharge to the aquifer is 650 mgd. The aquifer
in the District also receives about 150 mgd as underflow
from outside the District. Water from recharge areas in the
northern part of the District and adjoining parts of the
Southwest Florida Water Management District moves generally
southward, and then east and west to the Atlantic Ocean and
Gulf of Mexico.
Discharge from the Floridan aquifer is through withdrawal
from wells, upward leakage through the confining beds to
shallow aquifers, and flow from submarine springs at the
aquifer's offshore outcrops. Withdrawals from wells in the
Orange County area and the phosphate mining district of Polk
County have been large enough in recent years to have caused
a decline of more than 10 feet in the potentiometric surface
in those areas. The agricultural areas near Lake Okeechobee
make extensive use of Floridan aquifer water during dry
periods, causing some decline in the pressure level in that
The quality of the ground water found in the Floridan aquifer
varies widely over the District, with total dissolved solids
content generally increasing to the south and toward both
coasts. The total dissolved solids (TDS) content of ground
water is less than 500 mg/l throughout most of the Kissimmee
River Basin area. Mineralization increases sharply to more
than 1,000 mg/l in southern Highlands and central Okeechobee
Counties, and to more than 4,000 mg/l in the southernmost
counties of Palm Beach, Broward, Dade, Monroe, and Collier.
The principal chemical constituents of ground water north of
Lake Okeechobee are calcium, magnesium, and bicarbonate.
Increasing amounts of sodium, chloride, and sulfate contri-
bute most of the increased mineralization of ground water in
the southern part of the District. Over most of the District,
the mineral content of water from the Floridan aquifer has
not changed appreciably for at least the last 30 years. In
some very localized areas, notably in Lee and Collier Counties
on the West Coast, some large increases in mineralization of
water from a few wells has been recorded. In these instances,
the increases in mineralization appear to be related to
natural fractures or unusually deep wells, which provide
communication between deep saltwater aquifers and the
Shallow Aquifers. Shallow aquifers occur throughout the
District in a variety of sediment types. These aquifers are
the main use aquifers (for freshwater supply) where the
Floridan aquifer contains nonpotable water. In the northern
interior portion of the area, sand and gravel deposits
underlying the ridges produce large quantities of water.
The Tamiami Formation, present throughout much of the area,
is very permeable in its sand and shell faces but is of low
permeability where the formation is marly. The Caloosahatchee
Marl, which is exposed in much of the southern part of the
area, is generally of low permeability and frequently contains
rather poor quality water. Many of these shallow aquifers,
particularly in the ridge areas of the northern portion and
in parts of Lee County, are artesian. Where present, these
secondary artesian aquifers are important sources of good
The water table is usually within a few feet of the land
surface in lower elevations and often more than 100 feet
deep in the ridge areas. The thickness of the water-bearing
zones varies from a few feet to several hundred feet. In
the highland portion of Polk County the shallow aquifer is
more than 600 feet thick.
The shallow aquifer underlying a large area in the southern
interior of the District contains only nonpotable water. In
this area, poor permeability of the aquifer has impeded
recharge and resulted in brackish water being incompletely
flushed from the aquifer. The relatively impermeable muck
which is present in much of the central part of the peninsula
south of Lake Okeechobee also serves to isolate these shallow
sediments from significant recharge. Finally, the low
elevations typical of the southern peninsula limit the
amount of head available to drive the recharge process. In
the Lee-Glades-Hendry-Collier County area the land surface
is at a higher elevation, more than 20 feet above sea level,
and is underlain by more permeable sandy sediments.
In the coastal areas north of Broward County, water is
obtained from the sand and shell deposits of the Anastasia
Formation. These deposits are found to a depth of 150 feet
in St. Lucie County to more than 300 feet in southern Palm
The permeability of this aquifer varies somewhat from place
to place but is generally high. Wells completed in it yield
up to 500 gpm.
In the interior portions, St. Lucie, Martin, and Palm Beach
Counties, freshwater is obtained from the limestone, shell,
and sand of the Tamiami, Fort Thompson, and Upper Hawthorn
Formations. The thickness of these sediments varies from
more than 120 feet in parts of St. Lucie County to less than
30 feet in extreme western Palm Beach County.
A shallow artesian aquifer system comprised of sand, sand-
stone, limestone, and shell furnishes most of the fresh
ground water in Lee and Collier Counties. This system,
which may actually be several separate aquifers, is recharged
by rainfall in the southern interior parts of these and
The thickness of the shallow aquifer ranges from about
300 feet in parts of Lee and northern Collier Counties to
less than 100 feet in southern Collier County. At any given
location, sediments referred to as the shallow aquifer may
contain several permeable zones, frequently with differing
water quality. Shallow nonartesian aquifers are present in
Orange, Polk, Osceola, Highlands, and northern Okeechobee
Counties. The thickness ranges from 40 feet to more than
600 feet in the Central Highlands portion of the northern
interior area. Although relatively productive, these aquifers
are used only for small supplies, larger supplies being
obtained from the Floridan aquifer.
The Biscayne aquifer is found in virtually all of Dade and
Broward Counties. The northern edge extends a few miles
into Palm Beach County and the southwestern edge extends to
Monroe County. The sediments comprising the aquifer are
highly permeable limestones, sandstones, and sands of Lake
Miocene to Recent Age.
The thickness of the aquifer increases toward the coast and
thins out near the Dade-Monroe County line. The top is at
the land surface throughout and forms the floor of Florida
Bay and reappears in.the Keys. The aquifer reaches a thick-
ness of more than 170 feet along the coast and thins to less
than 10 feet at the edge of the Everglades. The aquifer is
most productive near the coastline where transmissivity
values of more than 15 mgd/foot have been recorded. Wells
drilled into the aquifer in eastern Dade and Broward Counties
typically have very high yields.
