Interim report on the ground-water resources of Putnam County, Florida ( FGS: Information circular 15 )

STATE OF FLORIDA
STATE BOARD OF CONSERVATION
Ernest Mitts, Director

FLORIDA GEOLOGICAL SURVEY
Robert O. Vernon, Director

INFORMATION CIRCULAR NO. 15

INTERIM REPORT
ON
THE GROUND-WATER RESOURCES
OF
PUTNAM COUNTY, FLORIDA

By
Gilbert W. Leve, Geologist
U. S. Geological Survey

Prepared by U. S. Geological Survey
in cooperation with the Florida Geological Survey

Tallahassee, Florida
1958

TABLE OF CONTENTS

Page

Abstract . . . .
Introduction . . . .
Previous investigations . .
Well-numbering system . .
Geography . . . .
Geology ........ .........
Ground water ..............
Nonartesian aquifer . . ..
Artesian aquifer .. ....
Piezometric surface . ..
Area of artesian flow ... .
W ells . . . .
Quality of water...... ....
Salt-water contamination . .
Summary and conclusions . .
References . . . .

ILLUSTRATIONS
Figure

1 Map of Florida showing the location of
Putnam County .................
2 Generalized geologic section showing the
formations penetrated by water wells in
Putnam County .................
3 Diagram comparing the velocities of water in
well 943-144-1, six miles northwest of Palatka
when water is flowing from the well and when
no water is flowing from the well . .
4 Hydrographs of wells 939-138-1 and 925-138-1
5 Map of Putnam County showing the piezometric
surface . . . . . .
6 Map of Putnam, St. Johns and Flagler
counties showing the piezometric surface ..
7 Map of Putnam County showing the area of
artesian flow ..................

j j

*
.
.

8 Maps of the farming area east of Palatka
showing the height to which water will rise
above the land surface in wells that penetrate
the artesian aquifer and the area of artesian
flow. . . . .. .. 21
9 Map of Putnam County showing the locations
of wells.. ..... .. .. .. .. 23
10 Map of Putnam Countyshowing-th'e.approxi-
mate chloride content of water from the
artesian aquifer ..... ..' .. .. .26
11 Graph showing the relation between the chloride
content of the water and the water level in well
940-134-2, three miles northeast of Palatka 28

Table

1 Analyses of water from wells in Putnam

Page

Figure

County . .

. . . 25

INTERIM REPORT ON THE GROUND-WATER

RESOURCES OF PUTNAM COUNTY, FLORIDA

By
Gilbert W. Leve

ABSTRACT

Putnam County, in the northeastern part of the Florida
Peninsula, has an area of 803 square miles. Sand, clay,
and peat of Pleistocene and Recent age are exposed at the
surface. They are underlain by deposits of Miocene or
Pliocene age that consist principally of clay with a thin,
fairly widespread limestone at the base. The Miocene or
Pliocene deposits are underlain by limestones of Eocene
age whose upper surface ranges from about 25 feet to about
170 feet below sea level.

Ground water in the county occurs under both nonarte-
sian (water-table) and artesian conditions. Pleistocene and
Recent sands contain water under nonartesian conditions.
The limestones underlying the Miocene or Pliocene clay
contain water under artesian conditions, and locally the
water inbeds of sand and shell withinthe Miocene or Pliocene
deposits is artesian. The artesian aquifers are replenished
by rain falling on recharge areas partly or completely within
the county.

Records of water level show maximum seasonal fluctu-
ations of 10 feet and a progressive decline of artesian head
in recent years. The most. pronounced seasonal fluctuation
is in the winter vegetable farming area, east of Palatka,
where discharge from irrigation wells lowers the artesian
head and reduces the area of artesian flow during times of
heaviest withdrawals.

The chloride content of water from wells in the principal
artesian aquifer ranges from less than two ppmto 1, 080 ppm.
Water of the lowest chloride content is in and near recharge

FLORIDA GEOLOGICAL SURVEY

areas in the upper part of the aquifer; water of the highest
chloride content is in discharge areas, where the artesian
head is lowest. In areas of seasonal discharge, the chloride
content increases when the artesian head declines and de-
creases when it recovers.

INTRODUCTION

The economy of Putnam County is largely dependent
upon the income from winter vegetables. From December 1,
1954, to November 30, 1955, the gross income from the
marketing of Irish potatoes and cabbage was approximately
four million dollars. 1 .The most important farming-area is
in the lowlands east of Palatka, where adequate supplies of
water for irrigation are available from flowing artesian
wells.

In recent years there has been a decline in the artesian
head in the farming area near Palatka. This decline has
resulted in a decrease in the area of artesian flow, and
necessitated the use of pumps in wells that had previously
produced an adequate supply of water by natural flow. In
addition to the loss of artesian,head, there has been a
noticeable increase in the salt content of the water.

Recognizing the threat to the fresh-water supplies of
the county, the U. S. Geological Surveyand the Florida Geo-
logical Survey decided to make an investigation of the ground-
water resources of the county in conjunction with similar
investigations in adjoining St. Johns and Flagler counties.
The investigation was begun in February 1956.

The purpose of the investigation is to make a detailed
study of the geology and ground-water resources of the
county. Special emphasis has been placed on the problems
of declining water levels and salt-water contamination.

iH. E. Maltby, County Agent, Putnam County, Florida,
personal communication, October 1956.

INFORMATION CIRCULAR NO. 15

This report reviews briefly the progress of the investiga-
tion through November 1956. The investigation consists of
the following phases:

1. An inventory of wells, to obtain information on
the location, diameter, depth, yield, water
level, use, etc.

2. Periodic collection and study of water-level
data, to determine the seasonal fluctuations
and progressive trends.

3. Analysis of the chloride content of ground
water, to determine the location and extent of
areas in which the water is salty.

4. Periodic analyses of water from selected wells
to determine the chloride content and the re-
lation between chloride content and artesian
pressure.

5. Studies to locate the water-bearing zones and
to determine their water-transmitting and
water-storing capacities.

6. Studies of the subsurface geology, to determine
the thickness, character, and extent of the dif-
ferent geologic formations.

