Water resource studies ( FGS: Report of investigations 7 )

STATE OF FLORIDA
STATE BOARD OF CONSERVATION
George Vathis, Supervisor

FLORIDA GEOLOGICAL

SURVEY

Herman Gunter, Director

REPORT OF INVESTIGATIONS
No. 7

WATER RESOURCE STUDIES

TALLAHASSEE, FLORIDA
1951

PRINTED BY
THE E. O .PAINTER PRINTING CO,
DE LAND, FLORIDA

AGURI.
CULTURAl
LIBRARY

FLORIDA STATE BOARD OF CONSERVATION

FULLER WARREN
Governor

R. A. GRAY
Secretary of State

CLARENCE M. GAY
Comptroller

THOMAS D. BAILEY
Superintendent Public Instruction

RICHARD ERVIN
Attorney General

J. EDWIN LARSON
Treasurer

NATHAN MAYO
Commissioner of Agriculture

I I

CONTENTS

Part I Potential Yield of Ground Water of the Fair Point
Peninsula, Santa Rosa County, Florida ---------- 1

Part II Geologic and Hydrologic Features of an Artesian
Submarine Spring East of Florida ------.------------------- 57

Part III Cessation of Flow of Kissengen Spring in Polk County,
Florida ---......-------------..--..-.... --. .--------------...._ 73

Part I

Potential Yield of Ground Water on

the Fair Point Peninsula

SSANTA ROSA COUNTY, FLORIDA

By
Ralph C. Heath and William E. Clark
SU. S. Geological Survey

Prepared by the
UNITED STATES GEOLOGICAL SURVEY

In cooperation with the
FLORIDA GEOLOGICAL SURVEY
and the
SANTA ROSA ISLAND AUTHORITY

JUNE 1951

CONTENTS
Page
Abstract ----...-..---...--------..... ---..... ----.. .....----..... --..--- --------.........- ......-.-... .-- 5
Introduction -..-----------.......---- _..--.--... ._ _--.---.---....------------.. -- ---.-- 6
Purpose and scope of investigation ...---...-... -------.-.. -----. 6
Acknowledgments ..----..........----------------.....-.-------- 7
Previous investigations ..------.---------.-----.------ 7
Geography .---. -..----.........----......-- --.----.. --..----.-------- 7
Location ...----.......---...-.. -. --------------..-.-..---- --.-.. .-- --- 7
Topography and drainage __. .-------------.-----------.....-.-.---. 8
Climate ..--...--.. ----....--.--.....--..--..--.._----------------------..--- ------- 10
Population -.......---........-.....---.--.-_---.--------.----------- 10
Geology .---..--...........-- ......----..------..-.------....-- ---------... ------- 10
Test-well drilling ..--....--..-..----.----.------- .---..----- ----.--. 10
Deposits of Miocene age .......-----------..--------.--...-..--- --- 13
Deposits of Pliocene(?) age ---....--.----- ....---.--.-------- ... -------- 13
Deposits of Pleistocene and Recent age ---- --..-.--------------- 15
Ground water --.--. ---. -------------..... -..........----.---.-------- 16
Upper aquifer ..----...--.---...--.-.---.- ----------------...-..... -...---. 17
Lower aquifer .-----..--....----..........-..-....-.....------------------------ 17
Water-level observations .... ...----.-....---.---. .---..------- ---- 18
Use of ground water ...----- ..... -------- .-------------.._.... ... 20
Quality of water -----........--. ...----------.-----.. ---.--- ---- 22
Quantitative studies .-......---...---..--.--....------....--..-.... .------.-- --- 24
Limitations of yield --.---.--------..---......---------- 24
Relation between ground water and salt water .....----- ---- 26
Lowering of the water table in response to pumping ------28
Recharge and discharge under natural conditions ..---------- 29
Recharge and discharge in relation to pumping ---------- 30
Boundaries of the aquifer ..--.-....----..--..._.-..._--_---_ .....--.-...----------. 30
Pumping test -......-----.. --.........--- --.-... ------------------...........-...-.....--.-.-- 31
The initial water table ----------_.. --. ----_---_-----_ 34
Method of computing drawdowns __- _..----.--_..-..- -----.----- 37
Effects of pumping in relation to salt-water encroachment -- -38
One pumped well- ......-- --.......--..._---.....---.-------.........--..- 40
Three pumped wells ------------...-.- ---.--.-------... ..-.....---.-. 40
Indefinite number of pumped wells ...-------------....--------..- 41
Spacing of wells --------------- ----.....------------ 42
Safe yield .........---. --- .......-..--.....-.-.-.-- ------.-----.-- 42
Conclusions .....--------------------------..---.---------.. .---- 43
Recommendations -----------------.... -----....- ---..-------..-.--..-......-. 43
Bibliography ...---....---... --.---- ---......-._ .-------.-.......--------...- ..---- .....-.---.-- 44

ILLUSTRATIONS
Figure Page
1. Outline map of Florida showing location of area investigated 8
2. Annual rainfall at Pensacola, Fla. ....-..-...-... ...---......-----.---------- 9
3. Map of Fair Point Peninsula, Santa Rosa County, Fla., show-
ing location of wells- .---.--.......---- ......------.--------.11
4. Geologic section of western end of Fair Point Peninsula .---.. 12
5. Section showing character of undifferentiated Pleistocene and
Recent deposits across the western end of Fair Point Peninsula 14
6. Water levels in wells on Fair Point Peninsula and at Pensacola,
and daily rainfall at Pensacola--- .-..-...............---..--.------ ...----- 19
7. Profiles of water table across the western end .of Fair Point
Peninsula ... .....-...-..-- ...- .....----....... 21
8. Profile of water table showing drawdown during pumping test
October 5 and 6, 1950 -.~... ....- --------.--------__ ..-._ ....... ..------ 31
9. Extrapolated decline of water level in well T7 during a hypo-
thetical prolonged period of no rainfall --....---.....--.......- --... --. 36
10. Profiles showing ultimate lowering of water table due to pump-
ing on an idealized peninsula bounded by straight shore lines
of infinite length .. ..... ........ ..------ ---..................... ... 39

TABLES
Table Page
1. Analyses of water from wells on the western end of Fair Point
Peninsula .............. --- ---. -----... -- .-. .......------....-..--- 25
2. Chloride content of water samples from well T22 collected dur-
ing construction of the well- .-------- _......--------...--.---- 26
3. Records of wells on the western end of Fair Point Peninsula,
Santa Rosa County, Fla.
Part A. Test wells ...-------........... -- .... -- ---------.. -----..... ----.. 46
Part B. Supply wells ............. ........................... 49

POTENTIAL YIELD OF GROUND WATER ON THE
FAIR POINT PENINSULA,
SANTA ROSA COUNTY, FLORIDA
By
Ralph C. Heath and William E. Clark
ABSTRACT
Test wells drilled on the western end of Fair Point Peninsula
show that the area is underlain by two relatively shallow aquifers.
The upper aquifer extends from the land surface to a depth of 60
to 85 feet and is composed of sands of Pleistocene and Recent age.
The lower aquifer begins at a depth of 80 to 110 feet and extends
to a depth of 120 to 160 feet and is composed of coarse to fine
slightly argillaceous sand of Pliocene(?) age. The two aquifers
are separated by a layer of relatively impervious clay, ranging
from 10 to 20 feet in thickness, which retards the movement of
water from one aquifer to the other. An inventory of the supply
wells in the area, made in the spring of 1950, showed that 79 of
them drew water from the upper aquifer and only one drew water
from the lower aquifer. The wells yield only small supplies of
water for homes and tourist courts. Their aggregate draft is
probably less than 50,000 gallons a day, most of which is returned
to the ground.
Samples of water from four wells that draw from the upper
aquifer contained less than 39 parts per million of dissolved solids,
whereas a sample from a well that draws from the lower aquifer
had 247 parts per million. The chloride content of water in the
upper aquifer is generally less than 25 parts per million, but was
as much as 83 parts per million in one well and 135 parts per mil-
lion in another. The water in the lower aquifer is fresh throughout
a large part of the peninsula but is quite salty in some places along
the shore.
'The upper aquifer is the principal source of water for existing
supplies and is the most favorable source for a public supply. The
results of a pumping test indicate that it has a coefficient of trans-
missibility of about 34,000 gallons per day per foot, and a coeffi-
cient of storage of about 0.23 or more. Computations based on the
results of the pumping indicate that the upper aquifer probably will
yield, without danger of salt-water encroachment, as much as 100,-
000 gallons per day to one well near the center of the peninsula,

FLORIDA GEOLOGICAL SURVEY

and more to a system of wells spaced along the center line of the pe-
ninsula. Where the lower aquifer contains fresh water, it may be a
suitable source for domestic supplies of only a few hundred gallons
a day. However, a relatively large draft from the lower aquifer, as
would be required for a public supply, might produce salt-water en-
croachment.

INTRODUCTION
PURPOSE AND SCOPE OF INVESTIGATION
Early in 1950 the Santa Rosa Island Authority, an agency of
Escambia County, began examining the possibility of developing
the ground water on the Fair Point Peninsula to supply a resort
on Santa Rosa Island. The tentative plans for the resort called
for an initial supply of 100,000 gallons per day and future supplies
of as much as 1,000,000 gallons per day. As it appeared possible
that the ground-water resources of the peninsula might not be
adequate, the Authority, through R. G. Patterson, who was then
its Chief Engineer, requested the assistance of the United States
Geological Survey and the Florida Geological Survey in evaluating
the potential yield of the ground-water resources in the vicinity
of Gulf Breeze, on Fair Point Peninsula.
Because of the proximity of sea water to the proposed develop-
ment, there was danger that the withdrawal of the required
quantity of water might cause an encroachment' of salt water. The
ground-water resources constitute the only source of water supply
on the peninsula, and its ruin by salt-water encroachment would
represent a loss to the local residents, to the State and thus to
the Nation. Therefore, the U. S. Geological Survey entered into
cooperation with the Santa Rosa Island Authority for an investi-
gation of the ground-water resources, as a part of the State-wide
cooperative program of the U. S. Geological Survey and the Florida
Geological Survey.
The field work of the investigation and supervision of the test-
well drilling was done by Ralph C. Heath during the period from
April to November 1950. The computations relating to the quanti-
tative studies were made by William E. Clark. The investigation
and the preparation of this report were under the immediate su-
pervision of H. H. Cooper, Jr., District Engineer of the U. S. Geo-
logical Survey, with the advice and approval of Dr. Herman Gunter,
Director of the Florida Geological Survey.

REPORT OF INVESTIGATIONS NO. 7- I

ACKNOWLEDGMENTS
The test wells were drilled by the Duval Lumber Co. of Pensa-
cola, Fla.; M. T. Long, of the Layne Central Co. of Memphis, Tenn.,
supplied well cuttings from a deep test well (T21) drilled by the
Layne Co. for the Santa Rosa Island Authority. Barney McClure,
C. H. Parker, and Clive R. Jenkins gave permission to drill the test
wells on their land. Mr. McClure also made water-level measure-
ments and rendered other valuable services during the investi-
gation.

O. J. Semmes, Jr., City Manager of Pensacola, Stanley Sweeney,
Superintendent of the Pensacola Water Department, and the well
owners of the peninsula were among others who gave helpful as-
sistance during the investigation. The office and other facilities of
the Santa Rosa Island Authority were placed at the disposal of
the authors.

PREVIOUS INVESTIGATIONS
A short investigation of the ground-water resources of Es-
cambia and Santa Rosa Counties was made by the U. S. Geological
Survey and the Florida Geological Survey in 1940 (Jacob and
others). Information on the quality of ground water and the con-
ditions governing the occurrence of ground water, especially those
pertaining to salt-water encroachment, was obtained during that
investigation. As a part of that investigation, a program to observe
the fluctuation of the water levels in selected wells in Escambia
County was begun in 1940 and has been continued to the present
time. General information on the occurrence of ground water in
Escambia and Santa Rosa Counties is given in two reports, one
published by the Florida Geological Survey in 1912 (Sellards and
Gunter, pp. 91-106), and the other published by the U. S. Geologi-
cal Survey in 1913 (Matson and Sanford, pp. 301, 401). The geo-
logic formations that crop out in Santa Rosa County have been
described by Cooke (1945, pp. 236, 276, 281, 285, 291, 296, 310).

GEOGRAPHY
LOCATION
The area covered by this report comprises the western end of
the peninsula that lies between Pensacola Bay and Santa Rosa
Sound, in the southern part of Santa Rosa County (fig. 1). In the
absence of an established name, this peninsula is referred to in
this report as the Fair Point Peninsula. The name refers to the

FLORIDA GEOLOGICAL SURVEY

peninsula which extends from Fair Point eastward for a distance
of approximately 20 miles. In the vicinity of Gulf Breeze the
peninsula is bordered by Pensacola Bay on the north and Santa
Rosa Sound on the south. Near the eastern end, south of Holley,
the peninsula is bordered on the north by East Bay and on the
south by Santa Rosa Sound.
TOPOGRAPHY AND DRAINAGE
The peninsula is composed of low, level areas that are broken
in places by old sand dunes. The southern coast is bordered by a
swampy area from Deer Point to the Pensacola Beach Bridge.
East of the bridge, for approximately 1 mile, it is bordered by a
relatively steep cliff that ranges from 10 feet to 20 feet in height.
North of the swampy area and sea cliff is a line of sand dunes which
extends from Fair Point to the vicinity of Oriole Beach. A cliff
similar to the one on the southern coast borders the northern
shore line, except where interrupted by swamps.

Figure 1. Outline map of Florida showing location of area investigated.

90

80-

70-

so60-

50-

40-

30-

20-

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CD cm UD

Figure 2. Annual rainfall at Pensacola, Florida. (From records of the United States Department of
Commerce, Weather Bureau.)