The water level of the Biscayne aquifer is influenced greatly
by the numerous drainage canals dissecting the area. At
high stages water recharges the aquifer near the coast. At
lower stages the canals receive water from the aquifer. The
water level is also influenced by the topography. The level
is significantly higher in the vicinity of the Atlantic
Recharge to the Biscayne aquifer occurs primarily from local
rainfall and inflow from adjacent areas. This dependence on
rainfall causes the level of water in the aquifer to vary
greatly. In the wet summer season the levels are high and
reach their minimum levels toward the late winter dry season.
Saline Water Aquifers. Saltwater aquifers which contain
water with concentrations of dissolved solids greater than
10,000 mg/l probably exist below the Floridan aquifer through-
out most of the southern portion of the District. The
saltwater aquifers below the Floridan aquifer in south
Florida have been named, collectively, the "Boulder Zone."
Oil exploratory and production wells drilled in various
places within the SFWMD provide most of the data regarding
distribution of the Boulder Zone. Notations on drillers'
logs such as "lost circulation," "cavity," and "boulders"
indicate the presence of these highly permeable zones, which
occur principally in cavernous and fractured dolostone.
In several places within the District, mostly along the
southeast coast, deep injection wells have been constructed
for this zone. The presence of the Boulder Zone has been
confirmed as far north as Vero Beach, as far south as the
Keys, and in most of Collier, Lee, and Hendry Counties.
Along the coast, the top of the Boulder Zone occurs at
depths ranging from 2,400 feet at Vero Beach to 2,800 feet
south of Miami, generally paralleling the regional dip of
the strata. Elsewhere in the District, Boulder Zone type
strata occur mostly in intervals between 2,000 and 4,000 feet
These deep aquifers are used for the disposal of municipal
and industrial wastewater at Margate, West Palm Beach, South
Miami, and Belle Glade. Facilities are under construction
near Homestead and Fort Lauderdale. The injection capacity
of facilities either constructed or planned for the near
future is in excess of 100 mgd.
Specific injectivities as high as 1,000 gpm per foot of
injection head have been recorded. Maximum injection rate
is apparently limited more by the maximum practical size of
the well, rather than by aquifer capacity. The largest
wells constructed to date have a capacity of about 7,000 gpm.
In the southern peninsula, the Boulder Zone contains cool
water and is a potential source of saline cooling water.
The area of unusually cool ground water extends from at
least as far north as St. Lucie County and extends down the
coast at least to the upper Keys. The lowest temperature
measured to date has been 590 F in a 3,100-foot-deep well at
Margate, near Fort Lauderdale. The lowest temperature
measured in a well in the upper part of the aquifer is 690 F
in a 980-foot well at Miami Beach.
Southwest Florida Water Management District
Ground water in the Southwest Florida Water Management
District occurs in two aquifer systems. The Floridan aquifer,
a regional artesian aquifer system underlying the entire
area, and the shallow aquifer system, consisting of several
local artesian and water table aquifers. The Floridan
aquifer is the main use aquifer for all purposes in Polk,
Hardee, and part of DeSoto County. From DeSoto County
southward, and along the coast, the Floridan aquifer contains
brackish water, and shallow aquifers are used for potable
water supply. Throughout the area, the Floridan aquifer is
used extensively for irrigation and industrial water supply.
Floridan Aquifer. The Floridan aquifer is comprised entirely
of limestone and dolomite of Miocene to Eocene age. The top
of the aquifer is at an elevation of about 100 feet above
sea level in Polk County in the northern part of the area,
and at about 500 feet below sea level in Charlotte County in
the southern part of the area. The depth to the top of the
aquifer ranges from about 200 feet in the northern part of
the area to about 500 feet in the extreme southern part.
The bottom of the aquifer, considered here to be the first
stratum which contains a significant amount of gypsum or
anhydrite (calcium sulfate), lies at a depth of 1,500 to
1,700 feet in the northern part of the area, and 2,400 to
2,500 feet in the southern part. The aquifer is not a single
homogeneous unit; in most places it contains several water
producing zones, separated by relatively impermeable strata.
In the southern part of the area, at least three distinct
zones are present. The individual zones are usually easy to
recognize, because they have different water qualities, the
deepest zone having the poorest quality. In the northern
part of the area, individual zones within the aquifer are
harder to recognize, because the water quality is similar
throughout most of the aquifer.
The aquifer is overlain by relatively low-permeability
strata which confine water in the aquifer under artesian
pressure. The artesian pressure is sufficient to produce
flowing wells along the coast, in southern Sarasota County,
most of Charlotte County, and along the Peace River Valley
in DeSoto County. Water levels in the aquifer are over
100 feet below land surface at higher elevations in Polk
The aquifer is recharged by percolation through the overlying
confining beds in those parts of the area where the potentio-
metric surface is below the water table. Most of the recharge
occurs in Polk County and northeastern Manatee County where
the land elevation is high and the confining beds relatively
Total recharge to the Floridan aquifer within the study area
is estimated to be about 800 mgd. About 116 mgd leave the
area as ground-water underflow to the St. Johns River Water
Management District (16 mgd) and the South Florida Water
Management District (100 mgd).
Discharge from the aquifer is principally by pumpage from
wells. Total estimated pumpage from wells in the study area
is 660 mgd, about 85% of which is withdrawn for irrigation
and industrial purposes. (About 15% of the water withdrawn
from the Floridan aquifer is nonpotable water used for
irrigation in the southern one-third of the area.) Much of
the potable water withdrawn for irrigation and industrial
use eventually returns to the aquifer as recharge.