The investigation was made under.the general super-
vision of A. N. Sayre, Chief, Ground Water Branch, U.S.
Geological Survey, and under the immediate supervision of
M. L Rorabaugh, District Engineer for Florida.

Previous Investigations

No detailed investigations of the geology and ground-
water resources of Putnam County had been made prior to
the present study. However, reports on several general
investigations have included information on the county.
These have been published by the U. S. Geological Survey
and the Florida Geological Survey. Some of them are men-
tioned below.

FLORIDA GEOLOGICAL SURVEY

Cooke (1945, p. 225, 236, 285, 291, 296, 310) briefly
describes formations exposed at the surface in the county.
A report by Vernon (1951, fig. 13, 33; pl. 2) includes
Putnam County in generalized subsurface structural maps
and in a generalized geologic cross section.

The geology and ground water of Putnam County are
discussed by Stringfield (1936, p. 147, 149-151, 162, 173,
187, 195; pl. 10, 12, 16) in a report on the artesian water
in the Florida Peninsula. This report includes a map show-
ing the area of artesian flow, a map showing the areas in
which the artesian water contains more than 100 ppm of
chloride, and the first published map of the piezometric
surface of the principal artesian aquifer. It also contains
water-level measurements and other data on 26 wells in the
county. A report by Stringfield and Cooper (1951, p. 61-72;
fig. 4, 5, 6) contains a geologic cross section and a brief
discussion of the artesian water of Putnam County.

Chemical analyses of water from wells in Putnam County
are includedin reports by Collins and Howard (1928, p. 226-
227), and Black and Brown (1951, p. 96).

Matson and Sanford-(1913, p. 391-393; pl. V) discussed
the topography and stratigraphy of Putnam County and the
occurrence and quality of ground water in the county. Their
report included also a table of well descriptions and logs of
three wells.

A report by Sellards and Gunter (1913, p. 206-213;
fig. 8) contains a map showing the area of artesian flowing
Putnam County, the log of an irrigation well near Orange
City, and chemical analyses of water from a well at Palatka
and a well at Welaka. It also contains descriptions of the
construction and yields of several wells in the county.

Well-Numbering System

Each well inventoried during this investigation was as-
signed an identifying well number. The well number was
assigned by first locating each well on a map which is divided

INFORMATION CIRCULAR NO. 15

into 1-minute quadrangles of latitude and longitude, then
numbering, consecutively, each inventoried well in a quad-
rangle. The well number is composed of the last three
digits of the line of latitude south of the well, followed by
the last three digits of the line of longitude east of the well,
followed by the number of the well in the quadrangle. For
example, well 939-134-1 is the well numbered 1 in the quad-
rangle bounded by latitude 29039' on the south and the longi-
tude 81034' on the east. With this system, wells referred
to by number in the text can be located on figure 9.

GEOGRAPHY

Putnam County, in the northeastern part of the Florida
Peninsula, has an area of 803 square miles, nominally
513, 920 acres (fig. 1). The mean temperature in the area
is about 720F, according to the records of the U. S. Weather
Bureau. The average annual rainfall at Palatka is 54. 59
inches, of which an average of 29. 16 inches falls between
June 1 and September 30.

Topographically Putnam County maybe divided into two
units: (1) relatively flat lowlands and (2) hilly uplands. The
lowlands are in the eastern and central parts of the county,
in the vicinity of Palatka and San Mateo, and in a large strip
between Crescent Lake and the St. Johns River. The land
surface of the lowlands ranges in altitude from about sea
level to about 42 feet above sea level, where the lowlands
merge into the hilly uplands. The hilly uplands occupy the
remainder of the county. The surface features of this area
consist of a few relatively level areas, numerous sandhills,
and sinkholes. The sinkholes were formed by the removal
of soluble limestone by ground water. In most cases these
sinkholes have been partly filled with water to form lakes.
The land surface of the uplands ranges in altitude from 42
feet above sea level, where it merges with the lowlands, to
more than 220 feet above sea level, but most of the area is
between 100 and 150 feet above sea level.

The surface drainage of the county is principally through
the St. Johns River and its tributaries. The hilly uplands,
especially in northwestern Putnam County and between

FLORIDA GEOLOGICAL SURVEY

Figure 1. Map of Florida, showing the location of Putnam
County.

INFORMATION CIRCULAR NO. 15

Crescent Lake and the St. Johns River, are partly drained
- through lakes and sinkholes into the limestone aquifer.

GEOLOGY

A few sets of well cuttings collected during the current
investigation and unpublished well logs in the files of the
Florida Geological Survey were used to construct figure 2,
a generalized geologic cross section showing the formations
penetrated by wells in Putnam County. The two lowermost
formations shown in figure 2 have beenpenetrated by only a
few water wells in the county, because the overlying forma-
tions generally yield sufficient water for domestic and irri-
gation: supply. Information on these two formations were
obtained from- logs of two -relatively deepwells described
by Vernon (1955).

The oldest formation shown in figure 2 is the Lake City
limestone of early middle Eocene age. It is predominantly
a tan to gray soft granular, porous limestone containing
zones of hard, dense finely crystalline limestone and dolo-
mite. The Avon Park limestone, of late middle Eocene age,
overlies the Lake City limestone and is predominantly a tan
dense, hard finely crystalline dolomite. It is 235 feet thick
in well 943-144-1, in the central part of the county.

The beds. of late Eocene age are referred to in this
report as the Ocala group. They include, in ascending
order, the Inglis, the Williston, and the Crystal River for-
mations (Puri, 1953,- p. 130). During the present investi-
gation no attempt was made to differentiate these formations.

The Ocala group in Putnam County consists of cream to

The stratigraphic nomenclature used in -this report
conforms to the usage of the Florida Geological Survey. It
conforms also to the usage of the U. S. Geological Survey
with the exception of the Ocala group and its subdivisions.
The Florida Survey has adopted the Ocala group as described
by Puri (1953). The Federal Survey regards the Ocala as a
formation, the Ocala limestone.

