Ground-water resources of the Lower Hillsboro Canal area, southeastern Florida ( FGS: Report of investigations 55 )

STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES

BUREAU OF GEOLOGY
Robert 0. Vernon, Chief

REPORT OF INVESTIGATION NO. 55

GROUND-WATER RESOURCES OF THE LOWER HILLSBORO
CANAL AREA, SOUTHEASTERN FLORIDA

By
H.J. McCoy and Jack Hardee
U. S. Geological Survey

Prepared by the
U. S. GEOLOGICAL SURVEY
in cooperation with the
BUREAU OF GEOLOGY
DIVISION OF INTERIOR RESOURCES
FLORIDA DEPARTMENT OF NATURAL RESOURCES
and the cities of
BOCA RATON and DEERHELD BEACH

Tallahassee, Florida
1970

DEPARTMENT
OF
NATURAL RESOURCES

CLAUDE R. KIRK, JR.
Governor

TOM ADAMS
Secretary of State

BROWARD WILLIAMS
Treasurer

FLOYD T. CHRISTIAN
Commissioner of Education

EARL FAIRCLOTH
Attorney General

FRED 0. DICKINSON, JR.
Comptroller

DOYLE CONNER
Commissioner ofAgriculture

W. RANDOLPH HODGES
Executive Director

LETTER OF TRANSMITTAL

Bureau of Geology
Tallahassee
April 14, 1970

The Honorable Claude R. Kirk
Governor of Florida
Tallahassee, Florida

Dear Governor Kirk:

The Bureau of Geology of the Department of Natural Resources is
publishing as its Report of Investigation No. 55 a report on the
"Ground Water Resources of the Lower Hillsboro Canal Area, South-
eastern Florida". The report was prepared as part of the cooperative
program between the Bureau of Geology, the U. S. Geological Survey
and the cities of Boca Raton and Deerfield Beach. It is written by
Messrs. H. J. McCoy and Jack Hardee of the U. S. Geological Survey
and was undertaken to determine the amount and kinds of water being
produced from the lower Hillsboro Canal Area in Palm Beach and
Broward counties.
All of the potable ground water being produced from the
Biscayne aquifer is developed from the canal through infiltration.
Rainfall in the area is the ultimate source for all of the water.
Careful control and management will allow the development of
large quantities of water from the canal toward Lake Okeechobee, but
a fresh water head must be maintained along the contact of fresh water
with sea water to prevent salt water intrusion.

Respectfully yours,

R. 0. Vernon, Chief
Bureau of Geology

ROV:ebl

Completed manuscript received
April 14,1970
Printed for the Bureau of Geology
Division of Interior Resources
Florida Department of Natural Resources
Designers Press of Orlando, Inc.
Orlando, Florida

iv

CONTENTS

Page

. . . . . . . . .1

Abstract . .

Introduction . . . . . . . . ......1

Purpose and scope .....

Previous investigations .

Acknowledgments .....

General features .......

Climate ..........

Population and industry .

Hydrologic setting..... .

Biscayne aquifer .... .

Floridan aquifer ..... .

Surface flow system .. .

Ground water . .

Recharge and discharge

Water-level fluctuations .

Hydraulic properties .

Water quality ......

Sea-water intrusion .

Water use and potential supply

Summary ........... .

Well numbers . .

References .........

.....................

. . . . . .

......................

.....................

. . . . . .

. . . . . .

. . . . . .

. . . . . .

. . . . . .

. . . . . .

.....................

. . . . . .

. . . . . .

.....................

.....................

.....................

.....................

.....................

.....................

LIST OF ILLUSTRATIONS

Figure

I Location of lower Hillsboro Canal area, Florida,
showing physiographic subdivisions. . . .
2 Parts of Broward and Palm Beach Counties showing
canals and levees of the Central and Southern
Florida Flood Control Project and the Lake Worth
Drainage District. .......................
3 Map of lower Hillsboro Canal area showing location
of wells and lines of geologic sections ...........
4 Geologic section of the Biscayne aquifer in the
lower Hillsboro Canal area along line A-A' in
figure 3 .............................
5 Geologic section of the Biscayne aquifer in the
lower Hillsboro Canal area along line B-B' in
figure 3 .............................

6 Hydrographs of wells PB 470 and PB 488 and monthly
rainfall at Boca Raton, 1963-1967. . . . . .
7 Hydrographs of wells G 1214 and G 1260 at Deerfield
Beach and monthly rainfall at Boca Raton, 1963-1967 .
8 Water-table contour map of the lower Hillsboro Canal
area, May 7, 1965, during low-water conditions . . .
9 Graph showing monthly municipal pumpage and rainfall
at Boca Raton, 1963-1967. .....................
10 Graph showing monthly municipal pumpage at Deerfield
Beach and monthly rainfall at Boca Raton, 1963-1967. .. .. .
11 Water-table contour map of the lower Hillsboro Canal
area, November 1, 1965, during high-water conditions. .
12 Contour map showing rise in water levels from May 7 to
November 1, 1965 in the lower Hillsboro Canal area. . .
13 Water-table contour map of the lower Hillsboro Canal
area, October 27, 1966, during high-water conditions. . .
14 Water-table contour map of the lower Hillsboro Canal
area, April 12, 1967, during low-water conditions. . .
15 An example of the preparation of a water-quality diagram
using the percentage figures in Table 3. . . . .
16 Relative concentrations of chemical constituents in
ground water of the Biscayne aquifer in the lower
Hillsboro Canal area. .........................
17 Chloride content of water at nine points in the El Rio
Canal between the Hillsboro Canal and Street. . . .
18 Chloride content of water at nine points in the
Hillsboro Canal upstream from the Intracoastal
Waterway, September 20, 1966. ...................
19 Section along line A-A' (figure 17) showing lines of
equal chloride content (isochlors) of ground water . .

. 14

. 15

. .16

S.18

. 19

. 20

. .21

. 22

. 23

. 31

S. 32

. 34

S.35

. .37

Page

. . 4

...... 10

20 Approximate daily maximum and minimum chloride content
of water in the El Rio Canal at 7th Street, Boca Raton,
Florida, for the period March 1964 through August 1965. ...... 39
21 Graph showing the discharge of the Hillsboro Canal at
the control near Deerfield Beach, 1965. . . . 41

TABLES

Table
1. Monthly rainfall at Boca Raton, Florida, 1961-1967.
2. Chemical analyses of water from selected wells in the
lower Hillsboro Canal area. ............. .
3. Selected constituents in water from well PB-487. .

Page
. . 15

. . 28
. . .. 30

GROUND WATER RESOURCES OF THE
LOWER HILLSBORO CANAL AREA

By
H.J. McCoy and Jack Hardee

ABSTRACT

The lower Hillsboro Canal area of this report occupies about 60
square miles of Palm Beach and Broward counties in southeastern
Florida. All potable ground water in the lower Hillsboro Canal area is
obtained from the Biscayne aquifer. The aquifer extends from the land
surface to a depth of about 400 feet and is composed of sand, sandy
limestone, shells, and indurated calcareous sand. Municipal well fields
of Deerfield Beach and Boca Raton and most of the domestic, irriga-
tion, and industrial wells obtain adequate water supplies from perme-
able limestone 90 to 130 feet below land surface. Rainfall in the area
and induced infiltration from controlled canals provide the recharge to
the aquifer.
Sea-water intrusion, although a constant threat, has not advanced
inland enough to contaminate either municipal well field. Intrusion
from the El Rio Canal toward the Boca Raton well field appears to be
stabilized, though further intrusion is a distinct possibility if fresh
water levels are further lowered in the area. Data collection stations are
maintained to monitor changes of the salt-water front in the aquifer.
Large quantities of water can be withdrawn from the interior part
of the area without the attendant threat of salt-water intrusion. Hy-
draulic characteristics of the aquifer are similar throughout the area
and high year-round water levels in the interior afford a potential
source of immediate and long-term recharge to the aquifer underlying
the coastal ridge.
The lower Hillsboro Canal area is still experiencing rapid growth
with resultant demands for larger quantities of potable water. Al-
though potable water is abundant, continuous observation and evalua-
tion of changes in the hydrology of the area should be maintained to
protect and efficiently manage the water resources of the area.

INTRODUCTION

Water problems facing the cities of Boca Raton and Deerfield
Beach are similar to those experienced by other coastal communities in
southeastern Florida with rapid growth and increasing water needs.

BUREAU OF GEOLOGY

Water supplies for Boca Raton and Deerfield Beach are obtained from
well fields located adjacent to the Intracoastal Waterway and to tidal
reaches of the Hillsboro and El Rio Canals, all of which are normally
salty. Recognizing that rapid population growth would mean large
water demands and that increased well field pumping could cause
sea-water intrusion, in 1963 officials of both cities requested the U.S.
Geological Survey to study water resources of the area to provide
information for the future development of water supplies.
PURPOSE AND SCOPE
The purpose of this report is to present an evaluation of the
ground-water resources of the lower Hillsboro Canal area and pertinent
supporting data to the officials of Boca Raton and Deerfield Beach,
Fla. The evaluation is the result of determining the following: (1) the
location, availability, and quality of potable ground water in the
Biscayne aquifer; (2) the occurrence and extent of sea-water intrusion
into the aquifer in the vicinity of the well fields; (3) the hydraulic
characteristics of the aquifer; and (4) the degree of interconnection
between the canals and the aquifer.
This report was prepared by the U.S. Geological Survey in cooper-
ation with the cities of Boca Raton and Deerfield Beach, and as part of
the statewide program with the Bureau of Geology, Florida Depart-
ment of Natural Resources. The field work and report preparation were
under the immediate supervision of C. B. Sherwood, Projects Engineer,
and H. Klein, Subdistrict Chief, Miami, Fla., and under the general
supervision of C. S. Conover, District Chief, Tallahassee, Fla., all of the
U.S. Geological Survey.

PREVIOUS INVESTIGATIONS
This report results from the first detailed ground-water resources
study of the lower Hillsboro Canal area. General information on the
hydrology and geology of the area has been published by the Florida
Geological Survey in reports by Cooke (1945), Black and Brown
(1951), and Schroeder and others (1958). Some additional informa-
tion on the area is included in a report resulting from a comprehensive
investigation of the water resources of southeastern Florida by Parker
and others (1955).

