UNITED STATES DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY

pf


MAP SERI


Timber, 1968


FLORIDA BOARD OF CONSERVATION
published by DIVISION OF GEOLOGY


-< cWAT ER


IN



m/BRO WA RD COUNTY



FL ORIDA



by
H. J. McCoy and C. B. Sherwood
Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
DIVISION OF GEOLOGY
4 FLORIDA BOARD OF CONSERVATION
Lu and
BROWARD COUNTY


Figure 1.- Brouard Counto receives an abundant supply of Iresh water from an annual rainfall of about 60 inches and water brought Into
Central l and Southern Florida Flood Control District. ThIe Biscayne aquifer readily stores and transmits this water. Salt-ater intrion


INTRODUCTION

Ihe purpose of this report is to present a general picture of the
water resources of Broward County, the regional and local water
management facilities designed to alleviate present and future water
problems, and the methods used for obtaining large municipal water
supplies. Selected data are shown to aid in understanding the
hydrologic system and the natural and man-made factors that affect the
quantity, quality, and movement of water within the system.
This is one of a series of reports resulting from a comprehensive
study of the water resources of the county begun in 1961 by the U.S.
Geological Survey in cooperation with Broward County, to provide
information needed for the management and protection of water
supplies.
Broward County receives an abundant 60 inches of rainfall during
most years, and it is underlain by water-bearing materials (an aquifer)
which can store and transmit water readily. It also has an extensive
network of controlled canals which are connected to inland
water-conservation areas (fig. 1).
The availability of an adequate supply of fresh water has been an
essential factor in Broward County attaining its rank as the Sth largest
in population and 10th fastest growing county in Florida (Florida
Devel. Comm.. 1965). Industry and agriculture also have expanded as a
result of the availability of an abundant water supply.

WATER PROBLEMS

Although the water picture is encouraging, the explosive
urbanization of this low-lying coastal area has been accompanied by a
number of natural and man-made water problems. Natural problems of
flood and drought are caused by extreme variations in rainfall that may
range from as much as 20 inches per day during hurricanes in the rainy
seasons to little or none during the dry seasons. Man-made problems
include 1) Sea-water intrusion that resulted from overdraimage of the
area; 2) obtaining adequate municipal water supplies for the
mushrooming population; and 3) disposing of increasing quantities of
man-made wastes.
During the floods of 1947 and 1948 caused by excessive rainfall
during hurricanes, several sections of downtown Ft Lauderdale were
under 2 to 3 feet of water and large inland residential areas were
flooded for several days. In contrast, the fires of 1962 in the western
part of the county occurred after a prolonged drought when water
levels declined below surficial peat beds which became so dry that fires
started as if by spontaneous combustion.
The threat of sea-water intrusion into municipal well fields has
been a historic problem. As large amounts of fresh water were removed
by drainage for urbanization, regional fresh-water levels declined and
sea water advanced up the canals and inland through the aquifer during
dry periods. In recent years, municipal well fields in Dania and Ft.
Lauderdale have experienced some degree of sea-water contamination.
This insidious invasion of salt water is an ever-present danger to the
fresh-water supply of coastal well fields.
The need to expand municipal water supplies is a natural
consequence of a rapidly increasing population. Also, per capital
consumption of fresh water has increased with increased population In
1955, the City of Ft. Lauderdale supplied about 15 mgd (million
gallons per day) for a population of about 86,000, or 175 gpd (gallons
per day) per person. In 1965, the average pumpage was 28.5 mgd for a
population of 139,000 or 205 gpd per person. The peak water needs
occur during the dry winter and spring when water levels are lowest but
when tourist and irrigation uses are high. The daily water needs for
Broward County in 1985 for municipal supplies alone are predicted to
be as high as 500 mgd.
Waste disposal is rapidly becoming a major problem in Broward
cls.o-nty. Most of the water used by man is discharged as effluent into
the Biscayne aquifer through septic tanks or directly into canals,
streams, and the ocean. The more water man uses, the greater the
problem of effluent treatment and disposal becomes. The method and
degree of treatment and the locations of disposal sites will have a
significant effect on the quality and the quantity of future water
supplies.