The heaviest withdrawal of ground water is in Polk and
Hardee Counties. In this part of the area the artesian
pressure has generally declined about 5 feet during the last
30 years. In south-central Polk County a net decline of
over 30 feet has occurred in response to heavy irrigation
and industrial pumpage. A seasonal decline of up to 15 feet
occurs over much of Polk, Hardee, Manatee, and DeSoto Counties
in response to the seasonal demands for irrigation water.
Water quality in the aquifer is highly variable in the study
area. Total dissolved solids levels increase from north to
south across the area. Total dissolved solids content also
increases with depth in the aquifer, especially in Manatee,
Sarasota, Hardee, DeSoto, and Charlotte Counties. The
chemical type of water in the aquifer varies from north to
south. In the northern part of the area, corresponding
generally to the area of recharge, the water is predominantly
a calcium/magnesium bicarbonate water. Further downgradient,
the type of water changes to calcium sulfate in Manatee,
Sarasota, and DeSoto Counties, and then to a sodium chloride
water in southern Sarasota and Charlotte Counties. In
addition to the principal constituents of calcium, magnesium,
sodium, bicarbonate, sulfate, and chloride, Floridan aquifer
water frequently contains two minor constituents, fluoride
and hydrogen sulfide, in significant quantities with respect
to use of the water.
Potable water extends to over 1,500 feet in depth, nearly to
the bottom of the aquifer, in Polk and northern Hardee
Counties. The depth of potable water becomes progressively
less toward the south and west, to less than 500 feet in
central Manatee and northern DeSoto Counties and less than
200 feet in eastern Sarasota and southern DeSoto Counties.
The Floridan aquifer contains no potable water in southern
Sarasota County or in Charlotte County.
The chemical quality of water in the Floridan aquifer does
not appear to have changed appreciably for at least the last
30 years. However, reliable data on possible water quality
changes are rare, because most wells penetrate more than one
aquifer zone. Some very localized cases of water quality
deterioration have resulted from well construction practices
which allow water from deep zones to intrude into shallow
zones. In other cases, the quality of water produced by
multizone wells has deteriorated because the upper zone has
been depleted by wells producing from only the upper zone.
Thus, the blend of water produced by the multizone wells is
predominantly from the more mineralized lower zone.
Shallow Aquifers. There are three types or categories of
shallow aquifers in the District: the surficial, or water
table aquifer, shallow artesian aquifers, and secondary
artesian aquifers. These designations do not refer to
regional aquifers, but to locally recognized components of
the hydrologic system.
The surficial aquifer occurs in the Pleistocene sand, gravel,
and shell deposits which blanket the area. These deposits
range from less than 20 feet in thickness in the southern
part to over 100 feet thick at the higher elevations in Polk
and Highlands Counties. As the aquifer name implies, water
contained in these deposits is under water table conditions.
The aquifer is recharged by local rainfall. Discharge from
the aquifer is via evapotranspiration and percolation to
underlying aquifers. Water in the aquifer is low in dissolved
solids, except where shells or other carbonate materials
comprise part of the aquifer. Dissolved iron is frequently
present in objectionable amounts. This aquifer is reasonably
productive in some places, but is relatively little-used for
water supply. Its most important function is to store water
and transmit it to underlying aquifers.
Shallow artesian aquifers occur at most places in the District.
These aquifers tend to be very local in nature and highly
variable in composition, water quality, and productivity.
In general, the shallow artesian aquifers are comprised of
middle to late Miocene sandy limestone, calcareous sandstone,
and shells, and are overlain by relatively impermeable
calcareous clay, silt, and hardpan. The shallow artesian
aquifer is generally, recognized as a distinct portion of the
hydrologic system only in the coastal and southern parts of
the area, where it is an important source of water supply.
In this area the thickness of the aquifer generally ranges
from about 30 to 100 feet. The depth of the top of the
aquifer is generally less than 30 feet. Recharge to the
aquifer is from rainfall and surface-water bodies. In most
places, the confining beds overlying the aquifer are generally
thin; therefore, recharge routes are high. The most effective
recharge occurs where the overlying surficial aquifer is
relatively thick, corresponding generally to the higher
elevations. In coastal areas, an elevation difference of
only 3 to 5 feet can greatly affect recharge to the aquifer
and aquifer productivity. Discharge from the shallow artesian
aquifer is via withdrawal from wells, discharge to surface
water bodies, and percolation to deeper aquifers. Most of
the well discharge occurs along the coast and in Sarasota
and Charlotte Counties. Elsewhere, the aquifer is commonly
used only for domestic, stock water, and other small supplies.
Water from the aquifer is relatively high in dissolved
solids, due to solution of the shells and carbonate minerals
comprising the aquifer. In some places, especially near the
coast in Sarasota and Charlotte Counties, the aquifer contains
nonpotable water. The high mineral content of water in
these areas is due to intrusion from salty surface water and
upward leakage from deeper aquifers. In some places the
intrusion is related to lowering of water levels, pumping,
or drainage, while in others such intrusion appears to be
due to variations in confining bed integrity.
The term "secondary artesian aquifer" is used locally to
designate an artesian aquifer which occurs immediately
overlying the Floridan aquifer. This aquifer is comprised
of sandy limestone of Miocene age. In the northern part of
the area, it is not differentiated from the Floridan aquifer.