ACKNOWLEDGMENTS
Well-field and water-supply information given by William Edd-
inger, Water Superintendent of Boca Raton, and Arthur Strock, former
City Engineer of Deerfield Beach is appreciated. Special acknowledg-

REPORT OF INVESTIGATION NO. 55

ment is expressed to Drs. F. A. Eidsness, J. I. Garcia-Bengochea and Mr.
Emmett Waite, of Black, Crow and Eidsness, Inc., Gainesville, Fla.,
consulting engineers for the cities of Boca Raton and Deerfield Beach.
GENERAL FEATURES
The area of study comprises about 60 square miles of Palm Beach
and Broward counties in southeastern Florida as shown in figure 1. The
area is bounded on the east by the Atlantic Ocean and on the west by an
extensive agricultural area and the Everglades; it extends about 6 miles
north and 4 miles south of the Hillsboro Canal. The county lines and
the city limits of Boca Raton and Deefield Beach coincide with the
Hillsboro Canal except near the mouth of the canal. The area is divided
into three physiographic sub-areas (Fig. 1): (1) coastal lowlands-barrier
island; (2) coastal ridge; and (3) interior flatlands and the Everglades.
The barrier islands parallel the mainland and are separated from it
by the Intracoastal Waterway. Barrier islands extend intermittently
along most of Florida's east coast. Relic sand dunes form the island in
the study area and reach heights of more than 25 feet above msl (mean
sea level) in some locations. The white, sandy beach on the ocean side
of the island is one of the main tourist attractions in the area. The
coastal lowland on the mainland is characterized by mangrove swamps
adjacent to the Intracoastal Waterway and is generally less than 5 feet
above msl except where dredging and filling has taken place for housing
developments.
Paralleling the coastal lowland is the coastal ridge. In Deerfield
Beach the ridge is relatively wide and flat, reaching a maximum
elevation of about 25 feet above msl. However, in Boca Raton it is
narrower, dissected, relatively steep-sided, and reaches a maximum
elevation of nearly 40 feet above msl. The ridge is composed of white
sand containing varying amounts of shelly material. Westward from the
crest of the ridge the land surface slopes to the interior flatlands; in
Deerfield Beach the slope is gentle but in Boca Raton it is steep,
especially in the vicinity of the El Rio Canal along the west flank of the
ridge.
The interior flatland extends westward from the coastal ridge to
the Everglades. It is characterized by a relatively flat surface and
supports a natural growth of palmettos, pine trees, and a variety of
palm trees. The average elevation of the interior flatland is about 15
feet above msl.
CLIMATE
The climate of the lower Hillsboro Canal area is humid subtropi-
cal. The nearness of the Atlantic Ocean accounts for the high humidity

BUREAU OF GEOLOGY

Figure 1. Location of lower Hillsboro Canal area, Florida showing physiographic
subdivisions.
but the Gulf Stream moderates the temperature. The average monthly
temperatures for January and August during the period 1946 through
1967 were 68 F. and 82 F. The average annual temperature for that
period was 75 F. (U.S. Weather Bureau).
Rainfall in the area is unevenly distributed with time and location.
The average annual rainfall for the long-term period 1951-1967 is
nearly 60 inches. During this period five years were above average, five
years were below average, three years were approximately average, and
four years were not totaled because of incomplete data.

REPORT OF INVESTIGATION NO. 55

ment is expressed to Drs. F. A. Eidsness, J. I. Garcia-Bengochea and Mr.
Emmett Waite, of Black, Crow and Eidsness, Inc., Gainesville, Fla.,
consulting engineers for the cities of Boca Raton and Deerfield Beach.
GENERAL FEATURES
The area of study comprises about 60 square miles of Palm Beach
and Broward counties in southeastern Florida as shown in figure 1. The
area is bounded on the east by the Atlantic Ocean and on the west by an
extensive agricultural area and the Everglades; it extends about 6 miles
north and 4 miles south of the Hillsboro Canal. The county lines and
the city limits of Boca Raton and Deefield Beach coincide with the
Hillsboro Canal except near the mouth of the canal. The area is divided
into three physiographic sub-areas (Fig. 1): (1) coastal lowlands-barrier
island; (2) coastal ridge; and (3) interior flatlands and the Everglades.
The barrier islands parallel the mainland and are separated from it
by the Intracoastal Waterway. Barrier islands extend intermittently
along most of Florida's east coast. Relic sand dunes form the island in
the study area and reach heights of more than 25 feet above msl (mean
sea level) in some locations. The white, sandy beach on the ocean side
of the island is one of the main tourist attractions in the area. The
coastal lowland on the mainland is characterized by mangrove swamps
adjacent to the Intracoastal Waterway and is generally less than 5 feet
above msl except where dredging and filling has taken place for housing
developments.
Paralleling the coastal lowland is the coastal ridge. In Deerfield
Beach the ridge is relatively wide and flat, reaching a maximum
elevation of about 25 feet above msl. However, in Boca Raton it is
narrower, dissected, relatively steep-sided, and reaches a maximum
elevation of nearly 40 feet above msl. The ridge is composed of white
sand containing varying amounts of shelly material. Westward from the
crest of the ridge the land surface slopes to the interior flatlands; in
Deerfield Beach the slope is gentle but in Boca Raton it is steep,
especially in the vicinity of the El Rio Canal along the west flank of the
ridge.
The interior flatland extends westward from the coastal ridge to
the Everglades. It is characterized by a relatively flat surface and
supports a natural growth of palmettos, pine trees, and a variety of
palm trees. The average elevation of the interior flatland is about 15
feet above msl.
CLIMATE
The climate of the lower Hillsboro Canal area is humid subtropi-
cal. The nearness of the Atlantic Ocean accounts for the high humidity

REPORT OF INVESTIGATION NO. 55

TABLE 1 MONTHLY RAINFALL AT BOCA RATON, FLA.1

(inches)
1961 1962 1963 1964 1965 1966 1967

January 8.56 0.47 2.93 1.85 0.73 3.27 2.41
February .85 .69 6.18 3.82 5.25 5.79 2.34
March 1.09 3.41 4.73 3.20 .97 1.85 3.57
April .67 6.51 .93 4.36 .71 1.66 0.00
May 6.47 1.91 13.01 6.20 1.22 4.93 2.07
June 2.80 5.20 7.47 7.93 10.91 16.51 11.86
July 1.22 10.42 2.02 5.31 11.01 7.63 3.71
August 5.06 6.08 5.43 7.89 3.44 6.18 6.83
September 4.50 7.59 12.51 6.31 4.24 8.32 7.41
October 6.93 1.98 7.11 11.13 29.64 6.95 5.42
November 1.09 1.63 2.42 .63 3.94 1.06 3.71
December .16 .88 3.74 1.93 1.01 1.00 1.72

TOTALS 39.40 46.77 68.48 60.56 73.07 65.15 51.05

Record from U.S. Weather Bureau's Climatological Data.

Table 1 shows the monthly rainfall recorded at Boca Raton for
the period 1961 through 1967. This period was chosen for presentation
because it includes the two dry years preceding the beginning of the
study. The average for this period is 58 inches, or two inches below the
long-term average. Abnormally heavy rainfall was recorded during
October 1965. Most of the rain occurred during the middle and at the
end of the month. At Pompano Beach, shown in figure 2, 24 inches of
rainfall was recorded in 24 hours on October 31 and November 1.
POPULATION AND INDUSTRY
The lower Hillsboro Canal area has been strongly affected by the
population boom of southeastern Florida. The area has grown in
population from about 3,000 in 1950 to more than 36,000 in 1966.
The predicted population for 1970 exceeds 50,000.
Although Boca Raton and Deerfield Beach are primarily tourist
and retirement communities, both cities have planned for the expan-
sion of light, clean industries. The largest employers are the private and
chain sales and service stores. Agriculture contributes significantly to
the economy of the area. Several private and state-owned educational
institutions also play a part in the overall economic structure.

BUREAU OF GEOLOGY

Figure 2. Parts of Broward and Palm Beach counties showing canals and levees of
the Central and Southern Florida Flood Control Project and the Lake
Worth Drainage District.

HYDROLOGIC SETTING

The lower Hillsboro Canal area abounds in water: the Atlantic
Ocean is to the east and the vast water control works of the Central and
Southern Florida Flood Control District (FCD) is to the far west and
south (Fig. 2). A latticework of controlled canals of the Lake Worth
Drainage District (LWDD) is immediately adjacent to the north and
west sides of Boca Raton; the canals of the FCD and the LWDD were
constructed primarily to improve drainage during periods of high
rainfall. The canals cut across the top of permeable shallow sediments
called the Biscayne aquifer. During periods of low rainfall, the canals
convey water from inland areas and replenish the aquifer by induced
infiltration. Because rainfall is the primary source of replenishment to

REPORT OF INVESTIGATION NO. 55

the Biscayne aquifer, water levels are highest during the wet part of the
year and lowest during the dry.

BISCAYNE AQUIFER

All fresh ground-water supplies in the lower Hillsboro Canal area
are obtained from the Biscayne aquifer. The aquifer extends from land
surface to a depth of about 400 feet (Tarver, 1964). Eight test wells
were drilled in the area to augment available data in determining the
lithologic composition of the upper part of the aquifer. Figure 3 shows
locations. The wells ranged in depth from 127 to 208 feet below the
land surface. Data from these wells were used in preparing the geologic
sections in Figures 4 and 5.
The Pamlico Sand of Pleistocene age blankets most of the lower
Hillsboro Canal area and is the uppermost unit of the Biscayne aquifer.
It is composed of very fine to coarse quartz sand, white to black or red,
depending upon the staining materials. The Anastasia Formation of
Pleistocene age underlies the Pamlico Sand and is composed of co-
quina, sand, indurated calcarcous sand, and sandy limestone. The
Anastasia Formation is the principal source of water from the Biscayne
aquifer in the lower Hillsboro Canal area.
The Tamiami Formation of late Miocene age underlies the Ana-
stasia Formation. Permeable limestone beds in the upper part of the
Tamiami Formation constitute the basal part of the Biscayne aquifer.
The formation is tapped by few wells in the lower Hillsboro Canal area
because equally good water and comparable yields can be obtained
from wells that are bottomed in shallower limestones in the Anastasia
Formation.
Rock materials penetrated by the test wells are shown by Figure
4. Test-well data plus data from a few existing wells were used to draw
Figure 5. Both Figures show that sand covers the lower Hillsboro Canal
area to depths as much as 60 feet below the land surface. The Pamlico
Sand accounts for about 20 feet of this section in the Deerfield Beach
area and as much as 50 feet in the Boca Raton area. The geologic
sections show that the limestone beds are discontinuous vertically and
horizontally. Additional information from drillers in the area indicates
that limestone beds are more persistent in the Deerfield Beach area
than in the Boca Raton area.
Beds of indurated calcareous sand, or sandy limestone are wide-
spread enough through the lower Hillsboro Canal area that wells can
usually be finished with open holes below the casing. However, irriga-
tion and municipal wells subject to heavy withdrawals are usually
screened and gravel packed. In the western part of the area private

BUREAU OF GEOLOGY

Figure 3. Map of lower Hillsboro Canal area showing location of wells and lines of
geologic sections.
supply wells penetrate permeable material at depths ranging from 60 to
90 feet. This permeable material could be the same limestone as that
penetrated at 70 feet in well PB488 or the shelly, friable limestone
penetrated at 89 feet in wells PB-556, 557, and 558 (see Fig. 3 for
locations).
The Boca Raton well field obtains water from the limestone
shown by well PB 548 in Figure 5. The limestone is discontinuous and
becomes increasingly sandy to the north. This is indicated by the

REPORT OF INVESTIGATION NO. 55 9

-J
z

AS 0o A

LEAND LEVEL

40'- q q I q:: 40t
aoa --ad

110'- -60

EXPLANATION
CALCAREOUS SHELL SAND SANDY
LEVEL ...O IMILE LEVEL

Figure 4. Geologic section of the Biscayne aqui*er in the lower Hillsboro Canal
obtaining water from the limestone shown in.................... wells G-1228 and G-1272

The Floridan aquifer is a thick sequence of highly permeable
:: .. ...:: :::: ..... .- ....... ..... ... ....