7"
r
"1*
t
0)

Ocalo

Avon Park

Lake City

Generalized geologic section showing the
water'wells in Putnam County.

group

limestone

limestone

formations penetrated by

Figure 2.

/

INFORMATION CIRCULAR NO. 15

Crescent Lake and the St. Johns River, are partly drained
- through lakes and sinkholes into the limestone aquifer.

GEOLOGY

A few sets of well cuttings collected during the current
investigation and unpublished well logs in the files of the
Florida Geological Survey were used to construct figure 2,
a generalized geologic cross section showing the formations
penetrated by wells in Putnam County. The two lowermost
formations shown in figure 2 have beenpenetrated by only a
few water wells in the county, because the overlying forma-
tions generally yield sufficient water for domestic and irri-
gation: supply. Information on these two formations were
obtained from- logs of two -relatively deepwells described
by Vernon (1955).

The oldest formation shown in figure 2 is the Lake City
limestone of early middle Eocene age. It is predominantly
a tan to gray soft granular, porous limestone containing
zones of hard, dense finely crystalline limestone and dolo-
mite. The Avon Park limestone, of late middle Eocene age,
overlies the Lake City limestone and is predominantly a tan
dense, hard finely crystalline dolomite. It is 235 feet thick
in well 943-144-1, in the central part of the county.

The beds. of late Eocene age are referred to in this
report as the Ocala group. They include, in ascending
order, the Inglis, the Williston, and the Crystal River for-
mations (Puri, 1953,- p. 130). During the present investi-
gation no attempt was made to differentiate these formations.

The Ocala group in Putnam County consists of cream to

The stratigraphic nomenclature used in -this report
conforms to the usage of the Florida Geological Survey. It
conforms also to the usage of the U. S. Geological Survey
with the exception of the Ocala group and its subdivisions.
The Florida Survey has adopted the Ocala group as described
by Puri (1953). The Federal Survey regards the Ocala as a
formation, the Ocala limestone.

INFORMATION CIRCULAR NO. 15

white granular soft porous limestone. Thelimestone is very
fossiliferous, and some zones are composed completely of
loosely cemented shell fragments. As shown in figure 2,
the depth of the top of the Ocala group is approximately 25
feet below sea level in the western part of the county and
125 to 170 feet below sea level in the central and eastern
parts. Because of the irregular surface of the Ocala group,
these depths may differ by as much as 50 feet within a few
hundred yards. The Ocala group is approximately 110 to
135 feet thick in the central part of the county, and it is the
principal artesian aquifer in the county.

The deposits'unconformably overlying the Ocala group
in Putnam County are referred to in this report as deposits
of Miocene or Pliocene age. They are shown by Vernoni
(1951, fig. 13, 33) as the Hawthorne formation, of middle
Miocene age, and overlying upper Miocene deposits. Pre-
viously, the upper Miocene deposits were described by Cooke
(1945, p. 214-215, 225) as Pliocene in age. No attempt was
made during the present investigation to determine the cor-
rect'age of these deposits.

In a typical section of the Miocene or Pliocene deposits
in Putnam County a thin, discontinuous gray dense, hard
limestone is overlain by phosphatic blue to green clay and
sandy clay. The beds of clay contain thin, lenticular beds
of coarse to fine -phosphatic sand and thin beds of gray dense
limestone. In most parts of the county the phosphatic clay
is overlain bynonphosphatic green calcareous clay and coarse
to fine tani to white sand. The green clay locally contains a
bed-of shells and thin beds of white marl. The clays serve
as confining beds for the artesian water in the Eocene lime-
stone and the adjacent discontinuous Miocene limestone and
for the small quantities of artesian water in the beds of sand
and shell within the clays.

As shovwn on figure 2, the surficial deposits of Pleisto-
cene and Recent age range in thickness from less than 10
feet to more than 125 feet. The Pleistocene deposits con-
sist of fine to medium quartz sand deposited in the form of
a series of marine terraces. The terraces rise progres-
sively from the flat lowlands in the eastern part of the county
to the.hilly uplands in the southeastern and western parts.

FLORIDA GEOLOGICAL SURVEY

The Recent deposits consist principally of isolated peat de-
posits and alluvial sand and clay.

The Pleistocene and Recent sand is the source of water
for a few shallow wells. in the county. Locally, the water
is confined beneath hardpan and will flow when tapped by
wells- .

GROUND WATER

Ground water is the subsurface water in thatpart of the.
zone of saturation in which all pore spaces in the rocks are
filled with water under pressure greater than atmospheric.
Rain that falls on the earth's surface is the most important
source of ground water, but only part of it reaches the zone
of saturation. Part of it is returned to the atmosphere by
evapotranspiration, and part drains overland into lakes and
streams.

Ground water moves laterally, under the influence of-
gravity, toward places of discharge such as wells, springs,
surface streams, and lakes. It may occur under either non-
artesian (water-table) or artesian conditions. Where the
ground water is not confined and its surface is free to rise
and fall, it is said to be under nonartesian conditions and
its upper surface is called the water table. Where the water
is confined in a permeable bed that is overlain by a relatively
impermeable bed, its surface is not free to rise and fall and it
is said to be under artesian conditions. The term "artesian"
is applied to ground water that is confined under sufficient
pressure to rise above the top of the permeable bed that con-
tains it, though not necessarily above the land surface. The.
height to which water will rise in an artesian well is called
the artesian pressure head, and the imaginary surface delin-
eated by a number of wells is called the piezometric surface.

An aquifer is a formation, group of formations, or part
of a formation, in the zone of saturation, that is permeable
enough to transmit usable quantities of water. Areas in
which aquifers are replenished are called recharge areas.
Areas in which water is lost from aquifers are called dis-
charge areas.