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FLORIDA GEOLOGICAL SURVEY

There is no surface runoff from most of the area because the
sands that underlie the surface readily absorb the rainfall. In the
swampy areas that are underlain by relatively impermeable beds
of peat, a small amount of surface runoff does occur during times
of heavy rainfall.
CLIMATE
The climate of the peninsula is humid subtropical. Records of
the U. S. Weather Bureau show the average rainfall at Pensacola
to be 59.62 inches for the 70-year period ending 1949. The greatest
annual rainfall during that period was the 90.32 inches recorded
in 1947 (fig. 2); the least, 35.58 inches recorded in 1891. Although
the rainfall is generally well distributed throughout the year, June,
July, and August are months of heaviest rainfall.
The mean temperature at Pensacola is 67.8'F. The mean temp-
erature for August, the warmest month, is 81.0*F.; that for Janu-
ary, the coldest month, is 53.10F. The mean daily maximum temp-
erature for August is 87.2*F. and the mean daily minimum for
January is 45.9F.
POPULATION
A census, made in the summer of 1950 as a part of the investi-
gation, showed that 154 year-round residents and 600 summer
residents used ground water as a source of supply on the western
end of the peninsula. No previous census figures for the western
end of the peninsula are available; however, the number of new
homes indicate the population has increased substantially in recent
years. The increase is further indicated by the fact that, of the
80 supply wells inventoried in the spring of 1950, only 15 were
drilled prior to 1940.
GEOLOGY
TEST-WELL DRILLING
As a part of the investigation, 20 test wells were drilled along
a line beginning several hundred feet west of Grassy Point and
extending in a northerly direction across the peninsula .(fig. 3).
Of these, one (T8) was drilled to a depth of 119 feet and 19 (T1
to T7 and T9 to T20) were drilled to depths ranging from 26 to
42 feet. Only two wells on the peninsula are deeper than well
T8: well T21, which was drilled to 809 feet by the Layne Central
Co. for the Santa Rosa Island Authority, and well T22, which was
drilled to 400 feet by T. E. Harrison for the U. S. Geological Sur-
vey in 1940.

10

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Figure 3. Map of Fair Point Peninsula, Santa Rosa County, Florida, showing locations of wells.

S.---- Pleistocene and Recent

Pliocene (?)

- --

Upper

Miocene

-500-

-600-

-800J
Figure 4.

EXPLANATION

Course to medium send

Fine send

Shells

Cloy

105

00 0 1000 2000
HORIZONTAL SCALE IN FEE.
HORIZONTAL SCALE IN FEET.

Geologic section of the western end of Fair Point Peninsula, Santa Rosa County, Florida.

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REPORT OF INVESTIGATIONS No. 7 I

The deposits penetrated by the test wells are shown in figures
4 and 5. Figure 4, a geologic cross section from well T22, near
Fair Point, to well T21, about half a mile southeast of the Gulf
Breeze Post Office, shows that the oldest deposits penetrated by
wells on the peninsula are late Miocene in age. The character of
the Pleistocene and Recent deposits is shown in figure 5, a geologic
cross section from well T1 to well T20.
DEPOSITS OF MIOCENE AGE
Wells T21 and T22 penetrated deposits of late Miocene age,
consisting of interbedded highly micaceous sands and clays. Those
upper Miocene deposits penetrated in well T22 were referred to
the Choctawhatchee formation by Stubbs in 1940 (Jacob and
others, p. 12). In 1945 Cooke (p. 168) classified the two upper
zones of the Choctawhatchee formation, the Ecphora and Can-
cellaria zones, as the Duplin marl and transferred the two lower
zones, the Area and Yoldia zones, to the Shoal River formation.
The top of the Miocene deposits in well T22, as recognized by
Stubbs and the present authors, is 270 feet below the surface. In
a preliminary study of the rock samples collected from well T21
the top of the Miocene has been placed tentatively at 295 feet
below the surface.
The Miocene deposits that have been penetrated by the test
wells are fine, compact, and of low .permeability, and hence it is
doubtful that a producing well could be developed in them. The
fine texture of the material indicates an offshore deposit, and it
is therefore assumed that the upper Miocene material is essentially
the same throughout the western end of the: peninsula.
DEPOSITS OF PLIOCENE(?) AGE
Deposits that may be of Pliocene age were penetrated between
75 and 275 feet below the surface in well T22 and between 105 and
295 feet below the surface in well T21. These deposits are com-
posed of interbedded sands and sandy clays that contain a few thin
layers of hard clay. Some beds of the sandy clay and clay are fos-
siliferous and a detailed study of the lithology and the fossil con-
tent must be made before their geologic age can be definitely
established.
The upper 45 to 50 feet of the material referred questionably
to the Pliocene consists of coarse to fine quartz sand which is
water bearing and permeable enough to yield appreciable quantities
of water to wells. This sand composes the lower of two shallow

14 FLORIDA GEOLOGICAL SURVEY

aquifers and is overlain by 10 to 20 feet of relatively impermeable

Pleistocene clay, which confines the water in the aquifer. For

reasons that will be given later, the danger of salt-water encroach-

ment in this aquifer is especially critical.

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REPORT OF INVESTIGATIONS NO. 7- I

The deposits in the lower part of the Pliocene(?) section con-
sist of argillaceous fine sands and sandy clays that have such
low permeability as to be of little or no value as a potential source
of supply.
DEPOSITS OF PLEISTOCENE AND RECENT AGE
Undifferentiated Pleistocene and Recent deposits underlie all
the Fair Point Peninsula. These deposits range in thickness from
75 feet in well T22, near Fair Point, to 105 feet in wells T8 and
T21, near Gulf Breeze.
The lower 10 to 20 feet of the Pleistocene and Recent deposits
consists of a very dense, compact fossiliferous blue clay that con-
tains fragments of decayed wood and other carbonaceous matter.
This clay probably underlies most of the peninsula and may ex-
tend beneath Pensacola Bay into southern Escambia County,
where drillers have reported penetrating a similar clay at about
the same altitude in some of the wells along the bay shore (Jacob
and others, p. 5). The clay is overlain by about 22 feet of fine
argillaceous sand, which contains abundant mollusk shells and
some foraminifers. This sand grades upward into a coarse to
fine peaty sand, which is approximately 25 feet thick in well T8
(fig. 5). Overlying the peaty sand are deposits consisting of
coarse to fine wind-blown sand which, below the water table, are
composed mainly of clear quartz grains and, above the water
table, of iron-stained quartz grains. Slightly sandy peat under-
lies the swampy areas along both coasts of the peninsula.
The sands of Pleistocene and Recent age are the principal source
of water for the peninsula and compose, the upper of the two
shallow aquifers. The layer of clay at the base of the Pleistocene
and Recent section serves as a relatively impermeable barrier be-
tween the two aquifers, retarding the movement of water from
one to the other. Although the layer of clay probably underlies
most of the peninsula and its vicinity, it may be very thin or
absent in some small areas. It is worthy of note in this connection
that a lens of sand 7 feet thick, and entirely included within the
clay, was penetrated in well T8 (fig. 5) but not in well T21, 60 feet
away (fig. 4). Obviously, if such a lens of sand were to extend
from the top to the bottom of the clay, or nearly so, the confining
character of the clay would be interrupted.
Wells that would yield several hundred gallons per minute for
short periods of time could doubtless be developed within the

15

FLORIDA GEOLOGICAL SURVEY

Pleistocene and Recent sand deposits. However, prolonged with-
drawal from individual wells at such rates would ultimately pro-
duce salt-water encroachment.

GROUND WATER
Ground water is the subsurface water that is in the zone of
saturation-the zone in which all pore spaces are completely filled
with water. The zone of saturation is the reservoir from which
all water from springs and wells is derived. The term "aquifer"
is defined as a rock layer or group of layers that will transmit
water in a usable quantity to wells or springs.

Only a part of the rainfall reaches the zone of saturation. The
remainder runs off on the land surface to open bodies of water
such as rivers, lakes, and bays, or is returned to the atmosphere
by evaporation or by the transpiration of plants. The amount of
rainfall that becomes ground water depends upon many factors.
These include the rate at which precipitation occurs, the slope of
the land on which the rain falls, the amount and type of vegetal
cover, and the character of the surface material through which
the water must percolate to reach the zone of saturation.

After the water reaches the zone of saturation it begins to
move more or less horizontally under the influence of gravity
toward a point of discharge, such as a spring. The ground water
thus moving may occur under either artesian conditions or water-
table nonartesian conditions. Where its surface is free to rise and
fall in a permeable formation, it is said to be under "water-table"
conditions. Where the water completely fills a permeable bed that is
overlain by a relatively impermeable confining bed, its surface
is not free to rise and fall. Water thus confined is said to be under
"artesian" conditions. Strictly, the term "artesian" is applied to
any ground water that is under sufficient pressure to rise above
the bottom of the confining bed, although not necessarily above
the land surface.

The source of all fresh ground water on the western end of
the Fair Point Peninsula, at least within the depths penetrated by
test wells, is the rain that falls on the peninsula. The fresh water
occurs in two relatively shallow aquifers. The upper one extends
from the surface to a depth of 60 to 85 feet. The lower one begins
at a depth of 80 to 110 feet and extends to a depth of 120 to
160 feet. The two aquifers are separated by a bed of clay that

REPORT OF INVESTIGATIONS NO. 7 I

ranges in thickness from 10 to 20 feet. The material penetrated
below the lower aquifer is composed of relatively impermeable
interbedded clays and fine sandy clays.
UPPER AQUIFER
The water in the upper aquifer, of Recent and Pleistocene age,
occurs under water-table conditions. Thus, the water level in a
well that penetrates this aquifer represents the top of the zone
of saturation, which is the water table. The water table is for-
ever rising in response to recharge from local rainfall or falling
in response to continuing loss of water from the zone of saturation,
through transpiration and evaporation, and through discharge of
water into the sea. Of each rain, the percentage that reaches the
water table is almost entirely dependent upon the amount of water
lost through the processes of evaporation and transpiration, there
being little or no surface runoff. Much of the water lost through
these two processes comes from water that is suspended in the
zone above the water table. As the water lost by evaporation and
transpiration from the zone of suspension must be replaced during
each rain, it can be seen that the percentage of the rainfall that
reaches the water table increases with the intensity and frequency
of the rains-at least up to the point where the sands are com-
pletely saturated so that nearly all the rainwater would have to
run off.
Water is lost from the zone of saturation through several pro-
cesses. A substantial amount is doubtless lost through the trans-
piration of plants whose roots reach the water table. Where the
water table is near the land surface, some is lost through evapora-
tion. Some water is lost from the upper aquifer also by slow
percolation into the lower aquifer through the layer of clay that
separates the two aquifers. However, the greatest loss of water
from the zone of saturation is that water which flows into the
bodies of salt water along the margins of the peninsula.
LOWER AQUIFER
The lower aquifer consists of the interbedded coarse to fine
slightly clayey sands that compose the upper 45 to 50 feet of
the Pliocene(?) deposits. It is overlain by the dense clay that
separates it from the upper aquifer, and is underlain by more than
600 feet of interbedded clay and fine sandy clay.
Water in the lower aquifer is confined under pressure by the
clay and is therefore artesian. Thus, the water level in a well

17

FLORIDA GEOLOGICAL SURVEY

penetrating this aquifer does not represent the top of the zone
of saturation but represents, instead, the height of the column
of water that will be supported by the hydrostatic pressure in the
aquifer.
The lower aquifer is recharged by the percolation of water from
the upper aquifer through the overlying clay. As the clay has
a very low permeability, the rate of percolation through it is
relatively slow, but the aggregate percolation over the area of the
peninsula as a whole is probably considerable. The percolation
results from the difference between the hydrostatic heads in the
two aquifers, and is proportional to that difference. As can be
seen in figure 6, by comparing the graphs for wells T7 and T8 the
artesian head in the lower aquifer generally stands slightly less
than a foot below the water table and rises and falls with the water
table.
As the hydrostatic head in the lower aquifer is small, and
as the aquifer is situated relatively deep, the potentialities of salt-
water encroachment are especially critical. However, individual
domestic supplies can be obtained from the lower aquifer at some
places so long as the aggregate consumption of such supplies does
not become excessive.
WATER-LEVEL OBSERVATIONS
Periodic observations of the rise and fall of the water levels
or artesian pressures in wells constitute an important phase of
quantitative investigations of ground water. In coastal areas,
where there is danger of salt-water encroachment, such observa-
tions are especially needed, because the extent to which the en-
croachment may occur is controlled by the height of the water
table or by the artesian head. Some of the changes in water level,
such as those that result from cyclic changes in rainfall, may ex-
tend over periods of several years, and hence a long record of
these changes is needed for an adequate interpretation of their
significance. Where an adequate record is not available, the inter-
pretations must necessarily be based largely on judgment.
Measurements of water levels in the test wells were made in-
termittently during the drilling and have been made weekly since.
Many of these measurements are shown graphically in figure 7,
which represents profiles of the water table through the line of
test wells at intervals beginning September 13, 1950. As indicated
by these profiles, the water table is generally highest at well T7,

REPORT OF INVESTIGATIONS No. 7 -I 19

which is several hundred feet north of the center of the peninsula.
The maximum observed water level in well T7 was 5.30 feet above

S0O
ej

1 0
L P-

7-
40

-, -

L 4-
S I / o I -
"

40
o .- / F1

+o+---,- -i5o ---,/ g -- =

,o ) "
-C7L/ n- -" I "O
.1 JL "
___ _______d __
-------- --o__ j

S3HONI

13A31US NNV3PI 3A09V 1334

FLORIDA GEOLOGICAL SURVEY

mean sea level on September 7 (fig. 6), after the hurricane that
passed through the area during the last two (lays of August.
Shortly after September 7 the water table began to decline and
continued until early in March 1951, when a water level of 2.61
feet above sea level was observed in well T7.
The manner in which the water table responds to local rain-
fall is indicated by the hydrograph of well T7 in figure 6. In re-
sponse to the heavy rainfall during the period of August 29 to
September 2, when 11.32 inches was recorded by the U. S. Weather
Bureau at Pensacola, the water level in that well rose approximately
1.5 feet between August 29 and September 4. It then continued
to rise very slowly through September 7, by which date only 0.04
inch of additional rain had fallen at Pensacola.
Also represented in figure 7 are measurements of the water
level in well T8, which is screened in the lower aquifer. The
water level in this well generally stands slightly less than a foot
below the water table.

The water table in the upper aquifer and the hydrostatic head
in the lower aquifer both fluctuate with the tide in Santa Rosa
Sound and Pensacola Bay. The response of the water table in the
upper aquifer to the tide is pronounced in wells T1 and T20, but
is probably not appreciable at a distance of more than a few hun-
dred feet from the shore. On the other hand, the hydrostatic
head in the lower aquifer fluctuates with the tide throughout the
width of the peninsula, as revealed through a comparison of the
water level in well T8 with measurements of the tide level in
Santa Rosa Sound.