..... ............ :.... .:::: :* -*:* ::

: _: .... ... . T . . .
400......... 4- 10 '
L C U .... .... ....... .... S L ..

PAMLICO:

.......
. ...... ..
.... ... ..... ..........
...... '"A A tA Q
. ........ .... .

........... .. .....
........ ....
:::14N. ut 6"

777 2 -k-.

... ... ..

.1~

#~,

A
cli
C2
N r I--j

D ..... ..
.. ....... .
5,
..... ..... ...... A -
................. 4
I" "A .......
.......... .. ........

..........

.. ........

40'.

SEA
LEVEL

40-

80o'

120-

200'-

CALCAREOUS
SAND

SHELL LIMESTONE

SAND

SANDY
LIMESTONE

0 MILE

Figure 5. Geologic section of the Biscayne aquifer in the lower Hillsboro Canal area along line B-B' in
figure 3.

EXPLANATION

40

- 40'

-80'

-120'

- 160

-200'

...........

A EAEL

REPORT OF INVESTIGATION NO. 55

is about 1,000 feet below the land surface and the water is under
greater than atmospheric pressure. The water level in a well penetrating
this aquifer in the lower Hillsboro Canal area will rise more than 25 feet
above msl. Such a well may yield as much as 2,000 gpm (gallons per
minute) by natural flow. However, in the study area, as in most of
south Florida, water from the Floridan aquifer is too mineralized for
most uses. Because of the tremendous quantities of water available, the
upper, less mineralized part of the aquifer, may be considered as a
potential source of supplemental water. However, the deeper, more
mineralized part of the aquifer is already being used as a reservoir for
discharge of chemical wastes near Lake Okeechobee, and sewage wastes
for a municipality near Pompano Beach.

SURFACE FLOW SYSTEM

The Hillsboro Canal is one of the primary canals of the controlled
network of the regional Central and Southern Florida Flood Control
District (FCD) as shown in Figure 2. The Hillsboro Canal extends
eastward from Lake Okeechobee between water Conservation Areas 1
and 2, where excess water is stored, to the Intracoastal Waterway. The
canal not only provides gravity drainage for flood control, but also
conveys water from the conservation areas eastward for replenishment
of the aquifer near the coast during droughts. This is accomplished by
keeping the control structure near the coast closed during the dry
season, thereby maintaining water levels in the canal higher than the
adjacent ground-water levels. During wet periods when ground-water
levels begin to rise higher than the canal levels the control structure is
opened to prevent flooding and the canal level and ground-water levels
are lowered.
Water levels in Boca Raton are affected more by operations of the
Lake Worth Drainage District than by the Hillsboro Canal. The Lake
Worth Drainage District is immediately west of Boca Raton (Fig. 2) and
consists of a system of controlled canals. The primary (equalizing)
canals flow southward bringing water during wet periods from areas
north of Boca Raton and discharge excess waters into the Hillsboro
Canal several hundred feet east of the control structure. The secondary
(lateral) canals are oriented east-west and connect to primary canals.
In September 1965 a salinity barrier was constructed on the El
Rio Canal about 1;600 feet north of State Road 808 bridge to prevent
sea-water intrusion into the Boca Raton well field. The barrier was
placed as far downstream as economically feasible.

BUREAU OF GEOLOGY

GROUND WATER
Ground water occurs beneath the land surface in the zone of
saturation where it fills the interstices, joints, crevices, fissures, solu-
tion holes, and any or all other voids and is the supply for springs and
wells (Meinzer, 1923, p. 38-39). The subsurface formations containing
ground water, and from which this water is collectible for use, are
called aquifers.
The upper surface of the zone of saturation, which is under
atmospheric pressure and free to rise and fall, is called the-water table.
Where ground water is confined in a permeable bed overlain by a
relatively impermeable bed its surface is not free to rise and fall and the
water is under greater than atmospheric pressure. Water thus confined
under pressure is called artesian. Direction of ground-water movement
is from areas of high water levels to areas of low water levels.
The Biscayne aquifer is essentially a nonartesian (or water-table)
aquifer, but in most locations in the lower Hillsboro Canal area the
permeable limestone beds are partly confined by discontinuous over-
lying layers or lenses of less permeable materials.

RECHARGE AND DISCHARGE
The amount of fresh water potentially available in the lower
Hillsboro Canal area is determined by the recharge to and discharge
from the Biscayne aquifer and the quantity available from storage in
the aquifer. Infiltration of rainfall through surface materials and seep-
age from controlled canals are the means of recharge. Recharge by
rainfall is greatest, naturally, during the rainy season of June to
November. Recharge from canals is greatest during the dry season,
December to May, when canal levels are higher than adjacent water
levels in the aquifer.
Discharge from the aquifer is by evapotranspiration, by ground-
water flow to canals and by pumping from wells. Discharge by ground-
water and surface-water flow and losses by evapotranspiration are
greatest during and after periods of rainfall when water levels are high;
discharge by pumping from wells is greatest during the dry periods, at
the peak of the tourist season. Discharge by wells constitutes only a
small part of the total discharge from the area.
The average annual rainfall of 60 inches evenly distributed over
the lower Hillsboro Canal area would be equivalent to about 170 mgd
(million gallons per day). Probably as much as 100 mgd would be lost
by evapotranspiration and discharge to the ocean. The remaining 70
mgd would be available to recharge the aquifer.

REPORT OF INVESTIGATION NO. 55

WATER-LEVEL FLUCTUATIONS
Ground water in the Biscayne aquifer moves from areas where
water levels are high to areas where water levels are low. Water levels are
highest in recharge areas or in areas that are the greatest distance from
points of discharge; water levels are lowest in discharge areas along the
coast, along uncontrolled drainage canals, or in the vicinity of heavy
pumping.
Fluctuations of the water levels reflect the effects of recharge to
and discharge from the aquifer. Water levels in the lower Hillsboro
Canal area fluctuate in response to rainfall in the immediate area;
therefore water levels generally are high during the rainy season (June-
November) and low during the dry season (December-May). A rise in
water levels does not register the total replenishment to the aquifer, but
the rise is an indication of the excess of the recharge over the discharge.
Fluctuations are determined by water-level measurements in a network
of observation stations in canals and on wells; some stations are
equipped with automatic recording instruments which provide con-
tinuous, detailed records. The network is shown in Figure 3.
Water level changes in selected wells in Boca Raton and Deerfield
Beach for the period 1963-67 are shown by hydrographs on Figures 6
and 7. Monthly rainfall at Boca Raton is shown for the purpose of
correlation. The hydrographs show both the day-to-day changes and
the long-term trends. Well PB 470 (Fig. 6) is on the coastal ridge about a
half mile east of the Boca Raton municipal well field, and the water
level in the well is mildly influenced by well-field withdrawals. During
extended dry periods, such as the spring of 1964 and 1965, water levels
there approached one foot above msl. On the other hand, water levels
in the vicinity of well PB 488 (Fig. 6) about 2 miles west of the well
field are not affected by well-field withdrawals and remain high
throughout most of the year. During 1967, levels near well PB 488 were
5 feet or more higher than levels east of the well field. Also, the
magnitude of fluctuations at well PB 470 is greater than it is at well PB
488 because well PB 470 is influenced by well field pumping and is
located near the coast where ground water is being discharged into the
Intracoastal Waterway.
The hydrographs of both wells show that the response to rainfall
is rapid, indicating that infiltration to the water table takes place
quickly.
The hydrograph of well G-1260 (Fig, 7) in Deerfield Beach, 1500
feet west of the municipal well field, is similar to that of well PB-470 in
Boca Raton. Levels in the Deerfield Beach well are generally higher
than those in the Boca Raton well because the Deerfield Beach well is

Figure 6. Hydrographs of wells PB 470 and PB 488 and monthly rainfall at Boca Raton, 1963-1967.

.J
u=
_1
W
W
-I

w
z
UC
W
aJ

I

'a'

Figure 7. Hydrographs of wells G 1214 and G 1260 at Deerfield Beach and monthly rainfall at Boca
Raton, 1963-1967.

BUREAU OF GEOLOGY

Figure 8. Water-table contour map of the lower Hillsboro Canal area, May 7,
1965, during low-water conditions.

farther from an area of natural discharge (Hillsboro Canal), and because
the significantly lower pumping rate at the Deerfield Beach well field
causes less drawdown of water level.
Water-level contour maps are representations of the three-dimen-
sional configuration of the water surface for a specific time. Figure 8
shows the configuration of the water table on May 7, 1965 the
record low-water levels for the period 1963-1967. For the time this

REPORT OF INVESTIGATION NO. 55

map was made, rainfall had been deficient for about seven months, and
pumpage from the two municipal well fields was record high as shown
in figures 9 and 10. The irrigation system west of Deerfield Beach was
continuously pumping water from the Hillsboro Canal into a network
of irrigation canals (not shown in Fig. 8) thus maintaining relatively
high water levels in the west during the drought.
The configuration of the contours north of the Boca Raton well
field shows that ground water was discharging into the El Rio Canal,
but adjacent to and for some distance southward of the well field,
water from the El Rio Canal was recharging the well field by induced
infiltration. This was because heavy withdrawals of water had lowered
the water table to four feet below msl in the well field. In addition,
these withdrawals lowered the water-table mound between the well
field and the Intracoastal Waterway to one foot above msl. Water levels
north of Boca Raton remained relatively high due to very little pump-
ing and the fact that less permeable sandy materials retarded the lateral
movement of the ground water.
In the Deerfield Beach area, hydrologic conditions contrast rather
sharply with those in Boca Raton. Water from the recharge area west of
the. well field, and outseepage of water from the controlled reach of the
Hillsboro Canal maintained relatively high water levels in the vicinity of
the well field. Pumping lowered water levels in the Deerfield Beach well
field only to about one foot above msl, which was considerably higher
than the pumping levels in the Boca Raton field. However, the water-
table mound between the Deerfield Beach well field and the tidal reach
of the Hillsboro Canal was still only one foot above msl.
Figure 11 represents the configuration of the water table on
November 1, 1965 the highest water levels for the period 1963-67.
The absence of depression contour lines in the well fields indicates that
municipal pumping was not significantly affecting the configuration of
the water table at that time.
A salinity barrier was constructed in the El Rio Canal in Sept-
ember 1965 about one-half mile north of the State Road 808 bridge.
The top of the barrier is two feet above msl and is designed to limit tidal
flow in the canal and to impound fresh water upstream of the barrier
for recharge to the well field. The water level in the canal was above the
top of the salinity barrier at the time the map in figure 11 was
compiled; therefore the effect of the barrier can not be seen.
The coastal ridge is delineated by the high water-level contours
paralleling the coast. The saddle in the contour lines east of the Boca
Raton well field corresponds to a natural depression in the land surface.
The distorted contour lines in and northeast of the Deerfield Beach
well field conform to a natural drainageway.