HYDROLOGIC SYSTEM

GENERAL DESCRIPTION

Most municipal, domestic, irrigation, and industrial supplies in
Broward County are obtained from the Biscayne aquifer (fig. 2). The
aquifer extends from the surface to depths of more than 200 feet near
the coast and thins out near the surface 25 to 40 miles westward in the


Everglades. The aquifer contains beds of pure or sandy limestone
separated by beds or lenses of sand. Any of the limestone beds of
adequate thickness are capable of yielding large amounts of water to
wells. Wells that tap the thick limestone in the deep part of the aquifer
near the coast commonly yield more than a thousand gallons per

Broward County lies within the Central and Southern Florida
Flood Control District (CSFIFCD). The CSFFCD accomplishes its
function of flood control and water conservation by means of a
network of levees, canals with control structures, and pumping stations
to regulate water levels and flow in the canals.
During flood periods, the gated structures (fig. 3) near the coast are
opened and ground water moves to the canals and is discharged to the
ocean thereby lowering water levels. Pumping station S-13 on the South
New River Canal assists gravity flow to the ocean during wet periods
but station S-9 (fig. 4), farther inland, pumps flood waters westward
into the conservation areas. During droughts the gated structures near
the coast are closed and pumping station S-9 pumps fresh water
eastward from the conservation areas through the canals. As a result,
the levels of the canals near the coast are generally higher than the
adjacent ground water, and the aquifer is replenished from the canals.

CHEMICAL QUALITY OF WATER

The quality of the water in the integrated flow system is generally
good. Water from the aquifer is typically a hard, calcium- bicarbonate
type suitable for most uses with simple treatment. Surface water is of
good but variable quality-soft and highly colored by drainage from
inland swampy areas during high-water periods, but increasingly
mineralized by ground-water inflow during low-water periods.
Effluent from some sewage and industrial plants in the county is
discharged directly into controlled canals. Irrigation water containing
fertilizers and pesticides also drains into the canals from inland farm
areas. Analyses of water samples from canals indicate that pollutants at
present (1967) do not constitute a health hazard. However, increases in
the amounts of these pollutants caused by future increases in
population and farm activity will necessitate detailed monitoring of the
quality of the water in the canals and aquifer to protect the water
resources of the county.

RECHARGE, DISCHARGE AND WATER MANAGEMENT

The amount of water potentially available for withdrawal in
Broward County is determined by the recharge to and the discharge
from the hydrologic system. Infiltration of rainfall through surface
materials and seepage from controlled canals are the means of recharge
to the Biscayne aquifer in Broward County. Discharge from the aquifer
is by evapotranspiration, by ground-water flow to canals and the ocean,
and by pumping from wells. Discharge through the canals and
evapotranspiration are greatest during and after periods of heavy
rainfall, when water levels are high, whereas discharge by pumping is
greatest in the dry periods, at the peak of the tourist season. In general,
the discharge by evapotranspiration and canal flow greatly exceeds the
discharge by pumping from wells.
Because canals are closely controlled to minimize losses, and
because they extend far inland to areas where ground-water levels are
relatively high throughout the year, water levels adequate to provide
recharge to the aquifer near the coast can be maintained.
Broward County's annual rainfall averaged about 60 inches for the
1950-65 period, ranging from 35 to more than 75 inches. Although
most of the rainfall occurs in the summer and fall (see fig. 5) coinciding
with the hurricane season, it usually is unevenly distributed. This is
clearly demonstrated by records of October 14-15, 1965 when 25
inches of rainfall was recorded at the coastal yacht harbor in Fort
Lauderdale, and less than 5 inches was recorded at an agriculture
station eight miles inland.
If rainfall during the wet season is deficient, water levels during the
following dry season will be correspondingly low. For example, the
rainfall for the 12 months prior to June 1962 was 36 inches, but the
rainfall for the 12 months prior to November 1965 was 81 inches.
Countywide water levels at the end of these two periods represented
the low and high levels respectively since 1948.
Fluctuations of the water level reflect the effects of recharge to and
discharge from the aquifer. These fluctuations are recorded by
water-level measurements in a countywide network of canal stations
and observation wells. Some of the stations and wells are equipped with
continuously recording instruments and provide detailed record.
Records from some of these stations and wells for the years 1962 and
1965 are shown in the hydrographs in figures 6 and 7.
Hydrographs show fluctuations of the water level with respect to