USE OF GROUND WATER
An inventory of the existing wells on the western end of the
peninsula was made at the beginning of the investigation. There
were 80 supply wells in the area, 79 of which drew water from
the upper aquifer and only one of which (well 66) drew from the
lower aquifer.
As shown in table 3, part B, the depths of the wells that draw
from the upper aquifer range from 18 to 55 feet, but most are
between 25 and 40 feet. The wells range in diameter from 1-1/4 to
4 inches and are equipped with screens that range in length from
2 to 12 feet. Well 66, which penetrates the lower aquifer, is 4

20

0
0

z
ri2

0

z
w

i-t
sn
5

5;

0 500 1,000 1o500 2,000 2,500 3,000 3,500 4,000' 4,500 5,000 5,500 Feet
Figure 7. Profiles of water table across the western end of Fair Point Peninsula, Santa Rosa County, Florida.

FLORIDA GEOLOGICAL SURVEY

inches in diameter and 120 feet deep, and is equipped with 20 feet
of screen.
In studying the safe yield of an aquifer it is desirable to have
information on the current rate of withdrawal of the water. In
order to obtain such information a census was taken of the number
of persons residing in the area, and of the number and size of
gardens and lawns irrigated. The total consumption of water for
household purposes was then estimated by multiplying the number
of inhabitants by a factor of 50, which represents roughly the
average daily per-capita consumption in gallons. The results in-
dicate that the household consumption is approximately 40,000
gallons per day in the summer and 10,000 gallons per day in the
winter. The average daily consumption over a period of a year
is probably about 25,000 gallons.
An estimate of the water used for irrigating lawns and gar-
dens was derived from a study of the records of the Pensacola
Water Department. The records of consumption at nine homes
having lawns that were irrigated were selected for the study. The
figures indicate that about 1,280,000 gallons a year per acre or
an average of about 3,500 gallons a day per acre is used for lawn
irrigation. According to the census made by the writers there are
about 4.5 acres of lawns and gardens in the area. Thus, it is es-
timated that consumption of water for irrigation is in the order of
5,750,000 gallons a year, or an average of 21,000 gallons a day.
The estimated consumption of water for household uses and
for lawn and garden irrigation amounts to a total of 46,000 gal-
lons a day. Of the quantity consumed in the homes practically all
is returned to the ground through septic tanks. Of that used for
irrigation, an appreciable part doubtless seeps back into the ground.
Furthermore, the places at which the water is returned to the
ground are generally no more than 50 to 100 feet from the wells
from which the water is drawn. It appears reasonable to con-
clude, therefore, that the net current draft on the ground water
is not large in comparison with the potential yield. of ground
water on the peninsula.
QUALITY OF WATER
Chemical analyses of five samples of water collected from se-
lected wells on the western end of the peninsula were made by
the Quality of Water Branch of the U. S. Geological Survey. These
analyses are shown in table 1. Four of the analyses (wells T7, 38,

22

REPORT OF INVESTIGATIONS No. 7- I

61, and 90) show the chemical character of water from the upper
aquifer. The chemical character of water from the upper part of
the lower aquifer is shown in the analysis of water from well T8.
It can be seen from a study of the analyses that the chemical
character of the water differs considerably between the two aqui-
fers. However, none of the analyses show any chemical constituent
to be present in such a large amount as to make the water objec-
tionable for most uses.

The relative mineralization of water from the two aquifers
can be seen by comparison of the amount of dissolved solids. The
analyses show the dissolved solids in the upper aquifer to range
from 25 to 39 parts per million, whereas the one water sample
obtained from the lower aquifer (from well T8) had 247 parts
per million of dissolved solids. Thus it can be seen that water
from the upper aquifer is less mineralized than that from the
lower aquifer. The analyses show the water from the upper aqui-
fer is very soft, the total hardness of the water expressed as
calcium carbonate, ranging from 3 to 10 parts per million. On the
other hand, the water from the lower aquifer (from well T8) was
moderately hard, having a total hardness of 152 parts per million
as calcium carbonate. One of the most important differences in
the chemical character of water from the two aquifers is the
difference in the pH. The pH indicates the degree of acidity or
alkalinity of. the water. A pH of 7.0 is neutral, indicating that
the water is neither acid nor alkaline. Values progressively lower
than 7.0 denote increasing acidity and values above 7.0 indicate
alkalinity, the degree of alkalinity increasing as the pH increases.
The analyses of the pH of water from the upper aquifer range
from 5.2 to 5.9, and the pH of the one sample of water from the
lower aquifer is 7.2. Thus, it can be seen that water from the
upper aquifer is somewhat acid and water from the lower aquifer
is almost neutral.

Considerable publicity has recently been given, through articles
in newspapers and magazines, to the fluoride content of water
and its effect on the development of sound teeth. This publicity
has called attention to studies that show that children who drink
water that contains not less than 1 part per million of fluoride
have fewer dental caries than children who drink water that con-
tains much less than 1 part per million (contents higher than 1.5
parts per million tend to cause mottling of the enamel of the per-

23

FLORIDA GEOLOGICAL SURVEY

manent teeth of young children who habitually use the water).
It is interesting to note in this connection that three of the
analyses show no fluoride to be present and the other two show
only 0.1 part per million.
Color in water is generally derived from peat, leaves, and
similar organic substances. Although it is not harmful to persons
who use the water, it is objectionable to them when present in
noticeable amounts. Only one of the three samples on which
color determinations were made had a color higher than 20, above
which concentration it is usually objectionable. A sample that
had a color of 40 was obtained from well 90, and the high color
doubtless indicates that the well is screened in the fine peaty sand
that comprises part of the upper aquifer (see fig. 5).
In ground-water investigations in areas adjacent to salt water,
it is a general practice to determine the chloride content of water
samples collected from wells throughout the area. Such determina-
tions are valuable in that they can give an indication of the salt
content and show the extent of any salt-water encroachment.
Analyses of water samples obtained from wells that draw from
the upper aquifer on the peninsula (see tables 1 and 3) show that
the Chloride content was generally lees than 25 parts per million
in most of the wells, but was 83 parts per million in well 45 and
135 parts per million in well 43. Wells 45 and 43 are within a
few hundred feet of the shore. The chloride content of samples
from wells in the lower aquifer has ranged from 54 to more than
16,000 parts per million, the higher chlorides being present in
samples obtained from well T22 (see table 2).
QUANTITATIVE STUDIES
LIMITATIONS OF YIELD
The perennial yield of a given aquifer may be limited by any
one of a number of factors. In general, the yield is determined
by the extent to which water levels may be lowered by pumping
without adversely affecting the quality of the water, or making
the cost of obtaining it prohibitive, or causing the wells to fail.
A certain amount of lowering of water levels inevitably accom-
panies the withdrawal of water from wells. In fact, a lowering
of the water level in a pumped well is necessary to cause ground
water to flow into the well from the surrounding formations. The
amount of lowering is more or less proportional to the withdrawal.

24

TABLE I.

ANALYSES OF WATER FROM WELLS ON THE WESTERN END OF
FAIR POINT PENINSULA

(All results are in parts per million except those for specific conductance, color, and pH.)

_______ .I .-- -)* I I I

.4.

+3

4.3
0

41

119

40

40

44

PM4
+3

00-

W

______________ I. --I I I *I 1- 1

10-17-50

10-17-50

7-8-50

7-4-50

7-8-50

53.2

392

39.1

41.7

47.9

5.4

7.2

5.9

5.9

5.2

-- _______

4.5

16

11

12

12

*0.72

* .25

.01

.02

.02

1

51

1.3

.7

.6

1.8

5.9

.2

.3

.3

5.8

11

4.8

4.6

5.1

0

ci 0
0cc
M -
on 'O .- -
~ Q ~ Q

0.7

1.6

1.5

2.0

3.2

4

111

3

2

3

4.9

2.8

2.8

3.0

5.5

11

58

7.2

7.5

7.5

0.1

.1

.0

.0

.0

- I 4. .1 I 1 1-

(Analyses

by Quality of Water Branch, U. S. Geological

*-Total iron.

T7

T8

38

61

90

d

0
0

o

.OS

152

4

3

3
3

m

.o
P-

39

247

25

27

31

Z

0.2

.3

.5

1.5

.3

Survey)

I I

-L

FLORIDA GEOLOGICAL SURVEY

TABLE II
CHLORIDE CONTENT OF WATER SAMPLES FROM WELL T22
COLLECTED DURING CONSTRUCTION OF THE WELL
SFrom Jacob, C. E., and others, Report on the ground..water resources of
the Pensacola area in Escambia County, Fla., p. 71 (manuscript report in
files of U. S. Geological Survey)]
(G. J. Petretic, analyst)
Date Depth of sample Chloride content
(1940) (feet) (parts per million)
Feb. 21 21.1 10
23 75 4,150
24 88 6,650
26 104 12,600
27 119 16,100
Mar. 4 184-190 830
8 250-253 3,500
11 300 1,130
*-Sample may have been diluted with fresh water used in the drilling process.
Where salt water from the sea cannot encroach into the aqui-
fer, the extent to which the water levels can be lowered may be
limited only by the maximum economic pumping lift. In some
areas adjacent to the sea coast, however, a lowering that would
be considered to be moderate elsewhere might be sufficient to per-
mit sea water to encroach into the aquifer and ruin the water
supply. On the Fair Point Peninsula an encroachment of salt
water would be the first consequence of an excessive lowering of
water levels by pumping. Thus, the safe perennial yield of ground
water on the peninsula is the quantity that can be withdrawn
without causing salt-water encroachment.

Relation Between Ground Water and Salt Water
The relation between the head of fresh water and the position
of the interface between the sea water and the fresh ground water
may be expressed as follows:
t
h-=
g-1
where h depth of fresh water below mean sea level, t = fresh-
water head, in feet, above mean sea level, and g== specific gravity
of sea water. The relationship is generally referred to as the Ghy-
ben-Herzberg principle, after the names of the two men who first
described it.
The specific gravity of ground water is, for pract \ purposes,
1.000, and the specific gravity of sea water is ordinarily about

26

REPORT OF INVESTIGATIONS No. 7-

1.025, except at places where the sea water is diluted to a con-
siderable extent by the discharge of fresh water from the land.
In order to determine the specific gravity of the salt water on
each side of the peninsula, water from Santa Rosa Sound and
Pensacola Bay was sampled on January 7, 1951. The water from
the sound was found to have a specific gravity of 1.024 and that
from the bay, 1.021. Thus, the density of the water from the
sound is the greater and is the one that should be used in the
formula. Where the specific gravity of sea water is 1.024, one
finds from the above equation that h = 41.7t, which means that
a head of 1 foot of fresh water above sea level will give a
depth of 41.7 feet of fresh water below sea level. Likewise, a
head of fresh water of 2 feet would give a depth of 83.3 feet of
fresh water-and so on. As pointed out by John S. Brown (1925,
p. 17) who reviewed the studies made by Ghyben and Herzberg
in connection with his investigation in Connecticut, the Ghyben-
Herzberg principle "appears to apply particularly to small islands
and narrow land masses that are made up of freely pervious mater-
ial, especially sand." It does not apply to inland areas. Even in
those areas very close to the sea where the water-bearing forma-
tion is stratified or bounded by materials of low permeability its
application must be modified. On the Fair Point Peninsula, the
principle might be expected to apply rather closely within the
upper aquifer. However, according to the equation, if the water
table in the center of the peninsula is 4 feet above mean sea level,
salt water should first be penetrated at a depth of 168 feet below
sea level. In fact, however, one should. not expect to find the
depth to the interface of salt water and fresh water to be 168 feet
because a layer of clay intervenes between the water table and
the interface (see fig. 4). As shown in figure 6, the hydrostatic
head of the water beneath the clay, in the lower aquifer, is less
than the height of the water thble in the upper one at the center
of the peninsula. It is the head in the lower aquifer that should
be used to determine the depth to the interface in that aquifer.
Thus, with an average head of 3.0 feet in the lower aquifer the
salt water should occur at a depth of about 126 feet below sea
level, which is well below the top of the relatively impervious
sandy clay that comprises the bottom of the lower aquifer.
The figure of 126 feet appears to inconsistent with the fact
that fresh water was pumped from well T21, which was screened
between depths of 102 and 152 feet below sea level. The incon-

27

FLORIDA GEOLOGICAL SURVEY

sistency may be explained in either of two ways, (1) that for
some undetermined reason the Ghyben-Herzberg principle did
not apply in this case, or (2) that well T21 yielded water only
from the upper part of the screened interval, which might occur
if the drilling mud in the lower part of the screened interval was
not thoroughly washed out.
Lowering of the Water Table in Response to Pumping
In view of the foregoing, it will be seen that the height of the
water table after the ground water in the peninsula has been de-
veloped is the factor that will determine whether salt-water en-
croachment will occur. Therefore, consideration must be given
the extent to which the water table will be lowered by pumping.
The extent to which water levels will be lowered by a given rate
of pumping is determined by several factors. These factors in-
clude (1) the water-bearing characteristics of the aquifer, such
as its capacity to store water and transmit water, (2) the con-
ditions under which the aquifer is recharged with water and under
which water discharges from it, and (3) the boundaries of the
aquifer.
Every aquifer functions in two capacities: as a reservoir and
as a conduit. In its capacity as a reservoir the aquifer stores water,
as the water table or artesian pressure rises, and releases water
as the water table or artesian pressure declines. As a conduit,
the aquifer serves to transmit water from areas of recharge to
places at which the water is naturally discharged or withdrawn
through wells.
A measure of the capacity of an aquifer to store water is the
coefficient of storage (Theis, 1938, p. 894) which is the volume of
water, in cubic feet, released from storage in a vertical prism
of the aquifer having a height equal to the thickness of the aquifer
and a base that is 1 square foot in area when the water table or
artesian head declines 1 foot. Under water-table conditions the
coefficient of storage is, for practical purposes, equivalent to the
specific yield, which Meinzer (1923, p. 28) defines as the ratio of
(1) the volume of water which the aquifer will yield by gravity
after being saturated, to (2) its own volume.
A measure of the capacity of an aquifer to transmit water is
the coefficient of tranmissibility (Theis, 1938, p. 894) which, in
units ordinarily used, is the quantity of water in gallons per day
that will move through a vertical section of the aquifer 1 foot wide