S225- 1 O 24
o -j1
0200- I 20 I

-2 Al 21335. 1!1111 ,i 11 6 O
5 175- lei 0"

,,5 iil 51i fl!P
Hin 232321
2 M1 : 'i: 1 Hi ilf iii / |n'!!
,,, ili I it I M
is IV I \ i 1 : ii ;' l" M S= ""S

75 llla lllslf iIEli lS ^Ii iflilfl~llB I Bl l
1963 1964 1965 1966 1967

-Figure 9. Graph showing monthly municipal pumpage and rainfall at Boca Raton, 1963-67
l i t : 32 ~ 1 2 3 1 3 1 1 1 1 3
1112.222 1' N12 .22.. 212 I2. 1. 11' 1"'~ 2
h if22 1 1 12''213*22

S2.. 2 3 3...22.il : ~ 223 M2 i ll. li 2Hi222,
1132113 1232212 . .........1.I3. M.',".3 0m:11U
1963 1964 1965 1966 1967

Figure 9.' Graph showing monthly municipal pumpage and rainfall at Boca Raton, 1963-6 7

-J

i 0

-J 80 .16. ..I
Mi .... I-NM
60nni^ PiM.i i
g 1- 0 .l ill r ~iiiiiii!i' iLiii{ii{{i~ ii P

-
I !ii ii iiL![ pii F.I{ I iB i^ ., I

2 : !4 !! i I
-1963 1964 1965 1966 1967

Figure 10. Graph showing monthly municipal purnpage at Deerfield Beach and monthly rainfall at Boca
Raton, 1963-67.
VS ~ ~ .. M:ii Siii! M N. MUEMiiiii L 'iiiiii i it..." IM: W! :!:!g!:...!:!:!11!!":1:!!!: :"!: Z *
Sl 1 i?? ^ iSi A m^ ;!!;;!-J !:!!!!!!!! "U ^ !" i'i!!!!! "ii "!'!! !1- i iii~iiiiJ~i I llhi ""Si~ii S!!!!M .......!!"!! .."; I" MM:^ ,- 5
3! i M | I (:m< 1 i t: .;!! !! :::! *. j! i .....!;!!!: ...... !! .t| i :! : !: !;!ii ::: !!!!::!!!::!!ii M
^ I II 111 II 11 II IIIlll ll I 111111111 if li~ ii iil iiill........ l i ...11111111..11.111111N1111111..lll.......lllll ....llll^
i !.. i MI. it T *!! !' 1" ; ;*::;! ii !!;!! it !;: i!i: !: ; ;;;;; ;:.; ;;!; .:...:i!!!;!; :i.. :;!!::. :::!ii! l:l:i:;!.;!! !!:IS
U i l r !;' !! !!.N ;!' M ; MIN,;;." ;;;!; .; / |;;! ;; '* !!!;.l;i ;r ; i itiiiii iiiiii M U Mi.;;! .;;;;! *"i.;!;!!;';;!"''''"--1''''""'''''
A O 1: 'il il !;;;!' 'l" '"1 [ :;!:;;; i!;; :;^ i .... I. H it;;;! l! \\ \ ; i;;;;;!:;;;;! ;l!!!/ !!^ ;; i;;;;;;;;;" ;!;;'!;;;;;;;;;;; _
N .I M ifii Ii!!!/ iil ;!. !! W ''KN.* ";! i I;;! i;. ; IM," 1;!! I; 2.iiiii~ ii" iiiiiiiiiiii; '" !" ",*;; ;;;
1 l" liN60-' ^ ^ llllll \p y i"i iii~ ~ iH'i !H! i" .....ii^Hi'ii~t.~ y cc co
!!!& !'! ;;;; !;; 1 ; !!l;;;; : !!;!!!!! !:; i/ ;i!! 1; i ii! !!:!:; ;:!I!! ;; :; ::;|;; ;;"; ;;;~ l.;;!.....!i:ii::;!::'i :: !i!l!i .!!\ ....!
;;A i :ii ::t : ;!;\i;;: ;;::: ;/ i;V ii li! ;! ih i;1!; ;; :; ; : A ;;' ; ^ Y;^ i;; ;:::::;; ;11 / ;; ; !^2
U!/ i 1 / : !i .\!.. : !!:!!!f ii:::!! : :!! :;S!!!i i i INN ...... :M / :!!!:!!:;::|!i:|/ !!:!;f ::!
; ;/.* ,!.'! ;!!;; !!!/ ;:;;;\;;; .!!.!;;;!; !).*.!! '.**;! !! 11;;!; .*; !!!:!:::!!( : !!! ;; .' ; "i/ ~liiii!!81 I t ;.;.* !!!.*I.'";; ;l:;;.!;.;;;;!!';..'f!.',!!....'.;;.;..!.;.... S
2 ; W; \ I, H;'; ;/ i! i ;!;!/ ; i'i'i!; : :i; ;; it ::!:!!!!;; i -" iMUM H .. .ii .;;; .ii ;; .i;;!;:l; ^ .
~ ~ ~ ~~~~~~~~ ~ ~ ~~ ~ .. .! .i;:! .: .!\ .i !!.iy .i!; .!: .! .i;!! .!! .!!!ii!'! !!i .! .;! l[ *< J ;;: ~:!:i!1i!;: ;ii:!!::i:i:! i
'/~ ~~~~ ~ ~~~~~ ~~~~~ ;\ .\ !!!!l. .! ./)>; .! .! .; .;;; .!! .;;;;;! !!... !! ... .; .! .i!!\ ./ ./ !; .!~ i/ .!!!!!! .!!!1!:!\ .
CLii W :/ .. .. .. .. .iii! .iiiii .! ; Ii II'! .ii .iii / .; .ii' .i ."' .iii l i ./?' . ."""

196 .... 1965UM UNNU 196 16

Figure .10.. it ap s oin g ...hl ......... Iu p g ..... MM.M'Ml Beach aNdN o thyrinalat,
04on N1963-67... .....

BUREAU OF GEOLOGY

Figure 11. Water-table contour map of the lower Hillsboro Canal area, November
1, 1965, during high-water conditions.

The net increase in storage in the aquifer from May 7 to November
1, 1965, is shown by the rise in water level on Figure 12. The average
rise in water levels from the low period to the high period was about six
feet for the area contoured, and the average estimated rise in the
remainder of the area was about two feet. If an average porosity of 25
percent is assumed for the Biscayne aquifer in the area, then the rise in
levels during the period represents an increase in storage of about 10.2

REPORT OF INVESTIGATION NO. 55

Figure 12. Contour map showing rise in water levels from May 7 to November 1,
1965, in the lower Hillsboro Canal area.

billion gallons or 60 mgd. This large increase in net storage was possible
because over 60 inches of rainfall was recorded at Boca Raton during
this six-month period nearly 30 inches of it during October (see
Table 1), resulting in this substantial recharging of the aquifer.
Figures 13 and 14 reflect high and low water level conditions on
October 27, 1966 and April 12, 1967. Additional shallow observation
wells were installed in the inland area between the El Rio Canal and

BUREAU OF GEOLOGY

Figure 13. Water-table contour map of the lower Hillsboro Canal area, October 27,
1966, during high-water conditions.

Canal E-3 in the Boca Raton area and around the Deerfield Beach well
field to allow monitoring of the effects of the salinity barrier on the El
Rio Canal, the extension of the configuration of the water table west of
the El Rio Canal, and more accurate delineation of the pumping levels
in the Deerfield Beach well field.
The top of the control structure on Canal E-3 just north of L-43 is
about 16 feet above msl, and the top of the structure near the Hillsboro

REPORT OF INVESTIGATION NO. 55

Figure 14. Water-table contour map of the lower Hillsboro Canal area, April 12,
1967, during low-water conditions.

Canal is set at about 12 feet above msl. Thus when canal levels in the
northern reach of Canal E-3 exceed 16 feet msl, the excess water is
discharged southward where it is impounded until it reaches, a level
about 12 feet msl. When levels exceed 12 feet at the lower structure,
water is discharged into the uncontrolled reach of the Hillsboro Canal.
The contours in Figure 13 represent high water levels of October
27, 1966, and show that the water table west of the El Rio Canal was

BUREAU OF GEOLOGY

approximately the same level as the water table west of Deerfield
Beach. The similar water table levels are due primarily to Canal E-3
replenishing 'he aquifer west of the El Rio in the same manner as the
irrigation district west of Deerfield Beach replenishes the aquifer there.
Small drainage canals have reduced water levels in the highly urbanized
area adjacent to the west side of the El Rio Canal. The drawdown in the
Boca Raton well field is small because of the reduction in pumping
(see Fig. 9). The depression contours have extended west of the
Deerfield Beach well field, probably as a result of large withdrawals for
irrigation at the municipal golf course. The control structure on the
Hillsboro Canal was closed and was maintaining a canal level more than
seven feet above msl on the upstream side. The level in Canal E-2
upstream of the control at the Hillsboro Canal was more than 10 feet
above msl.
Figure 14 depicts the low water conditions of April 12, 1967 and
shows the effects of the pumping in the well-field extensions of the two
cities. Although withdrawals from each well field are at record high, the
pumping levels do not exceed the record low levels in either well field
(Fig. 8). Instead, the pumping level in the Boca Raton well field was
two feet higher than on May 7, 1965 (Fig. 8). This higher level is due in
part to the recharge contributed to the Boca Raton well field extension
from the controlled reach of the El Rio Canal. The position of the zero
contour line in figure 14 is more than a quarter of a mile farther from
the canal than it was in Figure 8. The additional pumping in the well
field extension in Deerfield Beach made the pumping level depression
more circular and displaced it farther inland from the tidal reach of the
Hillsboro Canal.