Recharge to the secondary artesian aquifer is principally by
percolation from overlying aquifers and surface waters where
its artesian head is below the water table. At lower elevations
and along the coast, this aquifer receives some recharge by
upward leakage from the Floridan aquifer. Water is discharged
from the aquifer by withdrawal from wells, as seepage to
surface water, and, where the artesian head is higher than
the head in the Floridan aquifer, by downward leakage. The
secondary artesian aquifer is an important source of ground
water in Sarasota, Manatee, and southern DeSoto Counties;
where the Floridan aquifer contains nonpotable water, and
productivity of shallower aquifers is low. In most of the
area the aquifer contains potable water. Dissolved solids
content increases to the south and west. Along the coast
and a few miles inland, water quality resembles that of the
Saline Water Aquifers. Water containing more than 10,000 mg/l
of dissolved solids occurs in permeable zones near the
bottom of the Floridan aquifer over most of the area from
central Manatee and Hardee Counties southward. In Charlotte
County, a highly transmissive zone, possibly equivalent to
the Boulder Zone further south, is present beginning at a
depth of about 2,000 feet and extending to an unknown depth.
Depth to saltwater in the Floridan aquifer ranges from about
1,100 feet at Sarasota, to about 1,800 feet in eastern
Little is known about saltwater aquifers beneath the Floridan
aquifer. There have been reports of such aquifers in Polk,
Hardee, DeSoto, and Manatee Counties, generally between the
depths of 2,400 and 3,200 feet. These reports are mainly
contained in data from oil test well drilling, which give no
definite indication of aquifer productivity. Test wells
over 3,000 feet in depth have been drilled at St. Petersburg
and Sarasota. Both of these wells confirmed the presence of
highly transmissive saline aquifers in the Floridan aquifer;
only low-transmissivity aquifers were found below the Floridan
aquifer. It is probable that high-transmissivity zones
below the Floridan aquifer occur in the District only in
Charlotte County. Elsewhere in the District, the saline
aquifers below the Floridan aquifer have relatively low
Potential uses for the saline aquifers in the District
include waste disposal and underground storage of surplus
freshwater and cooling water supplies. The saltwater portions
of the Floridan aquifer are suitable for municipal wastewater
disposal where the disposal zones are adequately separated
from potential drinking water supplies. Except in Charlotte
County, the deeper aquifers do not have adequate capacity
for large-volume injection, although they are potential
zones for the disposal of relatively low-volume industrial
Most of the saltwater aquifers contain water at a temperature
in excess of 850 F and therefore are not especially desirable
for cooling water supplies. One well in Charlotte County
produces water at 960 F, and was used briefly as a "health
Desalination of this water is unlikely, as there are very
large supplies of less mineralized water more suitable for
this purpose available in the area.
Suwannee River Water Management District (SRWMD)
The part of the District within the study area is the portion
east of the Suwannee River and north of the Santa Fe River,
including Columbia, Suwannee, and Union Counties, most of
Bradford County, and a small part of western Baker County.
The part of the study area within the District, together
with adjoining parts of the St. Johns River Water Management
District (SJRWMD), comprise a single hydrologic unit with
respect to ground water. The Suwannee and Santa Fe Rivers
act as ground-water divides. That is, little or no ground
water flow takes place across these boundaries.
Ground water in the study area portion of the District
occurs in two major systems. The majority of the usable
water is provided by the Floridan aquifer, which underlies
the entire District. Where the Floridan aquifer is deeply
buried and the quantity of water needed is relatively small,
shallow aquifer systems provide potable ground water. In
many places, particularly in the eastern portion of the
District, the shallow secondary artesian aquifers are the
most frequently utilized of the several sources of ground
Floridan Aquifer. The top of the Floridan aquifer occurs at
or near land surface in a broad band approximately parallel
to the coast. Within this band, the aquifer is unconfined
and constitutes the water table aquifer. This top is found
progressively deeper toward the northeast, reaching more
than 150 feet below sea level in northern Baker County and
more than 300 feet below sea level in the northeastern
corner of Bradford County. In these deeper sections, the
aquifer is overlain by relatively impermeable sediments and
is under artesian pressure.
The base of the Oldsmar Limestone, considered to be the base
of the aquifer, occurs between 1,500 and 2,000 feet below
sea level. This surface is slightly dome-shaped within the
District, with the apex located in the east central portion
of the District. The usable portion of the aquifer, delineated
by the depth of potable water, extends from minimal depths
along the coast to more than 1,250 feet in the northeastern
corner of the District.
The Floridan aquifer within the District is recharged
principally by precipitation and inflow from adjacent areas
and discharged through spring discharge, well withdrawals,
and diffused seepage to the surface. In areas where the
aquifer is poorly confined and the water table elevation is
above the potentiometric level, precipitation not lost by
evapotranspiration leaks through the overlying sediments and
recharges the aquifer. This process occurs throughout most
of the District. In areas where the potentiometric surface
is higher than the water table, discharge occurs in the form
of upward leakage and, where the confining beds are breached,
flow from springs. The estimated annual recharge to the
aquifer within the study area is 682 mgd. The aquifer
receives an additional 18 mgd of water as underflow from the
Discharge from the Floridan aquifer occurs principally by
seepage and spring flow into the rivers and streams of the
District where the potentiometric surface is higher than the
stage level. Some seepage also occurs into overlying aquifers
where the potentiometric surface of that aquifer is lower
than the underlying Floridan aquifer. It is estimated that
about 20 mgd of ground water is presently withdrawn from
wells in the area. Spring flow from the Floridan aquifer in
this District accounts for most of the ground-water discharge
from the area. Available records indicate that the combined
flow of 38 of the 67 springs identified by SRWMD is approxi-
mately 1.2 billion gallons per day (bgd). This flow is
slightly more than 13% of the estimated surface-water discharge
from the District. Six springs within the District are of
first magnitude and together account for 0.6 bgd. All of
these six springs occur along the Suwannee River and a large
but undetermined part of their flow is derived from the
Floridan aquifer in the study area.
