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STATE OF FLORIDA
STATE BOARD OF CONSERVATION
DIVISION OF GEOLOGY



FLORIDA GEOLOGICAL SURVEY
Robert O. Vernon, Director






REPORT OF INVESTIGATIONS NO. 43







GROUND WATER IN DUVAL AND NASSAU
COUNTIES, FLORIDA

By
Gilbert W. Leve, Geologist









Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
DIVISION OF GEOLOGY
and
DUVAL COUNTY
and the
CITY OF JACKSONVILLE


1966








FLORIDA STATE BOARD

OF

CONSERVATION







HAYDON BURNS
Governor


TOM ADAMS
Secretary of State




BROWARD WILLIAMS
Treasurer




FLOYD T. CHRISTIAN
Superintendent of Public Instruction


EARL FAIRCLOTH
Attorney General




FRED O. DICKINSON, JR.
Comptroller




DOYLE CONNOR
Commissioner of Agriculture


W. RANDOLPH HODGES
Director






LETTER OF TRANSMITTAL


Jlorida geological Survey

'allakassee
May 19, 1966

Honorable Haydon Burns, Chairman
State Board of Conservation
Tallahassee, Florida

Dear Governor Burns:
The Division of Geology, of the State Board of Conservation,
will publish as Report of Investigations No. 43, a detailed report on
"Ground Water in Duval and Nassau counties, Florida." This report
was prepared by Gilbert W. Leve, Geologist with the U. S. Geo-
logical Survey, in cooperation with this Division, Duval County, and
the City of Jacksonville.
It has been discovered that there are at least three aquifers in
the area, a shallow ground-water aquifer and two distinctive
aquifers in the Floridan aquifer system. Water under high pres-
sure, but of less satisfactory quality, is available throughout the
area, even though the pressures of the upper artesian aquifer have
been reduced as much as 100 feet. About 200 million gallons of
water per day is used from these aquifers in the vicinity of Jack-
sonville. Some concern was felt that salt-water intrusion had be-
:un, but the study shows that there is little danger of contamina-
ion of these supplies and that Duval and Nassau counties have
adequate water for the future, if properly managed and utilized.

Respectfully yours,
Robert O. Vernon
Director and State Geologist





















































Completed manuscript received
January 31, 1966
Printed for the Florida Geological Survey
By the E. O. Painter Printing Company
DeLand, Florida

iv







CONTENTS
Abstract ---------------------- --.. -..--.. -................ -- ........ 1
Introduction ----------..---............................... ....... ..... 2
Previous investigations ..--------- .--------------------........--.... ....- .. 3
Acknowledgments ----------. -.-----.....-..-......-----------............ 4
Well-numbering system --------..---.- --------------------............ ....- .... 5
geography y ---------- --------.........-------------.......... ............. 5
Location and area --------------------------------........................... 5
Climate ---.......-.. ..-.................................-------------------- 6
Population and industry ----------................-------------------.....------- 7
Physiography .. ...-----------....-------------------------------------------........ ......--......... 8
Occurrence of aquifer systems ---.........--~~...--...-..-..... ---------...--...... 10
General principles _.... ........... .------------------ --.. ..... ................. 10
Geologic setting -....-...--------------------------------..... .-------------. 11
Oldsmar Limestone ..-------- .................................. .... 12
Lake City Limestone ....---------.. ...-....-....----------.......-.. 14
Avon Park Limestone -.-----------....-.--..--........---------------.... 15
Ocala Group ---------..--------------.. ..............---------------.. 16
Inglis Formation ---..........-----....... ---------------------........ 16
Williston Formation .- ..--.-----. ----...-------...... ---------- 17
Crystal River Formation --- ------------------...........---....... 17
Hawthorn Formation -------- ------------------........ ... ... __....... ...._...... 18
Upper Miocene or Pliocene deposits ----...---.------....-----.-------.... 18
Pleistocene and Recent deposits _-----..------.-- ----------- 19
Structure -.---------.... .............-------------------.... 19
Shallow aquifer system ....------.----.----. --.... ----------------..... 220
Aquifer characteristics ------------------------------..--...... 21
Water supplies -------.-------------.......-.--....... --------.. 23
Floridan aquifer system ----...-------------. ----......... --------... ......... ........ 24
Permeable zones ------------------------................ --------------. 24
Current-meter studies ---------------------.........-------...... 28
Water supplies ----.--..-..--..-..-.--..-...-------------------- ...........31
Recharge and discharge ---.... ---..---_ ---- ----............ -----.......................... 33
Area of flow ........ ----------------..-----------------------.. 37
Water use --...---------------.....- --..-... ----..................................--- 38
Public water use ...--------.......-... ----.. -- --------.. ---. 38
Industrial water use ------------------------............ ..---....... 39
Commercial and private water use ----.----------------..............-- 39
Decline in artesian pressure -- -------..............--------............. .. ---- 40
Quality of water .. ..--------.. ......... .. ....... ......................... 46
Quality of water in the shallow aquifer system ----------------... 48
Quality of water in the Floridan aquifer system ..-.....---- ---.---------.- 48
Chloride -------------- ...--------------------- ..-- -----------............ 55
Dissolved solids .......-------.-- --. -..-...-------.... .- ....-............----. --- 55
Hardness -------- --------- ----. ------------.. ......----------. 55
Hydrogen sulfide gas ---.......-- -----. --.--..------------..... 56
Salt-water contamination --.. __ --------_...-.. ------------------56
summary -.. ..--..----.... .- ------ ---- ........... --..-.. -- -.. ................... 65
uture studies .........-- ..-.......------- ----........-........ ..-...-.-...... 69
references -------- -_.------------........-...... ..........--...---... ... ..- ...- 71







ILLUSTRATIONS
figure Page
1 Map of peninsular Florida showing the location of Duval and
Nassau counties and illustrations of well-location numbering
system -.._. -----____-_--................_------- _-----------.. -------------. 6
2 Map of Duval and Nassau counties showing the location of wells
for which information was obtained -----.....--------....____---____ _- 7
3 Map of Duval and Nassau counties, Fla., showing the Pleistocene
marine terraces ___ -- ----... In pocket
4 Geologic cross sections showing the formations penetrated by
wells in Duval and Nassau counties, Fla. -------.....-----...........--.... 13
5 Map showing the altitude of the top of the Crystal River Forma-
tion and the Avon Park Limestone and the approximate depth
below land surface to the top of the Crystal River Formation,
Duval and Nassau counties, Fla __. -.._ _---_---------_ -.... In pocket
6 Graphs showing rainfall at Fernandina Beach and Jacksonville
and the water levels in well 040-127-211A, at Fernandina Beach,
and 017-136-241B, near Jacksonville ___ __. 22
7 Hydrographs and geologic data from wells 026-135-342A, B, and
C, about 4 miles northeast of Jacksonville ____25
8 Diagrams showing geologic and current-meter data from wells in
Duval County ____26
9 Diagrams showing geologic and current-meter data from wells
in Duval and Nassau counties .--------------- ..........-.............. ...... ..... 27
10 Map of Florida showing the generalized piezometric surface of
the Floridan aquifer _____ __-------------...--.....-... ......... -.. 34
11 Graphs showing relation of water levels in wells 019-140-421 and
033-150-242, to pumping and precipitation, Jacksonville area, Fla. _.... 36
12 Map of Duval and Nassau counties showing piezometric surface
of the Floridan aquifer system and the area of artesian flow in
May 1962 ____-____________________ In pocket
13 Hydrographs of selected wells in Duval County -----..--------.............. 41
14 Hydrographs of selected wells in Nassau County ..........-..----.......--... 42
15 Map and cross sections of Duval and Nassau counties showing
the change in artesian pressure during the periods July 1961
to May 1962 and 1940 to May 1962 ..-- ____ _...___........_-......--... ... 43
16 Graph showing annual discharge of artesian water by municipal
wells in Jacksonville and average annual rainfall at three wea-
ther stations in the recharge area ___ _........ ______ __ .. 44
17 Graphs showing the artesian pressure in two wells at Fernandina
Beach ------____ -------............................. __ ______...._-....... 45
18 Map of Duval and Nassau counties showing the approximate
chloride content of water from artesian wells in 1940 ......-----.. In pocket
19 Map of Duval and Nassau counties showing the approximate
chloride content of water from artesian wells in May 1962 .-..... In pocket
20 Map showing the chloride content of water from deep wells at
Fernandina Beach --..--------_--.....-- _--- __ .____. -.._ 53
21 Graphs of the chloride content of water from selected wells at
Fernandina Beach that penetrate formations below the Ocala
Group ------- -------------------.. ---_ -- .... 62





32 Graphs of the chloride content of water at different depths in
wells in the Floridan aquifer system at Fernandina Beach ---- --64

TABLES
Liable Page
1 Population of Jacksonville, Duval County, Fernandina Beach,
and Nassau County, 1940-62 _....-.....____ .... __ ____ ___........ 9
2 Nonagricultural wages and salaried employment in the Jack-
sonville area .---...------....-..- ......_ .... ...... .. 9
3 Stratigraphic units and aquifer systems in Duval, Nassau, and
Baker counties ------------.-------------- --...... -... ............ _.....k.. ..... In pocket
4 Artesian flow and pressure in five Jacksonville municipal wells
before and after each well was deepened -........-- ---------------. 32
5 Analyses of water from aquifers overlying the Floridan aquifer
system in Duval and Nassau counties _- --_-_ ---. __- 47
6 Analyses of water from the Floridan aquifer system in Duval,
Nassau, and Baker counties --................ ... .... -- .......... 49
7 Chloride content of water from wells in the Floridan aquifer
system in Duval and Nassau counties -----------------------.......... ..... 59
8 Record of wells in Duval and Nassau counties .- --------_--- --_. .. 74










GROUND WATER IN DUVAL AND NASSAU
COUNTIES, FLORIDA

By
Gilbert W. Leve

ABSTRACT

This report describes an area of about 2,000 square miles in
northeast Florida and extreme southeast Georgia. The topog-
raphy is controlled by a series of ancient marine terraces, and sur-
face drainage is through the St. Johns, Nassau, and St. Marys
Rivers and through brackish-water streams that empty either into
the intracoastal waterway or directly into the ocean.
Practically all the water used in the area is supplied from the
rock formations that underlie the surface. These formations, in
ascending order, are the Oldsmar Limestone, the Lake City Lime-
stone, the Avon Park Limestone, and the Inglis, Williston, and
Crystal River Formations of the Ocala Group, all of Eocene Age;
the Hawthorn Formation of Middle Miocene Age; deposits
of late Miocene or Pliocene Age; and undifferentiated depos-
its of Pleistocene and Recent Age. The formations of Eocene Age
and the limestone at the base of the Hawthorn Formation compose
the Floridan aquifer system. Surficial sand beds and a zone of
limestone, shell, and sand at the base of the upper Miocene or
Pliocene deposits are the most extensive aquifers in the shallow
aquifer system.
Increased pumpage from numerous wells in the shallow aqui-
fers has caused a steady decline of water levels in these aquifers.
However, additional water may be obtained from shallow aquifers
by proper well construction and by artificial recharge.
The principal source of fresh water in northeast Florida is the
Floridan aquifer system. The top of this aquifer is between 300
and 550 feet below sea level and water is confined under artesian
pressure in the aquifer by impermeable beds in the Miocene to
Recent deposits. At least three permeable zones separated by
lard, relatively impermeable zones, occur within the Floridan
aquifer system. More water, possibly of less satisfactory quality
mut under higher artesian pressure, can usually be obtained from
he deeper zones than from the shallower zones in the aquifer.





FLORIDA GEOLOGICAL SURVEY


Most of the recharge of water to the aquifer is outside of Duvrl
and Nassau counties where the overlying confining beds are thini
or missing. Discharge is by seepage into the ocean and by number.
ous wells throughout Duval and Nassau counties. Between 150
and 200 mgd (million gallons per day) is discharged by wells in
the vicinity of Jacksonville, and between 50 and 70 mgd is dis-
charged by wells at Fernandina Beach, causing depressions in the
piezoimetric surface in these areas. The piezometric surface has
been depressed from less than 30 feet above sea level to more than
15 feet below sea level, and artesian pressures in wells declined
between 50 and 60 feet at Fernandina Beach during the period
1939 to 1963 and between 12 to 22 feet at Jacksonville during the
period 1916 to 1963.
Water from both the shallow and Floridan aquifer systems is
suitable for most uses. The chloride content of water from wells
in the Floridan aquifer system ranges from less than 10 ppin
(parts per million) to more than 40 ppm in wells less than 1,250
feet deep. and it exceeds 1,100 ppm in wells more than 1,250 feet
deep at Fernandina Beach. The chloride content of water from
most wells increased only 2 to 14 ppm during the period 1940 to
1962 except in some deep wells at Fernandina Beach, where it
increased from 20 to 1,350 ppm during the period 1955 to 1962.
At present serious salt-water contamination is limited to a few
deep wells at Fernandina Beach, where salt water is migrating
laterally from a highly mineralized zone within the fresh-water
zone and vertically from highly mineralized zones below the fresh-
water zones. Proper well construction and spacing controlled dis-
charge, and careful development of the deeper water-bearing zones
may retard. and prevent further, salt-water contamination.
Future studies will include investigations of the shallow aquifer
system, quantitative studies of the Floridan aquifer system, and
detailed analysis of the spread of salt-water contamination in
northeast Florida.

INTRODUCTION

Ground water is the principal supply of fresh water in north.
east Florida. Practically all water for municipal, industrial, anc
agricultural use is obtained from wells. In recent years, expanding
industry and increasing population in the area have considerably
increased the use of ground water. To supply the increased need
for water many new wells have been drilled, many existing wells
have been deepened, and large-capacity pumps have been installed





REPORT OF INVESTIGATIONS NO. 43


o wells that previously produced an adequate supply by natural
11i)W.
Correlated with the increase in water use is the continued de-
cine in artesian pressures. Records of water levels in northeast
Florida show that since 1880 pressures have declined more than
(t; feet in some parts of the area. In many parts of Florida and
(eorgia, similar declines in artesian pressures have resulted in
salt-water intrusion into the fresh-water supply. The constant
decline in water pressure and the possibility of salt-water contami-
nation of the aquifers pose a threat to the future development of
the fresh water in northeast Florida. A shortage of fresh ground
water could inhibit the area's economic growth and result in hard-
ship for the population.
Recognizing the need for a comprehensive appraisal of the
ground-water resources of northeast Florida, an investigation was
begun in 1959 by the U.S. Geological Survey in cooperation with
the Florida Geological Survey. The purpose of this investigation
was to provide the basic information necessary for the safe and
cllicient development of ground water, one of the most important
natural resources of northeast Florida.
This report presents and interprets the information concerning
the location and availability of ground water collected by the U.S.
Geological Survey previous to and during this study. The report
is a convenient reference for those persons charged with the re-
sp)onsibility of developing and protecting water supplies and for
those who use or control water in significant quantities in Duval
and Nassau counties.
The investigation was begun under the immediate supervision
of M. I. Rorabaugh, the previous District Engineer, Ground Water
ranch of the U.S. Geological Survey, and completed under C. S.
('onover, the present District Engineer.
PREVIOUS INVESTIGATIONS
The occurrence and quantity of ground water in northeast
lorida are briefly mentioned in reports by Matson and Sanford
1913) and Sellards and Gunter (1913) as part of generalized in-
estigations of ground water in Florida. A report by Stringfield
1936) includes maps of the Florida Peninsula showing the area
,f artesian flow, areas in which the artesian water contains more
han 100 ppm of chloride, and the first published map of the piez-
,metric surface of the Floridan aquifer. Reports on ground-water
sources in southeastern Georgia by Stewart and Counts (1958)





FLORIDA GEOLOGICAL SURVEY


and Stewart and Croft (1960) include information on ground-
water discharge and maps of the piezometric surface in the Fer-
nandina Beach area. Ground-water resources in northeast Florida
are described in generalized reports by Stringfield, Warren and
Cooper (1941), and by Cooper, Kenner, and Brown (1953).
Chemical analyses of water from wells in northeast Florida
are included in reports by Collins and Howard (1928), Black and
Brown (1951) and the Florida State Board of Health (1960).
A report by Black, Brown, and Pearce (1953) includes a brief dis-
cussion on the possibility of salt-water intrusion in northeast Flor-
ida. The surface-water resources of Baker County are described
in a comprehensive report by Pride (1958).
Geologic information on northeast Florida is included in re-
ports by Cooke (1945), Vernon (1951), and Puri (1957). The
reports by Vernon and Puri both contain generalized cross sec-
tions that include northeast Florida, and the report by Vernon
also contains a generalized subsurface structural map of northern
Florida. Stratigraphic and paleontological studies of an oil-test
well in Nassau County are described in a report by Cole (1944).
Detailed studies of the ground-water resources and geology of
northeast Florida were made by Pirnie (1927) and Cooper (1944).
Eugene Derragon of the U.S. Geological Survey made a recon-
naissance of the area in 1955. Many of the data collected by Cooper
and Derragon were used in preparing this report.
During this study preliminary reports of the ground-water re-
sources of northeast Florida (Leve, 1961a) and the Fernandina
Beach area (Leve, 1961b) were prepared to determine the extent
of declines of water levels and salt-water intrusion in the area.
Most of the data presented in these preliminary reports are in-
cluded in this report.

ACKNOWLEDGMENTS

The author wishes to express his appreciation to Mr. D. M.
French, Duval Drilling Co., who supplied drilling information and
assisted in sampling and conducting tests on wells; to Mr. T. Oliver,
power superintendent, Container Corp. of America; to Mr. H. G.
Taylor, chief chemist, Rayonier Inc.; and to Mr. C. Washburn,
chief engineer, and Mr. D. C. Hendrickson, associate engineer,
Jacksonville Department of Electric and Water Utilities, all of
whom provided valuable data and either permitted or assisted in
conducting tests, sampling, and measuring of wells.





REPORT OF INVESTIGATIONS No. 43


Appreciation is expressed to the many consultants, well drillers
.nd members of the Florida State Board of Health who made
available many valuable data included in this report.
Special thanks are extended also to the many residents in the
area who permitted access to their properties.

WELL-NUMBERING SYSTEM

Wells inventoried during this investigation were each assigned
an identifying number. Figure 1 is a diagram illustrating the well-
numbering system. As shown in the diagram, the first two seg-
ments of the well number identify the 1-minute quadrangle of
latitude and longitude in which the well is located. Thus, well
021-139 shown in the figure is located in a quadrangle bounded by
latitude 30021'N on the south and longitude 81039'W on the east.
The third segment of the well-location number is based upon
dividing the 1-minute quadrangles into quarters, sixteenths, and
sixty-fourths, which are numbered 1, 2, 3, 4 in the following order:
northwest, northeast, southwest, and southeast. The first digit in
the third segment of the well number locates the well within the
quarter, the second digit locates the well within the quarter-
quarter tract, and the third digit locates the quarter-quarter-
quarter tract. If a well could not be located accurately within the
smallest tract, then a zero is used for the third digit of the third
segment of the well number. Similarly, a zero is used for the
second and first digits of the third segment if the well could not
be located more accurately within the 1-minute quadrangle. With
this system, a well referred to by number in the text can be lo-
cated on figure 2.

GEOGRAPHY

LOCATION AND AREA

This report describes an area of about 2,000 square miles in
he northeastern part of Florida and includes the bordering south-
*astern part of Georgia (fig. 1). The area extends from 30o05'
,arallel north latitude northward into southern Georgia and from
:2010' meridian of west longitude eastward to the Atlantic Ocean.
t includes all of Duval and Nassau counties, eastern Baker, and
northernn Clay and St. Johns counties, Florida, and the extreme
southern portions of Camden and Charlton counties, Georgia.






FLORIDA GEOLOGICAL SURVEY


81040'
30 22' --


25 0 25 50 75 100 miles
Approximate scale


30021' II _Wl I I

Well 021-139-443


Figure 1. Map of peninsular Florida showing the location of Duval and
Nassau counties and illustrations of well-location numbering system.


CLIMATE

The climate of the area is humid subtropical. According to
records of the U.S. Weather Bureau, the mean temperature i:D
69"F near the coast and about 68F inland. The lowest mean
monthly temperature at Jacksonville is 55.90F, in January; the





REPORT OF INVESTIGATIONS NO. 43


Figure 2. Map of Duval and Nassau counties showing the location of wells
for which information was obtained.
highest mean monthly temperature is 82.60F, in July. The aver-
,ge annual precipitation in the area is about 52 inches, of which
0 to 70 percent falls between June 1 and October 31.