INFORMATION CIRCULAR NO. 15

Nonartesian Aquifer

The Pleistocene and Recent sand that covers most of
Putnam County contains ground water under nonartesian
conditions, except in parts of central and southern Putnam
County where the sand is overlain by thin beds of clay that
confine the water under artesian conditions. Several shallow
wells tap this water for domestic use, particularly in the
western part of the county. These are usually either small-
diameter driven sandpoints or large-diameter hand-dug
wells.

The nonartesian aquifer is recharged principally by local
rainfall, although some of the water may have percolated
upward from the artesian aquifer in areas where the piezo-
metric surface is higher than the water table. Water is dis-
charged from the aquifer into lakes, streams, and canals,
and in small quantities through domestic wells. In addition,
water may be lost into the artesian aquifer in areas where
the water table is higher than the piezometric surface.

Artesian Aquifer

The artesian aquifer is the principal source of water in
Putnam County; therefore, most of the information collected
and.studied during this investigation concerns the artesian
aquifer.

The artesian aquifer consists principally of beds of
Eocene limestone but includes also a thin, discontinuous
dense limestone of Miocene age. In parts of the county,
thin, lenticular beds of sand and shellwithin the Miocene or
Pliocene clay contain water under artesian pressure. As
these thin beds yield a relatively small amount of water,
andarenot widespread, they are only briefly discussed in
this report. The limestones are referred to collectively,
in this report, as the principal artesian aquifer. Water is
confined under pressure in the principal artesian aquifer by
beds of clay in the deposits of Miocene or Pliocene age.

Differences in static head, chloride content, and tem-
perature of the water at different depths in some parts of

FLORIDA GEOLOGICAL SURVEY

the county suggest that impermeable beds within the prin-
cipal artesian aquifer may separate it into several relative-
ly thin aquifers. A deep-well current-meter traverse made
in well 943-144-1, six miles northwest of Palatka, in Septem-
ber 1955 gave evidence of the presence of several aquifers
within the principal artesian aquifer. A current meter is a
device for measuring the velocity of flow of water through a
well bore. The results of the current-meter test are shown'
graphically in figure 3. As shown on the figure, when the
well was completely closed in there was upward .movement
of water within the limestone aquifer in the zone between
500 and 430 feet and between 400 and 300 feet. This move-
ment shows leakage within the aquifer from zones, of higher
head to zones of lower head. The zones of different head
are probably separated by relatively impermeable limestone
beds within the aquifer.

In Putnam County the artesian aquifer .is replenished
by rain falling on recharge areas where many lakes and sink-
holes penetrate the confining.beds and allow water from the
surface to reach the limestone formations that constitute
the aquifer. The water in the artesian aquifer may also be
replenished by water from the nonartesian aquifer in areas
where the water table is higher than the piezometric surface.

From the recharge areas water moves laterally through
pores and cavities in the limestone toward areas where dis-
charge is occurring. Water is discharged from the artesian
aquifer in Putnam County by springs and wells.-. It may also
be discharged by upward percolation of water to the nonarte-
sian aquifer in areas where the piezometric surface of the
artesian aquifer is higher than the water table.

Periodic measurements of the artesian pressure heads
in wells 939-138-1 and 925-138-1 were made from 193.6 to
1950 by the U.S. Army Corps of Engineers. Since 1950 the
measurements have been made by the U. S. Geological
Survey. In addition, continuous water-level recorders have
been installed on two wells -and measurements are being
made periodically in 30 other wells in order to determine
the trends and seasonal fluctuations of water levels in dif-
ferent parts of the county.

FLORIDA GEOLOGICAL SURVEY

The Recent deposits consist principally of isolated peat de-
posits and alluvial sand and clay.

The Pleistocene and Recent sand is the source of water
for a few shallow wells. in the county. Locally, the water
is confined beneath hardpan and will flow when tapped by
wells- .

GROUND WATER

Ground water is the subsurface water in thatpart of the.
zone of saturation in which all pore spaces in the rocks are
filled with water under pressure greater than atmospheric.
Rain that falls on the earth's surface is the most important
source of ground water, but only part of it reaches the zone
of saturation. Part of it is returned to the atmosphere by
evapotranspiration, and part drains overland into lakes and
streams.

Ground water moves laterally, under the influence of-
gravity, toward places of discharge such as wells, springs,
surface streams, and lakes. It may occur under either non-
artesian (water-table) or artesian conditions. Where the
ground water is not confined and its surface is free to rise
and fall, it is said to be under nonartesian conditions and
its upper surface is called the water table. Where the water
is confined in a permeable bed that is overlain by a relatively
impermeable bed, its surface is not free to rise and fall and it
is said to be under artesian conditions. The term "artesian"
is applied to ground water that is confined under sufficient
pressure to rise above the top of the permeable bed that con-
tains it, though not necessarily above the land surface. The.
height to which water will rise in an artesian well is called
the artesian pressure head, and the imaginary surface delin-
eated by a number of wells is called the piezometric surface.

An aquifer is a formation, group of formations, or part
of a formation, in the zone of saturation, that is permeable
enough to transmit usable quantities of water. Areas in
which aquifers are replenished are called recharge areas.
Areas in which water is lost from aquifers are called dis-
charge areas.

INFORMATION CIRCULAR NO. 15

Flowing 440 G.RM.

No flow

0 50 100 150 200
R.EM. of current meter

0 5 10
R.M. of current meter

Figure 3. Diagram comparing the velocities of water in
well 943- 144-1, six miles northwest of Palatka,
when water is flowing from the well and when no
water is flowing from the well.

FLORIDA GEOLOGICAL SURVEY

Hydrographs in figure 4 show seasonal fluctuations and
progressive trends of the artesian pressure heads in well
939-138-1, in Palatka, and well 925-138-1, four miles south-
east of Welaka. Both hydrographs show noticeable decline
in the artesian pressure heads since 1953. Figure 4-shows
that the maximum seasonal fluctuation of the artesian pres-
sure head is less than four feet in well 939-138-1 and less
than three feet in well 925-138-1. In the winter vegetable
farming area east of Palatka, where large quantities of
artesian water are used for irrigation, the artesian pressure
head may be lowered by as much as 10 feet during times of
heaviest withdrawals.