The quality of the Floridan aquifer water in the District is
variable but displays certain trends. The mineral content
tends to be lowest near recharge areas and highest near
discharge areas. Total dissolved solids and sulfates increase
with depth. The principal mineral constituents are calcium
and magnesium bicarbonates. High-sulfate water has been
found in a few wells which penetrate near the bottom of the
Potable water occurs at depths exceeding 1,250 feet in the
northeastern part of the District. The depth of this water
decreases toward the south and west to about 800 feet along
the Suwannee River. No marked departures from this general
trend are apparent on a regional scale, although local
departures are probably present.
Shallow Aquifers. Permeable strata within the unconsolidated
surficial deposits which overlie the Floridan aquifer in the
area comprise the shallow aquifer system. These deposits,
of middle Miocene and younger age, consist principally of
sand and clay. At any given location, several permeable
zones may exist, some confined and some unconfined.
Distinct water table aquifers occur in most parts of the
District within 30 or 40 feet of the surface. The thickness
of the surficial deposits making up the shallow aquifer
varies considerably in the District. In the Trail Ridge
region to the east the sands are as much as 130 feet thick.
To the west and southwest of this ridge, the average thickness
becomes about 40 feet. Where the Hawthorn Formation outcrops
in Bradford and Union Counties, the sands are only a few
feet in thickness.
The shape of the water table is variable but generally
parallels the land surface. Downslope movement by gravity
drainage results in a somewhat lowered level in the higher
elevations and a higher level in the lower. In many low
places, this water level is higher than the land surface,
resulting in lakes and streams. Where the terrain is flat,
lateral water movement is slight and downward leakage pre-
dominates. This leakage results in recharge to the under-
The overall quality of the water in the water table aquifer
is very good. Total dissolved solids tend to be low although
high iron content is common. Color tends to be high, as a
result of contact with organic matter at the surface. The
pH of the water due to dissolved carbon dioxide tends to be
The close proximity to the surface makes the water table
very susceptible to pollution. High bacterial counts and
elevated biological content are frequently present near
Saltwater Aquifers. Permeable zones, containing water with
a total dissolved concentration of greater than 10,000 mg/l,
probably exists within portions of the lower Floridan aquifer
in the District. There is no evidence available, however,
indicating that distinct saltwater aquifers are present
below the Floridan aquifer. Several oil test wells have
been drilled in this area but little hydrologic and water
quality information has been reported. Little economic
incentive exists for drilling wells below the limits of
potable water that would provide such information.
The base of the Floridan aquifer probably occurs at the
first occurrence of evaporites (gypsum and anhydrite).
These deposits are reported in the eastern half of the
District at approximately 1,400 feet below sea level (Chen,
1965). The stratum in which they appear is relatively flat
with a slight dip toward the west and south. It can be
presumed that similar deposits occur at similar depths
throughout the District.
The depth to potable water in the northeastern portion of
the District is greater than 1,000 feet but becomes
progressively shallower toward the west and south.
Test wells drilled to investigate the possibility of deep
disposal of effluent near Gainesville in Alachua County and
near the town of Lawtey, in Bradford County, failed to show
that there were any deep saltwater zones capable of receiving
significant amounts of fluid. Existing data from oil tests
suggest that there may be some sandstone strata in the
interval between 2,000 feet and 3,000 feet in depth which
could be used for disposal of small volumes of wastewater.
Ei Chapter 5
OE WATER RESOURCES
Florida is a water-rich state, perhaps the richest in the
nation in terms of available water resources. The State
receives over 53 inches of rainfall per year, second only to
Louisiana's 56 inches. Two of the most prolific aquifers in
the world, the Floridan aquifer and the Biscayne aquifer,
along with numerous unnamed shallow aquifers, are present to
store the abundant rainfall, while the sandy soil and flat
terrain promote aquifer recharge. Numerous lakes and streams
and extensive wetlands provide storage for water on the
surface. The State also receives about 23 bgd (billion
gallons per day) of water as inflow from neighboring states.
The total water input to the State, including precipitation
and inflow, is approximately 170 bgd. Of this amount, an
estimated 105 bgd (62%) is lost by evapotranspiration,
42 bgd (25%) leaves the State as surface-water discharge,
and 21 bgd (12%) leaves as ground-water outflow. The amount
of water withdrawn for all uses is estimated to be about
2.3 bgd, about 1.4% of the total water input.
With this great abundance of water, the water resources of
Florida have seemed, in the not too distant past, to be
essentially inexhaustible. Although Florida continues to
have an abundance of water, it has become clear, especially
within the last decade, that, at certain times and places,
the resource is all too finite.
Some of the factors that contribute to local water resource
shortages in the midst of water abundance are:
1. Rainfall patterns--Florida has distinct wet and dry
seasons. In southern peninsular Florida, approximately
80% of the rainfall occurs between May and October.
Over much of the heavily populated southern peninsula
and in the citrus belt of central Florida, very dry
weather prevails from November through May. Much of
the rainfall occurs in very intense rainfall events
which affect relatively limited areas. Therefore, the
rainfall in any given year tends to be unevenly distributed.
2. Evapotranspiration--The State's high average temperature,
long growing season, and extensive wetlands produce
high evapotranspiration rates. An estimated 70% of the
rainfall in an average year is lost to evapotranspiration.
3. Topography--The terrain over much of the State is
relatively flat. Rivers tend to have shallow valleys
and large flood plains. Suitable sites for onstream
reservoirs are rare, and offstream reservoirs are
necessarily shallow and large. These physical constraints
imposed by topography lead to large evapotranspiration
losses from surface reservoirs.
4. Environmental sensitivity--The natural ecosystems of
Florida have evolved because of water abundance and
high evapotranspiration. These systems are adapted to
a particular set of water quantity, quality, and temporal
distribution conditions. Changes in any of these
conditions can result in undesirable environmental
effects. Tradeoffs between the environment and public
convenience and necessity must be made in connection
with almost every activity which affects the hydrologic
5. Population--In 1950, Florida's population was a little
less than 3,000,000. In 1978, the population is estimated
to have reached 9,000,000, representing a 200% increase.