POPULATION AND INDUSTRY
Jacksonville, Jacksonville Beach, and Fernandina Beach are
he three largest cities in the area. Most of the population is along
he St. Johns River in and near Jacksonville and along the coast
a- Duval County. Table 1 shows the population of Jacksonville and





FLORIDA GEOLOGICAL SURVEY


Duval County and of Fernandina Beach and Nassau County in
1940, 1950, 1960, and 1962 based on records of the U.S. Census
Bureau. The table also shows the percentage increase in popula-
tion between 1940 and 1962.
The economy of Fernandina Beach and Nassau County is based
upon the production of wood pulp and paper. Two large processing
plants, Rayonier Inc. and Container Corp. of America, are located
in Fernandina Beach, and their expansion has been a major rea-
son for the population increase in Nassau County.
Greater Jacksonville in Duval County is one of the major metro-
politan areas in the southeastern United States. A natural harbor
near the mouth of the St. Johns River and a vast network of
transportation facilities make Jacksonville the distribution center
for northern Florida and southeastern Georgia. A wide range of
products are manufactured and processed in Jacksonville. Some
of the major industries are paper manufacturing, shipbuilding and
repair, processing and packaging of food products, manufacturing
of cigars, chemicals and paint, building products, truck bodies,
steel castings, and furniture. In addition, there are 18 home and
regional offices of insurance companies and 3 major naval facili-
ties in the area.
An index of industrial growth of the Jacksonville area is the
total nonagricultural wages and employment of salaried workers
in the area as determined by the Bureau of Labor Statistics, U.S.
Department of Labor. These figures are given in table 2 for every
2 years since 1950.

PHYSIOGRAPHY
The topography of northeast Florida is controlled by a series
of ancient marine terraces (Cooke, 1945) which were formed -t
times in the Pleistocene when the sea was relatively stationary at
various higher levels than the present sea level. When the sea
dropped to a lower level, the sea floor emerged as a level plain cr
terrace and the landward edge of each terrace became an abandol-
ed shoreline, which is generally marked by a low scarp.
Seven terraces are recognized in northeast Florida; in descen.-
ing level they are the Coharie, Sunderland, Wicomico, Penholoway,
Talbot, Pamlico and Silver Bluff terraces. The original shorelines
and the level plains of the terraces have been modified and des-
troyed by stream erosion and only remnants of the original ter-
races can be seen. The general configuration of these terrace.
shown on figure 3 was mapped from topographic maps primarily .






REPORT OF INVESTIGATIONS NO. 43 9

' LBLE 1. Population of Jacksonville, Duval County, Fernandina Beach, and
Nassau County, 1940-62

Percent
Population increase
unit 1940 1950 1960 1962 1940-62

.Incksonville 178,065 204,517 201,030
Ilval County 210,143 304,029 455,411 482,600 130

Flrnandina Bench 3,492 4,074 7.276
NIIsau County 10,826 12,811 17,189 18,300 60


by their elevation above present msl (mean sea level) and from
aerial photographs.
The highest and oldest terraces, the Coharie, Sunderland and
Wicomico, are in the western part of the area. They form an up-
land that ranges in elevation from 70 to more than 200 feet above
msl. The highest and most prominent surface feature is a high
sandy ridge, called "Trail Ridge," that extends northward through
eastern Baker County into Georgia. The ridge, a remnant of the
Coharie terrace, ranges in altitude from 170 to more than 200 feet.
The Sunderland terrace in eastern Baker County and extreme south-
western Duval County is poorly developed and is modified by ero-
sion. Remnants of this terrace consist of rolling, eroded hills that
range in altitude from 100 to 170 feet. The most extensive occur-
rence of the uplands in the western part of the area consists of
an irregular flat plain from 70 to 100 feet above msl which is the

TABLE 2. Nonagricultural wages and salaried employment in the Jacksonville
area.

Total salaried
workers employed in
Year nonagricultural work

1950 08,600
1052 110,800
1054 116,400
1956 127,800
1958 134,000
1060 144,103
1962 148,100

Percent increase
r 1950-1062 50.2






FLORIDA GEOLOGICAL SURVEY


remnant of the Wicomico terrace. The outer boundary of this ter-
race extends northwestward through south-central Duval County
and western Nassau County into Georgia.
The Penholoway and Talbot terraces in the area are not clearly
defined in northeast Florida because they have been severely modi-
fied by the numerous streams that drain the higher and older ter-
races. Scattered remnants of these terraces occur in a belt that
extends through central Nassau County, north-central Duval Coun-
ty and southeastern Duval County east of the St. Johns River.
They form a coastal ridge at altitudes from about 25 to 70 feet
which is particularly well defined east of the St. Johns River in
southeastern Duval County. Ancient dunes on the coastal ridge
form a series of narrow sandy ridges and low intervening swampy
areas which are elongate parallel to the coastline.
The Pamlico and Silver Bluff terraces form a low coastal plain
throughout most of the central and eastern part of northeast Flor-
ida. The altitude of the plain ranges from slightly above sea level
to 25 feet; however, some dunes along the present coastline are
more than 50 feet above msl. In Nassau County and in northern
Duval County, the plain slopes irregularly eastward toward the
ocean. In central and southern Duval County, the plain slopes
toward the St. Johns River west of the coastal ridge and toward
the ocean east of the ridge.
Adjacent and parallel to the present coastline, remnants of the
Pamlico terrace form a series of offshore bars or islands. These
bars range in width from less than a few hundred feet to about
2 miles and are separated from the mainland by a series of tidal
lagoons and streams. Many of these tidal streams comprise the
Intracoastal Waterway.
Surface drainage in the western and central parts of the area
is through the St. Johns, Nassau, and St. Marys rivers and their
tributaries. East of the coastal ridge, drainage is primarily by
numerous small brackish-water streams that empty either into the
channel of the Intracoastal Waterway or directly into the ocean.
Much of the relatively flat Pamlico, Silver Bluff, and Wicomico
terraces is marshland because drainage is poor.
OCCURRENCE OF AQUIFER SYSTEMS
GENERAL PRINCIPLES
Rainfall on the land surface may be returned directly to the
atmosphere by transpiration and evaporation, drained off into sur-
face bodies of water, or absorbed by the soil and rocks. Some cf






REPORT OF INVESTIGATIONS No. 43


the water that is drained into lakes and streams or is absorbed
1 the soil and rocks eventually moves downward through the
ground to the zone in which the interstices of the rocks are com-
pletely saturated with water, where it becomes a part of the
ground-water body. Ground water moves laterally from zones of
higher hydrostatic head, such as recharge areas where the water
is replenished, to areas of lower hydrostatic head, such as dis-
charging wells and springs.
Ground water occurs under either nonartesian or artesian con-
ditions. Nonartesian water is unconfined, so that its upper surface
is free to rise and fall; artesian water is confined under pressure,
so that its upper surface is not free to rise and fall. The height
to which artesian water will rise above its confined surface in a
tightly cased well is called the artesian pressure head. The imagi-
nary surface coinciding with the altitude of such artesian pressure
heads in wells is called the piezometric surface.
Ground water occurs in rocks in the zone of saturation; how-
ever, only aquifers transmit usable quantities of water to wells.
An aquifer may be a formation, group of formations, or part of a
formation that is porous and relatively permeable. Relatively im-
permeable rocks that restrict the movement of water are called
aquicludes. Thin, discontinuous, relatively impermeable zones that
locally separate permeable zones are called confining beds. A ser-
ies of similar aquifers or permeable zones together with associated
confining beds and aquicludes constitute an aquifer system.
In northeast Florida, ground water occurs in two separate aqui-
fer systems: the shallow aquifer system and the Floridan aquifer
system. Although both aquifer systems were studies during this
investigation, the Floridan aquifer system is described in greater
Detail in this report because it is the principal source of ground
v'ater in the area.

GEOLOGIC SETTING'

Fresh-water supplies in Duval and Nassau counties are obtained
itirely from wells drilled into the rock formations that compose
1 e aquifer systems. Therefore, an essential part of this study

'The stratigraphic nomenclature used in this report conforms to the usage
SCooke (1945) with revisions by Vernon (1951) except that the Ocala
mestone is referred to as the Ocala Group. The Ocala Group, and its
divisions as described by Puri (1953), has been adopted by the Florida
logical Survey. The Federal Geological Survey regards the Ocala as a
Srmation, the Ocala Limestone.






FLORIDA GEOLOGICAL SURVEY


was to differentiate the formations and to determine their water-
bearing properties. This was done by collecting rock cutting from
a number of water wells drilled in the area and examining these
cuttings to determine the texture, mineral composition, and fauna
of the different formations. Additional geologic information was
obtained from drillers' logs, and from lithologic and electric logs
on file with the Florida Geological Survey. Current-meter tra-
verses were made in a number of wells to locate the water-bearing
zones and to determine the relative yield of water from the differ-
ent formations.
The rock formations that are tapped by water wells in the area
include, in ascending order, the Oldsmar Limestone, the Lake City
Limestone, the Avon Park Limestone, and the Inglis, Williston,
and Crystal River Formations of the Ocala Group-all of Eocene
age; the Hawthorn Formation, of middle Miocene age; deposits of
late Miocene or Pliocene age; and, exposed at the surface, un-
differentiated deposits of Pleistocene and Recent age. These rocks
are listed in table 3 and their lithologic character and water-
bearing properties are described briefly.
Rock formations older than the Oldsmar Limestone have not
been tapped by water wells in northeast Florida because sufficient
water can be obtained from the overlying formations and the wa-
ter from the deeper rocks is more highly mineralized. One deep
oil-test well in northwestern Nassau County penetrated rocks
deeper than the Oldsmar Limestone. In this well, marine dolomite
and limestone beds of Eocene age are 2,235 feet thick and extend
to a depth of 2,640 feet below msl. A sample of water collected
between the depths of 2,100 and 2,130 feet below msl and analyzed
for mineral content was found to contain 33,600 ppm of chloride
which is about 11/ times the chloride content of sea water.
The following discussion of the formations include only rocks
penetrated by water wells in Duval and Nassau counties. The cross
sections in figure 4 show these geologic formations.

OLDSMAR LIMESTONE

The Oldsmar Limestone of early Eocene age (Applin an.
Applin, 1944, p. 1699) is the deepest and oldest formation utilize
as a source of water in northeast Florida.
The only well in the area that completely penetrates the
Oldsmar Limestone is a deep oil-test well, 044-156-110, in north-
western Nassau County (Cole, 1944). The top of the Oldsmar








REPORT OF INVESTIGATIONS NO. 43


RECENT


200-

SEA


200O

400



600-


I0-0
BOO -

1200-


s T
a ?


SITS


11


I .
PQs t__i


DEPOSITS
UPPER MIOCENE OR

HAWTHORN



FORMATION

FORMATION

LIMESTONE


R MATIO N

UD





AVON


LAt


0 5 .OmtlN

'Sure 4. Geologic cross sections showing the formations
in Duval and Nassau counties, Fla.


penetrated by wells


'mestone is about 1,270 feet below msl in this well and the

' rmation is 846 feet thick. Well 038-127-324, in Fernandina
i 'ach (fig. 4), reached the top of the Oldsmar Limestone at 1,746
1 et below msl and penetrated more than 340 feet of the formation
v without reaching older formations.


CRYSTAL RIVER

S IINGLIS
AVON PARK -I
LAKE CITY


- 200
A'

--SA LEVEL

-200

--000


--600

-800

-1000

-1200


l RIVER FM
LISTEN FM-. 6

PARK LIMESTONE


(E CITY LIMESTONE


--`--~






FLORIDA GEOLOGICAL SURVEY


In wells in northeast Florida, the Oldsmar Limestone consists
of a cream to brown, soft, massive to chalky granular limestone,
and cherty, glauconitic, massive to finely crystalline, sugar-
textured dolomite. The formation is lithologically similar to the
overlying Lake City Limestone and is differentiated from the
Lake City by its fossil content. The top of the Oldsmar Limestone
is picked by the first occurrence of the foraminifer species
Helicostegina gyralis Barker and Grimsdale.


LAKE CITY LIMESTONE

Lake City Limestone is the name applied by Applin and Applin
(1944) to limestone of early middle Eocene age that conformably
overlies the Oldsmar Limestone in peninsular Florida.
Depths to the top of the Lake City Limestone in northeast
Florida range from about 580 feet below msl in south-central
Duval County to about 1,260 feet below msl at Fernandina Beach.
Only a few wells in northeast Florida completely penetrate the Lake
City Limestone. The Lake City is 486 feet thick in a well (044-156-
110) in northwestern Nassau County and 475 feet thick in a well
(038-127-324) at Fernandina Beach. A well in southwestern Duval
County (014-153-420) penetrates more than 490 feet of Lake City
Limestone without reaching older formations.
Lithologically, the Lake City Limestone consists of alternating
beds of white to brown, purple tinted lignitic, chalky to granular
limestone and gray to 'tan massive to finely crystalline, sugar-
textured dolomite. It contains beds consisting entirely of cone-
shaped (Valvulinidae) foraminifers and locally contains thin beds
of lignite.
The Lake City Limestone contains abundant fossil foraminifei s
that are different from those in the underlying Oldsmar Limestore
and overlying Avon Park Limestone. The most distinctive fossil
of the Lake City Limestone is Dictyoconus americanus which w s
selected by Applin and Applin (1944) as a guide fossil for the
formation. The fossils most often found in well cuttings from th3
Lake City Limestone include Dictyoconus americanus (Cushman),
Fabularia vaughani Cole and Ponton, Discorbis inornatus Colk,
Fabiania cubensis Cushman and Bermudes, Archaias columbiensH
Applin and Jordan.






REPORT OF INVESTIGATIONS NO. 43


AVON PARK LIMESTONE

Deposits of late middle Eocene age penetrated by wells in Polk
( county were named Avon Park Limestone by Applin and Applin
(1944). Outcrops of the formation in Citrus and Levy counties
were later recognized and described in detail by Vernon (1951, p.
95).
The Avon Park Limestone ranges in thickness from 150 feet
to more than 700 feet in central and southern Florida; however,
it has been considerably thinned by erosion in northeast Florida.
The geologic cross sections in figure 4 show that the formation
averages only about 50 feet in thickness throughout the western
and central parts of northeast Florida. It thickens toward the
coast and is about 190 feet thick in a well (019-124-210) at Atlantic
Beach and more than 250 feet thick in a well (038-127-324) at
Fernandina Beach.
The Avon Park Limestone unconformably overlies the Lake
City Limestone and unconformably underlies the Ocala Group.
Contours constructed on the irregular upper surface of the Avon
Park Limestone in northeast Florida are shown on figure 5. As
shown, the top of the formation is less than 500 feet below msl
in south-central Duval County and more than 950 feet below msl
in northeastern Nassau County.
The lithology of the Avon Park Limestone varies both laterally
and vertically throughout northeast Florida. In the western and
central parts of the area where the formation has been consider-
ably thinned by erosion, it consists predominantly of tan to brown,
hard, massive dolomite beds containing thin zones of tan granular,
fossiliferous limestone. In the eastern part of the area where the
Information is thickest, it consists of alternating beds of tan hard,
massive dolomite; brown to cream granular, calcitic limestone; and
irown, finely crystalline, sugar-textured dolomite.
The top of the formation usually can be detected during the
STilling of wells because the hard dolomite beds in the upper part
f the formation retard the drilling rate. In addition, the Avon
ark Limestone can be identified and differentiated from the other
-rmations of Eocene age by its fossil content. The following
!agnostic foraminifers were identified in the Avon Park
limestone from well cuttings in the area:Coskinolina, floridana
ole, Dictyoconus cookei (Mobert), Dictyoconus gunteri Cole,
ituonella floridana Cole, Spirolina coryensis Cole.






FLORIDA GEOLOGICAL SURVEY


OCALA GROUP

Cooke (1915, p. 117; 1945, p. 53) defined all deposits of late
Eocene age in Florida as one formation; the Ocala Limestone.
These deposits were later redefined by Vernon (1951, p. 111-171)
as two formations; the Moodys Branch Formation and the Ocala
Limestone. More recently Puri (1953, p. 130; 1957, p. 22-24)
divided the late Eocene limestone into three separate formations.
These are, in ascending order, the Inglis, the Williston, and the
Crystal River Formations. These three formations are now
referred to collectively as the Ocala Group by the Florida
Geological Survey.
All three formations of the Ocala Group are fragmental marine
limestones and were differentiated in cuttings from wells in
northeast Florida by slight changes in lithology and on the basis
of fossil content. However, in some wells from which cuttings were
collected and examined, it was not possible to differentiate each
of these formations because of lithological similarities and the
absence of diagnostic fossils in the cuttings.

INGLIS FORMATION

The Inglis Formation lies unconformably on the Avon Park
Limestone and ranges in thickness from about 40 feet to about
120 feet in northeast Florida. As shown on the geologic cross
section in figure 4, it is thickest west of the St. Johns River in
western and central Duval County.
Lithologically, the Inglis Formation is a tan to buff granular,
calcitic, marine limestone. It contains beds consisting entirely
of a coquina of Miliolidae foraminifers. These coquina beds are
loosely cemented and porous and have a mealy texture. Thin,
discontinuous zones of gray to brown, hard, crystalline dolomite
are prevalent near the base of the formation.
The lithologies of the Inglis and the overlying Williston
Formations are similar and in many sets of cuttings from wells
in the area the upper contact of the Inglis is not clearly defined.
However, in most cases it was possible to differentiate the forma-
tions on the basis of changes in fossil content. The following
diagnostic fossils were used as guide fossils (Puri, 1957, p. 48) t)
identify the Inglis Formation in cuttings from wells in the area:
Fabiana cubensis Cushman and Bermudez, Periarchus lyelli (Con-
rad), Spirolocidina seminolensis Applin and Jordan, Spirolinu
coryensis Cole.






REPORT OF INVESTIGATIONS NO. 43


WILLISTON FORMATION

The Williston Formation lies conformably between the under-
lying Inglis and the overlying Crystal River Formations. It
ranges in thickness from about 20 feet to 100 feet and has an
average thickness of about 50 feet throughout northeast Florida.
The lithology of the Williston Formation is similar to that of
the underlying Inglis Formation, consisting of a tan to buff
granular, marine limestone. However, the Williston is generally
more indurated and does not contain the mealy-textured coquina
beds that are found in the Inglis Formation.
The Williston Formation can further be differentiated from
the other formations in the Ocala Group by a distinct fossil
assemblage. The following fossils were identified in well cuttings:
Amphistegina pinarensis cosdeni Applin and Jordan, Operculi-
noides moodybcranchensis (Gravell and Hanna), Operculinoides
willcoxi (Heilprin), Operculinoides jacksonensis (Gravell and
Hanna), Nummulites vanderstoki Rutten and Vermunt, Heteroste-
gina ocalana Cushman.
Several of these species of fossils occur in the other formations
of the Ocala Group but not as frequently nor in as great numbers
as in the Williston Formation. The top of the formation was
determined by the first appearance in well cuttings of
Amphistegina pinarensis cosdeni, which is the most diagnostic
fossil of the Williston Formation in northeast Florida.

CRYSTAL RIVER FORMATION

The Crystal River Formation is the youngest Eocene forma-
lion generally penetrated by wells in northeast Florida. It
conformably overlies the Williston Formation and unconformably
underlies the Hawthorn Formation of middle Miocene age. The
sickness of the formation varies considerably throughout the
rea and, as shown by the geologic cross sections in figure 4,
anges from less than 100 feet in central and western Duval
county to 300 feet in well 038-127-324 at Fernandina Beach.
Lithologically, the Crystal River Formation is a white to cream,
halky massive fossiliferous, marine limestone. It is lighter in
olor, less granular, and more friable than the underlying Williston
'ormation, and contains abundant Molluscan shells and relatively
irge foraminifers that are not common in the underlying forma-
ions of the Ocala Group. The fossils identified in well cuttings
rom the Crystal River Formation include: Lepidocyclina ocalana






FLORIDA GEOLOGICAL SURVEY


Cushman, Lepidocyclina ocalana pseudomarginata Cushman, Oper-
culinoides ocalana Cushman, Operculinoides floridensis (Heilprin),
Sphaerogypsina globula (Ruess), Nummulites vanderstoki Rutten
and Vermunt, Heterostegina ocalana Cushman.

HAWTHORN FORMATION

Rocks of middle Miocene age in peninsular Florida were first
named the Hawthorn Formation by Dall and Harris (1892, p. 107).
The Hawthorn Formation lies unconformably on the eroded surface
of the Ocala Group throughout all of northeast Florida.
As shown in the geologic cross sections in figure 4, the thick-
ness of the Hawthorn Formation ranges from about 250 feet in
southern Duval County to about 500 feet in north-central Duval
and central Nassau counties. Locally, the formation may vary in
thickness by as much as 50 feet where it fills depressions in the
irregular surface of the Crystal River Formation.
The Hawthorn Formation consists of gray to blue-green
calcareous, phosphatic sandy clays and clayey sands, interbedded
with thin, discontinuous lenses of fine to medium phosphatic sand,
phosphatic sandy limestone, and gray hard dolomite. The limestone
and dolomite lenses are thicker and more prevalent near the base
of the formation than in the higher parts. They occasionally
contain some poorly preserved mollusk casts and molds. The only
other fossils in the formation are sharks' teeth, which are most
often found in the clay beds.