28

REPORT OF INVESTIGATIONS NO. 7- I

when the hydraulic gradient is unity. Determinations of these
two coefficients are involved in almost all quantitative ground-
water studies. Once they are determined, they may be used to
estimate the decline of water levels in response to pumping from
a well or system of wells. The method used in determining the
two coefficients with respect to the upper aquifer on Fair Point
Peninsula will be discussed in the section entitled "Pumping Test."
In an artesian aquifer, such as the lower aquifer on the Fair
Point Peninsula, the coefficient of storage is relatively very small,
being in the order of several hundred or several thousand times
smaller than the coefficient of storage of a water-table aquifer.
Thus, it may be assumed that the lower aquifer has a much smaller
capacity to store water during rainy seasons than the upper one.
In fact, the capacity of the lower aquifer to store additional water
is doubtless negligible, and, hence, the water that it will yield in
droughts must be derived almost wholly from storage in the upper
aquifer, by seepage through the bed of clay that lies between the
two.
Recharge and Discharge Under Natural Conditions
The source of all fresh water on the Fair Point Peninsula, to
the depths that have been explored by wells, is the rain that falls
on the peninsula. Over most of the peninsula the surficial material
is permeable sand which permits the water that falls as rain to
percolate to the water table rapidly. In a few places beds of peat
of somewhat lower permeability retard the downward percolation
of the water. In general, the surficial material is so permeable
that little or no water is discharged as surface runoff, except
possibly in the low, swampy areas. The high rate at which the
water may percolate to the water table was demonstrated during
the pumping test (which will be described later). At that time,
water was discharged onto thd surface of the ground at a rate of
90 gallons per minute for 31 hours, and was observed to spread
over an area of no more than about 100 square feet before per-
colating into the ground.
Part of the water that falls as rain is returned to the atmos-
phere by evaporation and transpiration, and only the remainder
percolates to the water table. Of the water that reaches the water
table, a part continues to percolate downward through the clay
bed under the upper aquifer and serves as recharge to the lower
aquifer. Another part is drawn from the zone of saturation by

29

FLORIDA GEOLOGICAL SURVEY

plants. Finally, a third part is discharged by submarine seepage
from both aquifers into Pensacola Bay and Santa Rosa Sound.
Recharge and Discharge in Relation to Pumping
Prior to the withdrawal of water from wells, the rate of re-
charge through an aquifer is balanced by the rate of discharge,
except for temporary differences due to changes in the amount
of water stored in the aquifer. After a withdrawal from wells
begins, the natural balance is upset. For a certain period of time
after the withdrawal begins, practically all of it is derived from
storage in the aquifer surrounding the well. The removal of water
from storage lowers the water table, and thereby creates a cone
of depression. As the withdrawal continues, the cone of depres-
sion deepens and broadens until ultimately a new balance is es-
tablished wherein the rate of recharge is once more equal to the
rate of natural discharge, plus the rate of withdrawal. The new
balance may occur through an increase in the rate of recharge if
circumstances are favorable, or to a decrease in the rate of natural
discharge, or to a combination of these changes. It is only when
the equation is once again in balance that the decline of the water
table due to pumping ceases and the water table once again becomes
stable, except for fluctuations due to natural causes such as in-
termittent rainfall.
A lowering of water levels will cause an increase in the rate
of recharge only where there was some rejected recharge prior to
the pumping. On the Fair Point Peninsula, recharge would appar-
ently be rejected only if rain should fall in such abundance as to
saturate the aquifer completely, in which event surface runoff
would occur. If this situation were to occur frequently, it might
be concluded that less water would be rejected if the water table
were lowered by pumping. However, the investigation has dis-
closed no evidence of there having been any appreciable surface
runoff. Therefore, it appears reasonable to assume, in considering
the potential yield of the aquifer, that the withdrawal of water
from wells must be derived altogether from a lessening of natural
discharge. The mechanics by which natural discharge could be
lessened by pumping may be understood if it is recognized that a
lowering of the water table where the discharge occurs will de-
crease the discharge.
Boundaries of the Aquifer
The boundaries of the upper aquifer are the shore lines of
the peninsula. These boundaries influence the extent to which the

30

REPORT OF INVESTIGATIONS NO. 7-I 31

water table will be lowered by pumping by holding the water at or
slightly above sea level along the shore line.
PUMPING TEST
In order to determine the coefficients of transmissibility and
storage of the upper aquifer, a pumping test was made on October
5 and 6, 1950. The test consisted of pumping well T7 at a rate of
90 gallons per minute for a period of 31 hours and of making
frequent measurements of the resulting drawdowns in observa-
tion wells within a few hundred feet to the north and south of well
T7. The observation wells in which measurements of drawdown
were made during the pumping test include, among others, wells
T5, T6, and T10 to T14. The spacing of these wells and the draw-
downs in them after 31 hours of pumping are shown graphically
in figure 8. The drawdowns shown in the figure, and all those used
in the computations, have been adjusted for partial penetration.
That is, they have been adjusted to compensate for the fact that

4.0
4.0 -------

I a

.-Waotr lo ble prior to pumping

S Water toble after 31 hours pumping
at rate of 90 gallons per minute
(adjusted for partial penetration)

200 200 160 100 50 0 5 00 100 10 200 250
Diltanoe from pumped well, In feet
Figure 8. Profile of water table showing drawdown during pumping test
on October 5 and 6, 1950. Drawdowns are adjusted for partial penetration
of pumped well.

well T7 was not screened throughout the saturated zone of the
aquifer, but only a part of that zone. Thus, the drawdowns rep-
resented in figure 8 are not the measured ones but have been ad-
justed to what they would have been if well T7 had been screened
throughout the saturated zone. The adjustment was based on a
method devised by Jacbb (1945).
Not shown in figure 8 are eight sand-point wells that were driven
a few feet below the water table near wells T5 to T6 and wells T9

FLORIDA GEOLOGICAL SURVEY

to T14 for the purpose of observing the effect of the partial pene-
tration of the pumping well. The effect of the partial penetration
was manifested in the fact that the water levels in the very shallow
sand-point wells stood higher, at all times during the pumping,
than the water levels in the deeper wells.

The adjustment for partial penetration was made first on the
observed drawdowns in wells TS, T6, and T10 to T14, and second
on the drawdowns in the corresponding shallow sand-point wells.
In each case the adjusted drawdown which was finally adopted is
a weighted average of the two.

The complete record of the water-level observations made dur-
ing the pumping test is too lengthy for inclusion in this report.
Altogether, about 580 measurements of water levels were made
during the 31 hours of pumping from well T7. The adjusted draw-
downs determined from these measurements were used to com-
pute the coefficients of transmissibility and storage by a method
devised by Theis and described by Wenzel (1942, pp. 87-90). The
method involves the following formula, which relates the draw-
downs in the vicinity of a discharging well with the rate and
duration of the discharge:

-u

114.6qwhich the drawdown is s

S 1.87 rS
where u=
Tt
s = drawdown, in feet, at any point
r= distance, in feet, from discharge well to the point at
which the drawdown is s
q = discharge of well, in gallons per minute
t= time of pumping, in days, required to produce draw-
down, s, at distance, r
T= coefficient of transmissibility, in gallons per day per
foot
S= coefficient of storage, a dimensionless fraction.
The formula involves several simplifying assumptions, all of which

32

REPORT OF INVESTIGATIONS No. 7- I

appear to be reasonably approximated by the conditions under
which the pumping test was made.
The analysis of the results of the pumping by Theis' method
indicates that the upper aquifer has a coefficient of transmissibility
of 34,000 gallons per day per foot and a coefficient of storage of
0.23.
The figure for the coefficient of transmissibility was corrobo-
rated by laboratory determinations of permeability of sand samples
from the upper aquifer obtained during the drilling of well T8.
The coefficient of permeability as defined by Meinzer (1942, p. 452)
is the rate of flow of water at 60F. in gallons per day through a
cross section of 1 square foot under a hydraulic gradient of 100
percent. The determinations of permeability are as follows:

Depth from which sample
was obtained, in feet below
land surface
6
12
18
25
30
35
40
45
50
55
60
65
70
75
80
83

Coefficient of permeability
of sample

261
573
819
663
507
616
388
316
452
320
500
616
124
67
34
(Relatively impermeable
clay)

The coefficient of transmissibility is equal to the average coef-
ficient of permeability, adjusted for the temperature of the ground
water, multiplied by the thickness of the aquifer. It may be ob-
tained from the individual determinations of permeability by (1)
multiplying each determination of permeability by the thickness
of the interval represented by the sample, (2) adding these pro-
ducts, and (3) adjusting the sum for the temperature of the

33

FLORIDA GEOLOGICAL SURVEY

ground water of the upper aquifer. The figure for the trans-
missibility so obtained is 37,000 gallons per day per foot. This
figure agrees well with the one obtained from the results of the
pumping test. However, the closeness of agreement may be more
or less accidental because laboratory determinations of the permea-
bilities of disturbed samples do not, in general, constitute a reliable
indication of the average permeability of an aquifer.
THE INITIAL WATER TABLE
Having determined the coefficients of transmissibility and stor-
age from the pumping test, we may compute the extent to which
the water table will be drawn down as the result of pumping at
any given rate from one or more wells. Before doing so, however,
it is necessary to establish an initial water table on which the com-
puted drawdowns may be superimposed. The water table is not
static, but, instead, fluctuates constantly over a range of several
feet. At first thought, it might appear that the minimum stage
of the water table should be used as the initial one, as it would rep-
resent the most unfavorable condition with respect to salt-water
encroachment and its use would lead to the most conservative
conclusions. However, when we consider the fact that the salt
water will move inward only a short distance during a temporary
low stage and will be forced back toward the sea during a subse-
qluent high stage, it becomes apparent that the.use of the mini-
mum stage would yield results that would be unduly conservative.
In this light, it appears that we may reasonably assume the average
water table as the initial one for the purposes of our computations.
If a record of the water table over a sufficiently long period of
time were available, the average water table could be established
from that record. Unfortunately, the record is too short for this
purpose. Therefore, it is necessary to estimate the average water
table by a mathematical analysis that will be based on certain
simplifying assumptions. One assumption that will be made is
that the rate of accretion to the water table from rainfall is di-
rectly proportional to the rainfall. Another is that the loss of
water from the upper aquifer into the lower one, by seepage through
the underlying layer of clay, has a negligible effect on the water
table. A third assumption is that the coefficients of transmissibility
and storage are the same at all places and at all times.
An equation for the water table under steady-flow conditions-
that is, when rain is falling at a steady rate and the water table

34

REPORT OF INVESTIGATIONS No. 7- I 35

remains stable-is given by Jacob (1944, pp 565-566), as follows:
ho= (W/T) (ax- x2/2),
where ho is the height of the water table above sea level, W is the
rate of accretion to the water table from rainfall, T is the coef-
ficient of transmissibility, a is half the width of the peninsula, and
x is the distance from one of the shore lines to the point at which
the height of the water table is ho.

From a comparison of the rainfall records with several ob-
served stages of the water table on the peninsula, W, the rate of
accretion to the water table on the peninsula, was determined to
be in the order of 40 percent of the rainfall. An average figure
for W was then obtained by taking 40 percent of the average rate
of rainfall as determined from the records of the U. S. Weather
Bureau station at Pensacola. The average water table shown in
figure 10 A, B, and C was then computed by substituting the figure
for the average W in the equation, given above.
The average water table, as established in the foregoing, will
compose one of the basic assumptions in the computations of the
effects of pumping. In view of the fact that it has been established
mathematically with only sparse water-level data and that it is
higher than the observed water levels over most of the short period
of record, one might consider that it is too high. Therefore, it ap-
pears desirable to test its plausibility by comparing the observed
water levels on the peninsula with those on the mainland, where
the period of record of water levels is much longer. Such a com-
parison is shown in figure 6. The figure gives the hydrographs of
water levels in wells T7 and T8 on the peninsula and in Escambia
County well 62-A, which is on the north shore of Pensacola Bay,
at the foot of H Street, in Pensacola. The average water level in
Escambia County well 62-A during the period 1940 to 1950 was
about 2.4 feet above sea level, bitt, as shown in figure 6, the water
level in that well near the end of February 1951 was only about
1 foot above sea level. Thus, near the end of February 1951 the
water level was about 1.4 feet below the average. Correspondingly,
the water table on the peninsula near the end of February 1951 was
doubtless substantially lower than the average water table. We
may conclude, therefore, that the calculated average water table
is not implausible.
It appears, in fact, that the water table shortly after the end
of February was as low, or very nearly as low, as it has been at
$

36 FLORIDA GEOLOGICAL SURVEY

any time during the past 70 years, as may be seen from a study
of the rainfall recorded at the Pensacola station since 1880. The
rainfall during the 6-month period that ended in February 1951 was
13.08 inches. At only five times during the 70-year record has the
rainfall in any 6-month period been less. The record low for any
6-month period is the 11.04 inches that fell during the period
August 1938 to January 1939.

It is well to consider, in passing, the rate at which the water
table will decline during a prolonged absence of rainfall. As shown
by Jacob (1944, pp. 566-567) the decline of the water table on a
peninsula during the absence of rainfall is expressed by the equa-
tion,

h = ho exp (- ,r2Tt/4a2S),
in which h is the height of the water table above sea level at any
given time, t, after the rainfall ceases, and the other terms are as
previously defined. It may be shown from this equation that the
logarithm of h decreases directly with time, and, hence, that a
plot of the logarithm of h versus t will be a straight line. This
relationship provides a means for extrapolating the decline of the
water table graphically as shown in figure 9. The figure is a

1950 1951
Oct. Nov. Dec. Jan. Feb. Mar. Apr. May

4.0-

~a

I

2c

0 0

S o Circles represent measurements of water 2
level in well T7 during a period of no o
rainfall.