HYDRAULIC PROPERTIES
The hydraulic properties of the Biscayne aquifer must be known
in order to determine the ground-water potential of the area and to
plan properly for large-scale withdrawals of ground water. The princi-
pal properties of an aquifer are its capacities to transmit and store
water, which are generally expressed as transmissivity and the storage
coefficient. Transmissivity (T) is the quantity of water in gallons per
day that will flow through a vertical section of the aquifer one foot
wide and extending the full saturated height, under unit hydraulic
gradient, at the prevailing temperature of water (Theis, 1938, p. 892).
The storage coefficient (S) is defined as the volume of water released
from or taken int6 storage per itffit surface area of the-aquifer per unit
change in the component of head normal to that surface. The most
commonly used method for determining these properties is by an
aquifer test, whereby a well penetrating the aquifer is pumped and the

REPORT OF INVESTIGATION NO. 55

resultant lowering of the water table in nearby nonpumped wells is
observed to relate the lowering of the water level to distance and time.
Aquifer tests were made on wells in the Deerfield Beach well field
in August 1961 and on test wells west of Boca Raton (Fig. 3) in August
1967. In both areas the water is pumped from permeable limestone
that is overlain by thick sections of less permeable sand, silt, shells, and
marl. In the test west of Boca Raton, well PB-556 was pumped and
water levels were observed in well PB-558 200 feet to the east. Both
wells are 92 feet deep with 89 feet of casing. In Deerfield Beach,
municipal well number 9, which is 90 feet deep with 80 feet of casing
was pumped and water levels were recorded in an observation well 95
feet deep with 80 feet of casing and 100 feet to the east.
The data collected from the aquifer tests were analyzed by the
leaky-aquifer method described by Hantush (1956, p. 702) which
assumes, among other things, that the aquifer is artesian, is overlain by
a leaky confining bed, and that the pumped well is open to the full
thickness of the aquifer. None of these assumptions were completely
satisfied in either of the two tests. Although under long-term condi-
tions water levels in the Biscayne aquifer respond as if the aquifer were
a water-table aquifer, the presence of less permeable sands overlying
the highly permeable pumped zone causes the aquifer to react as a
leaky artesian system when subjected to short-term conditions such as
heavy pumping. Also, none of the wells in the lower Hillsboro Canal
area are open to the full thickness of the Biscayne aquifer.
The water level drawdowns, in feet, were plotted (on logarithmic
paper) against the quantity t/r2, where t is time, in minutes, since
pumping started, and r is the distance, in feet, between the pumping
well and the observation well. The resulting curve was matched to a
family of leaky-aquifer type curves (Cooper, 1963 p. C-48-55). By
superposition, match points were established for the best fit of the
observed data to the type curves, and the T and S were calculated from
the match points. For the test west of Boca Raton the T was 380,000
gpd/ft (gallons per day per foot) and at the test in Deerfield Beach, the
T was 400,000 gpd/ft. The value for S at the test site west of Boca
Raton was 0.04. At the Deerfield Beach test site the value for S was
0.0004.
Values obtained from specific capacity tests of wells indicate to
some extent the hydraulic properties of the aquifer and in some cases
are of more immediate benefit than T and S values. The specific
capacity is the amount of water in gpm discharged from a pumping well
per foot of drawdown in the pumping well.
Specific capacity tests were made on several wells in the north
extension of the Boca Raton well field. Well PB 550 had a drawdown of

BUREAU OF GEOLOGY

about three feet after being pumped for 8 hours at 1130 gpm or a
specific capacity of 377 gpm per foot. This figure conforms with the
data from the test wells west of Boca Raton and is similar to figures
furnished by Dr. J. I. Garcia-Bengochea (personal communication) for
wells in the Boca Raton and Deerfield Beach well fields. This indicates
that the hydraulic properties of the aquifer in both well fields and the
test area west of Boca Raton are similar.
The wells in the Boca Raton field range in depth from 115 to 120
feet with about 25 to 35 feet of open hole. The fact that the aquifer
yields about the same amount of water to wells with 10-15 feet of open
hole in the Deerfield Beach well field and 3 feet in the test area west of
Boca Raton, and 25-35 feet in the Boca Raton well field, indicates that
the aquifer is somewhat less permeable in the Boca Raton well field
area than it is in the other areas.

WATER QUALITY

Major influences on the quality of fresh ground water in the lower
Hillsboro Canal area are the quality of precipitation that reaches the
water table and the infiltration, from canals draining inland areas, of
highly colored water that is moderately mineralized. The chemical
characteristics of the ground water also depend upon composition of
the earth material through which the water moves and length of time
the water is in contact with the materials.
Ground-water samples for chemical analyses were collected
throughout the area from 26 private wells and 8 test wells. Depth of the
wells ranged from 40 to 206 feet below land surface; samples were
collected at different depths during drilling of each test well. Chemical
analyses of water samples are shown in Table 2. The concentration of
dissolved constituents is expressed as mg/1l (milligrams per liter).
Iron, the most objectionable constituent found in solution in the
ground water of this area, is derived from iron-bearing minerals within
the aquifer. In samples analyzed, iron ranged from 0.03 to 1.83 mg/l
and the average was about 0.45 mg/1. For public supply iron concentra-
tions in excess of 0.3 mg/1l are objectionable and impart a noticeable
taste if the concentration exceeds 0.5 mg/1. When used for lawn
irrigation, water containing iron in excess of 0.3 mg/1 may cause
staining on houses, sidewalks, and vegetation. The concentration of
dissolved iron in ground water in the lower Hillsboro Canal area cannot
be accurately predicted with reference to location or depth. Removal
of iron from large volumes of water can be accomplished economically
by aeration and filtration.

REPORT OF INVESTIGATION NO. 55

Hardness of water results from the solution of alkaline-earth
minerals (such as the carbonate compounds) from soil and rocks, or
from direct pollution by wastes. Calcium carbonate (limestone) is
prevalent in the Hillsboro Canal area but is only sparingly soluble in
pure water. Water that contains carbon dioxide or other acidic consti-
tuents will dissolve carbonate minerals readily; in the presence of
carbon dioxide the carbonates are converted to the more soluble
bicarbonates:
CaCO3 + CO2 + H2 --> Ca(HCO3)2
Hard water is generally believed to be harmless to man although urinary
concretions may result from the consistent drinking of hard water
(Rainwater, 1960, p. 173). Water having CaCO3 concentration in
excess of 120 mg/1 is considered hard. The CaCO3 concentration of
water sampled in the study area ranged from 126 to 368 mg/1 and
averaged about 235 mg/1. Hardness increases with depth and with
distance inland.

Acidity or alkalinity of water is measured by the hydrogen ion
concentration (pH). Water that is neither acid nor alkaline has a pH
value of 7.0. Values smaller than 7.0 denote acidity and usually
indicate a corrosive water; values greater than 7.0 denote alkalinity.
The pH values of the water analyzed ranged from 7.4 to 8.2 and
averaged about 7.7, which is slightly alkaline and would be expected to
be noncorrosive.
Color in water is expressed in terms of platinum-cobalt or Hazen
units starting at zero and increasing with added color. Visible colora-
tion of drinking water is aesthetically undesirable and concentrations
in excess of 15 units is considered by U.S. Public Health Service (1962)
to be unsuitable for use on interstate carriers. The range of concentra-
tion in the Hillsboro Canal area is from 0 to 50 units, the higher
concentrations occurring in the western areas. Color in water is usually
caused by decomposition of organic matter such as peat and muck
which are common in the western part of the area and in buried
mangrove swamps along the coast. Discoloration of water in the study
area is also due partially to iron in solution. Material that causes high
coloration in water can sometimes be recognized by its odor.
The odor of hydrogen sulfide gas (H2 S) was noted in water
samples from some wells. This gas is derived from decomposition of
organic matter, and it imparts an undesirable "sulphur water" odor
which is easily removed by aeration. Hydrogen sulfide is not usually
shown in standard complete analyses because of special techniques
involved in obtaining samples.

28 BUREAU OF GEOLOGY
TABLE 2 CHEMICALS ANALYSES OF WATER FROM SELECTED WELLS
IN THE LOWER HILLSBORO CANAL AREA (chemical constitu-
ents are expressed in milligrams per liter).

S E
Well Dateof c "
number1 Collection I 3 I- c t 3 C2 ce o

G-1228
6-1228
6-1239
6-1239
G-1272
6-1272
G-1298
6-1299
6-1300
G-1301
6-1302
G-1303
G-1304
G-1314
PB-220
PB-251
PB-472
PB-473
PB-474
PB-475
PB-476
PS-477
P"4784
PB-479
PB-480
PB-481
PB-482
PB-483
PB-484
PB-485
P8486
P8487
PB488a
PB-488
PB8489
PB-489
PB-490
PB490
P8-491
P8-4S1
PB-492
P8-492

12-0&63
01-06-64
11-19-63
11-25-63
02-01-65
02403-65
03-12-64
04-14-64
03-12-64
04-14-64
03-12-64
04-14-64
04-05-62
03-12-64
03-11-64
04-14-64
01-24-64
01-24-64
03-10-64
03-10-64
03-13-64
03-11-64
03-11-64
03-11-64
03-11-64
03-13-64
03-13-64
04-14-64
04-14-64
12-02-64
12-02-64
12-03-64
01-18-65
01-20-65
01-21-65
01-25-65
01-26-65
01-27-65
01-28-65
01-30-65
02-04-65
02-05-65

22
195
56
102
62
173
165
145
106
62
100
104
83

174
150
97
105
56

95
120
97
121
40
112
75
100
120
40
30
80
83
163
60
208
65
135
66
205
81
163

22
195
56
102
61
168

54

82
158
55
204
61
131
61
202
79
161
- -

- -
- .

- -
- -
- -

- -
--

. -
- -
--
- -
--
- -

161

G wells are in Broward County
PB wells are in Palm Beach County

22
195
56
102
62
173
165
145
106
62
100
104
83

174
150
97
105
56

95
120
97
121
40
112
75
100
120
40
30
80
83
163
60
208
65
135
66
205
81
163

79
79

73
71

74
75
77
77
77
75
78
82
77
75
76
76
78
78
76
78
77
77
77
76
76
77
78

78
73
68
69
69
69
72
70
71
68
71
70

3.2
9.8
3.3
14
6.0
8.9
11
15
13
7.3
16
19
6.9
13
7.3
17
11
12
7.4
9.1
18
5.5
8.9
13
7.1
13
5.5
14
15
5.9
6.2
6.1
20
10
10
11
7.6
16
5.5
9.6
7.8
11

0.48
.03
.07
.07

.12
1.38
.42
1.03
.82
.10
.70
.98
.78
.30
1.83
.27
.20
.25
.31
.33
.85
.32
.39
.32
.11
.18
.05
1.30
1.20
.12

.--
- -
.-
-.-
-.