UPPER MIOCENE OR PLIOCENE DEPOSITS

Deposits overlying the Hawthorn Formation in peninsular
Florida were described by Cooke and Mossom (1929, p. 152) andi
Cooke (1945) as being Pliocene in age. They have been more
recently described by Vernon (1951, figs. 13,33) as late Miocene
in age. Because their age has not been determined exactly, they
are referred to in this report as Pliocene or upper Miocene deposits.
Pliocene and upper Miocene deposits are the oldest rocks ex-
posed at the surface in northeast Florida. They are exposed in roach
cuts, excavations, and the banks and beds of many streams in the
area. As shown in the geologic cross sections (fig. 4), these deposits
are about 100 feet thick adjacent to the St. Johns River in centra
Duval County and in central and eastern Nassau County, and les:
than 20 feet thick in western Duval and eastern Baker counties.






REPORT OF INVESTIGATIONS NO. 43


The Pliocene or upper Miocene deposits consist of interbedded
ay-green calcareous silty clay and clayey sand; fine-to medium-
grained, well-sorted sand; shell; and cream to brown soft, friable
limestone. They differ from the underlying Hawthorn Formation
in that they contain little or no phosphate. The limestone is most
prevalent at the base of the deposits and together with sand and
shell form a laterally extensive, continuous, relatively permeable
zone which locally is as much as 40 feet thick.
The contact between the Pliocene or upper Miocene deposits and
the Hawthorn Formation is an unconformity generally marked
by a course phosphatic sand and gravel bed. However, the contact
between the Pliocene or upper Miocene deposits and the overlying
Pleistocene and Recent deposits is not clearly defined. In some wells,
particularly in the eastern and northern parts of the area, the
contact appears to be gradational.

PLEISTOCENE AND RECENT DEPOSITS

Undifferentiated sediments of Pleistocene and Recent age
blanket most of northeast Florida, except where they have been
completely eroded by streams. As shown in the geologic cross
sections (fig. 4), the deposits are more than 150 feet thick in
eastern Baker County and average about 20 feet in thickness in
central and eastern Duval and Nassau counties.
The Pleistocene and Recent deposits in the western part of the
area consist primarily of fine- to medium-grained, poorly sorted
sand and clayey sand, locally stained yellow or orange by iron
oxide. In the central and eastern parts of the area, the deposits
are predominantly loose sand and gray to green clayey sand,
containing some shell beds near the coast.

STRUCTURE

The structural contour lines in figure 5 reflect the eroded
surface of the Avon Park Limestone and Crystal River Formation.
At the contour interval shown in the figure, the small irregularities
n the surface of the formations are not apparent and the configur-
tion of the lines reflects the approximate subsurface structure
*f the formations. As shown, the surface of the Avon Park
.imestone strikes approximately northwest-southeast and dips
northeast at about 9 feet per mile in the western part of the area,
nd strikes northeast-southwest and irregularly dips northwest
bout 16 to 20 feet per mile in the eastern part.






FLORIDA GEOLOGICAL SURVEY


Although the surface of the Crystal River Formation has been
modified by erosion more than the surface of the Avon Park
Limestone, the contour lines on the top of the Crystal River
Formation in figure 5 generally reflect the configuration of the
underlying Avon Park Limestone. The top of the Crystal River
Formation ranges from less than 300 feet below msl in southern
most Duval County to more than 550 feet below msl in north-
central Duval County. The Crystal River Formation is the initial
limestone of Eocene age penetrated by wells in the area, and in
most areas it is also the top of the Floridan aquifer system. There-
fore, these contour lines also show the top of the Floridan aquifer
system in Duval and Nassau counties.
The limestone formations of Eocene age in the western part of
the area, sloping northeastward, and in the eastern part of the
area. sloping northwestward, form an irregular trough or basin
extending from south-central Duval County northeastward into
northeastern Nassau County. A fault extends generally along the
axis of this basin, the upthrown side to the west. In southern
Duval County, the vertical displacement of the top of both the
Ocala Group and the Avon Park Limestone by the fault is about
125 feet. The vertical displacement decreasess northward and the
fault probably does not extend farther north than northern Duval
County.
The irregularities in the surface of the Eocene limestone
formations were filled and blanketed by the thick series of post-
Eocene sediments (fig. 4), and there is no surface reflection of
the subsurface structural features in the area.

SHALLOW AQUIFER SYSTEM

The shallow aquifer system consists of the limestone and sand
aquifers in the clayey sand and sandy clay confining beds in the
upper part of the Hawthorn Formation, the shell, limestone, and
sand aquifers in the Pliocene or upper Miocene deposits and the
sand and shell aquifers in the Pleistocene and Recent deposits
(table 3).
The lithology of these deposits changes laterally as well as ver-
tically and the aquifers and confining beds are discontinuous. Ir
some part of northeast Florida, particularly in western Duval.
Nassau, and eastern Baker counties, the shallow aquifer system
may consist of a single, relatively thick aquifer extending down
ward from the water table to the aquiclude in the Hawthorl






REPORT OF INVESTIGATIONS NO. 43


F formation. In other parts of the area, particularly in central and
e stern Duval and Nassau counties, the shallow aquifer system
may consist of a series of relatively thin permeable zones separated
,locally by a number of relatively thin confining beds.
The most laterally extensive aquifer in the shallow aquifer
system occurs as either a limestone, a shell, or a sand bed near the
base of the Pliocene or upper Miocene deposits. It is about 10 to
40 feet thick and is 50 to 150 feet below the surface throughout
most of Duval and Nassau counties.

AQUIFER CHARACTERISTICS

Although ground water in the shallow aquifer system is
generally under nonartesian conditions, some shallow wells located
in low areas immediately adjacent to the St. Johns River and its
tributaries yield artesian water. These local artesian conditions
are caused by confining beds that confine water under pressure in
an underlying aquifer, particularly in shell and limestone beds
near the base of the Pliocene or upper Miocene deposits.
The shallow aquifer system is recharged chiefly by local
rainfall. Discharge from this system occurs by evaporation,
transpiration by plants, seepage into surface bodies of water,
leakage downward into the underlying rocks, and discharging
wells.
The fluctuations and seasonal trends of water levels in wells
in the shallow aquifer system indicate the gain and loss of water
to and from the system. The hydrographs in figure 6 show the
fluctuations and seasonal trends of water levels in two wells in the
shallow aquifer system in northeast Florida. Part A of the figure
shows a hydrograph of the semi-daily water levels in well 040-127-
211A, at Fernandina Beach, and a bar graph of the daily rainfall
ait Fernandina Beach in April 1961. The graphs show the effect
4o local rainfall on the water level in the well. For example, the
:ise in water of more than 1 foot on April 15 reflects recharge
o the aquifer from a rain of 2.70 inches the same day. The overall
decline in the.water level between April 20 and 30 reflects depletion
f water in the aquifer system by the pumping from other shallow
ellss in the area and by the lack of rainfall after April 16.
Part B of figure 6 shows a hydrograph of the water levels in
,-ell 017-136-241B and a bar graph of the monthly rainfall at
acksonville between February 1961 and December 1962. As
iown graphically, the water level in the well generally declined






FLORIDA GEOLOGICAL SURVEY


(A)


S Doily rainfall ot Fernondino Be ch






S5 6 7 8 9 10 11 12 1314 15 16 11 18 19 2021 22 23 24 25 26 27 2829
APRIL 1961

SWELL 017-136-2418, Imile east
ol Jacksonville
(Shallow a uiler)



II -


1961


1962


Figure 6. Graphs showing rainfall at Fernandina Beach
and the water levels in well 040-127-211A at Fernandina
017-136-241B near Jacksonville.


and Jacksonvillie
Beach and wel!


even during periods when the rainfall increased. For example
rainfall during June and July 1962 was almost 7 inches greater
than during the same period in 1961; however, the water level:
in the well were about 2 feet lower in June and July 1962 thar
during the same period in 1961. The decline in water level was
irregular and generally months of greater rainfall resulted ir






REPORT OF INVESTIGATIONS NO. 43


slightly higher water levels. This general decline in water levels
w-as partly a result of a deficiency in total rainfall during 1961
ltnd 1962 compared to rainfall in 1960. However, as indicated by
(he lower water levels during periods of increased rainfall, the
decline was caused partly also by increased pumping from more
shallow wells in the area.

WATER SUPPLIES
Water in the shallow aquifer system is generally obtained from
two separate aquifers: (1) from surficial sand beds and (2) from
a limestone, sand, and shell zone near the base of the Pliocene
or upper Miocene deposits.
Some water for lawn irrigation, stock and domestic use is
obtained from the surficial sand deposits by using "surface"
sandpoint wells constructed of galvanized casing from 1/2 to 2
inches in diameter. The casing is either driven or jetted 10 to 30
feet below the surface to put the well screen below the water table.
The yields of the surface wells differ in different parts of the area,
primarily because of lateral changes in the water-transmitting
character of the aquifer. In most of northeast Florida, typical
surface wells 11/4 inches in diameter yield between 10 and 15 gpm
(gallons per minute). However, some wells in relatively thick and
permeable beach sands along the coast yield as much as 25 gpm.
Most of the water from the shallow aquifer system is obtained
near the base of the Pliocene or upper Miocene deposits. Water is
obtained from this aquifer by "rock" wells, generally 2 inches in
diameter and 50 to 150 feet deep. The casing is either driven or
jetted to the top of the aquifer and the bottom of the casing is
left open. An open hole is then drilled into the aquifer below the
casing and water enters the well throughout the entire length
of the open hole. Typical 2-inch "rock" wells throughout most of
northeast Florida yield 15 to 20 gpm. Locally, where the aquifer
!s relatively thick and composed of permeable limestone or shell,
: 2-inch well may yield as much as 80 gpm. A few 4-inch rock wells
n Jacksonville and a few 5-inch wells in Fernandina Beach yield
)0 to 80 gpm.
Water from the surficial sands generally contains iron (Fe),
vhich gives it a pronounced taste and stains plumbing fixtures.
surfacee wells .near brackish water are in danger of contamination
'y lateral encroachment of such water. Water from the "rock"
vells is generally of good quality and suitable for most domestic,
crigation," and industrial uses.






FLORIDA GEOLOGICAL SURVEY


The shallow aquifer system presently supplies only small to
moderate amounts of water to small-diameter wells. However,
properly constructed large-diameter gravel-packed wells in the
shallow sand aquifers may be capable of supplying large amounts
of water. The shallow aquifer in northeast Florida could become
an important source of water to supplement the supplies that are
presently obtained from the Floridan aquifer system. Although
the areal extent of the relatively thick aquifer at the base of the
upper Miocene or Pliocene deposits was not determined by this
study, it appears to underlie most of the area. It is possible that
this shallow aquifer could be artificially recharged locally with
surface water. When the aquifer is not completely saturated,
rainfall stored in shallow surface reservoirs could percolate down-
ward into the aquifer to replace the water discharged from shallow
wells.

FLORIDAN AQUIFER SYSTEM

The Floridan aquifer system is the principal source of fresh
water in northeast Florida; therefore, most of the information
collected and studied during this investigation was concerned with
this aquifer system. It includes part or all of the Oldsmar, Lake
City, and Avon Park Limestones, the Ocala Group, and a few
discontinuous, thin aquifers in the Hawthorn Formation that are
hydraulically connected to the rest of the aquifer system. The
Floridan aquifer system is separated from the shallow aquifer
system by the extensive aquiclude in the Hawthorn Formation and
in the Pliocene or upper Miocene deposits. Water in the Floridan
aquifer system is artesian.

PERMEABLE ZONES

The water-bearing zones within the Floridan aquifer system
consist of soft, porous limestone and porous dolomite beds. Thte
hard, massive dolomite and limestone are relatively impermeable
and act as confining beds that restrict the vertical movement o'
water. Where the confining beds are continuous for a considerable(
distance, they isolate these water-bearing zones.
The Ocala Group is one homogeneous sequence of permeable
hydraulically connected marine limestone beds that contain fev
hard dolomite or limestone beds to restrict vertical movement of'
water. The Avon Park Limestone consists almost entirely o2






REPORT OF INVESTIGATIONS NO. 43


h,lrd, relatively impermeable dolomite beds that restrict the
vertical movement of water between the overlying and underlying
permeable zones. The Lake City and Oldsmar Limestones each
contain alternating hard, relatively impermeable dolomite confin-
ing beds and soft, permeable limestone and dolomite water-bearing
zones.
The separation of the permeable zones in the Floridan aquifer
system in the vicinity of Jacksonville is indicated by the difference
in artesian pressure at different depths in the aquifer system.
Figure 7 shows hydrographs of three wells located within 40 feet
of each other and drilled and cased to different depths within the
Floridan aquifer system. The lowest artesian pressures were
recorded in well 026-135-342C which is open to the top 250 feet
of the Ocala Group. The highest artesian pressures were recorded
in well 026-135-342B which is open to about 175 feet of the Avon
Park and the Lake City Limestones. The water pressure in this
well was between 0.5 and 1.5 feet higher than that in well 026-135-
342C between January 1960 and February 1963. This difference
in pressure suggests that the zones supplying water to these wells
are isolated from each other.
Well 026-135-342A, drilled to 1,390 feet and cased to 584 feet
below the surface, is open to permeable zones in both the Ocala
Group and the Lake City Limestone. The artesian pressure



|"1 i Il-liw. in Il I I
A B C


IIN


\ I \ 026-135-342B



) U- \\\
:1-


026-135-32C

,___y


b" 0 0


12000

16000 bI -I
1600 z00 ( 00 400
/ no w,mn llon per
/\ I//- c 026-135-342 A FLow RDUCL On
IROW DISRIB'U' DN CLRW


and C, about 4 miles northeast of Jacksonville.


J F MAM J J AS OND J FMAMJ JAS ON J FMAM J JAS ON J FMAMJ
1960 1961 1962 1963
;ure 7. HvdrograDhs and geologic data from wells 026-135-342 A, B,


i
gI








FLORIDA GEOLOGICAL SURVEY


measured at the well head reflects the pressure in the permeable

zones in the Lake City Limestone modified by internal dissipation

into the Ocala Group, where the pressure is lower.

This internal dissipation of water within wells that penetrate

more than one aquifer in the Florida aquifer system was indicated

by current-meter traverses in wells 019-124-210, 021-141-423, 026-

135-342A, and 038-127-324, as shown in figures 8 and 9. Water

moved from permeable zones of higher artesian head to those of

lower head when the flow was shut off at the well head. In all wells

the water moved upward, and, except in well 021-141-423, the water

moved from lower formations into the Ocala Group. These zones


71







'A


tpMANATIoN
0I.1 wwii
E3m..


~~s*rr~r ;n~
t
""'
""" ~~sr

r ,rJ an
D---' y ~ I- C R -^
s'J UCI~LC~r LI *i~YI.1(Iml n*l

1

~-L1~~: I ;'i
i
--
WVr
Ir-
Irl'~~~sCI ~~~
-I~clr-




if
~


i-fL



_Jf


2::. -'~
.'2Z


Figure 8. Diagrams showing geologic and current-meter data from wells
in Duval County.


NEI---I









7'' rr


`'"

;


sw Mo








REPORT OF INVESTIGATIONS NO. 43 27


AllOJ9-124 2I0 RevoluAiom per mm ue of currenl meter

00400



0r Orlos per mnut





;00 |_A r\
K dre

A-",
















o ,to v lloi o
La.u. |j.-




\^
IOCO L x 5 3m0 4000 5000(,r) -Ip00 0 )0 20000 3X- 4p00 )W-
SMo Iurm low betlweer intcrvols, in
S3000 CAIBRATiON AIM gollDnS per minute
,o /, EXPLANATION
LSUr ,A taaLmegslone
S100 I Ipn -1gren











400.




















0 0 0 ow-lo per m ~eneu tg
S bDural and Nassau counties.
1 Iy -om








l a000. > rorr ol cuiningp 6K




LOW C-ty em between. 1* n Leru p
LGOO @ |aw'


Slmoli I i\ S\l ~ \T(IOC flow I

500 0 00 0 |m0 -ta%. gnaW pe --B9.

g 9. DLinigrt s or in g olI an c -mete a fm wl


u an gallons per minule




S00 lo poo 213 nor."n (ollonI Pit minun.

P igure 9. Diagrams showing geologic and current-meter data from wells in
I_. Duval and Nassau counties.






FLORIDA GEOLOGICAL SURVEY


containing water under different artesian pressure are separated
by hard, relatively impermeable limestone and dolomite beds within
the aquifer system.

CURRENT-METER STUDIES

In order to determine the depth, thickness, and relative yield
of the different water-bearing zones or separate aquifers within
the Floridan aquifer system, current-meter traverses of several
wells in the area were analyzed by flow-distribution curves. The
relative velocity of the water at different depths in a well was
determined from current-meter traverses. The actual rate of flow
of water at different depths is calculated by the formula q = av,
in which q is the quantity of water per unit time, a is the cross-
sectional area of the well at a given depth, and v is the mean
velocity of water at that depth as indicated by the current meter.
Because the cross-sectional area of a well bore is not the same
at all depths below the casing, relative velocity graphs are insuffi-
cient to determine q. The flow-distribution curve is constructed
from the velocity graph by connecting the points of maximum
velocity on the graph. The velocity is a maximum where the
diameter is a minimum, which is generally where the resistant
hard limestones and dolomites occur. Inasmuch as the minimum
diameter of the well is about the diameter of the bit used in
drilling the well, the diameter of these zones can only be equal to
or greater than the diameter of the bit. The flows calculated at
these hard zones using the bit diameter will be equal to or less
than actual flow. Therefore, these zones, which are all assumed
to have the same diameter, are utilized as markers in constructing
flow-distribution curves. The configuration of the curves also
depends on the geologic characteristics of the formations pene-
trated by the well.
Figures 8 and 9 show the geologic data, relative velocities,
flow distribution, and relative yield or loss of water between
regular intervals of the Floridan aquifer system for six wells in
Duval and Nassau counties. The flow-distribution graphs were
drawn by determining the rate of flow from the flow-distribution
curves for each well at approximately 100-foot intervals below
the casing. The increase or decrease in the rate of flow over each
interval indicates the quantity of water that entered or left the
well bore within that interval. The current meter was calibrated
in each well to convert relative velocity to rate of flow by recording






REPORT OF INVESTIGATIONS No. 43


,he revolutions per minute of the meter while water flowed or
,was pumped at different rates, or by recording the revolutions
per minute of the current meter in two casings of different
diameters in each well while the rate of flow was kept constant.
The flow-distribution curves and bar graphs for wells 021-139-
222, 021-141-423, 025-143-220, and 026-135-342A indicate at least
two separate permeable zones in the Floridan aquifer system. One
zone is in the Ocala Group at depths between the bottom of the
casing in each well and about 800 feet below land surface. The
other zone is in the Lake City Limestone at depths between about
950 feet and 1,200 feet below land surface. These two zones are
separated by about 100 to 200 feet of hard limestone and dolomite,
mostly in the Avon Park Limestone but also at the base of the
Ocala Group and at the top of the Lake City Limestone. Within
this impermeable zone little or no water enters the wells. A third
permeable zone occurs within the Lake City Limestone between
about 1,250 feet below the surface and the bottom of wells 021-141-
423 and 026-135-342A. This third permeable zone is separated
from the overlying permeable zone by about 100 feet of imperme-
able hard limestone and dolomite in the Lake City Limestone.
As shown by the flow-distribution curves and the bar graphs
in figures 8 and 9, the yield of water from the permeable zones
in the Ocala Group is considerably less than that from the other,
deeper zones. Generally, less than 30 percent of the total water
produced from each well comes from the Ocala Group. In well
025-143-220, less than 200 gpm of the 4,800 gpm produced by
natural flow is from the Ocala Group. The major water-bearing
zone in the wells tested in the vicinity of Jacksonville is in the
Lake City Limestone at depths between about 950 feet and 1,200
feet below land surface. As shown by the flow-distribution curves
and the bar graphs in the figure, this zone yields 50 to 98 percent
of the water produced by each well. In wells 021-141-423 and 026-
135-342A, the flow-distribution curves and bar graphs show that
about 15 to 20 percent of the water from each of these wells comes
from the aquifer in the Lake City Limestone at depths of more
than 1,250 feet below land surface.
In well 019-124-210 at Atlantic Beach, the water-producing
zone between 1,100 feet and 1,290 feet below land surface in the
Lake City Limestone can be correlated with the major water-
producing zone in the Lake City Limestone in the vicinity of
Jacksonville. In well 038-127-324, at Fernandina Beach, the water-
bearing zone between 1,300 feet and 1,700 feet below land surface






FLORIDA GEOLOGICAL SURVEY


in the Lake City Limestone can be correlated with the two aquifer;:
in the Lake City Limestone penetrated by the wells tested in the
vicinity of Jacksonville. The confining beds separating the two
zones in the Lake City Limestone in the vicinity of Jacksonville
are absent in Fernandina Beach.
The flow-distribution curves and bar graphs of well 038-127-324,
at Fernandina Beach, show that there is another permeable zone
in the Floridan aquifer system below the Lake City Limestone,
in the Oldsmar Limestone. This zone, which is separated from
the overlying zone in the Lake City Limestone by relatively
impermeable dolomite beds in the Oldsmar Limestone, yields about
one-third of the water produced in the well. It has not been
penetrated by any of the wells tested in the vicinity of Jacksonville.
Information obtained while wells 019-124-210, at Atlantic
Beach, and 038-127-324, at Fernandina Beach, were being drilled
indicates that in both wells the Ocala Group yielded water before
the deeper water-bearing zones were reached. However, current-
meter traverses made in both wells after they were drilled indicate
that the Ocala Group does not yield any water to the wells, but
instead, much water from zones of higher artesian pressure in
the Lake City Limestone and Oldsmar Limestone flows through
the well bore into zones of lower artesian pressure in the Ocala
Group. As shown by the flow-distribution curves and bar graphs
in well 019-124-210 when there was no flow of water at the surface,
about 1,600 gpm entered the Ocala Group through the well bore
from the zone in the Lake City Limestone; and when flow was
5,000 gpm at the surface, about 500 gpm entered the Ocala Group.
In well 038-127-324, when there was no flow of water at the surface,
about 700 gpm entered the Ocala Group through the well bore
from the deeper zones; but when the well flow was 623 gpm at
the surface, 650 gpm entered the Ocala Group; and when the well
flow was 1,900 gpm at the surface, only about 350 gpm entered
the Ocala Group.
The great difference in artesian pressures within the Floridan
aquifer system in well 019-124-210, at Atlantic Beach, and well
038-127-324, at Fernandina Beach, and to a lesser extent in wells
in the vicinity of Jacksonville, indicate that in these areas the
confining beds are extensive and the zones are separated and
somewhat isolated from each other. Presently, the deeper zones
yield more water, under higher pressure, than the zones in the
Ocala Group. However, as additional wells are drilled or deepened
into the deeper zones, internal leakage within the well bores and






REPORT OF INVESTIGATIONS No. 43


withdrawall of water from the lower aquifers will probably equalize
ihe pressures in the upper and lower zones.