the county by canals of the
is shoI n by the pink shad--


0 I 2 3 4 MILES
VERTICAL SCALE GREATLY
EXAGsERATED
Figure 2.- Broward County is IriE It more than 200 feet oIf permeable
tr-earing materials ,alled the Btsoavn' aquifer, The aquifer contains
beds of pur or and imetone separated by ieds or lenses of sand. Any
f e hmotone bds of adiqute thickness are capable of yielding large
Amounts of atr to ils. ells that tap the think limestone in the
oopr part of the aquifer ntear the oast commonly ild more than a
hnu eaton t per minute .e'tion t alon ]One 5-At in lioure )


*
, U-


i malleA.IU .4 a i ? j







I ur 3 alit control trueture S-37A on C press Creek Canal (C- 14) near
Pompeno tei help to print the intrusion of sea water ito th Fort Lau-
,rdale rospect l tto' fud h- h a rifall he u f t hi c it
t odi ng i the inland areai Itrlng drt periods the gI tes are closed
to e its.rv frh ctee lookfn upso tream toward t ,t.


"tori |,- Pitt ti iti*ton No 9t l e t chhe othNioii er locol
t lthd pleX t tf t''torm flot at the rate of u t1
mtilt n callo pr minute fr< iti i rai nai area and dischar' ti tt t
conslrvltlon area for itoras e and future 'to it dro porlods. tiec is looking
est (utrem) ro ( (romc I 6 itoh


tim. They indicate both instantaneous reactions and long term trends
Wathr-levei contour maps are three-dimensional representations of the
water surface for a specific tin'e and indicate the aimoun of water
stord in the aquifer. A comparison of hydrographs and contour mapr s
epiesenti ng low water levl periods and high water level pertiods aids
the determination ot the offctis man and nature hav o- tthe hydrologtic