Piezometric Surface

The piezometric surface of an aquifer is an imaginary
surface that everywhere coincides with the static level of
the water in the aquifer. It is the surface to which water
from a given aquifer will rise. under its full head. A map
showing the piezometric surface of an artesian aquifer is
constructed by first measuring the artesian pressure head
in casedwells that penetrate the artesian aquifer, referring
these measurements to a common datum, and then drawing
contour lines connecting all points which have the same
height above the common datum. The preparation of such a
map is an important part of a ground-water investigation,
as the shape of the contour lines indicates the direction of
movement of the water and the general areas of recharge
and discharge. Water enters the aquifer in those areas in
which the piezometric surface is high and moves ina direc-
tion approximately perpendicular to the contour lines toward
the areas in which the piezometric surface is low.

A map of the piezometric surface of the artesian aqui-
fer in Putnam County is shown in figure 5. In constructing
the map, all measurements of the artesian pressure head
have been referred to mean sea level. The elevations of
the measuring points were estimated fromtopographic maps
drawn on a 10-foot contour interval. In the southeastern
part of the county, where no topographic coverage was
available, the elevations were determined with an altimeter.

-" __BIn

WELL 95-138-1,
:V./_ ____r n,-- ."
29 29

4 miles outheost of Weloho
19356 1937 193B 1939 1940 | 1941 1912 1943 1944 1945 1948 1947 1948 1949 1950 1951 1952 1953 1954 1955 19566

Figure 4. Hydrographs of wells 939-138-1 and 925-138-1.

FLORIDA GEOLOGICAL SURVEY

EXPLANATION
-30 -
Contour nm rep ments opp mtely the height
in fee, to which ter wrl rise with reference to
:emn sea Icel in nqhtly csed wells that pene-
traed the prtnrciplt ortesn oqu.fe in April 1956
a:n uni~t rep-ern nt feed position of
r~alur Ien

Sc2 4 0 0 a

COr: Ln inieriol IC feel

Figure 5. Map of Putnam County showing the piezometric

surface.

'..' Ir 7.. 1

s''s ran- T4S

area eras s so

INFORMATION CIRCULAR NO. 15

The piezometric surface fluctuates continuously in re-
sponse to changes in storage within the artesian aquifer.
Therefore, figure 5, which was drawn from measurements
made in April 1956, is only an approximate representation
of the piezometric surface at other times. The positions of
piezometric contour lines were inferred in many parts of
the county where accessible wells were lacking.

Figure 5 shows two areas of relativelyhighpiezometric
surface inwhich recharge ispresumed to occur. One begins
approximately at Interlachen and extends west into Alachua
County and north into Bradford and Clay counties. The
other lies between the St. Johns River and Crescent Lake.
Both these areas generally coincide with areas of topographic
highs and are pocketed with numerous lakes and sinkholes
through which water from the surface can reach the lime-
stone aquifer.

The piezometric surface contains noticeable depressions
near the juncture of the St. Johns and Oklawaha rivers,
where natural discharge from the artesian aquifer by springs
forms some of the base flow of the St. Johns River, and in
the .winter vegetable farming area east of Palatka, where
large quantities of artesian water are dischargedby irriga-
tion wells.

Piezometric maps were made by Tarver (1956) and
Bermes (1956) as part of their investigations of ground-
water resources in St. Johns and Flagler counties. These
maps, together with a map of Putnam County, have been
compiled into one map (fig. 6) which shows the piezometric
surface of the artesian aquifer, in April 1956, in all three
counties.

Figure 6 shows that the piezometric surface slopes east-
ward from recharge areas in Putnam County to discharge
areas in. southwestern St. Johns and western Flagler
counties. The.curvature of the 15-foot contour line-in eastern
Putnam County shows the effect of discharge in southwe stern
St. Johns County.

FLORIDA GEOLOGICAL SURVEY

Map of Putnam, St. Johns, and Flagler counties
showing the piezometric surface.

Figure 6.

INFORMATION CIRCULAR NO. 15

Area of Artesian Flow

Artesian wells will flow where the piezometric surface
stands higher than the land surface. Figure 7 shows the
approximate area of artesianflow in Putnam Countyin April
1956. Owing to continuous changes in the altitude of the
piezometric surface, the area of artesian flow shown on this
map is only an approximation of the area of flow at other
times. Artesian flow occurs principally in the lowlands
along the St. Johns River and its tributaries. Within this
area, wells will not flow where the land surface locally is
relatively high. In the hilly uplands, artesian flow occurs
along some stream valleys and in isolated depressions of
the land surface. Many of these'areas of artesian flow could
not be shown on figure 7 because of their small size.

A progressive decline in the artesian head in recent
years (fig. 4) has doubtless reduced the area of artesian flow
in Putnam County. However, the piezometric surface and
the size of the areas of artesian flow change continuously in
response to changes in storage within the artesian aquifer.
In the winter vegetable farming area, east of Palatka, where
the piezometric surface is about, the same as the relatively
flat land surface, a slight decline in the altitude of the pie-
zometric surface can reduce the area of flow by as much as
seven square miles.

Two detailed maps of the area of artesian flow in the
farming area east of Palatka are shown in figure 8. The
contours in each of the maps represent the height, in feet
above land surface, to which artesian water would rise.
Wells in the shaded area have no artesian flow. The water-
level measurements used to draw these maps were made in
April 1956, when the piezometric surface was lowered by
discharge from numerous irrigation wells, and in August
1956, when the use of water was slight and the piezometric
surface was relatively high. Comparing both maps in figure 8,
it may be seen that the artesian pressure head is consid-
erably lowered and the area of artesian flow is much reduced,
during times of heavy withdrawals.

FLORIDA GEOLOGICAL SURVEY

Figure 7. Map of Putnam County showing the area of arte-
sian flow.

INFORMATION CIRCULAR NO. 15

APRIL,4956

EXPLANATION
5
Height, in feet, to which water
rises above the land surface in wells
that penetrate the artesian aquifer

Area in which artesian water does
not rise above land surface

Figure 8. Maps of the farming area east of Palatka showing
the height to which water will rise above the land
surface in wells that penetrate the artesian aqui-
fer and the area of artesian flow.