WATER SUPPLIES

Wells in the Floridan aquifer are generally cased to the top of
the aquifer, which in most areas is the top of the Crystal River
Formation. The wells are then completed without casing into the
Floridan aquifer system so that water may enter the open hole
from the various water-bearing zones penetrated. The diameter
of the casings ranges from 2 inches in small domestic wells to as
large as 20 inches in some industrial wells.
The approximate depth to the top of the Floridan aquifer
system in Duval and Nassau counties is shown in figure 5. The
figure also shows contours on the top of both the Crystal River
Formation and the Avon Park Limestone. Exact depths to the
top of the Floridan aquifer system can be computed for any
specific locations in the area by using the contours on the top of
the Crystal River Formation in figure 5 in conjunction with the
land-surface altitude.
The Ocala Group is the first permeable zone in the Floridan
aquifer and its thickness may be determined at any specific location
in the area by comparing the contours on the top of the Crystal
River Formation and on the top of the Avon Park Limestone. This
thickness added to the depth below land surface to the top of the
Floridan aquifer system and the approximate thickness of the
Avon Park Limestone, taken from the geologic cross sections
(fig. 4), is the approximate depth to the major water-producing
zone in the Lake City Limestone.
The yield of wells in northeast Florida depends greatly on the
depth of the wells. Wells drilled into the deeper zones in the
Floridan aquifer system generally yield more water than those
drilled only into the shallower zones. Table 4 shows the artesian
flow and pressure in five Jacksonville municipal wells recorded
before and after each well was deepened to penetrate the major
water-producing zone in the Lake City Limestone. In each well
there was a considerable increase in yield by natural flow and in
artesian pressure after the wells were deepened. Wells 020-139-413
and 020-139-322, in central Jacksonville, originally penetrated
about 520 feet of the Floridan aquifer system, which includes the
permeable zones in the Ocala Group and the top of the permeable
zone in the Lake City Limestone. After these wells were deepened















TABLE 4. Artesian flow and pressure in five Jacksonville municipal wells
before and after each well was deepened.


Well number
and location

018-189-281
Cedar St. between
Flagler and
Naldo Sts.
018-142-211
Corner of Plum
and Shearer Sts.
020-189-822
Corner of Fourth
and Pearl Sts.
020-189-418
Corner of Third
and Silver Sts.
021-141-423
Corner of Fairfax
and 20th Sts.


Depth of well
(feet)


Before
deepened


After
deepened


1,048 1.307


1,040


1,009


1,039


1,050


1,246


1,249


1,244


1,356


Amount
deepened
(feet)

259



206


240


205


306


Flow
(thousand rpd)


Before


1,985



1,914


468


647


1,732


After


3,420



4,338


1,00


1,988


2,707


Pressure
(lb/ft2)


Increase Before After


1,435 15 16



2,424 151/j 171


1,432 5 14


1,341 8 15


975 10 11%


In


crease

1



2


9 C


7
0 g


r






REPORT OF INVESTIGATIONS No. 43


1o penetrate about 750 feet of the aquifer system to include most
;f the second permeable zone in the Lake City Limestone, the
;'rtesian flow increased about 300 and 400 percent, respectively,
a:nd the artesian pressure virtually doubled.
The yield of wells in the Floridan aquifer system in Duval and
Nassau counties depends upon well construction, the artesian
pressure head, and the water-transmitting capacity of the zones
penetrated by the well. The average yield by natural flow of
typical small domestic wells between 2 and 6 inches in diameter
is generally less than 500 gpm. However, some 6-inch wells yield
as much as 1,000 gpm. The average natural flow of wells between
8 and 12 inches in diameter is generally less than 2,000 gpm. In
some 10- and 12-inch-diameter wells in the deeper zones the
natural flow may be as much as 5,000 or 6,000 gpm. Some
industrial wells between 14 and 20 inches in diameter in
Fernandina Beach and in the vicinity of Jacksonville are equipped
with deep turbine pumps and continually yield 4,000 to 5,000 gpm.


RECHARGE AND DISCHARGE

The general areas of recharge and discharge and the direction
of ground-water movement were determined by constructing a
contour map on the piezometric surface. A piezometric surface
is an imaginary surface to which water from an artesian aquifer
will rise in tightly cased wells that penetrate the aquifer. The
ground water moves from recharge areas, where the piezometric
surface is relatively high, to discharge areas, where the piezometric
surface is relatively low, in a direction approximately perpendicular
to the contour lines.
Figure 10 shows a generalized map of the piezometric surface
of the Floridan aquifer in Florida. The principal recharge area of
the aquifer system in northeast Florida is the area marked by a
piezometric high in western Putnam and Clay counties and eastern
Alachua and Bradford counties. Within this recharge area water
enters the Floridan aquifer through breaches in the aquiclude
caused by sinkholes, by downward leakage where the aquiclude is
thin or absent, and directly into the aquifer where it is exposed
at the surface. From this recharge area, the piezometric surface
slopes toward discharge areas. In Duval and Nassau counties,
water is discharged from the Floridan aquifer system primarily
by numerous wells that penetrate the aquifer, system. There is








FLORIDA GEOLOGICAL SURVEY


/7


EXPLANATION
-a-
Conta.our *pW ets Ie heWigh, in fe relfrr e to men s
levl. to which wa would hav rll In n lightly caed
wells tha poe wee tOf major wew.-be4rng frmnoloen
An the Florilan equhk. July 6.17, 1961.
Canour interval 10 and 20 f., changing ot men sea level.

Area eo earteen flow
Exmt and d4is"bution of flow Qrwes vy with fluctuations
of w paeonwic siaoc., poticulorly in wera of horvy
pumping. Rleiaivey small *eos of oweian flow are ro
nc luded immedlaely aedJece to end paelleting the
coaa and many of the mater i1"ms end springs.


0 10 20 30 40 5 mOes


Taken hefr Ma Swine No.4 by H.G. lMely. 1961 .I

I a* -s, 80' ,,
Ble 8)' 82* 61" 800


Figure 10. Map of Florida showing the generalized
of the Florida aquifer.


piezometric surface


I I -






REPORT OF INVESTIGATIONS NO. 43


probably natural discharge from the aquifer system into the
Atlantic Ocean off the coast of northeastern Florida.
Artesian pressures rise in response to recharge and decline in
response to discharge. Water levels in wells close to recharge areas
show more response to rainfall than those further away. The
reduction of artesian pressure induced by a discharging well
decreases with distance from the well.
The effect of variations in discharge on artesian pressure head
in wells in Duval and Nassau counties is shown in figure 11. Well
019-140-421 is near the center of the discharge area at Jacksonville.
The monthly municipal pumpage at Jacksonville compared with
the hydrograph for well 019-140-421 shows that as the pumpage
increases the artesian pressure in well 019-140-421 declines, and
vice versa. Seasonal fluctuations of more than 10 feet are common,
particularly during the late spring and summer when municipal
pumpage is greatest. Well 033-150-242 is at Callahan, more than
20 miles from the heavily pumped areas at Jacksonville and
Fernandina Beach. At this distance from the center of the
discharge area, the seasonal fluctuations due to pumping are
small and do not mask the fluctuations in response to recharge by
rainfall. A comparison of the average monthly and annual rainfall
at three stations in the recharge area with the hydrograph of
well 033-150-242 shows that periods of relatively high and low
artesian pressure in well 033-150-242 generally occur about 6
months after corresponding periods of high and low rainfall. This
lag probably indicates the time necessary for the rainwater to leak
into the Floridan aquifer system. The greatest declines in artesian
head in well 033-150-242 occurred during the years of least rainfall
and the greatest increases in head occurred during years of highest
rainfall. It is possible that pumpage at Jacksonville and
Fernandina Beach, both more than 20 miles from this well, also
affect the rise and decline of artesian head to some extent.
The effects of discharge in northeast Florida on the piezometric
surface of the artesian aquifer system are shown in detail in
figure 12. As artesian pressures are continually changing, the
altitude and configuration of the piezometric surface in 1962 shown
in this figure are only an approximate representation of the
surface.
The closed contour lines at Fernandina Beach and in the
vicinity of Jacksonville (fig. 12) indicate depressions in the
piezometric surface. These depressions, termed "cones of depres-
sion," are a result of well discharge which lowers the artesian






FLORIDA GEOLOGICAL SURVEY


WELL 033-150-242,
ao Collohon, more Ihon 20milcs
S frotm Center of pumping_

J-- -" ----^ = --





~-,- -- -- ^ -


1 Annual Ramfoll














G St May WELL 019-140-421 We
r Roanfall station
c a, Note: Starke weather staton
-oh 1' I used oftle 1957. Comp
spir '- Blonding discontinued



0 1 20 30 40 M .mk.


Figure 11. Graphs showing relation of water levels in wells 019-140-421
and 033-150-242, to pumping and precipitation, Jacksonville area, Fla.:


36



30




21
CC ,u


a3
c6


:R




M


4


1;





REPORT OF INVESTIGATIONS NO. 43


head, thus creating a hydraulic gradient toward the points of
discharge. In Jacksonville, the altitude of the piezometric surface
within the center of the cone of depression is less than 20 feet
above sea level and the hydraulic gradient toward the center of
the cone is irregular. The slightly steeper gradient on the west
side of the cone indicates recharge to the aquifer system from the
west. The north-south elongation of the cone of depression may
indicate that recharge from the west is partially blocked in the
aquifer by the geologic fault. (See figs. 4 and 5). The cone of
depression is partly prevented from expanding to the west of the
fault and, therefore, expands to the north and south of the center
of discharge.
About 3 miles northeast of Jacksonville, at Eastport, with-
drawals by industrial wells have created a relatively small cone
of depression. In this area, the altitude of the piezometric surface
has been depressed to about 30 feet above sea level. Along the
coast, east of Jacksonville, discharge from municipal and private
wells has lowered the piezometric surface to less than 40 feet
above sea level.
The most pronounced depression in the piezometric surface
shown on figure 12 is at Fernandina Beach, where it is below mean
sea level over an area of about 15 square miles and is more than
15 feet below sea level over about 3 square miles of the area. As
shown by the configuration of the 40-foot contour line in central
Nassau and north-central Duval counties, the piezometric surface
has been depressed as far as 20 miles southwest of the center of
the cone of depression by discharge from wells at Fernandina
Beach. The steeper hydraulic gradient on the east side of the
cone may indicate either recharge to the aquifer system from that
direction or rocks with better water-transmitting properties east
of the center of the depression.

AREA OF FLOW

Figure 12 also shows the approximate areas of artesian flow
.n northeast Florida in May 1962. Artesian wells flow where the
piezometric surface stands higher than the land surface. As shown
)n the figure, artesian flow occurs principally .on the low coastal
plain in eastern and central Duval and Nassau counties. Areas
on the coastal plain in which the wells will not flow are on high
sand ridges east of Jacksonville, where the land surface is higher
than the piezometric surface, and in the vicinity of Jacksonville






FLORIDA GEOLOGICAL SURVEY


and Fernandina Beach, where the piezometric surface has been
depressed below land surface by discharging wells. In the hilly
uplands in western Duval and Nassau counties and in Baker
County, artesian flow occurs only in wells along some stream
valleys.
Because the altitude of the piezometric surface is continuously
changing, the area of flow shown on figure 12 is only an approxi-
mation of the area of flow at other times. The greatest changes
in the areas of flow occur in the vicinity of Jacksonville and
Fernandina Beach, where the piezometric surface is about the
same as the land surface. A slight decrease or increase in the
altitude of the piezometric surface considerably reduces or
increases the area of flow in these areas.

WATER USE

All the public water and most of the industrial and private
water supplies in Duval and Nassau counties are obtained from
wells developed in the Floridan aquifer system.

PUBLIC WATER USE

Jacksonville is one of the largest cities in the world to obtain
its entire water supply from deep artesian wells. The city uses
water from 46 wells whose depths range from about 1,000 to
1,500 feet. Water from seven well fields in the city is pumped
into seven elevated reservoirs. In 1962 they produced an average
of 38 mgd as compared to 27 mgd in 1950.
In addition to municipal wells, there are about 100 privately
owned water utilities in the vicinity of Jacksonville, each of which
has at least one artesian well. Their combined yield is estimated
to average 15 to 20 mgd.
Jacksonville Beach uses an average of about 2 mgd of water
that is obtained from seven wells ranging in depth from 600 to
1,000 feet.
Each naval facility in the area has its own water system. U.S.
Naval Air Station, Jacksonville, uses water from 12 wells between
400 and 1,096 feet deep, which produce an average of about 31/
mgd. Cecil Field Naval Air Station in western Duval County uses
an average of about 700,000 gpd obtained from five wells that
range in depth between 800 and 1,350 feet. U.S. Naval Station,
Mayport, uses an average of 11/ mgd from two wells about 1,00Q
feet deep.






REPORT OF INVESTIGATIONS No. 43


Fernandina Beach uses about 1 mgd of water that is supplied
Sy six wells ranging in depth between 700 and 1,200 feet.
Other small towns in the area, such as Hilliard, Callahan,
1 .aldwin, Atlantic Beach, and Neptune Beach, each use water from
at least one well drilled into the Floridan aquifer system.


INDUSTRIAL WATER USE

The greatest industrial use of ground water in Duval and
Nassau counties is for the processing of wood pulp. In Fernandina
Beach, Rayonier Pulp and Paper Inc. uses an average of 32 mgd
from 11 wells that range in depth from 1,050 to 1,400 feet.
Container Corp. of America uses an average of 21 mgd from six
wells between 930 and 1,865 feet deep. In the vicinity of Jackson-
ville, St. Regis Paper Co. uses an average of 18 mgd from eight
wells between 1,350 and 1,400 feet deep.
Other industries in the area that have their own water-supply
system from the Florida aquifer system include chemical and
paint manufacturing, dairies, laundries, icemaking, shipbuilding
and food processing. Many of the larger industries use 5 to 10 mgd.

COMMERCIAL AND PRIVATE WATER USE

Many of the larger commercial buildings and stores have their
own wells, which produce water for drinking, heating and cooling,
kitchen and toilet, lawn irrigation, and washing. For example,
May-Cohens Department Store and the Prudential Life Insurance
Building in Jacksonville each uses an average of 60,000 to 80,000
gpd from wells about 750 feet deep.
Numerous private wells, generally 6 inches or less in diameter
and less than 750 feet in depth, are scattered throughout Duval
and Nassau counties, particularly near Jacksonville and Fernandina
Beach. These wells provide water for drinking, lawn irrigation,
and swimming pools.
The amount of water produced by all the wells in the Floridan
aquifer system in Duval and Nassau counties was estimated on
the basis of a general survey of the water used by municipal and
private water utilities, major industries, large commerical build-
ings, and individual well owners. It is estimated that an average
of 150 to 200 mgd is discharged from wells in the vicinity of
Jacksonville and 50 to 70 mgd from wells at Fernandina Beach.






FLORIDA GEOLOGICAL SURVEY


DECLINE IN ARTESIAN PRESSURE

Artesian pressure has been measured periodically in northeast
Florida in 7 wells since before 1934, in 18 wells since 1938, and
in 4 wells since 1951. Hydrographs of a few selected wells in
Duval and Nassau counties, shown in figures 13 and 14, show the
seasonal fluctuations and the long-term trends of the artesian
pressure head. All the hydrographs show an irregular but con-
tinual decline in artesian head.
The greatest declines in artesian pressure are in wells closest
to the center of the cones of depression in Jacksonville and Fern-
andina Beach. In wells 038-127-344 and 040-126-332 at Fernandina
Beach, artesian pressure declined 50 to 60 feet between 1939 and
1963. In wells 018-143-234 and 018-140-123 at Jacksonville,
artesian pressure declined about 12 to 22 feet between 1946 and
1963.
Long-term changes in artesian pressure throughout northeast
Florida from 1940 to 1962 and short-term changes from July 1961
to May 1962 are shown by contours and cross sections in figure 15.
As shown by the contours in the figure, there has been a general
decline in the piezometric surface throughout northeast Florida
of about 10 feet to more than 25 feet between 1940 and 1962 and
from less than 2 to more than 10 feet between July 1961 and
May 1962. The cross section of the piezometric surfaces in the
figure show that the general slope of the piezometric surface has
remained approximately the same except in the vicinity of Jack-
sonville and Fernandina Beach. In these areas the cones of
depression in the piezometric surface have been deepened and
considerably enlarged.
The general decline in the artesian pressures in Duval and
Nassau counties is attributed primarily to a great increase in the
use of artesian ground water in the area and to a lesser extent
to relatively long-term declines of rainfall on the recharge areas
in northcentral Florida.
Figure 16 shows the average annual rainfall at three stations
in the recharge area and the annual discharge of artesian water
by municipal wells in Jacksonville from 1940 to 1962. The annual
discharge by the city wells is only a fraction of the total amount
of artesian ground water discharged by all wells in the Jacksonville
area. However, it serves as an index to determine the trend of
ground-water discharge. As shown by. the bar graphs in the









REPORT OF INVESTIGATIONS NO. 43


Zi iL2LL1


F1


,4 3 miles soulhesl o Jocl, ille _










_l ----J -- .- --43- .L WELL OIB-140-123,-_ _I
in Jocksonville





33


29
27
<25-
23


t34 in weslen pwT o Jack nill










18-



1 T I- Z/ -- /-' i- I .
14
24 WELL 028-137-334,
2 45 milem north of Jocksonvlle





14


4-



1940 1945 1950 1955 1960 196

Figure 13. Hydrographs of selected wells in Duval County.


t-1


WELL 013-135-230,
5mlect Soullit" of jocnmille


pj . .








FLORIDA GEOLOGICAL SURVEY


I I Ii II
36' -- 4 -i ---

32L..' 1 T-

28.




T6T
16

8I
4LC---


W
U
C
e

o
r

r
o
a
a
,-
c
w
b'
Q
c
w
w
r,
r
-I
j:
-I
w
c


b3 i


m r-454 CO- 95 1960IU
Figure 14. Hydrographs of selected wells in Nassau County.