1.0- ------__ -----__ ------------_____-- -----._ ------__ ______
Figure 9. Extrapolated decline of water level in well T7 during a
hypothetical prolonged period of no rainfall.
semilogarithmic hydrograph of the water level in well T7, with
the height of the water level on the logarithmic scale. The five

6 Imoth

3 onh

REPORT OF INVESTIGATIONS No. 7- I 37

measurements of water level that were chosen for the plot are
those made during the period October 23 to November 20, 1950, in
which no appreciable rainfall was recorded at the Pensacola sta-
tion. Thus, these five measurements show the decline of the water
table in the absence of rainfall, and the projection of a straight
line through their plot gives an extrapolation of the decline. It
may be seen from figure 9 that if no rain were to fall on the penin-
sula for a very prolonged period the water level in well T7 would
fall from 4 feet (the height of the average water table near the
center of the peninsula) to 2.70 feet over a period of 3 months,
and to 1.87 feet by the end of 6 months. The extrapolation is, of
course, hypothetical, as the possibility of there being no appre-
ciable rainfall over a period of 6 months is very remote.
The rate of decline of the water table is, theoretically, directly
proportional to its height. In the first few weeks following a
period of heavy rainfall when the water table is relatively high, it
declines relatively rapidly. As time continues, the rate of decline
steadily diminishes. Thus, it may be seen from figure 9 that, start-
ing with a height of 4 feet, the water table will, in the absence of
rain, decline 0.50 foot during the first month but only 0.26 foot,
about half as much during the sixth month.
METHOD OF COMPUTING DRAWDOWNS
The drawdowns that will be produced in the vicinity of a
pumped well may be computed from Theis' formula,

( 00
I -u
114.6q e
T u du,
J
u
)
the terms of which were defined in the section entitled "Pumping
Test." The formula is based on several simplifying assumptions.
Among these are the assumptions that the aquifer has an infinite
areal extent, and that the discharge of the well is derived entirely
from storage. Because of these assumptions the drawdowns com-
puted from the formula do not approach a limit, but continue to
increase indefinitely, although at a gradually diminishing rate.
Obviously, however, the upper aquifer is not infinite in areal ex-
tent but is bounded by the shore lines of the peninsula. Along the
shore lines the water table, will remain at or slightly above sea

FLORIDA GEOLOGICAL SURVEY

level at all times, regardless of the rate and duration of pumping
on the peninsula. Thus, the shore lines serve to control and limit
the drawdowns on the peninsula. In so doing, each shore line
approximates what is known as an infinite line source, a straight
line along which water levels will remain constant. The method
for computing drawdowns in an area adjacent to an infinite line
source is given by Muskat (1937, pp. 175-181).
The method makes use of a convenient theorem wherein it is
premised that the effect of the infinite line source is the same
as that which would be produced by an "image" recharge well,
whose rate of recharge is equal to the rate of pumping from the
pumped well, and whose location is such that if the infinite line
source were a mirror the image well would be a reflection of the
pumped well in that mirror. The net drawdown at any point in the
aquifer is the algebraic sum of (1) the drawdown that would be
produced by the pumping well, computed from Theis' formula and
(2) the negative drawdown, or rise in water level, that would be
produced by the image well, also computed from Theis' formula.
Where two parallel infinite line sources occur, as on a peninsula,
the method is much the same except that each image well is re-
tlected successively from one line source to the other, and the com-
putations are multiplied.
To estimate the drawdowns that will occur on the peninsula
we will postulate, for the purposes of computation, an idealized
peninsula having a width of 5,200 feet, an infinite length, and
straight parallel shore lines (fig. 10). We may then compute the
drawdowns that would occur on the idealized peninsula and view
them as being indicative of what might occur on the Fair Point
Peninsula.
EFFEC'r OF PUMPING IN RELATION TO SALT-WATER
ENCROACHMENT
The number of supply wells that will be needed on the penin-
sula will be determined by the quantity of water required. If the
requirement is moderate, a single well might be sufficient. However,
excessive pumping from one well might cause salt-water encroach-
ment, whereas that same rate of pumping from several wells
spaced along the length of the peninsula might be safe.
So as to provide a guide to the number of wells that may be
needed for any given quantity of water that may be required,
computations of drawdowns to determine the safe yield of one

38

REPORT OJ INVESTIGATIONS NO. 7- I

) 500 0 500
Dlilonce from pumped well, in feet

1,000 1,500 2,000 2,500

Figure 10. Profiles showing ultimate lowering of water table due to
pumping on an idealized peninsula bounded by straight shore lines of infinite
length.

A. Profile through one well (section A-A') 'pumping 100 gallons per
minute continuously.
B. Profile through the center well of three wells (section B-B'), each
pumping 60 gallons per minute continuously. Wells spaced 1,000 feet apart.
C. Profile through any one of an infinite number of wells (section C-C'),
each pumping 40 gallons per minute continuously. Wells spaced 1,000 feet
apart.

39

FLORIDA GEOLOGICAL SURVEY

well, for three wells, and for an indefinitely large number of wells,
spaced along the center of the peninsula, have been made. In
figure 10 the computed drawdowns are shown superimposed on
the computed average water table. The drawdowns shown in this
figure are those that would ultimately be produced by prolonged
pumping-that is, they are the drawdowns that will occur when
steady-flow conditions have been established.
One Pumped Well
Figure 10-A shows the profile of the water table that would
occur if one well located at the center of the peninsula were
pumped at the rate of 100 gallons per minute. Between the pumped
well and the shore line, the height of the water reaches a maximum
of about 2.7 feet above sea level. According to the Ghyben-Herz-
berg principle, then, the depth of the salt-water interface would
be 113 feet (2.7 x 42) below sea level. This is well below the im-
pervious clay layer at the bottom of the upper aquifer. Therefore,
there could be no lateral movement of salt water through the
upper aquifer into the pumped well.
Drawdowns are approximately directly proportional to the
rate of pumping. Thus, if the pumping rate were 200 gallons per
minute instead of 100 gallons per minute, the drawdowns would be
twice as much. It is considered that the safe yield of one well is
in the order of 100 gallons per minute. This is not to say, how-
ever, that intermittent pumping at higher rates would produce
salt-water encroachment. The figure of 100 gallons per minute is
an average one. Within limits, the rate of intermittent pumping
may exceed 100 gallons per minute so long as the average rate
does not exceed 100 gallons per minute. As indicated by the results
of the pumping test and by mathematical analyses, a change in
the rate of pumping does not influence water levels at a distance
of as much as 1,000 feet from the pumping well until more than
a day elapses after the change occurs. Therefore, if, for example,
the well were pumped at the rate of 200 gallons per minute 12
hours per day, the water levels at a distance of 1,000 feet, more
or less, from the well would respond as though the well were
being pumped at the rate of 100 gallons per minute 24 hours a
(lay.
Three Pumped Wells
When two or more wells are pumped in proximity with one
another, the pumping from one will produce drawdowns in the

40

REPORT OF INVESTIGATIONS No. 7 I

others. As a result, the drawdowns in each well will be more than
if it were the only one being pumped. Therefore, as the maximum
practical drawdowns are limited by the potentiality of salt-water
encroachment, the safe yield from each of a group of wells will
be less than if that well were the only well being pumped.
Figure 10-B is the profile of the water table through the center
well of a group of three wells, spaced at intervals of 1,000 feet
along the center of the hypothetical peninsula, pumping 60 gallons
per minute each. The maximum height of the water table be-
tween the pumped well and the shore line is seen to be about 2.5
feet. Again, this height of fresh water above sea level is suf-
ficient to hold the salt-water interface well below the impervious
layer of clay and thereby prevent the lateral encroachment of
salt water into the pumped well.

Indefinite Number of Pumped Wells
An approach to an appraisal of the perennial yield of ground
water on the peninsula may be made by considering the draw-
down that would occur as the result of pumping from an indefi-
nitely large number of wells spaced at equal intervals along the
center of the peninsula. As in the previous example, the wells
will be spaced at intervals of 1,000 feet. The maximum drawdowns
would occur along a line perpendicular to the shore lines of the
peninsula and passing through one of the wells.
The profile of the water table that would be produced along
such a line by the pumping of 40 gallons per minute from each of
the wells is shown in figure 10-C. It may be observed that at a
distance of about 800 feet on each side of the pumped wells the
profile of the water table stands a little more than 2 feet above
sea level. A height of 2 feet is sufficient to hold the salt-water
interface to a depth of approximately 84 feet, which is below the
bottom of the aquifer. Therefore, a lateral encroachment of salt
water cannot occur. There appears to be little reason to believe
that the salt water might rise beneath the area around the pumped
well where the drawdowns are largest, because the relatively im-
pervious clay at the base of the upper aquifer will serve to mini-
mize the lowering of hydrostatic head in the lower aquifer. It
is this hydrostatic head, rather than the water table, which con-
trols the depth to salt water beneath the bed of clay that separates
the aquifers.

41

FLORIDA GEOLOGICAL SURVEY

Spacing of Wells
The optimum spacing of a system of wells along the center
of the peninsula is dependent not only on hydrologic considera-
tions, but, also, on economic ones such as the cost of constructing
collecting mains, the availability of the land, and the cost of each
well. Therefore, the determination of the distribution of the
wells is not properly a part of a hydrologic study such as the one
on which this report is based. The spacing that was chosen as
the basis for computations in this report is more or less arbitrary
and should be considered so. It is well to consider, however, that
the optimum spacing will fall between certain limits. If, for an
extreme example, two pumped wells were to be located within
100 feet of one another, the effect of their pumping, so far as it
applies to the problem of salt-water encroachment, would be the
same as if their combined rate of pumping were all from one well.
On the other hand, if the wells were spaced so far apart that the
effect of pumping from one did not reach another, a large part
of the potential yield of ground water on the peninsula would re-
main undeveloped.
Safe Yield
The analysis of the effects of pumping from an infinite number
of wells spaced along an idealized peninsula of infinite length
provides a basis for appraising the total yield of ground water
on the peninsula. As indicated by the analysis, the peninsula will
yield in the order of 40 gallons per minute, or approximately
60,000 gallons a day, from each 1,000 feet of its length. One must
not fail to consider, however, that the peninsula does not have
the straight, parallel shore lines that were assumed as a basis
for the computation. At some places the peninsula is only about
two-thirds as wide as the idealized peninsula. At other places it
is wider. Where the peninsula has a lesser width, the safe yield
will be correspondingly less than that of the idealized peninsula.
Where it has greater width the safe yield will be more. There-
fore, it is apparent that the figure of 40 gallons per minute-
60,000 gallons a day-per thousand feet of length must be used
only as a guide in the first stages of the development. Informa-
tion that will provide a more reliable appraisal of the safe yield
may be obtained after the ground water is partially developed and
the withdrawal has begun, if an adequate program of water-level
observations and chloride analyses is continued. Thus, an evalua-
tion of the observed effects of the initial rate of withdrawal will
indicate how additional quantities of water may best be developed.

42

REPORT OF INVESTIGATIONS NO. 7 I

CONCLUSIONS
1. The drilling of test wells on the Fair Point Peninsula in-
dicates that fresh water occurs only in those deposits that lie with-
in about 150 feet of the land surface. The deposits that contain
fresh water may be divided into two aquifers: an upper aquifer
which extends from the land surface to a depth of 60 to 85 feet, and
a lower one which occurs between a depth of 80 to 110 feet and
a depth of 120 to 160 feet. The two aquifers are separated by a
layer of relatively impervious clay that ranges in thickness from
10 to 20 feet.

2. The water in the lower aquifer is salty at some places,
especially near the shores of the peninsula. Where the water in
it is fresh, the aquifer may be generally satisfactory for domestic
supplies that consume only small quantities of water. It is prob-
able, however, that the withdrawal of a relatively large quantity
of water, as for a public supply, would ultimately permit the en-
croachment of salt water.
3. The upper aquifer is the principal source of water for
the existing supplies. It is also the most favorable source for a
public supply that would require a relatively large quantity of
water. The results of the investigation indicate that the upper
aquifer will safely yield as much as 100,000 gallons a day to one
supply well near the center of the peninsula and an appreciably
larger quantity to a system of wells adequately spaced along
the center of the peninsula.
4. The figures relating to the safe yield of ground water on
the peninsula are considered to be the best that can be obtained
prior to the development of the supply. They may be used as a
guide in planning the first stages of the development. However,
it is important that the figures be considered only as estimates.
The first supply wells that will be needed to provide the immediate
requirements might be planned on the basis of the figures given
in the report, but further development to meet additional require-
ments may best be planned after the effects of prolonged pumping
from the first wells have been observed.

RECOMMENDATIONS
The 20 shallow observation wells on the peninsula were drilled
principally for observing the effects of pumping from the first
supply well. They were located along a line through what was

FLORIDA GEOLOGICAL SURVEY

considered by the Authority's Chief Engineer to be the most likely
site of the first supply well. It is recommended that the observa-
tion of water levels in these wells be continued at weekly intervals.
It is recommended further that determinations of chloride content
of water from the supply wells and from each of the observation
wells be made at least every 6 months. The water-level observa-
tions and chloride determinations will constitute a basis for de-
termining from time to time whether the ground water on the
peninsula is adequate for any additional supplies that may be
required. More to the point, they will serve to confirm or modify
the estimates of safe yield given in this report. If the estimates
are too optimistic, the recommended program will reveal the fact
in ample time for the adoption of measures to prevent any ma-
terial encroachment of salt water. Such measures might include
a wider distribution of the total draft.
BIBLIOGRAPHY
1. Brown, J. S., 1925, A study of coastal ground water with
special reference to Connecticut: U.S. Geol. Survey Water-
Supply Paper 537, p. 17.
2. Cooke, C. Wythe, 1945, Geology of Florida: Florida Geol. Sur-
vey Bull. 29, pp. 236, 276, 281, 285, 291, 296, and 310.
3. Jacob, C. E., Cooper, H. H., Jr., and Stubbs, S. A,, Report on
the ground-water resources of the Pensacola area in Escambia
County, Fla.: (manuscript report in files of U.S. Geological
Survey).
4. Jacob, C. E., 1944, Correlation of ground-water levels and pre-
cipitation on Long Island, New York: Am. Geophys. Union
Trans. 1943-44, pp. 565-567.
5. Jacob, C. E., 1945, Partial penetration of pumping well, ad-
justments for: U. S. Geol. Survey duplicated report, Aug. 10.
6. Matson, G. C., and Sanford, Samuel, 1913, Geology and ground
waters of Florida: U. S. Geol. Survey Water-Supply Paper
319, pp. 301 and 401.
7. Meinzer, 0. E., 1923, Outline of ground-water hydrology: U.S.
Geol. Survey Water-Supply Paper 494, p. 28.
8. Meinzer. 0. E., 1942, Ground water in Physics of the earth,
vol. 9, Hydrology, p. 452, New York, McGraw-Hill Book Co.,
Inc.