The thirteen graphs shown in figures 5, 6, and 7 inmdcate the
hydeologic conditions in Broward County during 1962 (red) and 1965
(blue). Discharge of the Hillsboro Canal and stage and discharge of the
North New River and Snake Creek Canals for 1962 and 1965 are shown
on figure 6. Seven of the hydrogaphs (fig. 7) show water levels in wells.
These graphs are identified by the well number and the location of the
wel as shown by number on figures 8 and 9. The combmted pumpatge
for the two Fort Lauderdale well fields and ramufall at Iort Lauderdale
for 1962 and 1965 is shown on figure 5
The graphs show the effects on the water level caused bv seasonal
variations in rainfall and the effects of man's control and use. They
reflect the characteristic tow levels of the long winter dry season and
the high levels of the wet season, June through October The graph of
pumpage (fig. 5) indicates that the time of greatest water needs
corresponds with period of lowest levels because peak needs for the
tourist influx and irrigation occur during the dry season.
At the beginning of 1962 the effects of extended drought are
sho-n in the hydrographs by the relatively low water levels and canal
flow. The rainms of the summer and early fall of 1962 raised the water
levels appreciably and canal discharge increased correspondingly. Figure
8 represents the low-of-record water levels that occurred (May
22-13,1962) at the end of a prolonged drought. This was also a period
of large ground- water withdrawals. All coastal canal structures were
cloed to conserve as much fresh water as possible for recharge to the
aquifer. The contours show that pumping from the major municipal
wel fields had created large water-level depressions. In the Prospect
Well Field, the water level had declined to two feet below msl (mean
sea level), and in the Dixie and Pompano Beach well fields they had
decked to msl. The contours also indicate that the control structures
in the Middle River and North New River Canals are too far inland to
provide adequate water for recharge to effectively minimize well-field
depressions, and protection against salt-water intrusion from the tidal
reat es of those canals.
Water conditions during the first half of 1965 were similar to those
of 962 in most parts of the county. Several of the hydrographs show
tha water levels during May and June of 1965 were lower than they
were during the period of the area-wide low-water conditions of 1962.
Ho vere, most of these graphs represent relatively local areas where
water levels were lowered by heavy well-field pumping or by
uncontrolled reaches of canals, whereas the water level contour maps
were prepared from measurements made in more than a hundred wells
thr-ughout the county and represent regional conditions. Also,
pumping and the resultant water-level drawdowms had increased
appreciably in all major well-field areas during the interval between
t9t2 and 1965-
1igure 9 shows the configuration of the water surface on November
1, 1965 a time of extremely high levels. This extreme condition
resulted after 42 inches of rain had fallen during October (see fig. 5).
Co npared to the low-water map, water levels in figure 9 are as much as
10 feet higher in the northeastern part of the county and about five
fee higher in the remainder of the county. All coastal controls in canals
were partially or completely open to release flood waters to the ocean.
Puip station S-9, near the west end of Canal C-I 1, was pumping water
werIward into the conservation area, and pump station S-13 near the
cost was pumping water eastward to the ocean. The high water
cot figuration of the water table shows the effectiveness of the existing
networks of canals of the C&SFFCD in controlling flooding.
Nevertheless, the flood-control system was not designed to conductt the
excess water resulting from rainfall of the October 1965 intensity and
extensive flooding occurred. Canal discharge increased sharply as
cor.trol structures were opened to remove excess flood waters. The
Hillsboro Canal, in the area of heaviest flooding, reached a peak
discharge of 2,900 cubic feet per second (nearly 1.9 billion gallons per
day).

SEA-WATER INTRUSION

The pink shaded area in figure 8 represents the maximum inland
extent of sea-water intrusion at the bottom of the Biscayne aquifer in
Broward County in 1964. The salt-water body in the aquifer is wedge
shaped (fig. 1), thickest at the coast and thinning inland toI an edge
where it underlies fresh ground water at depths of 160 to 200 feet.
Greatest inland penetration of sea water is in the vicinity of tidal canals.


Because sea water is slightly heactvier than Iresh water,1 it oll move
inland until balanced by fresh-water levels tht a te appreciably higher
than sea levels When fresh-water levels are high, sea water is held near
the coast, but when fresh-water levels are low, sea water moves up the
tidal canals and tolasd in the aquifet beneath the fresh water.
Theoretically, oin a coastal oquifte c ah foot of fresh water above
sea levels would indicate b0 f oeerffr shawater belo se alevsl Wilthis
in eund it would seem thatthe three principal well fields s Broward
County should he contamontated by alty er bec taue levels in the
fields are at or below sea level. However isntrut la retarded. hby
fresh water mounds that persist between tiltc ell field and rite sea
Although these mounds decline to only 0. foot salove ml during dr
periods, this height is sufficient lin ost casce to hold ack the salt
water unt rainfall occurs or pumpug in the wstll feld Is reduced and
ea erle l r over. In the S sical id lverPri ect Well field
arta"aft'edoeraoaanand conttrolost8ru r g o8ald t)arebeing
constructed by Brward t county agencies to retard sea matter ltruon.
from tidal canals which threatens fort audeirdeti major well filcd
he feeder canal will Rconnect to the controlled reach of the Middle
River Canal to provide cnnstant recharge t tthe ell field area Higher
fresh-water levels from thisrechargce ll act as a barrier to further
sea water intrusion