FLORIDA GEOLOGICAL SURVEY

Wells

A well inventory consists of a collection of pertinent
information such as location, diameter, depth, length of
casing, and use of each well, and supplies much valuable
information concerning the ground-water resources of an
area. Figure 9 shows the locations of 161 wells thathave
been inventoried during this investigation. All these wells
are believed to have been completed in the principal artesian
aquifer, except 14 wells which draw water either from the
nonartesian aquifer or from the beds of sand and shell with-
in the Miocene or Pliocene clays.

Figure 9 shows that the greatest concentration of wells
is east of Palatka, in the winter vegetable farming area.
The wells in that area range from three to eight inches in
diameter and are used for irrigation. They range in depth
from 130 to 460 feet, although most are between 180 and 300
feet deep. Except for a few deep, large-diameter public
supply and industrial wells, the wells in the remainder of
the county are used for domestic supply. They range in di-
ameterfromone to three inches and are generally 75 to 200
feet deep.

Not all the wells shown on figure 9 are in Putnam County.
Lack of accessible wells in the sparsely populated areas
along the northern, southern, and western boundaries of the
county made it necessary to inventory wells in adjoining
areas outside the county.

QUALITY OF WATER

The chemical character of ground water is largely de-
pendent upon the type of material with which the water comes
in contact or by contamination with sea water. In recharge
areas, where the water first enters the ground, it is only
slightly mineralized. As the water moves through the ground
it dissolves mineral matter from the rocks through which
it flows and mixes with mineralized water already in the
rocks.

Information on the mineral content of the ground water

INFORMATION CIRCULAR NO. 15

SII-L SI u
L I^ ^ ru

NI I

L"

-i .-L I .\I k I I t vI I 7-9n '1 _'
U- -V---- I1-- I
- .....-- ...

-C ", -- !-I

II-I jjd
-l^ 'Ii^Z^^3 "^i I ""EA

"EXPLANATION
Inventoried "ell
Swle 5, Mit.. *

I 1
I *1'
1Lt~y~u

~iI[ii]iriI -
-I--

Figure 9. Map of Putnam County showing the locations of
wells.

I I I I 1 I! I I I I L I--J.

-W \i

FLORIDA GEOLOGICAL SURVEY

in Putnam County was obtained from chemical analyses of
water from seven wells. Table 1 shows the results of the
chemical analyses. The wells range in depth from 62 to 564
feet and are distributed throughout the county. The degree
of mineralization, expressed bythe dissolved-solidcontent,
differs widely throughout the county. In general, however,
the water from wells in and near recharge areas is less
mineralized than that from other wells.

Salt-Water Contamination

Saline water is present in the principal artesian aquifer
in the southern part of Florida and in some other areas,
particularly near the coast and the St. Johns River. The
presence of this saline water appears to be due principally
to the infiltration of sea water into the aquifer during Pleis-
tocene time when the sea stood above its present level and
much of the present land surface was inundated (Cooke, 1939,
fig. 12-16). Subsequently, the Pleistocene seas receded
and fresh water circulating through the aquifer began grad-
ually to dilute and flush out the salty water. The flushing
has not been completed, and the remaining diluted sea water
is a source of ground-water mineralization.

Water samples were taken at different depths from a
few wells that penetrate the principal artesian aquifer in
Putnam County. Analyses of these samples showed that the
chloride content of the water increased with depth. The
chloride content of the .water, which is an index of salt-water
contamination, suggests that diluting and flushing have pro-
gressed less in the lower part of the aquifer than in the
upper part.

Water samples from more than 160 wells in Putnam
County were analyzed for chloride content. The chloride
content of water from wells that penetrate the principal
artesian aquifer ranged from less than two ppm in well
945-136-1 to 1, 080 ppm in well 940-134-3. Figure 10 shows
the generalized results of these analyses. It shows that the
chloride content of the water is lowest inand near recharge
areas, thus indicating that flushing has been most effective
in the recharge areas.

Table 1. Analyses of Water from Wells in Putnam County
(Chemical constituents in parts per million)

Well number
Depth in feet
Diameter in inches
SDate collected

Silica (SiOg)
Iron (Fe) dissolved1
Iron (Fe) total
Calcium (Ca)
Magnesium (Mg)
Sodium (Na)
Potassium (K)
Bicarbonate (HCO3)
Carbonate (CO3)
Sulfate (S04)
Chloride (C1)
Fluoride (F)
Nitrate (NO3)
Dissolved solids sum
Dissolved solids residue on evap. 180"C
Hardness as CaCO .
Noncarbonate
Specific conductance (micromhos at 25 'C)
pH
Color
Density in gms/ml at 20C

lln solution at time of analysis,

947-137-1
350
4
8-28-56

12
.00
.56
25
15
5.9
1. 3
140
0
8.5
6.0
.4
.2

142
124
9
251
7.7
2

930-139-1
62
4
8-27-56

14
.04
.13
327
243
1,960
50'
150
0
551
3,840
.1
.0
7,060

1,820
1,690
12, 100
7.5
9
1.002

S940-134-2
452
6
8-27-56

17
.12
1. 3
166
116
190
9.0
128
0
535
430
.5
.6
1,530

891
786
2,390
7.8
9

944-131-2
245
4
8-27-56

11
.11
2.7
142
99
80
5.0
80
0
595
155
.4
.8
1,130

762
696
1,600
7.7
4

932-152-1
189
8
8-28-56

11
.00
.22
26
8. 1
3. 1
.6
113
0
1.2
4.5
.0
.1

109
98
6
195
8.1
2

932-145-2
85
4
8-28-56

12
.00
.15
58
23
80
2.8
138
0
39
169
.2
.6

482
239
126
836
7.8
3

943-144-2
564
20
12-6-55

13
.00
--- '
32 -
11 0
4,1 z
.6 0
144
0
6.5
6.8
E
.0

146. .
125
7
249 P
8.1 U1
9

FLORIDA GEOLOGICAL SURVEY

EXPLANATION
CHLORIDE CONTENT
PaRs Per ilioan

25t-o 500 50 n ore
s^n J> MilE

Figure 10. Map of Putnam County showing the approximate

chloride content of water from the artesian aqui-
fer.