44

REPORT OF INVESTIGATIONS No. 7 I 45

9. Muskat, Morris, 1937, The flow of homogeneous fluids through
porous media, pp. 175-181, Ann Arbor, Mich., J. W. Edwards,
Inc.
10. Sellards, E. H., and Gunter, Herman, 1912, The water supply
of west-central and west Florida: Florida Geol. Survey 4th Ann.
Rept., pp. 91-106.
11. Theis, C. V., 1938, The significance and nature of the cone of
depression in ground-water bodies: Econ. Geology vol. 33, no.
8, p. 894.
12. Wenzel, L. K., 1942, Methods for determining permeability of
water-bearing materials: U. S. Geol. Survey Water-Supply
Paper 887, pp. 87-90.

TABLE III.
RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA,
SANTA ROSA COUNTY, FLORIDA
Part A. Test Wells

*Measuring point Water level Chloride content

e

T1 W-2332 38.6 2 37.2 37.2-08.6 21.72 1.4 9-7-50 1.64 8-24-50 19 29
3-5-51 0.27
3 2.7 90 16 8 1

T2 W-2333 26.2 2 22.5 22.5-23.6 7.14 2.5 9-7-50 3.11 8-23-50 3 19
3-5-51 1.44 8-23-50 22-24 12
T3 W-2334 40.8 2 39.4 39.4-40.8 25.26 2.9 9-7-50 3.96 10-17-50 39-41 16
3-5-51 1.99
T4 W-2335 34.9 2 33.4 33.4-34.9 17.89 2.0 9-7-50 4.68 9-5-50 33-35 10
3-5-51 2.40
T5 W-2336 36.4 2 34.6 34.6-36.4 16.87 2.8 9-7-50 5.31 10-17-50 35-36 13
3-5-51 2.57
T6 W-2337 34.9 2 34.7 34.7-36.1 12.00 0.5 9-7-50 5.25 8-17-50 8 10
3-5-51 2.62 9-21-50 35-36 16
T7 W-2338 40.3 6 32.7 32.7-41.3 14.88 3.3 9-7-50 5.32 8-8-50 17 12
3-5-51 2.61 8-9-50 29 14
8-10-50 33-41 17

*-Measuring point is top of casing on wells T7, T8, and T20, and top of coupling on all others.

TABLE III.
RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA
SANTA ROSA COUNTY, FLORIDA
Part A. Test Wells-Continued

Measuring point

a

00

Water level

Chloride content

c

CD
o?1-
00
"
*^
'3
'0 t
Q)Q
i* e^

W-2339 119.0

W-2340 35.7

W-2341

39.0

W-2342 39.4

W-2343 40.5

W-2344 37.0

W-2345 36.1

W-2346

39.9

6 90.1
23.8

2 31.2

2 37.7

2 38.7

2 37.8

2 35.5

2 35.2

2 39.5

112.0-117.0

31.2-33.7

37.7-39.0

38.7-39.4

37.8-40.5

35.5-37.0

35.2-36.1

39.5-39.9

o .

bo
JSS
*S3
o5
*y
'8
,d -
BO 5s ^

T8

r4)

cu
P.

T9

T10

Tll

T12

T13

T14

T15

15.20

11.91

14.07

14.02

13.63

13.72

13.83

15.42

3.6

0.4

2.5

2.5

2.1

2.2

3.1

2.8

15
40
51
60
100
112-117
7

15
17
21
25
43
63
16

10-17-50
3-5-51

10-23-50
3-5-51
9-7-50
3-5-51
9-7-50
3-5-51
9-7-50
3-5-51
9-7-50
3-5-51
9-7-50
3-5-51
9-7-50
3-5-51

2.76
2.23

4.31
2.60
5.23
2.60
5.27
2.61
5.29
2.59
6.01
2.59
5.22
2.53
5.12
2.58

8-1-50
8-2-50
8-2-50
8-3-50
8-7-50
10-17-50
9-15-50

8-11-50

9-21-50

8-15-50
9-21-50
8-16-50
9-21-50

38-39

36-37

7
35-36
9
39-40

16
12
10
11

- -

-----

TABLE III.

RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA
SANTA ROSA COUNTY, FLORIDA

Part A. Test Wells-Continued

Measuring point

ccc~
.4.

o! t~4

G)6

.Q1

Water level

Chloride content

co

low
cc

T16 W-2347 39.7 2 38.7 38.7-39.7 20.63 3.5 9-7-50 4.77 9-21-50 39-40 12
3-5-51 2.33
T17 W-2348 34.5 2 31.1 31.1-34.1 16.57 2.4 9-7-50 3.89 8-28-50 15 19
3-5-51 2.03 8-28-50 31-34 11
T18 W-2349 28.0 2 23.2 23.2-25.6 5.93 3.0 9-22-50 2.71 9-20-50 13 135
3-5-51 1.66 9-22-50 23-26 10
T19 W-2350 26.2 2 20.9 20.9-23.9 4.66 2.4 10-2-50 2.01 9-14-50 2 2975
2-26-51 1.23 9-15-50 21-24 11
T20 W-2351 32.0 2 26.4 26.4-29.4 5.26 2.2 9-7-50 1.26 8-24-50 3 240
3-5-51 .58 8-25-50 26-29 115
T21* 809.0 5 113 113-163 _11-29-50 113-163 54
T22 W- 577 400.0 6 104 23.52 2.3 7-4-50 .66 (See table 2)

*-Well was destroyed after water sample was obtained.
-Sample may have been drawn only from upper part of

screened interval.

cis >b
V
0.0

0P
-3 c
CS >

d2
C >

cis
bO
'4.
0D,

P4)
4.3

4)4.
4)4
4) i-
k.4 ..-.

TABLE III.
RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA,
SANTA ROSA COUNTY, FLORIDA
Part B. Supply Wells
Date Total Depth Chloride content
Well com- depth cased Diameter Parts per
number Owner Driller pleted (ft.) (ft.) (in.) million Date Remarks

12 Ed Peake
Gulf Breeze
Fla.
13 Do.

14 G. A. Lewis
Gulf Breeze
15 Do
16 J. L. Kahn
Gulf Breeze
17 Do

18 Do
19 F. R. Smith
Gulf Breeze
20 G. A. Duncan
Gulf Breeze

Alex Jackson
Pensacola, Fla.

Ed Peake
Gulf Breeze
G. A. Lewis
Gulf Breeze
Do
Alex Jackson
Pensacola
C. E. Smith
Pensacola

James Eagins
Pensacola
C. E. Smith
Pensacola

1 C. J. Heinberg Alex Jackson
Gulf Breeze Pensacola

21-A C. J. Heinberg
Gulf Breeze
22 J. A. Pfeiffer
Gulf Breeze

Alex Jackson
Pensacola

1947

1949

1945

1945
1943

1950

1937 ?
1941

1937

1948

1944

1949

26

28

20

25

4-20-50

1.25

18

18
16

4-19-50 Chloride analysis of mixed
water sample from wells
4-19-50 14 and 15.
4-19-50
4-19-50

22

28?
28

28

21

2.5

7-4-50
7-4-50

4-19-50

7-14-50

7-4-50

TABLE III.
RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA,
SANTA ROSA COUNTY, FLORIDA
Part B. Supply Wells-Continued

Date
kom-d
pleted

Driver

Diameter Parts per
Sin. million

Chloride content

Date

23 G. W. Reese
Gulf Breeze
24 Filo Turner
Gulf Breeze
25 Do

26 R. G. Martin
Gulf Breeze
27 W. O. Walker
Pensacola
28 Arthur Butts
Pensacola
29 E- Faireloth
Gulf Breeze
30 B. F. Born
Gulf Breeze
31 Do
32 J. D. Johnson
Gulf Breeze
33 Do

Alex Jackson
Pensacola
James Eagins
Pensacola
Harvey Hardware
Pensacola
James Eagins
Pensacola
Do

Do

D. L. Johnson
Brent
C. E. Smith
Pensacola
Do
Harvey Hardware
Pensacola
Do

1945

1937

1946

1935

1946

1939 ?

1950

1950

1942.
1947

1947

31

33.5

28

28

28

35

29.5

30
31

32

23

22.5

2.5

2.5

3

23

23

23

30

20.5

22
26

24

1947 31 23 3 11

7-4-50

4-19-50 Chloride analysis of mixed
water sample from wells
4-19-50 24 and 25.
4-19-50

7-4-50

7-4-50

7-4-50

7-7-50

7-14-50

7-14-50 Chloride analysis of mixed
water sample from wells
33 and 34.
7-14-50

Well
number

Owner

Total
depth
I ft.

Depth
cased
j ft. I

Remarks

34 Do Do

TABLE III.
RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA,

SANTA ROSA

COUNTY, FLORIDA

Part B. Supply Wells-Continued

Date Total Depth Chloride content
Weli com- depth eased Diameter Parts per
number Owner Driller pleted (ft.) (in.) million Date Remarks
35 John M. Coe Do 1947 32 27 2 1 7-4-50

Gulf Breeze
36 W. C. Coe
Gulf Breeze
37 Dixie Beggs
Gulf Breeze
38 Charlie Born
Gulf Breeze
39 A. M. Cohen
and J. Q. Owen
Gulf Breeze
40 Sam Hyams
Gulf Breeze
41 M. Parker
Pensacola

42 J. N.
Gulf
43 C. T.
Gulf
44 Do
45 Do
46 Do

47 Mary A. Duncan
Gulf Breeze

T. E. Harrison
Pensacola
James Eagins
Pensacola
Do

Alee Jackson
Pensacola

Do

Do

James Eagins
Pensacola
Do

Do
Do
Do
Do

1949

1949

1940

1949

1949

1949

1945

1943
1949
1940
1944

30

40

40?

38

26

18
46
35
28?

33

21

21

19

22

15
40
31
25?

2

3

3

3

2

1.5

12

13

11

13

15

14

12

135

35
83
12
11

4-19-50

7-4-50

7-4-50 Complete
in table 1.
4-20-50

7-4-50

4-20-50

4-20-50

4-20-50

4-20-50
4-20-50
4-20-50
7-14-50

analysis given

McLane
Breeze
Hoffman
Breeze

TABLE III.
RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA,

SANTA ROSA
Part B. SupD

COUNTY, FLORIDA
vy Wells-Continued

Date Total Depth Chloride content
Well cor- depth cased Diameter Parts per
number Owner Driller pleted (ft.) (ft.) (in.) million Date Remarks

48 Frank Giri
Groveland, Ala.
49 Geo. Hoffman
Pensacola
50 Do

51 Do
52 H. Pfeiffer
Pensacola
53 G. Pfeiffer
Pensacola
54 J. C. Pfeiffer
Pensacola
55 J. Tarber, Jr.
Pensacola
56 V. Quiroga
Gulf Breeze
57 M. X. Benson
Gulf Breeze
58 Do

59 P. Crook
Pensacola
60 N. C. Cook
Pensacola

James Eagins
Pensacola
Wilson Pump Co.
Pensacola
Do
James Eagins
Pensacola
James Eagins
Pensacola

C. E. Smith
Pensacola
Al Harrison
Pensacola
Charlie Malone?
Pensacola
C. E. Smith
Pensacola
T. E. Harrison
Pensacola
C. E. Smith
Pensacola

1935

1948

1948 ?
1935

34

25

25
21

1946

1935 ?

1950

1950

1942

1938

1938

33

40

35

35

28

36

30

30

13

10

14

14

1948 31 27 2 14

5-2-50

5-2-50

5-2-50

5-2-50
5-2-50

5-2-50

5-2-50

7-4-50

7-4-50

5-2-50

5-3-50

5-3-50

5-3-50

)I

TABLE III.
RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA,

SANTA ROSA

Part B. Supply

COUNTY, FLORIDA

Wells-Continued

Date Total Depth Chloride content
Well cor- depth cased Diameter Parts per
number Owner Driller pleted (ft.) (ft.) (in.) million Date Remarks

61 E. L. Bonifay
Gulf Breeze
62 0. T. Benson
Alabama
63 A. Johnson
Perisacola
64 A. Johnson
Pensacola
65 Eunice Hughey
Pensacola
66 A. Cafiero
-Gulf Breeze

67 M. X. Benson
Gulf Breeze
68 B. F. Benton
Pensacola
69 C. S. Goodrich
Gulf Breeze
70 R. R. Atwell
Gulf Breeze
71 Geo Atwell
Gulf Breeze
72 Mack Tripp
Gulf Breeze

E. L. Bonifay
Gulf Breeze
Alec Jackson
Pensacola
T. E. Harrison
Pensacola
T. E. Harrison
Pensacola
Harvey Hardware
Pensacola

D. L.
Brent.

Johnson

C. E. Smith
Pensacola
Mr. Hutchins
Pensacola
Rayford Woods
Pensacola
Al Harrison
Pensacola
Alec Jackson
Pensacola
Wilson Pump Co.
Pensacola

1937

1944

1949

1949

1948

1949

1940

1950

1946

1949

1949

1949

33

25

25

30?

120

42

41

28?

36

28

32

100

38

2

2

1.25

2

4

2

36

22?

31

18

22

10

10

11

14

151
162
159
13

13

16

5-2-50 Complete analysis
in table 1.
5-3-50

5-2-50

5-2-50

.5-3-50

5-3-50
7-14-50
11-30-50
5-3-50

5-2-50

5-2-50

5-2-50

5-3-50

5-4-50

given

TABLE III
RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA,
SANTA ROSA COUNTY, FLORIDA

Part B. Supply

Wells-Continued

Chloride content
Diameter Parts per
(in.) million Date

73 B. McClure
Gulf Breeze
74 Do

75 A. F. Gerhold
Gulf Breeze
76 Do

77 C. W. Parker
Pensacola
S78 W. D. Walker
Gulf Breeze
79 Do

80 Gulf Breeze
Cottages, Inc.
Gulf Breeze
81 Do
82 Grover Todd
Gulf Breeze
83 D. B. Williams
Gulf Breeze

C. E. Smith?
Pensacola
C. E. Smith
Pensacola
Harvey Hardware
Pensacola
Horace Rogers
Gulf Breeze
C. M. Roberts
Pensacola
C. E. Smith
Pensacola
T. E. Harrison
Pensacola
Harvey Hardware
Pensacola

Do
James Eagins
Pensacola
T. E. Harrison
Pensacola

1948

1950

1947

1947

1949

1938

1942

1944

1948
1948

35

29

39

22

31

35

46

37

38
20

30

24

31

20

28

30

40

29

28
16

4-21-50

4-21-50

4-20-50

1.5

3

3

3

3
2

1937 ? 41 35 2

12

13

13

14

14
11

4-21-50

5-2-50

5-2-50

5-2-50

5-2-50
5-2-50

16 5-3-50

Driller

Well
number

Owner

Date
lcom-
pleted

Total
depth
(ft.)