50 0.2
61 1.5
30 29
96 20
64 1.1
62 1.3
138 5.7
138 5.7
123 1.6
98 3.8
135 3.6
175 23
66 .9
139 4.1
86 2.8
82 3.3
104 4.0
136 3.5
59 3.2
66 2.8
84 1.6
50 2.2
106 3.8
78 2.8
104 15
133 1.9
110 3.8
83 4.6
90 3.3
94 1.3
76 .6
100 4.5
69 1.0
64 2.1
48 2.4
125 1.9
75 3.2
220 61
82 4.7
1420 148
72 .1
78 1.3

2 Sampled while drilling
3 Dissolved solids (Sum)

2.6
8.5
15
210
7.1
8.0
22
23
17
8.4
29
298
8.7
15
12
13
22
14
15
12
13
8.3
17
12
115
16
22
21
14
10
8.3
65
6.8
5.3
7.0
21
22
700
17
4850
18
12

0.2 146
.6 176
1.0 206
7.2 310
.6 204
.7 196
1.2 293
1.0 388
1.3 384
.4 288
1.1 364
8.0 522
.5 194
1.0 422
.6 220
1.4 250
1.2 312
.6 404
1.2 178
.6 204
1.2 250
1.6 140
.5 236
1.1 240
3.9 200
1.1 396
1.4 328
1.2 264
1.0 274
1.4 260
1.3 228
3.0 194
1.0 210
.6 194
.8 140
1.6 356
.8 220
7.0 282
3.4 218
30 261
1.0 212
.8 248

REPORT OF INVESTIGATION NO. 55

Hardness
as D
CaC 03
B_ 3 cc5 L)
-, S" *-- -T 0 CM

C, ~ ~ c 0 0CC
:-- = CC -E c E
o o a C 00 .. C e "
0 0J~ r- U
5 3 CC Cu
^ ~ ~ L E iE i -l 3 i ^

4.8
3.6
15
32
.0
.0
32
31
.0
4.4
17
120
7.2
.0
33
2.4
2.4
4.0
5.6
1.6
2.4
16
68
.0
48
3.2
1.6
2.4
.0
20
10
44
.0
.0
2.0
16
8.0
136
41
974
17
.8

5.0- 0.5
16 .3
28 .1
340 .4
8.0 .2
13 .1
36 .2
36 .2
25 .3
14 .3
63 .3
518 .4
15 .0
24 .3
19 .2
18 .3
39 .3
28 .4
22 .1
18 .1
21 .3
12 .2
30 .1
18 .1
232 .1
26 .7
38 .3
26 .2
24 .2
17 .2
11 .3
141 .1
12 .1
7.0 .2
9.0 .3
32 .2
34 .1
1290 .2
25 .1
9410 .2
22 .2
19 .1

.0
.0
.4
,.1
.1
.2
16
.0
.1
.0
11
.1
1.4
1.5
4.0
.1
.0

144
180
262
872
1873
1913
494
482
386
336
492
1458
204
420
264
294
346
406
208
200
264
160
406
270
748
408
358
310
310
2783
2293
4753
2133
1853
1483
3953
2593
25703
2873
170003

126
158
194
320
164
160
368
368
326
260
352
530
168
364
226
218
276
354
160
176
216
134
280
206
320
340
290
226
238
240
192
268
176
168
130
320
200
800
224
4150

2423 180
2453 200

6
14
25
66
0
0
47
50
12
24
54
102
9
18
46
13
20
23
14
9
11
20
86
10
156
16
21
10
14
27
2
109
4
9
16
28
20
569
46
3940
6
0

232
312
429
1520
317
322
740
741
650
485
755
2700
360
690
460
435
585
659
361
370
440
290
585
415
1100
645
600
485
491
468
390
840
339
315
248
632
440
4400
478
23900
400
408

7.9
8.0
7.8
7.6
7.9
7.8
7.6
7.6
7.5
7.7
7.7
7.7
7.9
7.6
7.8
7.6
7.5
7.9
7.9
7.5
7.5
7.5
7.4
7.4
7.5
7.6
7.6
7.5
7.4
8.0
8.2
7.9
8.1
8.0
7.6
7.9
8.0
8.0
7.9
7.6
7.7
8.1

S Remarks

70 2
20 2
20 2
20 2
10 2
5 2
25 Pumping
15 Pumping
15
90 Pumped sample
20
10
25
15
5
20 Pumped sample
25
40
5
5
20
5 Pumped
25
5
5
50
40
25
15
40
50 Pumping
0 Golf Course
3 2
15 2
120 2
45 2
20 2
20 2
5 2
15 2
5 2
10 2

BUREAU OF GEOLOGY

Dissolved solids content of water represents the degree of mineral-
ization of water and is determined by either of two methods: (1)
evaporation of a measured amount of sample to dryness and weighing
the residue; and (2) the sum of amounts of individually determined
cations and anions. Cations are constituents which have positive electri-
cal charges whereas anions have negative charges.
Chemical analyses in Table 2 are expressed in mg/1 by weight of
the constituent. However, most of the chemical characteristics of water
can be better understood and more accurately represented from anal-
yses expressed in epm (equivalents per million). Equivalents per million
takes into account not only the weight of each constituent, but also the
chemical reacting properties of the constituents. Therefore an analyses
expressed in epm can be used more effectively in comparison of waters.
Chemical type of water is commonly classified according to the
concentration of seven principal chemical constituents or ions. Diffi-
culty in comparing seven constituents simultaneously can be overcome
by using geometric figures or polygons (Stiff, 1951) to represent the
type of water.
The preparation of a polygon that represents a specific chemical
analysis can be shown with the analysis of water from well PB-487, in
Table 2. The principal constituents are converted from mg/1 to epm by
using conversion factors found in most chemical handbooks. Equiva-
lents per million of each constituent is then converted to a percentage
of the total cation of anion. The results of the conversions are shown in
Table 3. Percentage values are then used to construct the polygon,
figure 15.

TABLE 3- SELECTED CONSTITUENTS IN WATER FROM WELL PB-487.
Constituent mg/I epm Percent

Calcium (Ca) 100 4.99 60
Magnesium (Mg) 4.5 .37 5
Sodium (Na) and Potassium (K) 68 2.91 35
Total cations 8.27 100
Bicarbonate (HCO3) 194 3.18 38
Sulfate (SO4) 44 .92 11
Chloride (Ci) 141 3.98 48
Fluoride (F) 0.1 .01 --
Nitrate (N03) 16 .26 3
Total anions -- 8.35 100

Dissolved solids 475 mg/1

REPORT OF INVESTIGATION NO. 55

Points show percent concentration of dissolved constituents in
water from well PB-487
Ca HCO3

Mg

Na and K

-So4

- Cl

100% 50% 50% 100%

cations anions

Equivalents per million

a. Details and scale for preparing a polygon. b. Polygon showing the general
chemical type of water in well
number PB-487.
Figure 15. An example of the preparation of a water-quality diagram using the
percentage figures in table 3.

Figure 15a shows the basic scale with seven constituents plotted
on the graph. Joining the six points by straight lines gives the polygon
shown in Figure 15b. The shape of the polygon and the relative length
of the "spears" show the water to be somewhat equally strong in both
calcium bicarbonate type and sodium chloride type. The relatively
small amounts of magnesium and sulphate are typical of shallow
ground water in southeastern Florida.
Polygons showing the general type of the water from several wells
distributed throughout the lower Hillsboro Canal area are shown in
Figure 16. The diagrams also show the depth of the sample on the left
side and the dissolved solids content on the right side. The relatively
uniform shape of the polygons show that, except for a few samples, the
water in the area to a depth of 200 feet is the same type (calcium
bicarbonate type) containing dissolved solids generally less than 400
mg/1.
Ground water in the narrow coastal ridge area is of exceptionally
good quality, but ground water of good quality in larger quantities is
available for future development farther inland.
Well G-1239, located 4 miles west of State Road 7, is not in the
immediate study area, figure 17, but should be considered in the overall
water picture. At a depth of 56 feet the dissolved solids concentration
of 226 mg/1 is normal, but the concentrations of magnesium and
calcium ions are almost equal. The increase in magnesium is caused by
the presence of dolomite, a carbonate rock and equal amounts of
calcium and magnesium. Dissolved solids increased to 872 mg/1 at a

BUREAU OF GEOLOGY

Figure 16. Map showing relative concentrations of chemical constituents in ground
water of the lower Hillsboro Canal area.
depth of 102 feet, caused by the increase in sodium chloride. Saline
water in shallow aquifers in inland areas of southern Florida may be
residual from invasions of the sea during Pleistocene time (Sherwood
and Klein, 1963).
In general the data show water in the area to be good in quality
except in areas adjacent to the coast and the uncontrolled reaches of
the Hillsboro and El Rio Canals where sea-water intrusion has occurred.

REPORT OF INVESTIGATION NO. 55

SEA-WATER INTRUSION
Sea-water intrusion in the Biscayne aquifer usually occurs from:
(1) direct intrusion of sea water into the coastal parts of the aquifer and
along uncontrolled canals; and (2) sea water that remained in the
sediments after deposition during Pleistocene interglacial, when the
ocean inundated most of south Florida. Present day intrusion of sea
water is the only source of salt-water contamination in the lower
Hillsboro Canal area. Farther west, the chloride content of the water
increases with depth, indicating that residual sea water is present in the
aquifer. However, part of the salty water comes from materials of lower
permeability that lie below the Biscayne aquifer.
Sea-water intrusion in the lower Hillsboro Canal area of the
Biscayne aquifer is governed by the relationship of ground-water levels
to mean sea level. If a specific gravity of 1.025 is assumed for seawater,
each foot of fresh water above mean sea level should indicate 40 feet of
fresh water below mean sea level as described by the Ghyben-Herzberg
principle (Brown, 1925, p. 16-17). However, in southeast Florida,
geologic and hydrologic conditions are such that the depth to salt water
is generally more than 40 feet for each foot of fresh water head, but the
relationship is sufficiently valid to the extent that intrusion would be
expected in areas where ground-water levels were persistently low.
The uncontrolled canals and waterways are connected to the
ocean, which facilitates sea-water intrusion in two ways: (1) drainage is
allowed which lowers adjacent ground-water levels and reduces fresh-
water head that normally would oppose the inland movement of sea
water; and (2) sea water is conveyed inland during dry periods, provid-
ing a source of intrusion by infiltration of the sea water into the
aquifer.
Because about 91 percent of the dissolved constituents in sea
water are chloride salts, analyses of the chloride content of water
samples can be used reliably to determine the extent of sea-water
intrusion. Figures 17 and 18 show the results of chloride traverses of
the uncontrolled reaches of the El Rio and Hillsboro Canals. Water
samples taken during these traverses were from the bottom of the canal
at each station. Although the chloride content of the canals has a wide
range, the figures illustrate that the chloride content decreases with
increasing distance inland from the sea-water source. Decreased chlo-
ride content in the upper reaches also results from increased ground-
water flow to the canals due to higher ground-water levels there than in
the area adjacent to the lower reaches of the canals.
The El Rio Canal is relatively shallow throughout most of its reach
in the vicinity of Boca Raton the depth decreases northward from

BUREAU OF GEOLOGY

Figure 17. Chloride content of water at nine points in the El Rio Canal between the
Hillsboro Canal and 13th Street.

about seven feet at the confluence with the Hillsboro Canal to about
two or three feet at the N.W. 7th Street bridge (Fig. 17). The Hillsboro
Canal conveys salt water to the El Rio Canal; therefore the chloride
content of the water at the confluence of the two canals will determine
to some degree the chloride content of the upper reaches of the El Rio
Canal. The chloride content at the confluence depends largely on the
combination of tidal stage and discharges at the Hillsboro Canal and
E-3 Canal control structures. In Figure 17, the sample taken at the-

REPORT OF INVESTIGATION NO. 55

Figure 18. Chloride content of water at nine points in the Hillsboro Canal upstream
from the Intracoastal Waterway, September 20, 1966.