INFORMATION CIRCULAR NO. 15

A comparison of figure 10 with a map of the piezometric
surface (fig. 5) shows that the areas where the piezometric
surface is lowest generally correspond to the areas where
the chloride content of the water is highest. These areas
are in the vicinity of Welaka, where natural discharge from
springs in the St. Johns River maintains a depression in the
piezometric surface, and in the winter vegetable farming
area, east of Palatka, where discharge from many irriga-
tion wells seasonally depresses the piezometric surface.
Analyses of water samples collected periodically in the
farming area indicate that the chloride content of the arte-
sian water varies with changes in the artesian pressure
head. Figure 11 shows that decreases in the artesian pres-
sure head in well 940-134-2, in the farming area, are ac-
companied by increases in the chloride content of water
from the well, and vice versa.

Most water samples that were collected from irrigation
wells in the winter vegetable farming area during this in-
vestigation did not contain enough salt to endanger the crops.
However, as fresh water is withdrawn from the wells salty
water may move toward the wells and make them unsuitable
for irrigation.

Water from wells not drawing from the principal arte-
sian aquifer generally has a chloride content of less than 30
ppm, but water from well .930-139-1 (table 1)contains 3,840
ppm, the highest concentration in any water sample collected
during this investigation. As this well is relatively shallow,
it is believed that it draws water from.one of the beds of
sand or shells within the Miocene or Pliocene deposits.
These beds probably have not been flushed as much as has
the more permeable limestone aquifer.

SUMMARY AND CONCLUSIONS

The progress made during.the firstyear of this investi-
gation is summarized below.

1. More than 160 wells have been inventoried to
obtain pertinent information on the ground-
water resources of the county.

FLORIDA GEOLOGICAL SURVEY

Wells

A well inventory consists of a collection of pertinent
information such as location, diameter, depth, length of
casing, and use of each well, and supplies much valuable
information concerning the ground-water resources of an
area. Figure 9 shows the locations of 161 wells thathave
been inventoried during this investigation. All these wells
are believed to have been completed in the principal artesian
aquifer, except 14 wells which draw water either from the
nonartesian aquifer or from the beds of sand and shell with-
in the Miocene or Pliocene clays.

Figure 9 shows that the greatest concentration of wells
is east of Palatka, in the winter vegetable farming area.
The wells in that area range from three to eight inches in
diameter and are used for irrigation. They range in depth
from 130 to 460 feet, although most are between 180 and 300
feet deep. Except for a few deep, large-diameter public
supply and industrial wells, the wells in the remainder of
the county are used for domestic supply. They range in di-
ameterfromone to three inches and are generally 75 to 200
feet deep.

Not all the wells shown on figure 9 are in Putnam County.
Lack of accessible wells in the sparsely populated areas
along the northern, southern, and western boundaries of the
county made it necessary to inventory wells in adjoining
areas outside the county.

QUALITY OF WATER

The chemical character of ground water is largely de-
pendent upon the type of material with which the water comes
in contact or by contamination with sea water. In recharge
areas, where the water first enters the ground, it is only
slightly mineralized. As the water moves through the ground
it dissolves mineral matter from the rocks through which
it flows and mixes with mineralized water already in the
rocks.

Information on the mineral content of the ground water

U

in
az 4

3
-2
dm2

900

z 800
0
-J
-j 700

rE 600
LU
"in 500
.4
S400

JUNE JULY AUG SEPT OCT

1956
Figure 11. Graph showing the relation between the chloride content on the water and the
water level in well 940-134-2, three miles northeast of Palatka.

FEB MAR APR MAY

CHLORIDE CONTENT

-0---0
-., /

NOV

I

INFORMATION CIRCULAR NO. 15

2. Periodic measurements of water levels and
artesian pressures are being made in 32 wells,
and continuous water-level. recorders have
been installed on two wells, to determine sea-
sonal fluctuations and long-term trends.

3. Water samples from more than 160 wells have
been analyzed for chloride content, to delineate
areas in which the water is salty. Analyses
have been made of water from different depths
in a few of these wells.

4. -Periodic determination of the chloride content
of the.water from 13..wells have been made, to
determine the relationbetween changes in arte -
sian pressure and.chloride content.

5. Comprehensive chemical, analyses were made
of water from seven wells in different parts of
the. county.. _

6. Geologic, information-has been obtained from
sets of rock cuttings collected from several of
the wells drilled in Putnam County.

Final conclusions concerning many of the ground-water
problems in -the county are beyond the scope of the present
report. However, from data already collected, the follow-
ing conclusions can. be reached..

1. Thick Eocene limestones underlie the county
at the depths ranging from 25 to 170 feet below
sea. level. These limestones are overlain by
deposits of Miocene or Pliocene age which con-
sist principally of clay and thin beds of sand,
shell, and limestone. The Miocene or Pliocene
deposits are overlain by sand, clay, and peat,
*of -Pleistocene and Recent age, .that -range in
combined thickness from 10 feet to more than
125 feet.

2. In Putnam County ground water occurs under

FLORIDA GEOLOGICAL SURVEY

nonartesian conditions in the Pleistocene and
Recent sands, and under artesian conditions in
the limestone beds underlying the Miocene or
Pliocene clays and in the thin beds of sandand
shells within the clays.

The nonartesian aquifer is recharged over
most of its surface by direct infiltration of
rainfall. The principal artesian aquifer is re-
charged principally by rainfall in southeastern
and western Putnam County.

3. Water-level records show that there has been
a progressive decline of the artesian pressure
head in recent years and that the artesian pres-
sure head fluctuates, seasonally, as much as
10 feet in parts of the county. The most pro-
nounced fluctuations are in the winter vege-
table farming area, east of Palatka, where
pumping of irrigation wells lowers the artesian
pressure head. A decline in the artesianpres-
sure head in this area considerably reduces the
area of artesian flow.