Depth
eased
< ft.)

Remarks

TABLE III
RECORDS OF WELLS ON THE WESTERN END OF FAIR POINT PENINSULA,
SANTA ROSA COUNTY, FLORIDA
Part B. Supply Wells-Continued

Date Total Depth Chloride content
Well co- depth eased Diameter Parts per
number Owner Driller pleted (ft.) (ft.) (in.) million Date Remarks

84 Boy Scouts of
America
Pensacola
85 Boy Scouts of
America
Pensacola
86 Do

87 Do

88 Mrs. L. Daniell
Pensacola
89 Girl Scouts of
America
Pensacola
90 Do

91 Boy Scouts of
America
Pensacola

Wilson Pump Co.
Pensacola

D. L. Johnson
Brent
Wilson Pump Co.
Pensacola
Do

T. E. Harrison
Pensacola
Wilson Pump Co.
Pensacola

1949

1938

1949

1949

1935 ?

1935 ?

1949

26

40?

35

26

55

23.5

37?

30

23.5

51.5

1.25.

12

1.25

5-3-50

5-3-50

5-3-50

5-3-50

5-3-50

40

27

2

1.25

5-3-50 Complete analysis given
in table 1.
5-3-50

Part II

Geologic and Hydrologic Features of

an Artesian Submarine Spring

East of Florida

By
V. T. Stringfield and H. H. Cooper, Jr.
U. S. Geological Survey

Prepared by the
UNITED STATES GEOLOGICAL SURVEY
In cooperation with the
FLORIDA GEOLOGICAL SURVEY

JUNE 1951

CONTENTS
Page
Introduction ..--..--__.--...---.- ----... __. ............ 61
Geology and hydrology -----......--------------...--- -...-..-..-.. --.....--------.... 63
Quality of the water ...--------.... ............. ---------------66
Relation of the fresh artesian water to salty water .....--..-. ... 69
Conclusions -----.....-. ----..-...--... -----------.. ------ 71
References ...-....-----..-...-- --. ----- -. ..... ---...--.--------- 72

ILLUSTRATIONS
Figure Page
1. Map of Florida showing the location of two submarine springs
and the piezometric surface of artesian water .-----.---- .....-----..-- 61
2. View of smooth surface formed by submarine spring in the
Atlantic Ocean about 21 miles east of Crescent Beach, Fla. -.... 62
3. Structure contour map of Florida showing top of the Ocala
limestone (after David B. Ericson) --------...-..--.. -------.. --........-- 64
4. Structure section across Putnam and St. Johns counties, Fla. 65
5. Section across Putnam and St. Johns counties, Fla., showing ex-
tent of salt-water contamination ------...... ....._--.--- ...----- .....--- -- ...------- 68
6. Map of Florida representing the area in which the artesian
water has a chloride content of 100 parts per million or more 70

GEOLOGIC AND HYDROLOGIC FEATURES OF AN ARTESIAN
SUBMARINE SPRING EAST OF FLORIDA
By
V. T. Stringfield and H. H. Cooper, Jr.
INTRODUCTION
The large artesian springs in Florida from the limestones of
Eocene age and younger are well known and have been described
in several reports of the United States Geological Survey and of
the Florida Geological Survey (see references 1, 2, 3, and 4).
However, the submarine springs off the coast of Florida are not
so well known, and only two of them-one in the Atlantic Ocean
about 21/2 miles east of Crescent Beach, in St. Johns County, and
the other in the Gulf of Mexico, about 500 feet west of Crystal
Beach, in Pinellas County (see fig. 1)-have been charted (5, 6).

Figure 1.-.Map of Florida showing the location of two submarine springs
and the piezometric surface of artesian water.

FLORIDA GEOLOGICAL SURVEY

The spring offshore from Crescent Beach has been described in a
previous paper (7) and is the subject of this paper.
The following discussion of the spring, prepared as part of the
cooperative ground-water investigations of the Florida Geological
Survey and the U. S. Geological Survey, is given because of the
significance of submarine discharge in relation to studies of ar-
tesian conditions and salt-water contamination in the coastal areas.
The spring forms a more or less smooth surface where its
water emerges at the surface of the ocean (see fig. 2). As de-

.. I. o' ttl^t^i'^. .
'fv

(Photo by Herman Gunter).
Figure 2.-View of smooth surface formed by submarine spring in the
Atlantic Ocean about 21/2 miles east of Crescent Beach, Fla.
scribed by A. M. Sobieralski (7), of the U. S. Coast and Geodetic
Survey, "The location of the spring may easily be detected by the
appearance of the water; noticeable swirls, similar to those in
a swiftly running stream, can be seen at a distance of about a
mile. At times, especially in rough weather, there is a marked
disturbance of the water-a yellowish color which trails off to
the northeastward. In choppy weather, a 'slick' is the most notice-
able feature. In fact, it has all the appearance of a shoal or reef.
"A closer view shows a slick swirl with a slight overall, the
center of the swirl moving about 100 feet, first to the eastward and
then to the westward with a noticeable streak of current to the
northeastward. The swirls and overfalls vary rapidly in intensity

REPORT OF INVESTIGATIONS No. 7-II

as though large bubbles or intermittent volumes of water were
being emitted. A boat will be thrown out of the swirl, so that it
is difficult to hold it in position.
"The ocean bed in the vicinity of the spring is comparatively
level and about 55 deep, composed of fine gray sand. The spring
emerges from a hole only about 25 feet in diameter and 125
feet deep or 69 feet below the bed.,.
"To the northeast of the center of this spring, the hole is en-
larged to a diameter of about 300 feet; this shape of the en-
larged hole probably directs the current from the spring in the
northeasterly direction noted on the surface."
Some of the boil and swirls may be attributable to convection
rather than large discharge. However, the fact that the hole, 69
feet in depth below the ocean floor, through which the spring
flows, is not filled with sediment indicates a large discharge.

The shape of the spring is more or less characteristic of the
large limestone springs in Florida. In the limestone springs the
water emerges vertically under artesian pressure through fissures,
sinkholes, or circular openings, some of which are more than 100
feet deep. The available information indicates that the sinkholes
and subterranean channels were formed principally during Pleis-
tocene time when the sea stood at lower levels than it does at the
present time, and the circulation through the limestone was more
rapid. As the sea rose to its present level some of the artesian
water began discharging through the sinkholes, which thus became
springs, some of which are submarine.
GEOLOGY AND HYDROLOGY
The aquifer that yields water to the submarine spring and
the large terrestrial limestone springs in Florida has a thickness
of more, than 500 feet. It consists of the Ocala limestone and older
Eocene limestones, and, in some places, limestones of Oligocene
age and the Tampa limestone of Miocene age. These formations
form a broad arch or anticline that trends northwestward and
plunges toward the southern part of the State as shown in figure 3,
which represents approximately the top of the Ocala limestone.

A geologic cross section (fig. 4) extending westward from the
submarine spring across St. Johns and Putnam Counties toward
the crest of the Ocala arch shows the position of the Ocala lime-

63

FLORIDA GEOLOGICAL SURVEY

Figure 3.-Structure contour map of Florida showing top of the Ocala
limestone (after David B. Ericson).

stone and the overlying Hawthorn formation. In this section the
aquifer consists only of the Ocala limestone and older Eocene
limestones. The Hawthorn formation of Miocene age and younger
material overlie the Ocala limestone and serve as confining beds
for the artesian water. The limestones of Oligocene age and the
Tampa limestone are absent in this area. Along the cross section
the Ocala limestone dips gently toward the east. The top of the
Ocala is an irregular eroded surface, and its position is known
only approximately. It is above sea level in the western part of
the section and is estimated to be about 150 feet below sea level
at the submarine spring. A comparison of the estimated depth
to the Ocala limestone with the soundings of the U. S. Coast and
Geodetic Survey indicates that the thickness of the material over-
lying the Ocala at the spring is about 100 feet, and that the spring

64

fOcean floor

DEPOSITS

7,

Approximate scale in miles

Figure 4.-Structure section across Putnam and St. Johns counties, Florida.

surface

/

ATLANTIG OCEAN

OCALA

Id

UaS
0 J

u's
w
(I)

20

Z
!o-
100

0

-100 3
"3

a

-~rlrrC~

FLORIDA GEOLOGICAL SURVEY

vent penetrates this material. It appears, therefore, that the
spring is derived from the Ocala limestone.
In the western part of the section (fig. 4), in the vicinity of
Putnam Hall, the artesian aquifer receives recharge through sink-
holes that extend through the relatively impervious Hawthorn
formation into the Ocala limestone. Some of these sinks are open
and others are filled with permeable sands through which water
may percolate downward into the limestone aquifer. The areas in
which recharge occurs are indicated by the configuration of the pie-
zometric surface-the imaginary surface representing the height
to which water rises in tightly cased wells that penetrate the
limestone aquifer (figs. 1 and 4). Generally, the piezometric sur-
face is high where there is recharge and low where there is
discharge. Thus, the piezometric surface is about 90 feet above
sea level in the recharge area around Putnam Hall, and about 30
feet above sea level at Crescent Beach, about 21/2 miles west of
the submarine spring. As shown in figure 4, some of the water
that enters the aquifer at the recharge area moves eastward a
distance of about 50 miles and feeds the spring.
As indicated by the lowness of the piezometric surface, the
submarine discharge of artesian water is not confined to the sub-
marine spring, but occurs offshore along the coast from St. Johns
County to Brevard County. A large discharge in this area is to be
expected, because the Ocala limestone in much of the area is less
than 100 feet below sea level and is only about 55 feet below the
ocean floor, so that conditions are favorable for natural discharge.
North and south of this area of discharge, where the Ocala
limestone is overlain by several hundred feet of relatively im-
pervious material that prevents or retards the discharge of
artesian water, the artesian pressure is higher.
Part of the water entering the recharge area moves to the
west coast as indicated in figures 1 and 4. A comparison of the
profile of the piezometric surface with the top of the Ocala lime-
stone west of Putnam Hall, in figure 4, indicates that the artesian
water moves without relation to the geologic structure. In other
words, the artesian water moves westward up the dip, toward
the crest of the Ocala arch.
QUALITY OF THE WATER
The artesian water is relatively hard calcium bicarbonate
water, as is usual in a limestone aquifer. The hardness increases

6(

REPORT OF INVESTIGATIONS No. 7--II

with distance from the recharge area, ranging from less than
100 parts per million in the recharge area to more than 500 parts
per million on the east coast. In the recharge area the chloride
content of the water is less than 15 parts per million, and as far
east as Bostwick (see fig. 5) it is less than 50 parts per million.
Near Hastings, about 20 miles west of the coast, the chloride con-
tent is about 200 parts per million; at Elkton it is about 300 parts
per million; and at Crescent Beach it is about 4,000 parts per
million.
A sample of water taken from the bottom of the spring in
1934 by Herman Gunter, State Geologist of Florida, Frank C.
Westendick, then Assistant Geologist of the Florida Geological
Survey, and the senior author had approximately the same chlo-
ride content as sea water, and doubtless was contaminated with
sea water. Several samples taken from the bottom of the spring
and from the surface of the ocean in 1943 by A. P. Black, Pro-
fessor of the University of Florida, and G. E. Ferguson and S.
K. Love, of the U. S. Geological Survey, had chloride contents about
the same as that of sea water. Samples collected by the U. S.
Coast and Geodetic Survey from the bottom of the spring in
1923 had specific gravities that suggested admixtures of ocean
water with the spring water.
The fact that the samples of water were apparently heavily
contaminated with ocean water indicates that ocean water may
move to the bottom of the spring vent by convection while the
spring water rises to the surface. Conceivably, the ocean water
may move into the limestone channel that supplies the spring
during high tides and discharge from the spring as the tides
recede. It is pertinent in this connection that a flow of sea water
into the submarine spring offshore from Crystal Beach, in Pinellas
County, was recently observed by a diver, during a high tide, while
he was examining the bottom of the spring.* However, such a
reversal of flow would occur only in a spring around which the
artesian pressure is very low.
With an air temperature of 71F., the temperature of the
water, as determined by the U. S. Coast and Geodetic Survey,
ranged from 62 to 64F., at the surface and at a few points below
the surface, except for a measurement of 711/2F. at a depth of
121 feet. The temperature of the artesian water along the coast
*-Personal communication from W. A. McMullen, Jr., County Engineer, Pinellas County.

67

0=

E C
o C
a c
= 0

Land surface S
S-- ------- mtric surface 100

0 1010
..^d ,, s o o

n u00 1 Theoretical contact between salt
Swater and fresh waterSTRATA

I I
pr s s

/'*- -.Theoretical contact between salt
water and fresh water 5
S- --

/ 10K) 0 10 20
Aproxim sc in mile
-__/_

Figure 5.-Section across Putnam and St. Johns counties, Fla., showing extent of

salt-water contaminartion.