I L1 .* i 1 i _I 1H
,F .. -i--
o E--- 0~- -- |WELL 37-136 122,
12

8





401 WELL 037-142-443,
36 .--l -- in cenlrol Nossou county



ig ;__ ...-L- L-~- J_ .\ .. i |J- -\^ rjf~^\- -
^i iL_ L | -U, ,_, l__V< | I



40

32 .. _.. 1.5 miles south of
SS | i1 i i I jFernondino Beach














1 _.__ of Fernndino Bech


-28 i i
4
28
-4








-20'- A- Al-- + ,--- +
J- .. + ++++ + + l l+








REPORT OF INVESTIGATIONS NO. 43 43




















..N COUNTY 4






















+ AA












B A UVAU COUNTY BN
I -- --- I I----o-,--.------

5 -- I I --
-04




to o

J 42 ;j








Figure 15. Map and cross sections of Duval and Nassau counties showing
the change in artesian pressure from July 1961 to May 1962 and from 1940
to May 1962.






44 FLORIDA GEOLOGICAL SURVEY


ou.



70 -

A AVERAGEE RAINFALL LL
5 54.29 INCHES o
S60- 1940-1962)
_z6o-4


z
-Z



r 50-



40-


1940 1945 9SO 1955 1960


-15 u
-14

-12

10-
I
-8z
.7
-6
5


Figure 16. Graph showing annual discharge of artesian water by municipal
wells in Jacksonville and average annual rainfall at three weather stations
in the recharge area.


figure, pumpage from city wells progressively increased from about
5 billion gallons in 1940 to almost 14 billion gallons in 1962.
A comparison of the rainfall and discharge shown in figure 16
with water levels in wells shown in figures 13 and 14 indicates that
between 1940 and 1957 artesian pressures declined even during
years of above-average rainfall. This decline was probably due
to the progressive increase in the use of ground water. A combi-
nation of below-average rainfall and greatly increased discharge
during 1954, 1955, and 1956 resulted in the rapid decline of artesian
pressures during those years and the low artesian pressures in
1956 and 1957. From 1957 to 1960, above-average rainfall anc
nearly constant discharge resulted in a slight rise of artesiar
pressure. However, a decrease in rainfall and steady increase
in discharge during 1961 and 1962 caused a rapid decline of
artesian pressure in 1962, to the lowest of record in most wellE
in northeast Florida.
The amount of decline in artesian pressure in northeast Florida
varies in the different zones within the artesian aquifer system.
Three wells near Jacksonville, 026-135-342A, B, and C, are within
40 feet of each other but product from three different zones. Well


I


1


3 uJ






REPORT OF INVESTIGATIONS NO. 43


C was developed in a shallow zone, well B was developed in a middle
zYne, and well A was developed in both of these zones plus a third,
(dep-lying zone (fig. 7). In these wells the trend of artesian
pressures is the same, because the different zones are intercon-
nected through well A, but the artesian pressure in well C, which
is developed in the Ocala Group, is always considerably less than
the pressure in the other two wells, which tap the deeper zones.
In areas where there is little or no interconnection by wells
between the zones in the artesian aquifer system, the difference
in decline of artesian pressure in the different zones is even more
pronounced. Figure 17 shows hydrographs of wells 038-127-324
and 038-127-142 at Fernandina Beach which are located about
2,000 feet from each other near the center of the cone of
depression. The artesian pressures in both wells are drawn down
by the many discharging industrial wells in the area, Well
038-127-142 taps only the permeable zone in the Ocala Group and
well 038-127-324 taps that zone and the deeper zones in the
artesian aquifer system. As shown by the figure, between
November 1960 and October 1961 the artesian pressure in well
038-127-142 ranged from only 11 feet above msl to 3 feet below msl,
-J
_j 40
SWell 038-127-324,tapping permeable zones from the
w
Ocola Group to the Oldsmor Limestone
5
S30
0 Total depth=l,826
W -Delow ond surfccZ;
M cosed to 567
0
w
0 20 LAND SURFACE
1I

-LU
S10 --


1960 I 1961
Figure 17. Graphs showing the artesian pressure in two wells at
Fernandina Beach.





FLORIDA GEOLOGICAL SURVEY


while during the same period the artesian pressure in well 038-127-
324 ranged from 40 to 22 feet above msl. In addition, water in
well 038-127-324 remained higher than the land-surface datum
while water in the surrounding shallower artesian wells was drawn
down below the land surface.
The use of artesian water can be expected to increase and the
artesian pressure will continue to decline; however, the amount
of decline within a specified period is beyond the scope of this
report. The rate of decline will be faster during years of below-
average rainfall than during years of normal or above-normal
rainfall, and the pressure may even increase during years of
above-average rainfall. However, if the rate of discharge in north-
east Florida continues to increase, eventually the artesian pressure
will probably decline even during cycles of above-average rainfall.
The decline in artesian pressure in Duval and Nassau counties
alone is not a serious threat to the availability of water in the
area. At the present rate of decline, approximately 0.5 to 2.0
feet per year, it would take 100 to 400 years to lower the water
200 feet in most wells in the Floridan aquifer. This does not mean
that the wells would then cease to yield water but merely that
they would not flow at the surface, and that they would require
pumping to yield water at the surface. A much greater danger
than lowered pressure is that highly mineralized water would
enter the zone of reduced pressure, either vertically from deeper
highly mineralized zones in the aquifer system or laterally from
the ocean, and contaminate the existing fresh-water supplies in
the aquifers.

QUALITY OF WATER

The chemical character of ground water depends largely upon
the type of material with which the water comes in contact and
upon mixing with other water. Rainfall is only slightly-mineralized
when it first enters the ground; but as it moves through the
ground, it dissolves mineral matter from the rocks it contacts.
Table 5 shows analyses of water from wells that do not pene-
trate the Floridan aquifer system in the area and table 6 shows
analyses of water from wells that do penetrate the Floridan
aquifer. The dissolved chemical constituents are expressed in parts
per million; 1 ppm is equivalent to a pound of dissolved matter
in a million pounds of water; specific conductance is expressed in
reciprocal ohms mhoss); hydrogen-ion concentration is expressed





TABLE 5. Analyses of water from aquifers overlying the Floridan aquifer system in Duval and Nassau counties.

Source of analysis: (1) Container Corp. of America; (2) Florida State Board
of Health; (4) Southern Analytical Laboratory, Jacksonville.
(Chemical analyses in parts per million except pH and color.)

Hardness
40 i as CaCO,
e O. 0 8 (total) *


1 W' V 0 |
Well -S is I ||

number ^ i B______________

DUVAL COUNTY
014-148-180 1-18-58 185 .~ 0.8 44 9 .. 176 0 9 0.7 185 144 7.6 5 (2)
6-28-58 185 .. .1 46 10 ... 188 0 6 .7 210 158 7.5 5 (2)
016-187-100 10-30-58 70.100 .. 1.5 .. 52 6 .... .... 808 0 19 ..- 387 154 7.1 5 (2)
016-188-810 2-20-55 90 ...... -.. .. 84 0 .... 1.. 151 10 11 .05 159 124 7.1 5 (2)
018-185-840 7-20-68 80 -... 2.1 ... 68 11 .... 240 -.. 10 .4 280 202 7.2 5 (2)
019-185-480 6-17-58 200 ...... .... 89 7 .. .. .... 132 .... 18 .1 200 124 7.5 5 (2)
021-186-400 8-14-50 00 ...... 0.2 89 11 .... .. -.. 176 0 11 .1 195 142 7.6 5 (2)
021-142-100 6- 6-58 80 8.... 1 .0 .. 63 12 ............ 224 17 19 .25 280 216 7.3 100 (2)
028-129-880 4- 8-57 200 ...... 0.07 .... 86 5 .... .... .. 146 6 16 .15 146 112 7.5 5 (2)
2-20-59 200 ...... .06 .... 42 8 .. .. .... 180 2 15 .15 152 188 7.4 10 (2)
024-141-840 6-27-49 70 ...... ...... 46 12 .... .... .. 156 0 8 ...... 265 165 8.1 ..... (2)

NASSAU COUNTY


028-1-1000 1 6- 8.87
028-156-100 6-28-87
040-127-211 11- 1-566


201
96
93


100 0.60 26 94 8.9 .... .... 0 0 17 ...... 840
96 .20 22 104 15 .... .... .... O 96 10 ...... 444
...... .8 26 ...... ...... .... .... .... ...... 66 .... ...... 290


..... (4)
(4)
7.0 ...... (1)


Na + K + CO, = 17 ppm
Na + K + CO, = 29 ppm


-------~---- ---


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






FLORIDA GEOLOGICAL SURVEY


in standard pH units; and color is in units defined by the standard
platinum cobalt scale. In all analyses determined by the Florida
State Board of Health, the total dissolved-solids content was found
by weighing the residue after the water had evaporated at 1030
to 1050 C and in all other analyses the total dissolved-solids content
was found from the residue after evaporation of the water at
1800C.

QUALITY OF WATER IN THE SHALLOW AQUIFER SYSTEM

Water in the shallow aquifer system is generally not as hard
and contains less dissolved mineral matter than water from the
Floridan aquifer system in the same area. The sulfate content is
generally negligible and the amount of magnesium is considerably
smaller than the calcium content. The iron content of water from
the shallow aquifers is generally greater than that from the
Floridan aquifer system in the same area.
In some parts of northeast Florida, the chemical composition
of the water from both the shallow aquifer system and the under-
lying Floridan aquifer system is similar. For example, the water
in both the shallow and Floridan aquifers is similar in western
Nassau County, where the Floridan aquifer is closer to the
recharge area and the water is not as highly mineralized as in
the central or eastern part of the area. The water in both aquifer
systems is similar in sections of eastern Duval and Nassau
counties, where water from the shallower aquifers has been
mineralized by mixing with bodies of brackish surface water or
sea water.
Water from the shallow aquifers is generally suitable for
domestic use and for most industrial uses. Because it contains
relatively few impurities, it does not generally require treatment
though it occasionally contains enough iron to impart a bad taste
and to stain household equipment, clothes, and buildings. Iron can
be removed from water by aeration or chlorination followed by
filtration.

QUALITY OF WATER IN THE FLORIDAN AQUIFER SYSTEM

The chemical analyses of water from 50 selected wells that
penetrate the Floridan aquifer system in the area (table 6) show
that the quality of the water varies according to location, depth
of the aquifer sampled, and date of sampling.






TABLE 6. Analyses of water from the Floridan aquifer in Duval, Nassau, and Baker counties.

Source of analysis: (1) U.S. Geological Survey; (2) Florida State Board
of Health; (3) Black Laboratories Inc.; (4) Commercial Chemists, Inc.;
(5) Southern Analytical Laboratory, Inc.; (6) St. Regis Paper and
Pulp Co.; (7) Pittsburgh Testing Laboratory; (8) Rayonier Inc.;
(9) Permuit Co.

Dissolved solids: Residue at 1030C State Board of Health analyses. Residue
at 1800C for all other analyses.

(Chemical analyses in parts per million except pH and color.)

Hardness
as CaCOs g










DUVAL COUNTY
0 V 4


DUVAL COUNTY


-... 0.19 28 ......
610 .10 ...... 71 87
880 .01 18 52 22
........ .00 18 42 21
...... .02 17 29 12
...... .02 14 27 12
757 .... 68 6
757 .00 21 75 81
757 .00 ...... 68 82
I


........ ...... ...... 172 187 18 ...... ......
........ ... ...... 162 188 21 ......
8.8 2.4 0.00 138 101 10 0.5 0.1
9.7 2.8 .00 187 74 10 .6 .1
........ ........ ..... 124 27 6.5 .....
8.1 ...:... .00 124 22 6.0 .5 .0
........ ... .... 158 165 15
14 2.3 .00 156 176 16 .8 .0
........ ........ 00 161 184 8 ......


- (1)


2 (1)

3 (1)
-. (3)


5 1)
5 2)


; 008-180-810
0: 18 185-1.400
018-140-414A
018-140-414B
018-158-240

015-188-280


6-16-25
6- 8-60
6-20-62
6-20-62
1942
1-18-54
10-10-49
6-18-62
1-17-68


858
610
1,005
708
990
990
1,187
1,187
1,187


NA + K = 7.6 ppm

Crystal River Fm.
cased off


.__... .-.. -- --


- -


I I I


---------







TABLU 0, (Continued) n

lrdnels
SI s |CaCO,





I 8 number 1
Ii __ r"__ A__I: I of


015.188.-14 58-162 1,284 470 .00 22 74 28 14 2.0 .00 164 154 15 .7 .0 442 300 165 0 7.7 5 (1)
016145-280 2-22.1 1,000 400 .5 1 5.7 15.7 .. 84.6 14.2 .6 228 154 83 .... 7.7 (4) Na + K = 7 ppm
017-126440 10- 8.56 400 .93 -. 76 88 ...-.1 188 1983 20 .65 548 828 7. 5 (2)
4-1148 400 .1 77 4 .... 17198 19 .7 572 834 7.3 5 (2)
017-13-418 6-28-39 785 524 .008 19.4175 81 -- .00 1C3 210 10 .45 .. 490 812 178 8.2 1 (5) Na + K = 25 ppm
017o18-142 6-1842 1,500 .00 21 75 80 i1 1.9 .00 156 68 16 .8 .0 448 310 182 684 7.7 5 (1)
017.168480 10-29.42 750 483 19 3 1 12 -- -- -I 137 22 8 -. 170 127 15 (8) Na + K = 9.0 ppm
11.- -0 760 488 26 40 20. 20 18 38 -. 263 182 7.1 (8) Na + K = 27 ppm
017-158-110 1-1648 680 -- .1 34 14 -- 129 12 25 .45 .. 232 144 8 7.0 6 (2) J
018.124.222 9-24.41 22 882 .12 28 72 36 12 8.4 .00 160 190 14 1 7 30 455 324 .- (1)
018-186-241 114 685 508 0,55 -..66 28 -- 166 14 15 -... 8 279 272 7.5 5 (2)
018-188843 8 -20.50 1,848 604 _. 21 76 81 12 167 184 8 8 81 7.5 (1)
1 38-1.60 1,848 504 12 00 64 11 42 820 186 61 7.8 (1l
019.124210 8- 7.62 1,800 407 .4 55 26 -- 188 18 27 0.65. 450 24 98 7.6 10 (2)
019.189-280 9.27-41 655 491 1.9 21 ,9 88 11 8.2 .00 151 209 14 .7 0.00 468 882 -- (1)
1 981-60 666 491 13 -- .00 71 12 ~. 100 47 0 169 7.0 (1)
020.139-48 9-27-41 1.250 -. .. 27 61 28 178 96 16 ..... 825 246 .. (1)
.20-50 1,250 .. ... 60 22 -- 190 3 14 .. 848 240 5 7.6 (11
8 -8140 1,20 ...... .... .00 188 .... 8 .. .. .. 349 244 90 51 7.6 20 (1)
8-2941 1,250 .... .1 2 0 22 14 1. .00 187 87 17 .7 .0 7 240 87 504 7.9 5 (1
022-130-112 12 42 1.000 462 .2 .... 64 2 ...... ...- 1 19 .I 412 270 114 .-.. 7.6 10 (2)
:, L I-I1, 614220. 1 1.()






025-125-281
025.18s-2101



26.-13-342A


9-26-41
6- 3-41
1- 9-43
5-20-50
6-10-58
10-20-55
6-18-62


26-185-842B 10.20-55
6-18-62


26-185-842C

026-145.420
028-187.884


10-20-55
6-18-62
9.10.42
11- 8-52


840 450 .05 31
092 660 .02 .-.
992 660 .10 26
992 660 .08 27
992 660 .07 -
1,398 584 20
1,398 584 0.25 20
700 450 .0 27
700 460 .01 18
1,025 860 .5 28
1,025 850 .00 1.6
658 -- .5 81
500+ .1 80


---


47





9n
17

17





9


3.4








1.2
~


.00 186 142 104
.00 189 64 20
S197 72 4
- 204 98 22
- 168 63 26
.00 166 67 -
.00 140 48 22
- 162 69
.00 200 48 21
.00 164 67
.00 54 0
- 200 84 2
- 188 2 18


.6



.45

.6


T


.05 ..
.05





.0 -

.0 -


NASSAU COUNTY


028-056-430
083149-140

087-186-122
088-126-820


9-20-50
9- 4-59

9.10-42
6-25-87
80-560
4-17-56
12- 6-56
8. 7-57
8-20-57
4- 1-59


038-127-324 4.17-46
12- 6.56
8. 7-57
3- 7-68
12. 1-58
8-10-59
6.18-59
90 3-59
6-13-62


650
600
800
1,000
1,208
1,208
1,208
1,208
1,208
1,208
1,208
1,826
1,826
1,826
1,826
1,826
1,826
1,826
1,826
1,100


83 88
- 61


685


10.


842 1.8
192 53


148
177
168
141
145
153
184
860
875
'855
864
879
372
382
403
400


22
25

28
388
30
34
23
24
27
29
644
687
770
790
865
860
960
864
1,150


3481
5031

4560

478
504
504
6791
471
4641

1,9551
2,475
2,805!
2.375
2,365
2,748
3,095
3.050
3,020'
!


132 7.8 10

- __ 7.3 -
7.2 7.
... 7.5 -


1388 7.4 5
158 7.3 5







793 4,490 7.6


Na + K = 25 ppm



Na + K = 22 ppm
Na + K = 87 ppm
Na + K = 25 ppm


(8)
(8)
(8)
(8)
i8)
(8)
(St
(1) Plugged back, but
plug leaking.


, .


98

51

58

0


... .. .... ... < t
.. 15 (1)
7.2 (1)
S 7.4 (1)
7.8 5 (2)
S7.9 (6)
385 8.0 5 (1)
- 7.7 (6)
438 8.0 5 (1)
7.9 (6)
165 8.0 5 (1)
7.25 (8)
7.8 (7)


I I I


--


Na + K = 5.2 ppm
Na + K = 6.4 ppm






Crystal River Fm.
cased off

Na + K = 18 ppm










TABLE 6, (Continued)






i



Well
number .g S i JS s g


0.6



....
-. .







.


..
....


---

0.
.7
.~
.~
.




.
.

.'


ii] ,


i9a I
cav


Hardness
as CCO,


T92
160


Na + K = 28 ppm










Na + K = 41 ppm






Na + K = 20 ppm


-




Ii I


4-17-56 1,700
12- 6-56 1,700
8- 7-57 1,700
38- 758 1,700
12- 1-58 1,700
8-10-59 1,700
6-18-59 1,700
9- 8-59 1,700
1- 8-24 750
4- 1-59 750
6-13-62 7560

4-17-66 1,820
12- 6-66 1,820
8- 1-57 1,820
8- 7-58 1,820
12- 1-58 1,820
8-10-59 1,820
6.18-59 1,820
9- 8.59 1,820
1. 8-24 1,065
8- 7-57 1,0685
8- 7-58 1,065
12- 1-58 1,085
3.10-59 1,065
6-18-59 1,065
9- 8-59 1,065
5-80-50 1,054
4.17-56 1,054
12- 6-66 1,054


-22 2 .2 1


088-127-120


039-127-44


083-128-241


169
168
152
177
184
172
184
177
178
168
144
190
185
197
206
197
198
208
182
167
145
181
156
152
152
149
161
152
126


44
88
47
47
52
50
51
50
81
38
80
107
99
112
112
127
121
126
125

29
85
82
40
35
87
84
30
82
30


676


7.5 5
7.6 6


I r --r I I --I -. -. . -


'


I


-


- II---------












040-127-482A



040.127-482B


040-127-432C


040-127-482D
041-126-388

041-165-421
042-125-888
042-127-844
042-127-443
044-141-480


8- 7-68
12- 1-58
3-10-69
6-18-591
9- 3-59
9-28-37
9-27-49
4- 2-50
5-16-59
9-27-49
4- 2-50
4- 1-659

9-28-37
4- 2-50
4- 1-59
4- 1-69

6-13-62
4- 2-59
5-15-59
5-15-59
5-15-69
4- 2-59


1,054
1,054
1,054
1,054
1,054
1,100
1.100
1,100
1,100

1,026
1,025
1,025
781
781
731

1,205
1,961
857
800
800
800


549 -
549 --
5491 -
549-
549 -
-- .32
.82 .0
.01
.04
500 0.10'
500 .0
500 .0
540 .31
540 .01
540 .06
550 .09
1,828 .04
.17
500 .06
550 .0
520 .06
.17


BAKER COUNTY

014-208-400 4-16-69 650 600 .. -. 40 28 .. 151 65 14 0.45 202 196 72 7.7 5 (2)
'016-207-120 1-81.63 700 460 .. 6 17 ... 148 les 25 .5 217 10 88 7.6 (2)
than
_ ________o_ __-__ __,__o___-0 __ __ __ __ __t_ ___ _____________


68
-- 65
-- 66
__ 65
22 60
-- 82
84 66
61
-80
34 69
-- 72
22 60
38 71
-- 72

- 77
32 88
_ 69
-- 76
7- 72

-- 72
-- 75


I--


--4
II













48



--


...-


.... ..