OUTLOOK

Water control and management practices are being constantly
improved on both regional and local levels Recent legislation gives the
Broward County Water Resources Department and the Water Resources
Advisory Board the power to control man-made changes in the flow
system, subject to approval of the Board of County Commissioners.
Hydrologic information indicates that the network of canals and
hydrauhlally-ionnected aquifer form an integrated flow system which
provides the physical basis for management of the area's water
resources. Thus, the source of supply and the areas basic facilities for
efficient water management are available, and the methods for
development of maximum mumcipal supplies are clearly indicated. The
application of comprehensive water-management policies and careful
planning of changes within the flow system based on continuing
hydrologic studies seemingly cannot only provide solutions to Broward
County's growing water problems, such as floods, drought, sea-water
intrusion, and pollution, but also assure ample long-term municipal
supplies.
Further information and data on the water resources of Broward
County are included in the following reports:

1. Water Resources of Southeastern Florida. 1955, U.S.
Geological Survey, Water Supply Paper 1255.
2. Biscayne Aquifer of Dade and Brirward Counties, Florida.
1958, Florida Geological Survey Report of Investigations No. 17.
3. Ground water Resources of the Oakland Park area of eastern
Broward County, Florida 1959, Florida Geological Survey Report of
Ieestigasons No0 20O
4. Hydrology of the Biscayne Aquifer in the Pompano Beach
area, Broward County, Florida. 1964, Florida Geological Survey,
Report of Investigations No. 36
5. Water control Vrsus ea-water itrusion in Broward County,
Florida 1965, Florida Geological Survey Leaflet No. 5.
6. Chemical Quality of Waters of Broward County. Florida
1968, Florida Geological Survey Report of investigations No. 51.
7. Records of water levels, stroamfiow, and water quality are
published annually in "Waters Resources Data for Florida" prepared by
the U.S. Geological Survey in cooperation with the State of Florida and
other agencies.
For current information contact the U.S. Geological Somey, 51
S.W. First Avenue, Miamio, Floorida or Broaward County Water Control,
Broward County Courthouse, Fort Lauderdale, Florida.


t 1 6 mo
-0 -
r 4


-24



36
240
II I 28Z

I^L 4,


Figure i T tal monthly pumpage of the
lort L.auider iale Dixie and Prospect
well fields and monthly rainfall at Fort
Lauderdalo. or 1962 (rIed) and 1965
(blue)


HILLSBORO CANAL Near Deerfield Beach


2400 -
2200 -- -
2000 - - 5
0O \- Stage
1600 4.\ I


:0oo i i ,

8002---- ---
600 -

Disciarge
200-----
f-- --l ---- 0----r


2400- 6
2200-- --
2000--- --- - 5
1800 -- -- -I
1600 -Discharge

1400 -
1200 --- ----'-i------- --- -------------3
,000
1000 Stage ,--t/ -


So00 s-c'thar
600
400 r---At2

2400-- -I I




22001---- -- -------- -- -- -------
22000--- ------- ------4 -
12000 -- --- --r--- --- -- --- --
62400 -
1600 Discho e 4
400 -- --







40 I I I I I
20 F M A M J A
10 A,,Stag 4 ),









SNAKE CREEK CANAL at S-29

Figure 6.- Stage and discharge hydrographs of selected canals.
Lca tion6f re or eas re nt by he arelines and fi ecord
o d 2 cdis s hown y the red lHes "nd lI 65 d
ins hown 16 thecsloe iege.s


8-------------



6-







2-- ^^ -- -
I I


Cl-------------------------------------------------------|
G853 POMPANO BEACH WELL FIELD






5-
4-- -----











-2
-3
G820 PROSPECT WELL FIELD




i> 6 -










5 -




S57 -2'----------------

S329 DIXIE WELL FIELD


8
7-

6-

h4--


3
4--------- 7--


^ 3---------------------I-




2 o

H -il-----------------------------
0-9

" F291


G561

Figure 7.- Hydrographs of selected wells equipped with con-
tinuous.water-level recording Instrumernts. The 1962 record is
shown by the red line and the 1965 record by the blue line.
Location of well, are shown by their number on figures 8
and 9. Arrows indicate dates of record low and high water
levIel conditions shown on figures 8 and 9.


25' 20' 1 10'

Figure 9.- HIGH-WATER CONDITIONS -- Contours on the record high water table on November 1, 1965 are shown by blue lines.


.WtbRIDA GEOLOGIC SURVEY MAP SERIES


I