confluence on August 12, 1964 was during high tide. On the same day
discharge at the structure in the Hillsboro Canal was 37 cfs (cubic feet
per second) and had been low for several days prior to the sampling.
The September 20, 1966 sample was taken on a falling tide and the

BUREAU OF GEOLOGY

discharge was 198 cfs. The June 2, 1966 sample was taken on a falling
tide also, but discharge at the control was 485 cfs.
Figure 18 shows that on September 20, 1966, during a falling tide,
the chloride content of the Hillsboro Canal from the Intracoastal
Waterway to the El Rio Canal was about the same as that of sea water.
West of the confluence of the El Rio and Hillsboro Canals discharge
through the controls of the Hillsboro and E-3 Canals into the lower
Hillsboro Canal have freshened the water in the Hillsboro Canal.
Figure 19 shows isochlors in a subsurface section extending from
the barrier islands westward through the Boca Raton well field and into
the interior flatlands along line A A' in Figure 16. The dashed lines
(isochlors) connect points in the subsurface where the chloride content
of the ground water is equal to the value of the line. Examination of
Figure 19 indicates that sea water has intruded into the Biscayne
aquifer, at depth, from both the Intracoastal Waterway and the El Rio
Canal. The continuous pumping and the resultant lowering of water
levels in the Boca Raton well field has caused the most intrusion from
the El Rio Canal; this is indicated by the more gentle slope of the
isochlors on the west side of the ridge area than on the east side of the
ridge.
Sea-water intrusion from the Intracoastal Waterway into the
Biscayne aquifer in the Boca Raton area is indicated by the high
concentrations of sodium and chloride in the polygon diagrams of wells
PB 478 and PB 489 (Fig. 16). The wells are used for irrigation of a golf
course in south Boca Raton. The Diagrams in Figure 16 show that
although well PB 487 is twice as deep as PB 480 the dissolved solids
content of its water is only about half that of PB 480. This is probably
because well PB 487 is slightly farther from the major source of sea
water, Lake Boca Raton, and that well PB 480 has been in use 24 years
longer than well PB 487 and has had more time to induce a tongue of
sea water to move toward it.
Although some sea water has entered the Biscayne aquifer in the
Boca Raton area, fresh water levels have been sufficiently high between
the well field and the El Rio Canal to prevent the intrusion of a harmful
amount. This is indicated by the low chloride content of water in well
PB 492 to a depth of 162 feet below land surface (Fig. 16 and 19).
However, several consecutive dry years might change the situation
drastically, especially if pumping levels in the well field are lowered and
the El Rio Canal is deepened.
Figure 20 shows the fluctuations of the chloride content of the
water in the El Rio Canal at the 7th Street bridge. The relatively small
volume of water in the El Rio Canal allows the chloride content to

A
501

s0

0. MILE
EXPJ.ANATION
--- -o----
ISOCHLORS, MILLIGRAMS PER LITER
It

NUMBERS INDICATE CHLORIDE CONTENT
AT POINT SAMPLED IN WELL

Figure 19. Section along line A-A' (figure 16) showing lines
content (isochlors) of ground water.

of equal chloride

-J
2,

00 \
0

VCL
ioW\

;422

h- 1.0 -I

4-r Q ,,' I- cc ,
C J c

,-- I-- ,,

18/t8 2

22 1i
19 /1

/ 50
9410l

SEA.
LEVEL

50-

I002

15o0

" 50

SEA
LEVEL ,

0
-50o 0
0

-100 ,

z
200 z

a

5m

BUREAU OF GEOLOGYi-

change rapidly. These changes are in response to: (1) tidal action; (2),
ground-water inflow from adjacent areas where ground-water levels are
sufficiently high; and (3) discharge from the Hillsboro Canal and E-3
Canal. Discharge in excess of 500 cfs from the Hillsboro Canal with
attendant discharge from the E-3 Canal and ground-water inflow along
the uncontrolled reach of the Hillsboro Canal appears to be sufficient
to maintain fresh water in the Hillsboro Canal downstream of the
mouth of the El Rio Canal.
Sea-water intrusion into the Biscayne aquifer was not detected in
the Deerfield Beach area except in wells adjacent to finger canals off
the Intracoastal Waterway. Well G-1228 is located between the Hills-
boro Canal and the Deerfield Beach well field (Fig. 3 and 16), in an area
that would be most vulnerable to the threat of sea-water intrusion.
Water levels in the vicinity of the well G-1228 are affected by con-
tinuous drainage to the uncontrolled reach of the Hillsboro Canal and
by the pumping in the well field. Therefore, if sea water were to move
inland in the aquifer, sampling of well G-1228 would give an early
indication of the movement. No indication of movement has been
observed in the analysis of samples from this well.

WATER USE AND POTENTIAL SUPPLY
The Biscayne aquifer is the source for all municipal water supplies
in the lower Hillsboro Canal area. The rapidly increasing population of
the area will require larger quantities of water from the aquifer to meet
future needs. This is substantiated by past pumpage records shown in
Figures 9 and 10 for the period 1963-67. The capacities of the water
plants of Boca Raton and Deerfield Beach were both doubled in 1965,
Boca Raton to 23 mgd and Deerfield Beach to 16 mgd, to meet the
increased demands for treated water. The predicted population figure
of more than 50,000 for the area by 1970 will require further expan-
sion of the well fields or the establishment of new well fields. This is
partly due to the fact that the per capital use of water increases with
time: the per capital use in American cities in 1920 was 115 gallons per
day; in 1960 the average use had increased to 150 gallons per day, a 30
percent rise in 40 years; in 1966, the average per capital use of water in
the lower Hillsboro Canal area was about 180 gallons per day.
The potential supply available from the Biscayne aquifer in the
lower Hillsboro Canal area depends upon the factors which balance
recharge and discharge in accordance with the following equation:
Recharge =Discharge (surface-water discharge +
ground-water discharge + evapotranspiration
+ pumpage) + change in storage. -

Figure 20. Approximate daily maximum and minimum chloride content of water in the El Rio Canal at
7th Street, Boca Raton, Florida, for the period March 1964 through August 1965.

. :
L r
0^m<

0

01'

BUREAU OF GEOLOGY

Replenishment by rainfall can be assumed as constant, evapo-
transpiration and ground-water discharge rates will not change in
magnitude, and pumping will increase with time. Water levels have not
changed significantly during the period 1964-1967 indicating that the
net aquifer storage has remained unchanged. The total potential supply
of the area therefore represents the quantity of water discharged
through the Hillsboro Canal to the ocean, plus the amounts that can be
withdrawn from aquifer storage each year without lowering water
levels to the detriment of quality. Lowering of water levels as a result of
pumping from storage will not significantly change losses by evapo-
transpiration in the area.
The most critical periods affecting the water resources of the
lower Hillsboro Canal area are the prolonged droughts when water
levels are lowest and well field pumping is heaviest. A graph of the
discharge of the Hillsboro Canal at the control structure for 1965 is
shown in Figure 21. Discharge is greatest during the rainy season, the
maximum of more than 3,000 cfs (1,900 mgd) occurring at the end of
October.
The minimum discharge during the dry season was 40 cfs (26
mgd) and the average discharge for the year was 373 cfs (240 mgd). A
significant part of the flow through the Hillsboro Canal represents
water that could be used in the future if facilities were made available
for retention in the system water that could be salvaged instead of
being lost to the ocean.
In addition, vast quantities of ground water are available from
aquifer storage, primarily in the area west of the coastal ridge where
water levels are high throughout the year. Water control practices of
the Lake Worth Drainage District have maintained water levels in the
area west of Canal E-3 near 12 feet above msl. Because a large part
moves eastward, surface water in that District can be considered a
perennial source of recharge by underseepage to the aquifer between
the El Rio Canal and Canal E-3. Also, the aquifer in the inland areas of
Deerfield Beach is replenished during the dry season by seepage from
the controlled reach of the Hillsboro Canal and by ground water inflow
from the irrigation district farther west. These sources can also be
depended upon as perennial sources of replenishment to the aquifer.
Therefore large withdrawals of ground water can be made from the
inland areas between the Sunshine State Parkway on the west and the
Seaboard Coast Line Railroad on the east without seriously lowering
water levels.
Furthermore, additional supplies are yet (1969) available from
the coastal ridge north of Boca Raton well field but as indicated, the
aquifer there decreases in permeability and well-field expansion in that

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

Figure 21. Graph showing the discharge of the Hillsboro Canal at the control near
Deerfield Beach, 1965.

30

28

26

24
z
022
0
2

o 20
W
L1

U.

1 6

12
w

10

5 8
I-

0

0
0

Pf

BUREAU OF GEOLOGY

direction might not be feasible. On the other hand, the area south of
the Deerfield Beach well field is underlain by materials of moderate to
high permeability and possible expansion in that direction might be
considered. However, withdrawals along the coastal ridge should be
limited or closely monitored because of the constant threat of sea-
water intrusion.
As the area continues to urbanize and water demands increase,
greater reliance will have to be placed on interior water resources and
possibly on importation of water from the inland water conservation
system of the Central and Southern Florida Flood Control Project.
Expansion of the data collection network will be necessary to monitor
changes in the hydrology of the inland area for adequate management
and protection of the water resources of the lower Hillsboro Canal area.
SUMMARY
The Biscayne aquifer is the only source of fresh ground water for
municipal supplies in the lower Hillsboro Canal area. The aquifer
extends from land surface to a depth of about 400 feet near the coast,
thins to the west and decreases in permeability to the north.
The primary source of recharge to the aquifer is local rainfall, of
which more than one-third reaches the water table. An additional
source of recharge is infiltration from the controlled canals of the local
irrigation and drainage districts and the Central and Southern Florida
Flood Control District, especially the controlled reach of the Hillsboro
Canal.
The ground water is of generally good chemical quality except in
areas adjacent to the coast and uncontrolled reaches of the Hillsboro
and El Rio Canals where sea-water intrusion has occurred.
Data indicate that the greatest potential source of water from the
Biscayne aquifer is in the inland areas where water levels are high
throughout the year and perennial replenishment to the aquifer is
available by infiltration from the controlled canals and underseepage
from the conservation areas. Large quantities of fresh ground water can
be withdrawn from the Biscayne aquifer in the interior area to meet
future demands without the threat of sea-water intrusion. Much of the
average flow of 240 mgd through the Hillsboro Canal control repre-
sents water that could be used in the future if facilities were made
available for retention in the system.
As urbanization expands to the west, the accompanying demands
for water and the expansion of drainage systems for development will
have a significant effect on the hydrologic system of the area. This will
require that the data collection network now in existence be expanded
to monitor future changes in the system so the water resources of the
lower Hillsboro Canal area can be adequately managed and protected.