-




2.7


- 157
- 161
168
165
182
195 159
205 162
204 160
192 224
205 161
204 168
190 158
195 159
1200 166
202 144
192 157

186 198
185 138
192 228
190 198
180 198
202 155


87
41
41
as
38
88
83
36
29
30
84
83
as
29

88
76
82


88
86
82


32


-- ,













0.66
.65
.7
.56
.55

.65


.650


--
c







).

-0
.....






0.0


520
500
518
562
653

570
467
524

620
468
520


509
570

715
467
583
635
552,
501o


Total
170
184

202
240

162
186

160


174


- (8)

(8)
7.3 2)(8

7.8 7 2)

-, 7.4 (2)
... 7.4 (2)
S7.3 -1(2)
_ 7.8 (2)
S7.83 (9)

i ( I
7-. 7-4 628
S7.3 5 (2)
928 7.7 5 (1)
7.4 6 (2)
7.6 5 (2)
._ 7.5 5 (2)
7.8 (2)j
7.4 10 (2)


Na + K = 19 ppm
Na + K = 14 ppm
Na + K = 27 ppm

Na + K = 16 ppm
Na + K = 28 ppm

Na + K = 19 ppm




Ocala Group cased off






FLORIDA GEOLOGICAL SURVEY


Generally, water from wells closer to the recharge area is not
as hard, and contains less mineral matter than water from wells
farther away. As shown in table 6, except in the vicinity ot
Fernandina Beach, the total hardness as CaCOQ of water from the
Floridan aquifer system in the area ranges from 117 ppm in well
013-153-240, in southwestern Duval County to 336 ppm in well
008-130-310, at Bayard. The dissolved-solids content ranges from
90 ppm in well 026-135-342C near Jacksonville to 574 ppm in well
025-125-231 in eastern Duval County.
In the vicinity of Fernandina Beach, in eastern Nassau County,
the quality of water from wells in the Floridan aquifer system
varies considerably with depth or with the aquifer sampled (Leve,
1961b). Water from the deeper wells is more mineralized than
water from the shallower wells. In well 040-127-432C at
Fernandina Beach, which is 731 feet deep, the water contained
300 ppm hardness as CaCO, and 509 ppm dissolved solids on April
1, 1959. In well 040-127-432D, which is 1,205 feet deep and about
100 yards away from well 040-127-432C, the water contained
360 ppm hardness as CaCO:, and 570 ppm dissolved solids on the
same date.
The date of sampling generally makes only a slight difference
in the quality of the water, except in the deeper wells in the
vicinity of Fernandina Beach where changes in the quality of
water are caused by large variations in the piezometric head. As
shown in table 6, water from well 038-127-324 at Fernandina
Beach. 1.826 feet deep, ranged in hardness (as CaCOa) from 790
to 864 ppm and in dissolved-solids content from 1,960 to 3,100 ppm
between April 17, 1956, and June 18, 1959. This well was plugged
back to 1,100 feet in depth in 1962 and as shown in table 6, the
hardness of the water increased to 940 ppm and the dissolved-solids
content was 3,020 ppm.
An indication of the quality of water below the Eocene forma-
tions is given by the analysis of samples of water' from oil-test
well 044-156-100 in western Nassau County. The well was drilled
to 4,800 feet and samples of water were taken from 2,205 to 2,230
feet within the Cedar Keys Formation, of Paleocene Age. The
hardness of the water was 9,660 ppm and the dissolved-solids
content ranged from 64,300 to 100,900 ppm. The chloride content
ranged from 33,600 to 60,200 ppm, which is 11 times to more than
twice the chloride content of sea water.
Except in a few deep wells in Fernandina Beach, water from
the Floridan aquifer system in Duval, Nassau, and Baker counties






REPORT OF INVESTIGATIONS NO. 48


is suitable for domestic use and for most industrial uses. However,
locally, one or more of the chemical characteristics of the water
exceed the maximum limit of concentration recommended by the
U.S. Department of Health, Education, and Welfare (1962). Some
of the more important of these chemical characteristics are
discussed below.

CHLORIDE

Most of the water tested in the area contained less than 30 ppm
of chloride, which is well below the maximum limit of concentra-
tion suggested by the U.S. Department of Health, Education, and
Welfare for public supplies. However, water from well 038-127-
324, in Fernandina Beach, contained between 644 and 1,150 ppm
of chloride (table 6). Such large quantities of chloride in ground
water in areas where the content is generally much lower indicate
contamination by saline water, which will be discussed in detail
in the section "Salt-Water Contamination."

DISSOLVED SOLIDS

The dissolved-solids content of water shown in tables 5 and 6
is the residue of mineral matter left after evaporation of the water
and is an indication of the degree of mineralization of the water.
Water that contains less than 500 ppm of dissolved solids is usually
satisfactory for domestic use. In the wells sampled in Duval
County, only well 025-125-231 contained water with more than
500 ppm of dissolved solids. Many wells in Nassau County contain
water with more than 500 ppm of dissolved solids. However, only
the deeper wells in Fernandina Beach contained water with
extremely large amounts of dissolved solids.

HARDNESS

There are two types of hardness in water: (1) carbonate
harness caused mainly by calcium and magnesium bicarbonates
and (2) non-carbonate hardness caused primarily by sulfates,
chlorides, and nitrates of calcium and magnesium. Water with a
hardness of more than 100 ppm as CaCO., which is present in all
wells tested in the area, may be classed as hard to very hard.
Hardness of water retards the cleaning action of soaps and forms
a precipitate or scale on plumbing fixtures, boiler pipes, and






FLORIDA GEOLOGICAL SURVEY


utensils when the water is heated. Carbonate hardness can easily
be removed from the water by heating or by common soda-ash or
lime-soda softening processes. Noncarbonate hardness is more
difficult to remove, but it can be reduced by certain commercial
softening processes.

HYDROGEN SULFIDE GAS

Although the water samples shown in table 6 were not analyzed
to determine the amount of hydrogen sulfide gas present, most of
the water from wells in the Floridan aquifer system in the area
has the sulfur odor indicative of this gas. Hydrogen sulfide has
a corrosive effect on plumbing and it is undesirable in drinking
water. It can be removed easily from the water by simple aeration
or by natural dissipation to the atmosphere from an open tank
or pool.

SALT-WATER CONTAMINATION

Most of the water used in Duval, Nassau, and Baker counties
is from the Floridan aquifer system, and hence the following
discussion will include salt-water contamination of only that
system.
In northeast Florida as well as other parts of Florida, salt
water is present within the Floridan aquifer system. In most
areas this salt water entered the aquifer system during past
geologic time when the sea stood above its present level, or the
salt water was trapped within the rocks when they were deposited.
Subsequently, fresh water entered the aquifer system and diluted
or flushed out most of the salt water. The salt water that remains
where the flushing was not completed is a source of contamination
of the fresh ground water.
About 91 percent of the dissolved-solids content- of sea water
consists of chloride salts. The chloride content of ground water,
therefore, is generally a reliable indication of the extent to which
normally fresh ground water has become contaminated with sea
water. Water samples were collected from most of the wells that
were inventoried and were analyzed for chloride content. From
many wells, water was sampled periodically to determine if the
chloride content had changed.
The maps of figures 18 and 19 shown the chloride content of
water from wells in the Floridan aquifer system in northeast






REPORT OF INVESTIGATIONS NO. 43


Florida in 1940 and in May 1962. As may be seen, the chloride
content of the water is lowest close to the recharge area in
southern Duval County and in Baker County, and progressively
higher away from the recharge area toward the north. A
comparison of both maps shows that the chloride content of the
water from wells in the Floridan aquifer system has increased
since 1940. In 1940, wells throughout all of southwestern Duval
County and eastern Baker County contained water with a chloride
content of less than 10 ppm, and the chloride content of water from
wells sampled in Duval County did not exceed 20-29 ppm. In 1962,
only one well in south-central Duval County contained water with
a chloride content of less than 10 ppm, and wells near the mouth
of the St. Johns River and near the center of the cones of depres-
sion at Jacksonville and Eastport contained water whose chloride
content was over 30 ppm. In 1940, the chloride content of water
from wells sampled in Nassau County did not exceed 30-39 ppm,
except possibly in wells north of Hilliard, In 1962, the chloride
content of water from wells north of Hilliard and near the center
of the cone of depression at Fernandina Beach was 40 ppm or more.
Water in the deep wells at Fernandina Beach had the highest
chloride content shown in figure 20, ranging from 53 to 1,180 ppm
in May 1962 in wells more than 1,250 feet deep.
A comparison of the maps in figures 18 and 19 with the map
of change in artesian pressure in figure 15 shows that the increase
in chloride content of water from the Floridan aquifer system in
northeast Florida can generally be correlated with the decline
of artesian pressure in the area. In most parts of eastern Baker
County and western Duval and Nassau counties, where the
artesian pressure has declined less than 15 feet since 1940, the
increase in chloride content has been small. However, in the cones
of depression at Jacksonville, Eastport, and Fernandina Beach
where the piezometric surface has declined more than 15 feet since
1940, the increase is greater, particularly in the deep wells near
the center of the cone of depression at Fernandina Beach.
Table 7 shows the chloride content of water from wells that
penetrate the Ocala Group and from wells that penetrate forma-
tions deeper than the Ocala Group in Duval and Nassau counties
between the years 1940 and 1962. In Duval County and in most
of Nassau County, the chloride content of water from wells that
penetrate the Ocala Group and from wells in deeper formations
has increased only slightly, 2 to 14 ppm. However, in the vicinity
of Fernandina Beach, the chloride content of water from wells






FLORIDA GEOLOGICAL SURVEY


EXPLANATION i n
Well 404
165 Chloride contnt (ppm) 4140
j i404 ogh oB wI 1


AZ








0___ 2E miles

Figure 20. Map showing the chloride content of water from deep wells
at Fernandina Beach, May 1962.


that penetrate formations deeper than the Ocala Group has
increased at a faster rate. Between 1952 and 1962 the chloride
content of water in wells 039-127-321 and 039-127-114 at
Fernandina Beach approximately doubled, and that in well 038-
127-324 at Fernandina Beach increased to more than four times
the amount measured in 1952.
Figure 21 shows graphically the increase in chloride content
of water from four wells at Fernandina Beach that penetrate
formations deeper than the Ocala Group. The increase was only
slight between 1955 and 1962 in well 039-128-241, which is 1,054
feet deep and penetrates the Ocala Group and the top of the Avon
Park Limestone, and in well 039-127-114, which is 1,700 feet deep
and penetrates the Ocala Group, the Avon Park Limestone, anc
the Lake City Limestone. The chloride content of the water
increased much more rapidly in well 038-127-324, which is 1,826
feet deep and penetrates the Ocala Group, the Avon Park Lime-
stone, the Lake City Limestone, and a part of the Oldsmar
Limestone, and in well 041-126-333A, which is 1,961 feet deep
and open to the Lake City and Oldsmar Limestones. In well
038-127-324 it increased 1,820 ppm, from 550 to 1,800 ppm.




TABLE 7. Chloride content of water, in parts per million, from we2ls in the


Floridan aquifer system in Duval and Nassau counties.



depth Cased1 93 1954
(feet) (feet), 1940 1948 1950 1952 153 19541 1955 1956 1957 1958


19B60


1961 1962


WELLS IN THE OCALA GROUP
Duval County


1


14


011-141-141
018-185-230
015-141-111
017-126-232
018-123-123
019-182411
019-140421
020-136-484
020-144430
021-123-133
023-125-142
024-16-136
024-144-320
025-141-300
026-126-423
026-145420
027-143-314
028-137-334


17
20
1;8


14
14
158
22



19
20

26
26


I-I 2


'--Ilj

















._1


12
15-20
11
22
24
16
14-25
21
15
22
23
21
19
24
24
29
30-
17-19


- -- - ~


17-22
14-18





24-87











- ---- --


15-18
10


14-20
17-18
14







18
18


19



24


-I""'




----j


17-21
15
20



21
20
17
29



20


25
27
28


. .... ....0 nlr _... __.. .........


_- _


I


..........- 11- --- 1...... ................. -CI-l ~----~-i


I ~1 ~


-I


~I
II""'
""~~~l""i

---I

--

-I
11111111
Il----L/I

_II


==1


---
I ~'






,., ,i
I-.. 11
-----



_____~/


I
1
I










TAsDL 7. (Continued)

Well
Well depth Ce
number (teet) (feet) 1040 1948 1950 1052 1953 1954 1055 1956 1967 1958 1959 1960 1961 1962

Nassau County

082126-142 680 23 23 28 ,_. __2
088.1-0-242 580 26 28-20 -- -- .. -- 80-32 29.32 81-32
085.127-310 580 350 25 26.31 ___ ___0 26-31
0: 5-127-830 540 -- 26 27
660
037.12-6214 -- 28 28 -- 29 6 39
087-129.242 578 27 ........... .. 27 28 30so __ 31
087-180-380 540 504 27 28 -- __... -_ 33 23 29-2 2-82 30.81
087-142-480 569 24 24.26 -.- .- __ 24-27 26-30 28.30
S0389127-120 570 26 ----. __32-33 ______ ___ 34
089-181-2831 -.----- 29 30 33
04012l7-211B 900 530 -........- -- __ 54-58 62-56 32 36
S040-138410 600 29 .. ...... ....... ________________- 35 ____ 33
V042-126-888 800 550 82 ._____ _____.__. __ _____ 36-40 40
042-127-448 800 584 28 s...... 0 3... 2-33 ___ 34

WELLS IN FORMATIONS DEEPER THAN THE OCALA GROUP
Duval County
'I I I I, ....


09-189.230 650 .... 9----- ...... .
018.141-441 1,015 318 9 _


15 -.......-.
16 _


i


- -






TABLE 7. (Continued)


Well
Well depth Cased
number (feet) (feet) 1940 1948 1950 1952 1958 1954 1955 1956 1957 1958 1959 1960 1961 1962

019-140-241 785 14-16 -.--- -__________- 14-22 26-87 21
020.189448 1,250 17 22 24
021-188-121 1,060 548 18 ---- 28 21
021-141.414 1,068 580 16 i.-- -- -- _____--- ------ 18 19
026-185-842A 1,898 584 ----- --. _____ -- 24-26 24-27 24-29

Nassau County

087-186-122 1,000 460 80 28 2.7.. .. 30- a-6 80 80 -2 33
088-126-820 1,208 572 27 2980
088-127-824 1,826 567 2-. 420-460 480-580 560-60 644-687 770 790-865 860-1,060 1,550-1,690 1,870-1,780 1,180-1,800
089-127-844 1,820 545 --104 106-127 99-107 112 112-127 121-140 128-131 143-166 168
089-127-821 1,840 561 ---- .. 65-68 70-77 77-85 82-96 89-90 99 102-116 109-130 113-122 125-139 140
089-127-114 1,700 646 -- -- 82-88 86-43 40-43 37-48 38-44 47 47-52 50-55 66-60 51-58 56
089-128-131 1,065 550 30 80-32 30-32 35 32-40 33-37 34-40 82-37 82
089-128.241 1,054 549 30 --- 0-35 29.32 26 38-40 35-38 36-37 83-36
)40-127-482A 1,100 29 ___ 36 ... .. 26-29 ______- __-
040-127-482B 1,025 500 30 34 .. 33-35 ___ -- 35
41-126-388A 1,961 1,3281 .-.- 74-89 91-97
41-126-888B 1,404 560 -- -. -- 142-148 112-118 120 152-161 150-165







FLORIDA GEOLOGICAL SURVEY


40
30.
w oo
'i 600
S.400





S400
100
90
80

60
50
40


039-128-241 /
Total on 1,054'-



039-127-114




Ca,d 567- -- -t-o--
0-38-127-324 ~ .
.Tal arit^ l826 ___ _____ rJP1u!d
Coi7z t10ol,0








041-126-333 A-
Total deplh 6' .
coad IJ28' 9





i5 | 1956 1957 1958 1959 1960 1961 1962


Figure 21. Graphs of the chloride content from selected wells at Fernandina
Beach that penetrate formations below the Ocala Group.




The increase in chloride content of water from wells in the
Floridan aquifer system and the decline in artesian pressure
indicate that salt water is gradually moving into the zones of
reduced pressure and contaminating the existing fresh-water
supply. However, the relatively low chloride content of water
samples from most wells in the area indicates that serious
contamination is restricted at present to a few deep wells at
Fernandina Beach. The rapid increase in these deep wells shows
that the contamination is proceeding at a faster rate in the deeper
aquifers in the Floridan aquifer system in this area.
Water samples collected at depths between 2,205 and 2,230
feet in well 044-156-100 near Hilliard (p. 77), show that highly
saline water is present in the deeper aquifers in Nassau County.
The fresh water has a lower density than the saline water and
will remain above the saline water if it is undisturbed. When thp
fresh water is withdrawn from the aquifer system, the salt water






REPORT OF INVESTIGATIONS NO. 43


will cone up and enter the zone of reduced pressure by vertical
migration. However, analysis of water samples taken at different
depths in wells at Fernandina Beach gives evidence that all or
some of the contamination of water in deep wells is by lateral
migration from a salt-water zone or zones within the upper part
of the Floridan aquifer system.
Figure 22 shows graphically the chloride content of water
samples collected at various depths during the construction of
wells 038-127-324 and 041-126-333A at Fernandina Beach. Water
enters well 038-127-324 from the Ocala Group, and the Avon Park,
Lake City, and Oldsmar Limestones, but in well 041-126-333A the
Ocala Group, Avon Park Limestone, and part of the Lake City
Limestone are cased off and water enters the well only from part
of the Lake City and Oldsmar Limestones. The chloride content
of water found in both wells in a zone at the bottom of the Avon
Park Limestone and the top of the Lake City Limestone ranged
from about 100 ppm to about 430 ppm. The water was considerably
fresher immediately above and immediately below this zone, which
indicates that water in this zone is isolated from water in the
rest of the aquifer system. Although the maximum chloride
content of the water in this zone was about 150 ppm in well
038-127-324 and 430 ppm in well 041-126-333A when the wells were
constructed, the rapid increase with pumping (fig. 21) suggests
that salt water is entering the zone. Therefore, this zone is
probably a source of salt-water contamination of the fresh water
in wells at Fernandina Beach. Discharging wells that are drilled
into the Lake City and Oldsmar Limestones and are open to this
zone may induce lateral migration of relatively saline water into
the wells. Uncontaminated fresh water can be obtained from
below if salt water is prevented from entering the well bore by
casing off this zone.
The graphs in figure 22 also show that the chloride content of
water from both wells gradually increased below about 2,000 feet.
This indicates that salty water is present below this depth also
and wells drilled deeper than 2,000 feet in Fernandina Beach will
probably encounter highly saline water.
Except at Fernandina Beach, no wells in the area have been
drilled sufficiently deep to encounter salt water, and none of the
wells drilled into the Lake City Limestone have encountered the
salt-water zone at the base of the Avon Park Limestone and the
top of the Lake City Limestone. However, as more fresh water
is withdrawn from the aquifer system and the artesian pressure





















CRYSTAL RIVER FORMATION

)0- WILLISTON FORMATION
INGLIS FORMATION

)0- AVON PARK LIMESTONE

LAKE CITY LIMESTONE




)0-
OLDSMAR LIMESTONE


S0 0 60 120 180 240 300 360 420
scale CHLORIDE CONTENT, IN
PARTS PER MILLION

Well 038-27-324 swmles taken ItugQh drill stem durhg drilling
Well 041-126.533A sormes oaken with ibaler during dinag



Figure 22. Graphs of the chloride content of water at different depths in
wells in the Floridan aquifer system at Fernandina Beach.







REPORT OF INVESTIGATIONS NO. 43


continues to decline, more salt water may migrate either vertically
or laterally, or both vertically and laterally, into the fresh-water
zones in the upper part of the aquifer system. Then the fresh
water will become progressively saltier until, eventually, it may
become unsuitable for domestic and most industrial uses.
It is possible to retard or even to prevent vertical and lateral
encroachment of salt water by properly spacing wells and
controlling discharge rates to avoid excessive drawdowns. The
confining beds in the Avon Park, Lake City, and Oldsmar
Limestones will retard or even prevent vertical movement of water
in the aquifer system in most of the area. However, if these
relatively impermeable beds are penetrated by a well, any salt
water present will move upward at a faster rate. Therefore,
caution should be taken in developing the deeper water-producing
zones in the aquifer. More detailed information on the geologic
and hydrologic characteristics of these deeper zones and the depth
to salt water needs to be obtained before there is any extensive
development of these zones. Such information will insure proper
development of the deeper zones in the aquifer and lessen the
possibility of salt-water contamination.