4. The chloride content of water samples from
wells in the principal artesian aquifer ranges
from less than two ppm to 1, 080 ppm. Gener-
ally, the chloride content is lowest in and near
recharge areas and in the upper part of the
aquifer. Most of the wells that yield water of
high chloride content are in areas of discharge,
where the artesian head is low. In areas of
seasonal discharge, increases in artesian
pressure are accompanied bydecreases in the
chloride content of the water, and vice versa.

Water from wells not drawing from the
principal artesian aquifer generally has a chlo-
ride content of less than 30 ppm.

INFORMATION CIRCULAR NO. 15

Future studies in Putnam County will include:

1. An inventory of additional wells.

2. A more exact determination of the altitudes of
measuring points on observation wells, in order
to define the piezometric surface more exact-
ly.

3. Accumulation of additional geologic informa-
tion through well cuttings and electric logs, to
determine in more detail the thickness, char-
acter, and extent of the different geologic for-
mations.

4. The exploration of selected wells with a current.
meter, to determine the position and thickness
of the:aquifers, and use of deep-well sampling
equipment todetermine the quality of water in
each water-bearing zone.

5. Pumping.. tests to determine : the water--
transmitting and water-storing capacities of
the artesian aquifer.

6. A. detailed study of recharge areas, to deter-
mine the rate and distribution of recharge to
the artesian aquifer.

7. Additional comprehensive analyses of water
for more adequate coverage of the county.

INFORMATION CIRCULAR NO. 15

A comparison of figure 10 with a map of the piezometric
surface (fig. 5) shows that the areas where the piezometric
surface is lowest generally correspond to the areas where
the chloride content of the water is highest. These areas
are in the vicinity of Welaka, where natural discharge from
springs in the St. Johns River maintains a depression in the
piezometric surface, and in the winter vegetable farming
area, east of Palatka, where discharge from many irriga-
tion wells seasonally depresses the piezometric surface.
Analyses of water samples collected periodically in the
farming area indicate that the chloride content of the arte-
sian water varies with changes in the artesian pressure
head. Figure 11 shows that decreases in the artesian pres-
sure head in well 940-134-2, in the farming area, are ac-
companied by increases in the chloride content of water
from the well, and vice versa.

Most water samples that were collected from irrigation
wells in the winter vegetable farming area during this in-
vestigation did not contain enough salt to endanger the crops.
However, as fresh water is withdrawn from the wells salty
water may move toward the wells and make them unsuitable
for irrigation.

Water from wells not drawing from the principal arte-
sian aquifer generally has a chloride content of less than 30
ppm, but water from well .930-139-1 (table 1)contains 3,840
ppm, the highest concentration in any water sample collected
during this investigation. As this well is relatively shallow,
it is believed that it draws water from.one of the beds of
sand or shells within the Miocene or Pliocene deposits.
These beds probably have not been flushed as much as has
the more permeable limestone aquifer.

SUMMARY AND CONCLUSIONS

The progress made during.the firstyear of this investi-
gation is summarized below.

1. More than 160 wells have been inventoried to
obtain pertinent information on the ground-
water resources of the county.

32 FLORIDA GEOLOGICAL SURVEY

REFERENCES

Applin, Esther R. (see Applin, Paul L.)

Applin, Paul L.
1944 (and Applin, Esther R.) Regional subsurface
stratigraphy and structure of Florida and south-
ern Georgia: Am. Assoc. Petroleum Geolo-
gists Bull., vol. 28, no. 12, p.1673-1753.

Bermes, B. J.
1956 Interim report on the ground-water resources
of Flagler County, Florida: Florida Geol.
Survey Inf. Circ. 13.

Black, A. P.
1951 (and Brown, Eugene) Chemical character of
Florida's waters- 1951: Florida State Bd.
Cons., Div. Water Survey and Research,
Paper 6.

Brown, Eugene (see Black)

Collins, W. D.
1928 (and Howard C. S.)
waters of Florida: U.
Supply Paper 596-G.

Cooke, C. W.
1939 Scenery of Florida:
Bull. 17.

1945

Geology of
Bull. 29.

Chemical character of
S. Geol. Survey Water-

Florida Geol. Survey

Florida: Florida Geol. Survey

Cooper, H. H. Jr. (see Stringfield)

Gunter, Herman (see Sellards)

Howard, C. S. (see Collins)

INFORMATION CIRCULAR NO. 15

Matson, G. C.
1913 (and Sanford, Samuel)
waters of Florida: U. S.
Supply Paper 319.

Puri, Harbans S.
1953 Zonation of the Ocala
Florida (abstract): Jour.
ogy, vol. 23.

Geology and ground
Geol. Survey Water-

group in peninsular
Sedimentary Petrol-

Sanford, Samuel (see Matson)

Sellards, E. H.
1913 (and Gunter, Herman) The artesian water
supply of eastern and southern Florida: Florida
Geol. Survey 5th Ann. Rept.

Stringfield, V. T.
1936 Artesian water in the Florida peninsula: U.S.
Geol. Survey Water-Supply Paper 773-C.

1951 (and Cooper, H. H. Jr.) Geologic and hydro-
logic features of an artesian spring east of
Florida: Florida Geol. Survey Rept. of Inv. 7.

Tarver, G. R.
1956 Interim report on the ground-water resources
of St. Johns County, Florida: Florida Geol.
Survey Inf. Circ. 14.

Vernon, R. O.
1951 Geology of Citrus and Levy counties, Florida:
Florida Geol. Survey Bull. 33.

1955

Logs of wells 3635 and 3636 drilled in Putnam
County, Florida: Florida Geol. Survey open-
file releases.

FLRD GEOLOSk ( IC SUfRiW

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	Title Page
	Table of Contents
	Abstract
	Introduction
	Geography
	Geology
	Ground water
	Quality of water
	Summary and conclusions
	References