BUREAU OF GEOLOGYi-

change rapidly. These changes are in response to: (1) tidal action; (2),
ground-water inflow from adjacent areas where ground-water levels are
sufficiently high; and (3) discharge from the Hillsboro Canal and E-3
Canal. Discharge in excess of 500 cfs from the Hillsboro Canal with
attendant discharge from the E-3 Canal and ground-water inflow along
the uncontrolled reach of the Hillsboro Canal appears to be sufficient
to maintain fresh water in the Hillsboro Canal downstream of the
mouth of the El Rio Canal.
Sea-water intrusion into the Biscayne aquifer was not detected in
the Deerfield Beach area except in wells adjacent to finger canals off
the Intracoastal Waterway. Well G-1228 is located between the Hills-
boro Canal and the Deerfield Beach well field (Fig. 3 and 16), in an area
that would be most vulnerable to the threat of sea-water intrusion.
Water levels in the vicinity of the well G-1228 are affected by con-
tinuous drainage to the uncontrolled reach of the Hillsboro Canal and
by the pumping in the well field. Therefore, if sea water were to move
inland in the aquifer, sampling of well G-1228 would give an early
indication of the movement. No indication of movement has been
observed in the analysis of samples from this well.

WATER USE AND POTENTIAL SUPPLY
The Biscayne aquifer is the source for all municipal water supplies
in the lower Hillsboro Canal area. The rapidly increasing population of
the area will require larger quantities of water from the aquifer to meet
future needs. This is substantiated by past pumpage records shown in
Figures 9 and 10 for the period 1963-67. The capacities of the water
plants of Boca Raton and Deerfield Beach were both doubled in 1965,
Boca Raton to 23 mgd and Deerfield Beach to 16 mgd, to meet the
increased demands for treated water. The predicted population figure
of more than 50,000 for the area by 1970 will require further expan-
sion of the well fields or the establishment of new well fields. This is
partly due to the fact that the per capital use of water increases with
time: the per capital use in American cities in 1920 was 115 gallons per
day; in 1960 the average use had increased to 150 gallons per day, a 30
percent rise in 40 years; in 1966, the average per capital use of water in
the lower Hillsboro Canal area was about 180 gallons per day.
The potential supply available from the Biscayne aquifer in the
lower Hillsboro Canal area depends upon the factors which balance
recharge and discharge in accordance with the following equation:
Recharge =Discharge (surface-water discharge +
ground-water discharge + evapotranspiration
+ pumpage) + change in storage. -

BUREAU OF GEOLOGY

direction might not be feasible. On the other hand, the area south of
the Deerfield Beach well field is underlain by materials of moderate to
high permeability and possible expansion in that direction might be
considered. However, withdrawals along the coastal ridge should be
limited or closely monitored because of the constant threat of sea-
water intrusion.
As the area continues to urbanize and water demands increase,
greater reliance will have to be placed on interior water resources and
possibly on importation of water from the inland water conservation
system of the Central and Southern Florida Flood Control Project.
Expansion of the data collection network will be necessary to monitor
changes in the hydrology of the inland area for adequate management
and protection of the water resources of the lower Hillsboro Canal area.
SUMMARY
The Biscayne aquifer is the only source of fresh ground water for
municipal supplies in the lower Hillsboro Canal area. The aquifer
extends from land surface to a depth of about 400 feet near the coast,
thins to the west and decreases in permeability to the north.
The primary source of recharge to the aquifer is local rainfall, of
which more than one-third reaches the water table. An additional
source of recharge is infiltration from the controlled canals of the local
irrigation and drainage districts and the Central and Southern Florida
Flood Control District, especially the controlled reach of the Hillsboro
Canal.
The ground water is of generally good chemical quality except in
areas adjacent to the coast and uncontrolled reaches of the Hillsboro
and El Rio Canals where sea-water intrusion has occurred.
Data indicate that the greatest potential source of water from the
Biscayne aquifer is in the inland areas where water levels are high
throughout the year and perennial replenishment to the aquifer is
available by infiltration from the controlled canals and underseepage
from the conservation areas. Large quantities of fresh ground water can
be withdrawn from the Biscayne aquifer in the interior area to meet
future demands without the threat of sea-water intrusion. Much of the
average flow of 240 mgd through the Hillsboro Canal control repre-
sents water that could be used in the future if facilities were made
available for retention in the system.
As urbanization expands to the west, the accompanying demands
for water and the expansion of drainage systems for development will
have a significant effect on the hydrologic system of the area. This will
require that the data collection network now in existence be expanded
to monitor future changes in the system so the water resources of the
lower Hillsboro Canal area can be adequately managed and protected.

REPORT OF INVESTIGATION NO. 55

WELL NUMBERS
In order to coordinate data from wells on a nationwide basis, the
U.S. Geological Survey has adopted a well numbering system which
locates the well by a 16 character number based on latitude and
longitude. The consecutive county well numbers used in this report are
referenced to the nationwide system, as follows:

Latitude-Longitude
No.

261914N0800607.1
261838N0801513.1
261334N0800619.1
261527N0801138.1
261659N0800859.1
261704N0801022.1
261821N0800709.1
261856N0800842.1
261840N0801633.1
261908N0800622.1
261815N0801115.1
262256N0800531.1
262206N0800842.1
262454N0801236.1
262133N0801254.1
262306N0800507.1
262332N0800448.1
262159N0800844.1
262138N0800501.1
262222N0800527.1

County
No.

G-1228
G-1239
G-1272
G-1298
G-1299
G-1300
G-1301
G-1302
G-1303
G-1304
G-1314
PB-220
PB-251
PB-472
PB-473
PB-474
PB-475
PB-476
PB-477
PB-478

County
No.

PB-479
PB-480
PB-481
PB-482
PB-483
PB-484
PB-485
PB-486
PB-487
PB-488
PB-489
PB-490
PB-491
PB-492
PB-548
PB-549
PB-550
PB-555
PB-556
PB-557
PB-558

Latitude-Longitude
No.

262218N0800739.1
262039N0800503.1
262150N0801148.1
262211N0801008.1
262519N0800714.1
262123N0800738.1
262444N0800452.1
262443N0800453.1
262054N0800501.1
262205N0800717.1
262453N0800454.1
262117N0800550.1
262114N0800540.1
262120N0800532.1
262148N0800525.1
262219N0800538.1
262311N0800534.1
262118N0800515.1
262229N0800934.1
262229N0800934.2
262229N0800935.1

BUREAU OF GEOLOGY

REFERENCES

Black, A.P., and Brown, Eugene
1951 Chemical character of Florida's waters: Fla. State Bd. of Cons., Div. Water
Survey and Research, Paper 6.
Cooke, C. W.
1945 Geology of Florida, Fla. Geol. Surv. Bull. 29.
Cooper, H. H.,Jr.
1963 Type curves for nonsteady radial flow in an infinite leaky artesian aquifer
in shortcuts and special problems in aquifer tests: See WSP 1545-C for
U.S. Geol. Survey Water-Supply Paper 1545-C, p. C48-C55.
Cooper, H. H.Jr., and Jacob, C. E.
1946 A generalized graphical method for evaluation formation constants and
summarizing well-field history, Am. Geophys. Union Trans., v. 27, no. 4,
p.526-534.
Hantush, MC.
1956 Analysis of data from pumping tests in leaky aquifers: Am. Geophys.
Union Trans. v. 37, no. 6, p. 702-714.
Meinzer, 0. E.
1923 The occurrence of water in the United States, with a discussion of
principles: U.S. Geol. Survey Water-Supply Paper 489.
Parker, G. G., Ferguson, G. E., and Love, S. K.
1955 Water resources of southeastern Florida, with special reference to the
geology and ground water of the Miami area: U.S. Geol. Survey Water-
Supply Paper 1255.
Rainwater, F. H. and Thatcher, L. L.
1960 Methods for collection and analysis of water samples: U.S. Geol. Survey
Water-Supply Paper 1454.
Schroeder, M. C., Milliken, D. L., and Love, S. K.
1954 Water resources of Palm Beach County, Fla: Fla. Geol. Survey Bull. 13.

Sherwood, C. B., and Klein, Howard
1963 Saline ground water in southern Florida: Nat. Water Well Assoc. "Ground
Water", v. 1, no. 2.
Stiff, H. A.,Jr.
1951 The interpretation of chemical water analysis by means of patterns: Jour.
of Petrol. Tech., p. 15, Oct.
Tarver, G. R.
1964 Hydrology of the Biscayne aquifer in the Pompano Beach area, Broward
County, Fla.: Fla. Geol. Survey Rept. Inv. no. 36.
Theis, C. V.
1938 The significance and nature of the cone of depression in ground-water
bodies:Econ. Geology, v. 33, no. 8, p. 889-902.
U. S. Public Health Service
1962 U.S. Public Health Service drinking water standards: Public Health Ser-
vice Pub. 956, 61 p. See Public Health Repts.

FLRD GEOLIOWC( ICA SURflViEWY~

COPYRIGHT NOTICE
[year of publication as printed] Florida Geological Survey [source text]

The Florida Geological Survey holds all rights to the source text of
this electronic resource on behalf of the State of Florida. The
Florida Geological Survey shall be considered the copyright holder
for the text of this publication.

Under the Statutes of the State of Florida (FS 257.05; 257.105, and
377.075), the Florida Geologic Survey (Tallahassee, FL), publisher of
the Florida Geologic Survey, as a division of state government,
makes its documents public (i.e., published) and extends to the
state's official agencies and libraries, including the University of
Florida's Smathers Libraries, rights of reproduction.

The Florida Geological Survey has made its publications available to
the University of Florida, on behalf of the State University System of
Florida, for the purpose of digitization and Internet distribution.

The Florida Geological Survey reserves all rights to its publications.
All uses, excluding those made under "fair use" provisions of U.S.
copyright legislation (U.S. Code, Title 17, Section 107), are
restricted. Contact the Florida Geological Survey for additional
information and permissions.

MILLISECOND	CLASS.METHOD	MESSAGE
0	sobekcm_page_globals.constructor
0	sobekcm_page_globals.constructor	Application State validated or built
0	sobekcm_database.verify_item_lookup_object
0	sobekcm_page_globals.constructor	Navigation Object created from URI query string
0	sobekcm_database.verify_item_lookup_object
0	sobekcm_page_globals.display_item	Retrieving item or group information
0	sobekcm_page_globals.get_entire_collection_hierarchy	Retrieving hierarchy information
0	sobekcm_assistant.get_entire_collection_hierarchy
0	cached_data_manager.retrieve_item_aggregation
0	cached_data_manager.retrieve_item_aggregation	Found item aggregation on local cache
0	item_aggregation_builder.get_item_aggregation	Found 'all' item aggregation in cache
0	system.web.ui.page.page_load (ufdc.page_load)
0	sobekcm_page_globals.constructor.on_page_load
0	html_echo_mainwriter.add_style_references	Adding style references to HTML
0	html_echo_mainwriter.add_text_to_page	Reading the text from the file and echoing back to the output stream
57	html_echo_mainwriter.add_text_to_page	Finished reading and writing the file

	Title Page
	Department of Natural Resource...
	Transmittal letter
	Contents
	Abstract and introduction
	General features
	Hydrologic setting
	Ground water
	Water use and potential supply
	Summary
	Well numbers
	References
	Copyright