SUMMARY

Water supplies in northeast Florida are obtained almost
entirely from ground-water sources. The rocks usually penetrated
by water wells are thick limestone and dolomite beds of Eocene
age which underlie the surface at depths ranging from 300 to 550
feet below msl. These rocks, in ascending order, are the Oldsmar
Limestone; the Lake City Limestone; the Avon Park Limestone;
and the Inglis, Williston, and Crystal River Formations which
compose the Ocala Group. The limestones of Eocene age are
,verlain by the Hawthorn Formation, which is composed of beds
'f clay, phosphatic clay, sandy clay, phosphatic sand, limestone,
:nd dolomite of early and middle Miocene age. The Hawthorn
:ormation is overlain by beds of calcareous silty clay, limestone,
.hell, and sand of late Miocene or Pliocene age and of Pleistocene
:tnd Recent age.
A fault extending along the St. Johns River in Duval County
lisplaces the top of the limestones of Eocene age a maximum of
.bout 125 feet. West of the fault the top of the Avon Park
:imestone dips northeastward about 16 to 20 feet per mile.







FLORIDA GEOLOGICAL SURVEY


The shallow aquifer system, which is 300 to 550 feet thick in
the area, extends from the surface into the Hawthorn Formation.
The aquifers within the system consist of relatively discontinuous,
porous limestone, shell, and sand lenses within the Hawthorn
Formation, the upper Miocene or Pliocene deposits, and the
Pleistocene to Recent deposits. The aquifers are recharged directly
by local rainfall and by downward infiltration of water from
shallower aquifers in the system.
The aquifers in the shallow aquifer system most utilized by
wells in the area are the surficial sand beds and a relatively
continuous limestone, shell, and sand zone at the base of the upper
Miocene or Pliocene deposits. As the thickness and lithology of
these aquifers vary both vertically and laterally, the amount of
water available from them depends on the location and depth of
the well. Generally, the surficial sand beds yield about 10 to 25
gpm, and the aquifer at the base of the upper Miocene or Pliocene
deposits yields between 15 and 20 gpm to small-diameter wells.
As more information is obtained on these aquifers, it may be
possible to determine the proper location and construction of wells
to obtain more water. It may also be possible to recharge
artificially one or more of the aquifers so that more water is
available to wells. These aquifers may become a major source
of ground water, particularly if the water in the underlying
Floridan aquifer system becomes contaminated by salt water.
The Floridan aquifer system, which is composed primarily of
limestones of Eocene age, is the principal source of fresh water
in northeast Florida. The top of the Floridan aquifer system,
which ranges from 300 to 550 feet below msl, is overlain by an
aquiclude of relatively impermeable clay, sandy clay, and dolomite
beds in the Hawthorn Formation and in the upper Miocene or
Pliocene deposits that separate it from the shallow aquifer system.
Current-meter studies and information obtained while wells
were being constructed indicate that there are at least three
separate permeable zones within the Floridan aquifer system in
northeast Florida. The first zone includes all the formations of
the Ocala Group and, locally, limestone at the base of the Hawthorn
Formation and at the top of the Avon Park Limestone. In the
vicinity of Jacksonville, the second zone is in the top part of tie
Lake City Limestone, and the third zone is within the Lake City
Limestone, below a depth of about 1,200 feet. However, in
Fernandina Beach, the Lake City Limestone contains only ore
permeable zone, and a third zone is present below the Lake City







REPORT OF INVESTIGATIONS No. 43


Limestone in the Oldsmar Limestone. These zones are separated
by hard, relatively impermeable dolomitic limestone and dolomite
beds.
Water is generally under higher artesian pressure in the lower
zones than in the Ocala Group. The deeper zones yielded 50 to 98
percent of the total amount of water from the wells tested in the
vicinity of Jacksonville, and water was lost into the zone. in the
Ocala Group from the deeper zones in the well tested at Fernandina
Beach.
The yield of water from wells in the Floridan aquifer system
in the area depends largely upon the depth, the well construction,
the artesian pressure, and the transmitting properties of the
permeable zones. The natural flow of wells 2 to 6 inches in
diameter is generally less than 500 gpm, and that of wells 8 to 12
inches in diameter is generally less than 2,000 gpm. As much as
4,000 or 5,000 gpm may be pumped from some wells larger than
12 inches in diameter that penetrate to the second or third
permeable zones.
Water enters the Floridan aquifer system in north-central Flor-
ida through breaches in the aquiclude by sinkholes, by downward
leakage from surface bodies of water or from shallower aquifers
where the aquiclude is thin or absent, and directly into the aquifers
where they are exposed at the surface. The water moves generally
northeastward through the aquifer system into northeast Florida,
where some of it is discharged artificially through numerous
wells, and some is probably discharged naturally into the ocean off
the coast. Cones of depression have formed in the piezometric
surface in northeast Florida as a result of discharging wells which
lower the artesian head and create a hydraulic gradient toward
the discharging wells. Major cones of depression have developed
in Duval County at Jacksonville and Eastport and in Nassau
County at Fernandina Beach. The piezometric surface has been
depressed to less than 30 feet above msl at Jacksonville and to
riore than 15 feet below msl at Fernandina Beach.
In parts of Duval and Nassau counties where the piezometric
surface is higher than the land surface, the wells that penetrate
t ie Floridan aquifer system will flow. The size of the area in
Shich artesian flow will occur varies greatly with only slight
c ranges in the elevation of the piezometric surface.
Public water supplies in the vicinity of Jacksonville are
c -tained from 46 municipal wells and more than 100 private utility
'vells that are drilled into the Floridan aquifer system. The smaller






FLORIDA GEOLOGICAL SURVEY


towns in the area and the three large Navy facilities also obtain
water from the Floridan aquifer system. The three major paper
manufacturers in the area, many other industries, and a number
of the larger commercial buildings have wells in the Floridan
aquifer system. Many private residences also obtain water from
wells in this aquifer system. The total amount of water discharged
by artesian wells is estimated to average from 150 to 200 mgd
in the vicinity of Jacksonville and from 50 to 70 mgd at Fernandina
Beach.
Water-level records show an irregular but continual decline in
artesian pressure in the area. The greatest decline is in wells in
the shallower permeable zones in the Floridan aquifer system
near the centers of the cones of depression. At Fernandina Beach,
artesian pressure declined 50 to 60 feet during the period from
1939 to 1963, and at Jacksonville, artesian pressure declined 12 to
22 feet during the period 1946 to 1963. The piezometric surface
declined 10 to 25 feet in all of northeast Florida during the period
1940 to 1962. During the period July 1961 to May 1962, the
piezometric surface fell 1 to 10 feet because of below-normal
rainfall and increased withdrawals of artesian water. Artesian
pressure in the area will continue to decline if withdrawals of
water continue to increase. However, the decline of artesian
pressure does not pose an immediate threat to the availability
of water in the area. A much greater danger is that highly
mineralized water will enter the zone of reduced pressure and
contaminate the existing fresh water in the aquifers.
Water from most wells in the shallow aquifer system and in
the Floridan aquifer system is suitable for domestic use and for
most industrial uses. Water from wells in the shallow aquifer
system is generally softer, contains less dissolved mineral matter
and more iron than water from wells in the deeper Floridan aquifer
system. Wells in the Floridan aquifer system closest to the recharge
area in southwestern Duval County generally coritain softer water
with less dissolved mineral matter than wells in the central and
northern parts of the area. In the vicinity of Fernandina Beach,
there is considerable variation in the quality of water from wel s
of different depths in the Floridan aquifer system. Water from
the deeper wells is harder and contains a higher dissolved-solics
content than water from the shallower wells.
The chloride content of water from wells in the Floridan
aquifer system ranges from less than 10 ppm in the southwestern
part of the area, where the piezometric surface is highest, to more







REPORT OF INVESTIGATIONS NO. 43


than 40 ppm in wells less than 1,250 feet deep, and to more than
1,180 ppm in some wells more than 1,250 feet deep at Fernandina
Beach, where the piezometric surface is the lowest. Except in
some of the deeper weels at Fernandina Beach, the increase in
chloride content of water from most wells in the area ranged
from 2 to 14 ppm during the period 1940 to 1962. In many of the
deeper wells at Fernandina Beach, the chloride content of water
increased about 20 to 1,320 ppm between 1955 and 1962.
The increase in chloride content of the water from artesian
wells correlated with the decline of artesian pressure indicates
that salt water is gradually moving into the zones of reduced
pressure and contaminating the fresh-water supplies. At present,
serious contamination is limited to a few deep wells at Fernandina
Beach, where salt water is migrating laterally into the aquifer
from a highly mineralized zone at the base of the Avon Park
Limestone, and vertically from highly mineralized zones more than
2,000 feet below land surface.
Contamination of the fresh water will increase in northeast
Florida if the artesian pressure continues to decline. Further
contamination can be retarded and even prevented if, in the future,
wells are property spaced and their discharges controlled in a
manner that prevents excessive lowering of the artesian pressure.
The impermeable beds and the higher water pressure zones in the
Avon Park Limestone, Lake City Limestone, and Oldsmar
Limestone presently prevent upward coning of salt water from
the lower part of the Floridan aquifer system. Careful well
construction and proper development of these aquifers should be
employed to keep these natural barriers effective. Contamination
in some of the deep wells in Fernandina Beach may be retarded
by casing off the highly mineralized zone at the base of the Avon
Park Limestone.

FUTURE STUDIES

Many topics essential to completing the study of the ground-
eater resources of northeast Florida are beyond the scope of this
investigation. The findings from the following investigations to
complete this study will be reported in the future.
1. A detailed investigation of the shallow aquifer system,
particularlyy the aquifer at the base of the upper Miocene or
)liocene deposits, to determine its potential as a primary or
supplemental source of water. This investigation will include test






FLORIDA GEOLOGICAL SURVEY


drilling to determine the areal extent and thickness of the aquifers
and pumping tests to determine their water-bearing properties.
2. Quantitative permeability investigations of each of the
separate permeable zones in the Floridan aquifer system to predict
the results of using water from the deeper zones and to determine
the best method of developing these zones without causing salt-
water intrusion. This investigation will include pumping tests to
determine the water-transmitting and water-storing capacities of
each of these zones and mathematical and graphic analyses of the
aquifer system.
3. An investigation to determine the relation of water-level
declines to the amount of water being discharged from the
Floridan aquifer system in order to predict future declines. This
investigation will include continued measurement of water levels
and a detailed inventory of wells in the area to determine more
exactly the amount of water being used.
4. An investigation to detect any increase or spread of salt-
water contamination in the area. This will include continued
sampling and chloride analysis of water from wells throughout the
area. If possible, a deep well will be drilled near the center of the
cone of depression at Jacksonville to locate the exact depth to salt
water. This well will be sampled periodically at various depths
to detect any vertical movement of salt water into the fresh-water
zones in the upper part of the Floridan aquifer system.








REPORT OF INVESTIGATIONS NO. 43


REFERENCES

Applin, E. R. (See Applin, P. L)
Applin, P. L.
1944 (and Applin, E. R.) Regional subsurface stratigraphy and
structure of Florida and southern Georgia: Am. Assoc.
Petroleum Geologists Bull., v. 28, no. 12, p. 1673-1753.
Black, A. P.
1951 (and Brown, Eugene) Chemical character of Florida's waters,
1951: Florida State Board Cons., Div. Water Survey and
Research Paper 6, 119 p.
1953 (Brown, Eugene, and Pearce, J. M.) Salt-water intrusion in
Florida, 1953: Florida State Board Cons., Div. Water Survey
and Research Paper 9, 38 p.
Brown, Eugene (See Black, A. P., 1951, 1953, and Cooper, H. H., Jr., 1953)
Cole, W.
1944 Stratigraphic and paleontologic studies of wells in Florida-
No. 3: Florida Geol. Survey Bull. 26, 168 p.
Collins, W. D.
1928 (and Howard, C. S.) Chemical character of waters of Florida:
U.S. Geol. Survey Water-Supply Paper 596-G, p. 177-233.
Cooke, C. W.
1915 The age of the Ocala. Limestone: U.S. Geol. Survey Prof. Paper
95-1, p. 107-117.
1945 Geology of Florida: Florida Geol. Survey Bull. 29, 339 p.
1929 (and Mossom, D.) Geology of Florida: Florida Geol. Survey
20th Ann. Rept., 1927-28, p. 29-227.
Cooper, H. H., Jr. (See Stringfield, V. T.)
1944 Ground-water investigations in Florida (with special reference
to Duval and Nassau Counties) : Am. Water Works Assoc. Jour.,
v. 36, no. 2, p. 169-185.
1953 (and Kenner, W. E., and Brown, Eugene) Ground water in
central and northern Florida: Florida Geol. Survey Rept. Inv.
10, 37 p.
Counts, H. B. (See Stewart, J. W.)
Croft, M. G. (See Stewart, J. W.)
D)all, W. H.
1892 (and Harris, G. D.) Correlation paper: Neocene: U.S. Geol.
Survey Bull. 84, 349 p.
)erragon, Eugene
1955 Basic data of the 1955 study of ground-water resources of Duval
and Nassau counties, Florida: U.S. Geol. Survey open-file report.
Florida State Board of Health
1960 Some physical and chemical characteristics of selected Florida
waters: Florida State Board of Health, Bur. Sanitary Eng.,
Div. Water Supply, 108 p.
hunter, Herman (See Sellards, E. H.)
'arris, G. D. (See Dall, W. H.)
oward, C. S. (See Collins, W. D.)








FLORIDA GEOLOGICAL SURVEY


Leve, G. W.
1961a Preliminary investigation of the ground-water resources of
northeast Florida: Florida Geol. Survey Inf. Circ. 27, 28 p.
1961b Reconnaissance of the ground-water resources of the Fernandina
area, Nassau County, Florida: Florida Geol. Survey Inf. Cire.
28, 24 p.
Matson, G. C.
1913 (and Sanford, Samuel) Geology and ground waters of Florida:
U.S. Geol. Survey Water-Supply Paper 319, 445 p.
Mossom, D. (See Cooke, C. W.)
Pirnie, Malcolm
1927 Investigation to determine the source and sufficiency of the
supply of water in the Ocala limestone as a municipal supply
for Jacksonville: Hazen and Whipple, New York.
Pride, R. W.
1958 Interim report on surface-water resources of Baker County,
Florida: Florida Geol. Survey Inf. Circ. 20, 32 p.
Puri, H. S.
1953 Z~nation of the Ocala group in peninsular Florida [abs.]: Jour.
Sed. Petrology, v. 23, no. 2, p. 130.
1957 Stratigraphy and donation of the Ocala group: Florida Geol.
Survey Bull. 28, 248 p.
Sanford, Samuel (See Matson, G. C.)
Sellards, E. H.
1913 (and Gunter, Herman) The artesian water supply of eastern
and southern Florida: Florida Geol. Survey 5th Ann. Rept.,
p. 103-290.
Stewart, J. W.
1958 (and Counts, H. B.) Decline of artesian pressures in the Coastal
Plain of Georgia, northeastern Florida, and southeastern South
Carolina: Georgia Geol. Survey Mineral Newsletter, v. 11, no. 1,
p. 25-31.
1960 (and Croft, M. G.) Ground-water withdrawals and decline of
artesian pressures in the coastal counties of Georgia: Georgia
Mineral Newsletter, v. 13, no. 2, p. 84-93.
Stringfield, V. T.
1936 Artesian water in the Florida peninsula: U.S. Geol. Survey
Water-Supply Paper 773-C, p. 115-195.
1941 (Warren, M. A. and Cooper, H. H., Jr.) Artesian water in the
coastal area of Georgia and northeastern Florida: Econ. Geology,
v. 36, no. 7, p. 698-711.
U.S. Department of Health, Education and Welfare
1962 Manual of individual water supply systems: Public Health
Service Pub. 6, no. 24
Vernon, R. O.
1951 Geology and Citrus and Levy counties, Florida: Florida Geol.
Survey Bull. 33, 256 p.
Warren, M. A. (See Stringfield, V. T.)



























































































I '









TAsLE 8, Recoid of wells in Duval and Nassau counties.


Well number: See figure 1 for explanation of well-numbering system.
Owner: C, county; I, industry; M, municipality; 0, church; P, pri-
vate; S, State; U, U.S. Government.
Depth of well: Reported unless otherwise noted by M, measured by
U.S. Geological Survey.
Well finish: 0, cased to aquifer, open hole in aquifer; S, sand point.
Method of drilling: C, cable tool; J, jetted; R, rotary; X, other or
unknown.
Type of pump: C, centrifigal; J, jet; N, none; T, turbine.
Use of water: A, air conditioning; D, domestic; F, fire protection;
SI, industrial; M, mining; N, none; P, public supply or municipal;
S, irrigation; S, stock; T, test or, observation.
quifer(s): D, Floridan aquifer (deeper than Ocala only); F, Flor-
i 'ldan aquifer (Ocala Group); FD, Floridan aquifer (Ocala Group
'and deeper than Ocala); Sr, shallow aquifer, rock well; Ss,
shallow aquifer, surface well.


Casing




Wsi -
.0 5 -


Altitude of land surface: To tenth of a foot if determined by precision
leveling; otherwise, to nearest foot.
Water level: To tenth of a foot if measured by wet-tape method or
if taken from recorder chart. To nearest foot, if measured by
pressure gage or air line. P, periodic measurement; R, recorder
on well. Date of measurement applies also to temperature, chlor-
ide, specific conductance, and hardness, unless otherwise noted in
Remarks column.
Chloride: P, periodic determination.
Chemical analyses available: C, complete; D, complete and radio-
chemical; M, multiple-complete and partial; P, partial.
Yield and drawdown: Reported unless noted by M, measured by U.S.
Geological Survey; F, yield by natural flow; P, yield by pumping.
Remarks: W- or Wgi-, Florida Geological Survey well number. Logs
available: A, chloride or conductivity; C, caliper; D, drilling time;
Dr, driller's log; E, resistivity and/or spontaneous potential;
L, geologists's log and/or samples; V, current meter.





rsABLE 8. (Continued)


-- 545 4

4


D08-O80-181- P

)08-180-410 P



08-134-120 P



,"i,^,' ,
108-1385-340

109-186-244 0
9-187-120 P
109-189-280 p



100-140-240 P

ii0-1i8-244A P

10-138-244B P
11-138-211 P

11-141-141 U



1i-187-221 P


D F

D F



D F


;:Only the earliest and latest measurements and chloride values are shown on table.