This growth has brought not only increased demand for
public water supply but also increased demand for water
to serve the growing power generation and industrial
supply needs. Population increases also produce greater
demand for developable land; therefore, more land must
be drained, thus reducing the potential for aquifer
6. Population distribution--Florida's population is concentrated
in coastal areas and so is a large portion of the water
demand. Because of the proximity to saltwater and
their location at the "end of the pipeline" in the
hydrological sense, water resources in coastal areas
are very susceptible to saltwater intrusion and pollution.
Therefore, coastal areas sometimes must obtain water
from inland areas, thereby creating a number of economic,
political, legal, and regulatory problems.
In the following sections of this chapter, some of the
factors controlling water availability and development
potential are discussed.
DEVELOPMENT POTENTIAL--SURFACE WATER
The potential usefulness of any surface-water source is
dependent on three primary factors: (1) the quantity of
water available, (2) the quality of the water, and (3) the
feasibility of providing adequate storage and/or withdrawal
facilities. Factors 1 and 2 are hydrologic and apply both
to surface-water and ground-water sources. Factor 3 applies
primarily to flowing surface waters, since storage must be
provided to smooth the natural variability of streamflow.
The feasibility of providing surface-water storage is
governed to a large degree by geography, existing land use
and environmental factors rather than by the hydrology of
The availability of surface water for beneficial use is a
complex problem influenced by many hydrologic, economic,
environmental, and regulatory constraints. Hydrologic
constraints are defined by the characteristics of the water-
shed upstream from the point under consideration. These
watershed characteristics define the total annual volume of
water generated by the watershed and the time distribution
of the resulting streamflow. That is, hydrologic constraints
define how much water is physically available and when it is
Economic constraints are extremely site-specific and define
what portion of the physically available water can be economi-
cally withdrawn from the stream, stored, and used. In the
context of this areawide study, economic constraints can be
considered only in an intuitive sense.
Potential offstream storage sites must also be evaluated on
a site-specific basis. However, for the purpose of this study,
it is assumed that developable storage sites are available
except in established urban areas. The volume of the required
storage and the cost and availability of land for the storage
facility are questions which can only be addressed in the
course of more detailed studies.
Since land availability for storage is considered separately,
the major economic constraint is feasible rates of withdrawal,
which is related to reliability of the supply. Most stream-
flow is highly variable. Peak flow rates during floods can
be several hundred times greater than mean flow rates.
Extremely low flows can occur for weeks or months at a time.
Therefore, construction of pumping facilities to withdraw
all hydrologically available waters is unfeasible. Storage
reservoirs are required to provide a dependable supply
during periods of low flow. For the purpose of preliminary
evaluation of surface-water resources, the "dependable
annual flow" is defined as that flow which is equaled or
exceeded 70% of the time, or 256 days per year. That is,
there is a 70% chance that actual streamflow will be equal
to or greater than the dependable annual flow at any given
time. Pumping facilities design based on the dependable
annual flow should be economically feasible since full
design capacity will be utilized a large percentage of the
time. The question of optimum pumping facility design
capacity can only be addressed on a site-specific basis.
The effect of establishing a dependable annual flow is the
concurrent establishment of an upper bound on flow above
which water may not be economically available for withdrawal.
If environmental constraints did not exist, all of the
streamflow less than the dependable annual flow could be
withdrawn for beneficial use. However, it is necessary to
consider a minimum flow, below which water should not be
withdrawn in order to maintain environmental quality.
Thus, "minimum streamflow" criteria have been developed for
this report as follows.
1. Determine the monthly minimum flow for each month,
January through December. The monthly minimum flow is
defined as the average of the five lowest monthly flows
observed during the preceding 20 years or less of
2. Identify the six lowest monthly minimum flows.
3. Calculate the annual minimum flow by averaging the six
lowest monthly minimum flows and multiplying by 90%.
The intent of this definition is to identify a single flow
rate below which withdrawals should not be made. This
definition is somewhat different from the low flow definition
used in the SWFWMD, as described elsewhere in this report.
"Available water" is defined as the difference between
dependable annual flow and minimum flow. This value is
considered to be a planning level indicator of the quantity
of water which can reasonably be developed. It considers
hydrologic constraints directly and intuitively considers
economic and environmental constraints. Regulatory agencies
have great latitude in setting criteria for withdrawal and
use of surface waters. Therefore, regulatory constraints
are not considered directly in the definition of available
water. Stream.reaches with available water above 100 cfs
are considered to have significant development potential as
sources of water for power plant cooling, large municipal
supplies, or other purposes requiring actual withdrawals up
to about 25 cfs (average). Streams having available water
less than about 20 cfs are considered to have no significant
development potential in most cases.
Appendix A.presents a detailed discussion of surface-water
quantity including the flow definitions outlined above and
In addition to the requirements of water availability, water
quality must also be considered when evaluating a surface-
water source for potential water supply. Surface-water
sources may have highly variable water quality which fluc-
tuates widely between wet- and dry-weather conditions.
Streamflow is dependent upon both direct surface runoff and
ground-water inflow. The relative importance of these
components varies from watershed to watershed and from
season to season. Constituents such as hardness, alkalinity,
fluorides, and other dissolved minerals are generally asso-
ciated with ground-water inflows or base flow, whereas other
constituents such as suspended solids, nutrients, and color
are generally associated with direct surface runoff.