REPORT OF INVESTIGATIONS No. 7-II

of St. Johns County ranges from 740 to 82F. The fact that the
temperature at the bottom of the spring was slightly lower than
that of the artesian water is probably a result of an admixture
of relatively cool sea water with the spring water.
The spring water has a distinct hydrogen sulfide odor, which
is a characteristic feature of much of the artesian water in the
Florida peninsula.
Early oral accounts of the spring indicate that at one time
its water emerged at the surface of the ocean relatively fresh,
and that fishermen used the water for drinking. It appears quite
possible that the artesian water from the spring, if it were un-
contaminated with sea water, might be of about the same quality
as the water from wells at Crescent Beach, but it appears doubtful
that the water could have risen through 55 feet of sea water and
yet have emerged at the surface relatively fresh, unless it is
supposed that the jet of the spring was once much stronger than
it is now. Any decrease in discharge that might have weakened
the jet may be attributed either to a decline in the artesian
pressure over the general area or to a collapse of the limestone
channel that feeds the spring. However, the records of the
artesian pressure show that there has been no decline in pressure
sufficient to account for a considerable decrease in discharge. Al-
though the possibility of a decrease in discharge due to a collapse
of the limestone channel cannot be eliminated, one is nevertheless
inclined to doubt that there ever was, in the remembrance of
man, a discharge sufficient to produce potable water at the ocean
surface.
RELATION OF FRESH ARTESIAN WATER TO SALTY WATER
In part of the coastal area of Florida and in part of southern
Florida, the artesian water at moderate depths is salty. Within
the area indicated by shading in figure 6, the chloride content
ranges'from one hundred parts per million to several thousand
parts per million. This widespread occurrence of salty artesian
water along the coast has occasionally been erroneously attributed
to an encroachment of salt water from the sea.
Certain general relations pertaining to the encroachment of sea
water in coastal areas have been summarized by Brown (8). The
principle of equilibrium between fresh water and salt water, as
applied to seacoasts, may be expressed by the formula h= --
g-1

69

FL3RIDA GEOLOGICAL SURVEY

Figure 6.-Map of Florida representing the area in which the artesian
water has a chloride content of 100 parts per million or more.
in which h is the depth of fresh water below sea level; t is the
height of fresh water or hydrostatic head with reference to sea
level; and g is the specific gravity of salt water. The specific
gravity of sea water is generally considered to be 1.025, but it
varies somewhat from one locality to another, and may also vary
with depth. Where the specific gravity of sea water is 1.025, the
fresh water will, according to the formula, extend 40 feet below
sea level for every foot that the ground water stands above sea
level. This relationship is applicable to artesian conditions only
when proper allowance is made for the effects of impervious strata
and artesian pressures. The formula is not applicable in the
vicinity of the submarine spring because the artesian pressure is
sufficient to preclude any entrance of sea water into the aquifer
and to maintain a discharge of artesian water into the sea where
ever there are submarine passages through the confining layer.

70

REPORT OF INVESTIGATIONS No. 7-II

For purposes of comparison the theoretical contact of fresh
water and sea water, as determined by the formula, is shown in
figure 5. Chloride analyses of samples from many wells have
shown that salty water occurs much higher in the aquifer than
the theoretical contact. For example, water having a chloride con-
tent of 4,000 parts per million is yielded by a well only 300 feet
deep at Crescent Beach, whereas the theoretical depth to sea
water (which has a chloride content of about 19,000 parts per
million) is about 1,200 feet.
It appears, therefore, that the salinity of artesian water can-
not be a result of an encroachment of sea water under conditions
as they are today. The two remaining possible sources of the
salty water are, first, connate water or connate salt, or, second,
sea water that entered the formations prior to Recent time.
During the last glacial stage of the Pleistocene epoch the sea
stood several hundred feet lower that it is now, and the more
active circulation of ground water that occurred as a result of
this condition formed many solution channels in the aquifer and
probably flushed out most of the connate water and other salty
water. While the sea was low, a surface stream that followed a
course that is in part the same as the St. Johns River cut a chan-
nel as much as 100 feet below the present sea level. In late Pleis-
tocene time, when the Pamlico terrace was formed, and the sea
stood as much as 25 feet above its present level, the aquifer was
exposed at the ocean floor over a large area and became completely
filled with sea water. In the coastal area between St. Augustine,
Fla., and Savannah, Ga., where the chloride content of the ar-
tesian water is less than 50 parts per million, the Pleistocene sea
water was excluded from the aquifer by a high artesian pressure
and by a cover of as- much as 500 feet of the Hawthorn formation.
From these considerations it appears that the relatively high
chloride content of artesian water in the aquifer in the spring
area is due to incomplete flushing of sea water that entered the
Eocene limestone in Pleistocene time. In two areas in Putnam and
Volusia counties, where local recharge occurs, the flushing is
complete in the upper part of the aquifer (see fig. 6).
CONCLUSIONS
The submarine spring 21/2 miles east of Crescent Beach, Fla.,
is an example of artesian discharge from the principal artesian
aquifer (Eocene, Oligocene, or Miocene limestones) into the At-

FLORIDA GEOLOGICAL SURVEY

lantic Ocean, as indicated by the piezometric surface and the
hydraulic gradient of the artesian water (figs. 1 and 4). Water
feeding the spring enters the aquifer about 50 miles west of
it. Although no sample of water free from contamination with
sea water has yet been collected from the spring, it is believed
that the chloride content of an uncontaminated sample would be
no less than that of artesian water at Crescent Beach-about 4,000
parts per million.
The available geologic and hydrologic data do not support the
oral reports that the spring once yielded fresh water at the sur-
face of the ocean.

The relatively high chloride content of the artesian water along
the coast of Florida is a result of sea water that entered the aquifer
during Pleistocene time and that has not yet been completely
flushed from it.

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

(2) Meinzer, O. E., 1927, Large springs in the United States: U. S.
Geol. Survey Water-Supply Paper 557.

(3) Cooke, C. Wythe, 1939, Scenery of Florida: Florida Geol. Sur-
vey Bull. 17.

(4) Ferguson, G. E., Lingham, C. W., Love, S. K., and Vernon, R.
0., 1947, Springs of Florida: Florida Geol. Survey Bull. 31.
(5) U. S. Coast and Geodetic Survey chart 3258, Florida inside
route, St Augustine to Titusville, 1931; also, U. S. Coast and
Geodetic Survey Chart 1111, U. S. East Coast, Charleston
Light to Cape Canaveral, 1932.
(6) U. S. Coast and Geodetic Survey chart 1257, Tampa Bay and
St. Joseph Sound, 1943.
(7) Rude, G. T., 1925, St Augustine and its oceanic spring: Geog.
Soc. Philadelphia Bull., vol. 23, no. 3, pp. 85-91.
(8) Brown, J. S., 1925, A study of coastal ground water with
special reference to Connecticut: U. S. Geol. Survey Water-
Supply Paper 537.

72

Part III

Cessation of Flow of Kissengen Spring

in Polk County, Florida

By
Harry M. Peek
U. S. Geological Survey

Prepared by the
UNITED STATES GEOLOGICAL SURVEY

In cooperation with the
FLORIDA GEOLOGICAL SURVEY

JUNE 1951

CESSATION OF FLOW OF KISSENGEN SPRING
IN POLK COUNTY, FLORIDA
By Harry M. Peek

Kissengen Spring, formerly one of the largest of the numerous
artesian springs of the Florida peninsula*, has ceased to flow.
For several decades it provided bathing and recreational facili-
ties for tourists and residents of the Bartow area in Polk County,
Fla. (figs. 1 and 2). In February 1950 it became the only major
artesian spring of Florida to cease flowing completely.

N

/ ATLANTIC
GULF OF OCEAN
MEXICO

FIGURE IA-MAP OF POLK COUNTY SHOWING LOCATION FIGURE 1I-MAP OF FLORIDA SHOWING
OF KIOSSNEN SPRING AND AREA INVESTIGATED LOCATION OF POLK COUNTY

Records of the United States Geological Survey show that
the discharge of the spring was about 20 million gallons a day
when it was first measured in 1898, Miscellaneous measure-
ments made prior to 1982 are shown in the following tablet

Cubic feet Million gallons
Date per second per day
Dec. 21, 1898 81 20
Feb. 25, 1917: 21.8 14
Feb. 5, 1929 84.7 22
Sept. 14, 1980 80.5 20
May 28, 1981 84.0 22

Monthly measurements of the discharge were begun in March
1932 (fig. 4A). During the five-year period ending in 1936, the

-Fergubon, G. Ei, iinghath, C, W,,: Love, S. K., and Vernon, It 0., 1947, Springs of
Florida: Florida Geol. Survey Bull. 81.
+-Idehi, p. 142.

76 FLORIDA GEOLOGICAL SURVEY

Figure 2A. Kissengen Spring in April 1947.

Kissengen Spring in 1950.

Figure 2B.

REPORT OF INVESTIGATIONS No. 7-III

flow averaged about 19 million gallons a day. After 1936, how-
ever, the flow declined progressively until, in February 1950,
it ceased altogether.

In May and June 1950 the writer made a brief study to de-
termine the cause of the decline and subsequent cessation of the
flow of the spring. This study was made as a part of the coopera-
tive program of ground-water investigations in Florida by the
U. S. Geological Survey and the Florida Geological Survey. The
field work and the preparation of this paper were accomplished
under the supervision of H. H. Cooper, Jr., District Engineer of
the U. S. Geological Survey, and with the approval and advice
of Dr. Herman Gunter, Director of the Florida Geological
Survey. The field work consisted primarily of an inventory of the
consumption of ground water by the major users in southwestern
Polk County (fig. 1).

The water that supplies most of the artesian springs and
wells of peninsular Florida is derived from a series of limestones
of Tertiary age that forms an extensive ground-water reservoir
several hundred feet thick. The aquifer yields water to many
springs and artesian wells in the Florida peninsula and formerly
also to Kissengen Spring. It consists of the Ocala limestone and
older Eocene limestones, the Suwannee limestones of Oligocene
age, and the Tampa limestone of Miocene age. In Polk County,
these limestones are overlain by the Hawthorn formation of
Miocene age, which consists mainly of interbedded sand, clay,
and marl. The Hawthorn formation contains beds of permeable
sand and limestone that yield water to shallow wells, but the
relatively impervious clay, marl, and silty sand throughout most
of the peninsula serve as a confining bed for the artesian water.

As revealed by Stringfield*, water enters the limestone aquifer
in the. lake region of northern Polk County through numerous
sinkholes, filled with permeable material, that penetrate the Haw-
thorn and younger formations. The water collects in the sink-
holes by runoff from the land surface and also by ground-water
seepage from the permeable beds in the Hawthorn formation and
above the Hawthorn formation; it then percolates downward to
recharge the limestone, as shown diagrammatically in figure 3.
The direction of lateral movement of the water through the aqui-
*-Stringfield, V. T., 1936, Artesian water in the Florida peninsula: U. S. Geol. Survey
Water-Supply Paper 773-C, p. 148.

FLORIDA GEOLOGICAL SURVEY

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fer may be determined from the configuration of the piezometric
surface-an imaginary surface representing the height above
sea level to which water will rise in tightly cased wells (fig. 5);
water flows at right angles to the contours-the direction of the
steepest gradient. The water flows from the intake area, where

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REPORT OF INVESTIGATIONS No. 7-III

the piezometric surface is relatively

high, through the many

pores and caverns in the limestone, to the discharge area where

the piezometric surface is lower.

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FLORIDA GEOLOGICAL SURVEY

Flowing artesian wells and springs occur only when and
where the piezometric surface is above the land surface. A natural
channel leading from the aquifer to the land surface will form
a spring if the artesian head in the aquifer is sufficient to raise
the water above the land surface. If the piezometric surface
declines to a level below the vent of a spring, as it did at Kis-
senegen Spring, the flow of that spring will cease.

One aspect of the cessation of flow of the spring, which is
of special interest to the ground-water hydrologist, is that it
represents one of the few observable examples in Florida of the
capture of natural discharge of ground water by the withdrawal
of water from wells. It is generally recognized by ground-water
hydrologists that the water withdrawn from wells must be de-
rived from (1) an increase in the natural replenishment of water
to the aquifer, (2) a decrease in the natural discharge from the
aquifer, or, temporarily, (3) a reduction of the water stored in
the aquifer. In most cases the water withdrawn from wells is
probably derived from a combination of these changes rather
than from any one of them.
The discharge of Kissengen Spring was captured temporarily
once before during the drilling of an oil test well a few hundred
feet northwest of the spring. An account of this capture is given
in the original field notes of P. R. Speer, dated February 5, 1929,
as quoted by Lingham:*
"An oil test well about 300 feet east of spring was started drilling
in July 1927 and at the 220 foot depth tapped the spring flow practi-
cally draining it. It was cased and continued to 4,700 feet striking
a strong sulphur artesian flow the entire way. The casing is so ar-
ranged that it drains this flow back into the spring cavity and at the
time this was accomplished a noticeable increase in the spring flow
was reported by raising its elevation. This probably accounts for
some of the increase over the measurement of 1917."
Figures 4A, 4B, and 4C diagrammatically show the flow of
Kissengen Spring and for comparison, the use of ground water
in southwestern Polk County from 1931 to 1950 and the monthly
rainfall at Bartow. Seasonal fluctuations of rainfall caused cor-
responding fluctuations of the discharge from the spring, but
as there was no progressive decrease in the annual rainfall during
the period shown, a possible decrease in recharge may be dis-
counted as a cause of the progressive decline in the,flow of the
spring.
*-Ferguson, G. E.. Lingham, C. W., Love, S. K., and Vernon, R. 0., 1947, Springs of
Florida: Florida Geol. Survey Bull. 81, p. 141.

80

REPORT OF INVESTIGATIONS NO. 7-III

-/ I- .___;.__-_____''______" -" __-!____ I
( ,,, ( ...... j .-'1"" ,.,., 0 oE 0 R G I A ,.

ei the", Itwithdraw'l Iro
_xInA\o- ra-r.... a a a 4...''1

t -- -t-at- --a i| maipti a t --- --- 6r0 11 l1

wells was increased, beginning in 1937, the natural balance be-
tween recharge and discharge was upset, and a decline of the
face, in turn, caused the discharge of the spring to decrease
___,,-,_-_T .. .... .

progressively until it finally ceased.

The present maximum withdrawal of ground water in south-
western Polk County is approximately 110 million gallons a day,
of which about 75 million gallons a day is used by the phosphate
companies. About 20 million gallons of the total withdrawal is
derived from the capture of the flow of Kissengen Spring, and
the balance of 90 million gallons a day is derived partly from de-
creases in other natural discharge, partly from an increase in

82 FLORIDA GEOLOGICAL SURVEY

recharge, and-so long as a decline of the piezometric surface
continues-partly from a slight reduction in the amount of water
stored in the aquifer.
If there is no further increase in withdrawal, the piezometric
surface will cease to decline and will remain relatively stable. If
the rate of withdrawal of water is decreased sufficiently, all other
factors remaining the same, the piezometric surface will rise and
Kissengen Spring will begin to flow again. However, if the rate
of withdrawal increases, a further decline of the piezometric sur-
face may be expected.

FLRD GEOLOSk ( IC SUfRiW

COPYRIGHT NOTICE
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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
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Under the Statutes of the State of Florida (FS 257.05; 257.105, and
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the Florida Geologic Survey, as a division of state government,
makes its documents public (i.e., published) and extends to the
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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.

	Front Cover
	Front Matter
	Table of Contents
	Part 1. Potential yield of ground...
	Part 2. Geologic and hydrologic...
	Part 3. Cessation of flow of Kissengen...

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