Treatment of water withdrawn directly from a stream or
surface reservoir must consider the entire range of variable
raw water quality. Offstream reservoirs do provide some
modulation of water quality variations when adequate storage
is provided so that withdrawals do not occur during periods
of very poor water quality and withdrawals during wet- and
dry-weather periods are blended such that extremes in water
quality are attenuated. Treatment of surface water is
generally more costly than treatment of potable ground
With surface-water supply sources, potential water quality
degradation from point and nonpoint sources must be considered.
Point sources include municipal and industrial wastewater
effluent discharges upstream from the point of withdrawal
and nonpoint sources include agricultural and urban runoff.
Agricultural runoff may, on occasion, contain high levels of
nutrients, pesticides, and highly mineralized irrigation
waters, whereas urban runoff may contain high levels of
suspended solids, nutrients, and heavy metals.
The raw water quality parameter which is of most interest in
considerations of a potential source of cooling water is
total dissolved solids (TDS). This parameter will have
direct impact on cooling system requirements, because
evaporation from the reservoir will raise the concentration
of solids in the reservoir. A second important parameter is
nutrient content, particularly phosphorus. An overabundance
of nutrients in an offstream reservoir could induce eutrophic
conditions which may interfere with efficient plant operations
or result in the development of nuisance conditions within
the storage reservoir. Summaries of the average annual
water quality characteristics of selected streams are given
in Appendix B for each water management district. Parameters
reported include specific conductance, dissolved chlorides,
total dissolved solids, total alkalinity, total nitrogen,
total phosphorus, dissolved oxygen, and total coliforms.
DEVELOPMENT POTENTIAL--GROUND WATER
Florida's ground-water reservoirs contain by far the largest
storage of water in the State. However, the amount of water
storage in these reservoirs is no indication of the ability
of the reservoirs to provide a sustained yield of water of
any particular quality at any particular place. Among the
factors which influence ground-water development potential
in the study area are the following:
1. Well yields, which are controlled by the hydraulic
characteristics of the aquifers, are highly variable.
In theory, obtaining high yield from a well in Florida
is simply a matter of drilling a hole large enough and
deep enough to obtain the desired yield. However, this
approach would, in practice, result in the production
of salty or brackish water in much of the study area.
This factor is primarily economic: how many wells of
what size must be constructed to produce the required
amount of water of appropriate quality?
2. Water quality is highly variable with depth and, from
place to place in the study area, quality requirements
vary depending on the intended use of the water.
Ordinarily, public water supply imposes the most restric-
tive quality constraints, with agricultural quality
requirements somewhat.lower and most industrial require-
ments lower still. However, it should be noted that
water quality constraints are more complex than is
indicated by this generalization. There are processes
to make almost any water useable for public supply if
the need is great enough to justify the cost. Crops
vary widely in their tolerence of dissolved minerals in
irrigation water, and some industrial processes require
water of even higher quality than that required for
3. Environmental effects of ground-water production include
drawdowns in nearby wells; lowering of water levels in
lakes, ponds, and wetlands; reduction of streamflow;
saltwater intrusion; and possibly contribution to
sinkhole formation. The seriousness of any of these
effects or the likelihood of their occurrence depends
on the magnitude of water withdrawal and local hydro-
geologic conditions. Environmental considerations must
be weighed against necessity and public interest when
deciding whether or not potential environmental effects
are acceptable as a consequence of ground-water withdrawal.
4. Regulatory restrictions imposed by the water management
districts are often seen as the greatest constraint
upon water availability. However, it should realized
that the economic, water quality, and environmental
constraints described above are real and are present
whether restrictions are imposed or not. For example,
saltwater intrusion will restrict pumping from a well
field just as surely as a pumping limitation set by a
regulatory agency; only the timing will be different.
One function of the water management districts is to
anticipate and avoid such "management by crisis"
situations. In doing so, restrictions will be imposed
which raise the cost of water production and limit
water availability. However, in the long run, regula-
tory restrictions should be drafted in order to permit
development of our water resources to their maximum
potential, consistent with the public interest.
As discussed above, the availability of ground water in
Florida depends upon a number of interrelated and inter-
locking factors. The amount of ground-water that can be
developed in an area can be estimated by a simple "water
budget" calculation. An estimate can also be made of the
additional water which could be obtained using augmentation
methods described in Chapter 3. These estimates describe
water availability only in very general terms, whereas water
is used at specific places for specific purposes.
Evaluation of Development Potential
The potential for development of ground-water supplies in an
area is influenced by interacting economic, environmental,
and hydrologic factors. Therefore, except in relative
terms, assessing ground-water development potential is
seldom possible for other than site-specific or use-specific
purposes. For this report, subjective judgments of develop-
ment potential were made on the basis of the most dominant
influences affecting development potential in each water
management district in the study area.
In some districts, the diversity of conditions within the
district necessitated assessment of development potential
within smaller, hydrologically similar areas. Three general
aspects of ground-water development were considered in
delineating similar areas: (1) potable ground-water supply,
(2) nonpotable ground-water supply, and (3) injection disposal
potential. The criteria considered in assessing development
potential of each area with respect to these aspects of
ground-water development are summarized as follows:
Potable Ground-Water Supply.
Principal source--In most parts of the study area, one
ground-water source is used almost to the exclusion of other
available sources in terms of volume of water withdrawn.
The reason is usually economic; the source providing the
highest yield-to-cost ratio is selected.
Secondary source--In some areas, freshwater aquifers are
present which are not heavily used for water supply. In
most cases, these aquifers provide relatively low yields and
are used only when the required amount of water is small.
Usable thickness of aquifer--The depth of potable water is a
constraint on well depth and, consequently, on well yield.
For the Floridan aquifer, the thickness of an aquifer is
considered to be the interval between the top of the aquifer
and the depth at which the aquifer contains nonpotable
water. For shallow aquifers, the usable thickness is the
interval comprised of relatively permeable strata, capable
of yielding a reasonable amount of water. The usable depth
of shallow aquifers near the coast is generally less than
indicated for the area in general because of saltwater
Estimated well yield--This largely subjective estimate of
the highest practicable well yield for the area and aquifer
involves consideration of aquifer thickness and transmis-
sivity, available drawdown, saltwater intrusion potential,
and, when available, production records of existing high
capacity wells in the area.
Water quality--One of the criteria used to delineate hydro-
logically similar areas is water quality. The range of
total dissolved solids and the chemical type of water present
in the area in both the principal and secondary source are
considered in relation to possible intended uses of the
Present aquifer stress--Aquifer stress is characterized as
high, moderate, or low on the basis of present ground-water
withdrawals in the area and the extent to which these with-
drawals stress the aquifer system. Major ground-water uses
in the area are noted.
Relative water availability and limitations on development--
This is a subjective judgment of water availability in each
of the areas evaluated. This is a qualitative rather than
quantitative judgment of water availability. Limitations on
development potential are noted for each area.
Nonpotable Ground-Water Supply.
Source and depth--In most areas, there are two classes of
nonpotable ground water considered: brackish (less than
10,000 mg/l total dissolved solids) and salty (more than
10,000 mg/l total dissolved solids). The requirements of
the use, and the economics of water production, treatment,
and after-use disposal generally dictate the quality selected.
Estimated well yield--The estimated maximum practicable well
yield'is given when data are available. For many parts of
the study area, data are lacking regarding this parameter.
Water quality--An estimated range of TDS values is given.
Depth of well is likely to control TDS, especially in the
case of brackish sources. Ground-water temperature range is
also given because nonpotable ground water is a potential
source of water for cooling purposes.
Present use and area aquifer stress--Any major present uses
of nonpotable ground water are noted.
Relative water availability and limitations on development--
The relative availability of water is characterized as high,
moderate, or low. Major negative factors affecting avail-
ability are identified.
Injection Disposal Potential.
Approximate depth of disposal zone--The estimated depth to
the top of the most promising aquifer for the disposal of
relatively innocuous wastewater is given. Typical wastes
which might be considered would be treated sewage, hot
water, brine, and nontoxic industrial wastewater. The
feasibility of disposal of highly toxic or radioactive
wastes was not considered.
Estimated maximum practical well capacity--This is a subjective
estimate based on probable aquifer characteristics, integrity
of confining beds, fracture gradients, economics, safety,
and current regulatory policy.
Estimated feasibility and limitations--This is also a subjective
judgment based on some of the same parameters described
above plus the degree of confidence in the occurrence of any
suitable injection aquifer. Any special limitations on
feasibility of injection disposal are also noted.
WATER AVAILABILITY IN THE ST. JOHNS RIVER
WATER MANAGEMENT DISTRICT (SJRWMD)
The St. Johns River and its largest tributary, the Oklawaka
River, are the only streams in the District with available
water as defined previously, of at least 100 cfs. Both have
the potential for development of major water supplies.
Other tributaries of the St. Johns, having smaller but still
significant development potential, are Donns Creek, Jane
Green Creek, Econlockhatchee River, Wekiva River, Deep
Creek, Rice Creek, and Black Creek.
The Nassau and St. Marys Rivers, in the northern part of the
District, have only very limited development potential.
The short coastal streams discharging to the Atlantic Ocean
or Intracoastal Waterway have little or no water supply
The SJRWMD is the only part of the study area having a
number of large lakes with significant development potential.
The lakes with the highest potential are those created along
the main stem of the St. Johns River. Residential and
agricultural development around most of the upland lakes
restricts development potential around these lakes.
St. Johns River. Figure 5-1 illustrates those reaches of
the St. Johns River with available water greater than 100 cfs.
Except for the headwater areas in Indian River and Brevard
Counties, the entire river has enough water available to
justify serious consideration as a source of potential power
plant cooling water or other major water supply.
The water quality of the St. Johns River differs in the
various segments of the river and its tributaries and also
varies with seasonal changes. Generally, chlorides and
dissolved solids concentrations increase toward the mouth of
the river near Jacksonville. The upper segment of the
river, above the Lake Washington Dam, is much lower in
chlorides and dissolved solids than the downstream segments
of the river. All of the river is classified as Class II
water except the portion of the river and its tributaries in
Brevard and Indian River Counties, located south of Lake
Washington Dam, which is used by the City of Melbourne for
potable water supply. Appendix B details the monthly change
in eight water quality parameters for each of the 11 USGS
water quality stations located within the District. Figure 5-1
presents mean values of total dissolved solids for selected
sampling stations on the St. Johns River.
During the wet season, the chlorides and dissolved solids
concentrations of the river are much lower than in the dry
season due to the greater contribution of rainfall and
runoff to the total flow quantity of the river. In dry
periods, a large portion of the total flow is from springs
and upward leakage of saline and mineralized artesian ground
water. Tidal and wind effects are also greater during dry
periods. In the upper segment of the St. Johns River, near
Melbourne, chloride concentrations vary between approximately
20 mg/l and almost 200 mg/l during the year. Near Cocoa,
the chloride concentration varies between 60 mg/l and 280 mg/l.
These variations in chlorides in the upper segments of the
river reflect the effect of the increased ground-water
contribution to the river during dry periods. At Palatka
and Jacksonville, similar variations in chlorides and dis-
solved solids exist but in the lower segments of the river,
the variations are more influenced by tidal and wind effects.
The tributaries of the St. Johns River also experience
variations in certain water quality parameters during the
year. Appendix B also presents the monthly variations of
eight water quality parameters during a typical year for
selected tributaries of the St. Johns River. Jane Green
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