1960 1 500


fiji


200






337




500

457



425

252


0

0



0


0

0
0
0



0

0
O




















0
0

0



0
O I


X N

X N



C N


X N

R N
R -
X N



X C

X C

X N
R C

R N



J N


487

600
900




650

556

100
661

403


1961

1955




1936

1958



1946

1940



1956


Jr


D

D
P
DR



DR

DR

N
DR

DF



D


I-


23.6

28.5



26


22



88
16.5



2.1

25



20

16.1



10


F

F
FD
F



F

F

SR
F

F



F


650 I


I '


31.3
18.5
28.0
20.5
17.2
17.7
18.6
16.3
12.0
25.5
20.5
21.7


35.8
23.7
20.3
13.1
50.0
41.8
20.0
12.0
8.8
21.0
10.0
28.0
16.4
17.5
15.8
31.5
18.6


9-23-40
1- 4-60
9-27-40
1- 4-60
7-1161
5-14-62
1- 6-60
7-11-61
5-14-62
11- 1-61
5-14-62
1- 8-61


9-28-40
1- 7-60
7-11-61
5-14-62
9-28-40
1- 7-60
3- 1-61
5-14-62
3- 1-61
1- 5-61
5-14-62
8- 7-40
10-13-55
1- 4-60
5- 7-62
1- 5-61
5-14-62


31


23

21






10
15
24

21
15


12
12

13


71
71


I
W-8464, L




Cl, 11-4-5566



0


S2OFM









TAsIL 8, (Continued)


Cuing

I '








461 4 0 R N D

510 4 0 R C AFRI
380 12 0 R C PF



-- 10 0 R C PF
318 12 R C PF


400 12 O R N
- 10 0 R PF
286 8 0 -. DR
- 0 X P
467 20 0 R N N


439 10 0 R N N
485 20 0 R T PF
520 18 0 R T MI


F



FD



FD
FD


FD
PD
FD
SR
FD



F
FD


Water level
Iv


a ^ -
- j~i d -

++1 9 J 1

-=S~r l


25.2 28.6 P
7.4
-- 4
9.2 45.2
37.2
30.3
26.0


20.9
23.0
11.3
16-20 -
79.2 -16.23
16 -


79.8 -2S.72
-26.12
-29.54
80 -
85 -28
50 3.35


7-30-40
5- 1-12

3 5.40
1-1440
7-12-1
5-17-42



1-14-40
5-17-62



-- I
5-19-41



10613-0
5-1742


11- ?-V5
3- 1-61


I


C




C








C


I

a f
.8


76 3,000S M


4,JSOFM
i--I---



4,150rF





780P
i---





1,OOOP
1,i000P
2,000PF


* 018135-230

S013.-1-400
013-140-414A



013-140-414B
013-141-441


013-142-214
013-158-240
014-141-220
4-143-130
014-153-111A


014-1053-l1B
014-153-20
01 -1334,1


1957 610
1940 1,005



- 708
1940 1.015


21



35


U 1942
U 1941
P 1922
P -
U 1944


U 1942
U 1956
P 1957


988
990
669
185
1,005


780
1,305
1,246


Remwks


L


CI, 11-15-40




W-514, ; CL
11-15-40

V461, L
W-561. L
W.581,. L
W-2T, L


L


W-731
W-4113, L


t


I -. : __ __ _


--


----~--






015-138-443

015-188-314

015-138.410 '
16-5-141-111

015-145-230
015-145-330


i016-125-431

;016-137-100




0 42-414

17-126-282


017-126-440
S017-180-442

oi7-134-210
'01 -134-31


017-135-413

017-186-124


P

P

P
P

P
P


P

P
P

P
M

P
P

P


P
P


C

P


520 18

470 6


1967

1954

1949
1938

1961
1923
1924


1959 615 332

-_ 70-100 _
1953 733 531

- 99 -
1928 729 476


1939


550


400


480


1960 1,004M 487
1939 675 --


1939 785 524


56


O

0


R

R


1,254
194

1,264

1,187
600

1,000M
1,920
1.690


T MI

N DR

T P
N DN


757
470

460

800-1,000


0 R
0 X

0 R

0 X

0 R

0 X



0 X
O X

0 X


0 X
O X

O R
0 R


O R

0 J


N- P
N DR


J

]N


FD 5

FD 22

D 14
F 8.6

FD 33

FD 64.9

F 4

SR
F

SR
F 16.2

F 11.6


F
F 40

FD 13
F 24.1


P F

N S


26.7


-10.3
-19.6
19
11.9
23
41 P
16.4
S 7.36

-3.6 R
-17.16
383
29.4


11.7
Sl2


40 P
9.2
40.6
32.3
22.3
2-3

1.6
- 1.34


29.5
418
4.9
26.8


23 -14.76P I
'-19.25


T P

N T

C P

J DN
C DA


3- 1-61
5.14-62
2-24-61
5-14-62
5-22-62
7- 5-40
5- 9-62
5-17-62

4-16-41
5.2-62
2-27-61
5-15-62


2-24-61
7-12-61


5-22-30
5- 9-62
9- 6-40
1- 7-60
5-15-62


12-19-61
5-15-62


6- 7-39
1- 5-60
5-14-62
6- 5-39

2-28-61
5-14-62


21
25
20
20
19
10
15
13








is


17




20




21
IS
24
22
15

13


74.5


_ 2,OOFM


950



400F


C






C



- 2,00
71.5 4751


C


C

C


L; Clf, jZ-,o0
Cl. 10-13-55


L, Dr; CI
11-15-40


2,600P

960 -

2,T00FM _
450FM _


D
PN

D


P
DN


Ocala Group
csed of


L
Plugged at
1,920feet
ReAord,
record






14
a.r.






CL 10-T-55 "

s&;


" "


I


rM








TABLE 8, (Continued)


Water level


Casing




0 x
81 i

j J 111K,
sb. S .1
troiber 4 ^ S u a o j


017-136-241A



017-186241B

017-137-214
017-138-142

017-158-110
.017-158-480

018-123-128

018-124-222
018-131-240
018- 1-438




S1-136-241
777-aeu


1957



1957


2I.



245


1962 1,210M
1955 1,500


715
750

585

622
1,002
600.650




685


1957
1942

1934

1938
1959


515



200

530
500

465
433

357

382
427






508


1% 0


PN


-* f=A

a-l


F 11.

F 10
FD 42
F 17




F --


803 9278


30.3 R 9-27-60
19.5 5-14-62


2-18-61
5.14-62




3- 6-57

1-11-61
5-1762
10.14-39
5-19-62
12-12-38


9-27-60


- 6.29P
-13.18




1-35
-25.06
-29.4
42.4 P
21.6
40.3


19.2 R


4,$

0


%. A'
-- 3,501


3,25 .OFM


C


4




.3 em
Remairku


SPressu re.
border in-
staled 9-2.6
60, removed
2.3-62



L
V (incom-
plete)
W-4202





W-392, L
L,Dr.
Pressure r.-
corder in-
stalled 9
2760, re-
moved 10-
31-61


0,

5<


3.ltoI~b


72.5






018-136411 P


1018-138-343 M


018-139-230 M

(010-139-233 M


018-140-123 P

018-142-210 M




f," :.. ',
018-143-234 M

08-145-140 P







019-124-210 M


19-182411 P



O19-183-48 P

019-134-10 P


09-135430 P
019-18o-8 P

01-14-10 P


-- 630


1939
1949

1935
1943
1939
1959




1931
1948





1937


1938

1962


1929



1929

1938


1,071
1,348

583
1,307
1,037
1,280




736
1,247
900

80
650





1,300M1


762



875

635


200


-- 3


505 10


500 10

508 10


3

18


5



6

S3


16


O 1


0 R





0 X

0 X
0 R



0 X

0 X
0 X


0 R

0 X



0 X



0 x

0 C


C D


T P


T P

T P


N D

C P

N PN

J DA
N R


DR

DN


FD 20.5



FD 7
FD 5.1


F 4.5

F 14
FD
FD 24.6

SR -
F 12.6


F 10

FD 12


F 38.4


53.04

24.1


27.9
14
1
30
17
16.9



43.9
39.1
35.3
43.2 P
18.2



30.7 P
10.1


41.5
32.6
20
42.9
34.8
30


17.7

7.3
1.8 P
-21.94
31.5
20.2
9.5


2-22-39
1- 5-60
5-15-62
3-23-39
1-12-60
7-13-.61
I----


3-23-39
1-12-60
7-13-60
11-26-34
5- 9-62



11-28-40
5- 9-62


2-25-39
1- 7-60
5-15-62

2-25-39
1- 7-60
6- 4-62


6- 7-39

11-18-60
6-10-39
5- 9-62
6- S-39
1- 6-60
5-1662


75


1,700F


5,000FM


CI, 10-7.-5




CI, 10-14-5
i


_I


CI, 10-6-55


-22, L; CI.
11-7-40





11-T-40 W
CI, 5-21-41 ,



W-169, L





CI, 104-55 Q





A. C, E. L.
V, packer
li




testsA C
CI, 2119-40


(









TASL 8. (Continued)


Wbellr
number 0


0M388-a20
91489.124



019-140421

019.142.111
'i '


119-148-181

19 146-840


019-147-210
090.184-834


p2-136-240
MOl :. 1 1


1942
1061
1930
1954


1.074
758M
665
760
786


1011 1,075


1938



1929
1936



1932


612



1,060
765



750


Casinr

ir
I-


*1 I iD
a 4

f |


I
DA
DR
PRA
T

PN

I

DR



D
DR



DR


F
F

FD

F

F



FD
F



F


~ rrrr
:..-~..--1.1
L
L
r
I


a


10
ja

G'Su


I

'U
'5-


'91
US~
Hi


4
22.1
3.5
4
8.3

22.8

21.9

44.1



69
30.3



34.2


2,000F
150FM


" Y ..


lera


U U



83


7-20-42
5-17-42
3- 8-39
5-15-62
11-26-38
5- 9-62
8-1380
5. 9-62
7-16-40
1-18-60
7-23-40
1- 3-60
12-22-40
7-144-61
7- ?-29
6- 8-39
1- 6-60
7-12-1
6-16-62
6-11-39
1- 6-60
5-1562


hi


42
- 0.1
30.3
19.5
32.1 PR
13.3
39.2 P
13.2
36.8
25.5
15.1
4.45
3.97
1.88
8.1
30.8
10.7
11.3
5.67
23.5
12.8
2.1


73


73

73

72.5


RemuaI


W449. L
L. D
L, Dr
L. Dr
CI, 10-1530



CI, 1012-56

Cl. 10.12-5



W-116, L
CI, 10-14-55


76.5 I~


76


-- --


f





020-136-484 1 1940 tiuo 5 30 3 X N It F 29.4 23.5 8-23-40 14 76 CI. 11-4-55
16.5 1- 6-60 21
9.2 7-12-61
6.8 5-15-62 20

020-187-34 P 4 O X C I F 14.7 40.0 2-164 C 11
84.5 7-4-40 s18
S18.0 21-62 23
20-189-182 M 1911 1,015 488 10 0 X N PN FD 5.9 36.8 6-16-9 13 77 CI, 11-740
16 : ; CI, 5-21-41
0.3 1-12-60 21-21-4
18.3 5-24-62 24
0-189-22 M 1936 1,035 494 10 0 X C P FD 5.5 35.5 9-23-36 ,1351 W-304, L
039-448 M 1907 980 10 0 X C P FD 4 49.0 6-139 17 83 C 11-740
17 CL 5-4-44
,8' ; 36.8 1-12-60 22 C 5
833.5 7-18-61
34.2 -24-62 24 .
20-14's30 P 1,150 6 0 X N I FD 24.1 27.3 2- 0-9 17 83 20000F C, 10-(.-55
25.2 1-11-60
14.6 5-1762 18

)20-144430 P .. 630 500 3 0 X N DR F 24.7 25.9 7-23-40 11 81
6 CI, 10-12-5
18.6 1-13- i 18
S. 11.9 5-1-62 17
2i.128s-13 P 1937 575 6 0 X N R F 9.1 43.6 2-25-89 15 72 C, 11-1940
1 Cl, 10-7-65 W,
34.4 1- 7-60 22
26.3 5-15-62 29

1125.421 P 1961 703M 396 8 0 R P F 7.0 32.3 5-19-61 22 930FM LD
26.5 5-16-62 22

i)-82410 P 1987 540 475 3 0 X N R F 17.0 87.7 8-24-40 20 C, 10-14-55
21.8 1- 6-60 22

)21183-220 P 1953 610 522 4 O J N DR F 15 31.4 9-2-60 20 -
23.8 5-16-62 24

21-186-400 P 90 DR SR C -
)21-188-121 P 1938 1,060 543 10 0 X C R FD 16.7 39.5 2- 7-39 1 78 2.160F CI, 11-13-40
27.2 1-12-60 23
16.1 5-21-62 21
** l






TAra 8, (Continued)

;: .. .. ..


Cu*ing


31.2
24
14.4
23.0
35.2
27.7
18.9
40.8
26
20.11
32.9



7.2

37.7
26.8
15.3
37.3
25.9
22.5
15.7
26
19


7- 1-40
1-12-60
5-21-62
2- 8-62
7- 1-40
1.11-60
5-2162
&-14-39
1-12-60
5-24-62
6-14-39



9-25-60

2- P-39
1-12-60
5-21-62
2-11-39
1-12-60
7.1.-61
521-62
1-12-60
6524-62


Water lIvel


Sa-



4 I
ji ~ '~: JA
111 'Sii i


+.i 1

5 J .
Pg I emrk


78


80


78





76


1.900FM







1,500FM



900F
2,000P


473


550



530


513



462




510





469


I



7Y
^JS


CI, 10-5-55


L, V
Cl, 10.5-5


CI, 5-2141:
W-830,.L

L V '"




L. Dr1 '
Cl, 10-5-5


CI, 10.5-55





W-532, L


0214,-1,20



:02149-424


0214141414


021-141423

021-142-100
022-180-112
,.A' : '
022-188-400


022-189244



p22-140-10

022-148-320
4222
loe at,.,:


1939


1962



1939


1939
1941


1959

1923


1915



1951

1940


780


1,803M



1,053


1,055
1,356
800



1,076


700



1,303

690


0


0
0


0


0



0

0


0



0

0
O


-. --I. 1,020F .. -


N


N D



C P

_ R


21.8


20
19.0


16.4


24.4



89

19.2


16.4


FD 22.4


F 10.5 .. .


I____I___


--- -~-












' 1
|022-147-240



"028-125-142



023-129-830







S';: '. .


i -1: 22

0S4-128.233
04-136-130

0p4-141-340
,024-144820


o2-126-281

025-132-444

025-186.220

'0251810
026.13z8-l 210i


1953


1962 1,001 .
1939 510


1930

1925


200



905


435
-


570


1940 700 560


-- 70
1939 625


1930 840


1910

1942


556

942


c-





500


450


660


630


3

18
6



2
4

8






3

38%
6

2
3


8

4

8

8


0

0
0




0

0






0

0
0



0


0

0

0

0
O

O


O



O




O




O

O


O


O


O

O

O


N S


X

R
X



X
X




X




X

X

X

X
X



X
X

X

X


J DRF
N R


N




C


N






N

N
R

DR
D


F 23 24.5 10-19-40
18.6 5-17-62
FD 6.7 30.3 5-16-62
F 8.0 41.3 6- 9-39

36.4 1- 7-60
SR ____-
F 3.12 53.2 P 6-12-39


FD I 14.9


F

F


F
SR
F


6.0

4
29.2



20.7


DR IFD 15.7


DR F

IN F


PRI


FD


4.2

8.8

19.9


32.2
47.0 PR





23.7
43.8 P
28.8
28
28.0 P
3.4


35.3
23.3
17.0
45.2 P
25.8
42.3
36.2
44.5 P
18.3
21.7
23.6
18.5


5- 9-62
6-22-30




5-10-62
7-27-40
5-10-62
5-21-62
6-25-40
5-18-62


7-24-40
1-18-60
5-18-62
8-19-30
5-10-62
1-21-60
5-21-62
3-22-51
5-10-62
1-20-60
7-13-61
5-18-62


22
23



21
16





16
15



18



18
19
20
90
122
35
25
25

28
25


C



CD


- 2,500F
73 -


73.5



75 -


- 80--


PF
N


sj


1929 800
19290 800


W-5823
Flowing wld;
Cl, 11-19-40
Cl, 10-7-55 ;









Trit'dmn,
,ta 1-edl-60 -




62, 0-12removed
26-82; ,j,
5-20-41;
Tritium
CI, 1-7-80



Flowing wild





Cl, 10-12-55 '


Cl, 11-21-40
Cl, 19-601



CI, 3-8-60



00'








TAPLI 8. (Continued)





1,


Cuasing




It


-


i Well
'' number

03*288888



1 02141400







026-185-842A





26.185-42C




.02614110
.& S-i4t-i
,ii&13 ', ',


O1 8P


Ia

-


Water level


c

S,


14.5 31.15
29.5
24.5
17.7 39.2
26.8
25 ..
12.2 42.1

36.5
30.0


0 X C PRI FD


0 X N R F


O R C P FD
O X C D F



O R N T FD


O R N T D


37.0 P
22.5
33.1 P
23.2

32.9 P
22.2
28.8
27.72
17.8


1-20460
7-18-61
5.18-42
6-12-40
1-18-60


0.12-40

1-19-60
5.21-62
6-12-51
5-10-62
1-13-54
6-10-62

1-13-54
5-10-62
5-81-56
4-20-56
5-24-62


C.,


a
a
a


i





a


- 1,830F


1,830F





4,800FM





930F









6,700
456F


'5-


'a
YI
be


17.3


16.96


16.87

16.2
14.1
25.2


1941


1982


1962
1921


1,019


725


1,280M
455


IT


1951 1,393


1,025


700

1,878
1,390
700


1956
1956
1952


Reasrksu

W-M44, L


Cl, 11.14.40
CI, 10.-35

L, V
Cl, 11-21-40
C,. 6-20-41
CI, 10.25-55


w.-60 L, v,
E; Cl,
1-7-60
L4 Dr; Oeala
Group eased
off;: C,

L, Dr;CI,
12-9-0
W-8974, L
W-3869 :, 1 .
W-2410,' '. .





2145-100

102&1456420



8'ii8-220




027-143-1884
1028-137-334



f29-142-240
032-187-410


1954

1917



1936


P _19 __ 8
P 1985 485 -- 3


750

658



642

610


0

0



0

0



0

0
0
0
O


25

23.6



20.8

21.8



34.8

22


27.2
27.8
84.8
21.1
15.0
35.0 P
18.4
35.1
16.2

22.2 P
5.58
18
12.7
22.8
16.4
11


530F


1-11-56
1-18-60
7-24-40
1-1862
5-18-62
6-26-40
5-10-62
6-24-40
1-18-60

7-2440
5-10-62
4-25-62
4-25-60
1-16-40
10-25-55
1-18-60


r02-166-100A P .. 96 96 1% S X D SS 66 1 4- 9-34 0- T0 -
028-156-100B P 1928 201 100 2 0 X D SR 68 2.5 4- 9-34 C 70 -
02.-166-480 P 1900 650 6 0 X J D F 69 0.0 3- 1-51 C -- -- -
148-20 P ....... 500 -_ 3 0 X N D F 20 22.7 5- 9-62 -
126-142 P 1937 680 4 0 X N D F 13.70 41.75P 3-24-39 23 72 01,11-23-40
S18.8 5-10-62 26 CI, 3-8-60
28 CI, 9-19-60
.082150-800 P 500 3 0 X N DS F 20 27.7 1-12-61 31 -
8 8-149-140 M 600-800_ 0 X P F 20 -- --.. C -
088-150-242 P 1938 580 2 0 X D F 18.8 40.2 P 1-18-40 26 ..- 72 C1, 11-22-40
25.2 5-10-62 31


z:

P







,I
W'1
'\C


W-8345

Ci, 11-14-40
CI, 10-12-55


CI, 38-60
CI, 9-19-60 ,
CI, 11-1440
CI, 10-1.2-55
01, 5-18-62
CI, 11-1440


Z-1
/' ,.-*'.




Flowing wild;
CI, 11-14-40 ,








TABB 8. (Continued)






Si


number S I: i
__ 0( a ____


084.-11.438
084-186.288



0365-127.810

685-127.3o0

0835-127.410

08-1855-811
087.126-214








807-180-330
f';^.'


P 192 800 ... 8 0 X
P 192- 480 2 0 X


1982



1932

1953
1989



1927



1940


580

540-40

580

905





578



540


850



850

480
8


504


8

8

3

16
3



2



2


N
N



N

N

N



N



N



N


D
D



R

D

R

I
DR



DRS



D


F
SR



F

F

F

F
F



F



F


,1i



lag
.s8


9.9

14.7

15.4

25
16.9



6.0



12.6


Water level







00ii
sa(^


22.2 P
10.0



41.1 P
19.8
89.7

38.5
21.8


36.8
4.0
2.5
3.77
- 0.67
46.3
4.9
8.8
7.4
4.55
26.7 P
9.3


5- 8-62
5. 8-62



3-23.39
5-10-62
8-22-89

3-23-39
1-25-60


8-25-89
9- 8-55
11- 4-59
1-25-60
5-21-62
3-28-89
9-15-55
11- 5-59
1-25-60
6-21-62
6-26-40
5-10-62


k U


9d




R rIs
0 -s
.g g I
^5 JlItemarka 3J


71.4



72.6







73


865F


72.5 -


71.5


May be Flori-
dan aquifer,
leak in
easin
Cl, 11-28-40
CLI 12-9-40
Cl, 9-555


Cl. 9-7-55 : O

W-2964,'L
CI. 11.28-40



Cl, 11-23-40

C 11-2-40
.112 'i


!!





r u" ,,








087-142-480

088-126-820 *,





088-127-142A
012' i







* 'i .



















038-127-142B
'7/i ,


I1

P

M





I


























I


P

M


1988


11,208


1940 12,130


X

X


C

N

T





T


























N


I

DR

P


34.8

17.8

15





19.1


























19


8.22 P 11- 1-60


19.2 P
- 2.34
40.3 P
20.9


R


























R


1-16-40
5-10-62
1-18-40
5-10-62


28
33
24
81
27


29
80

1,680




















1,180





26
27
29
29


74.5

71.5 --

S 1,284P





S1.900F


1946


1962

1940


1,826


1,100

1,100


3.72





-22.2 P
-24.66


10- 5-61





11-10-59
5-10-62


BC





MC
iLIC


---------------------- --


C1, 9-10-42
Cl, 1-8-62
Cl, 11-23-40

W-4810, L,
Dr; Cl,
8-20-57, : .
CI, 4-1-59
Cl, 10-28-59
W-890, L, A,:,
E, V;
packer teets i
completee'.& '

analmsa,
artesian,
head and
flow mea-
sureuients : .
made at: '
different' ',
depths
while the,
weU was
being
drilled in '
1940. Pack-.,:
er tests and'
current-,
meter tra-
venes made, P 1
In 1945.
Plugged at ,
1,826 ft, CI, '
5-862

Plugged at
1,100 ft
Cl, 11-29-40
Cl, 105-42
Cl, 12-27-60
Cl, 9-662


: ; '


I I I r I n


I


--


. .~..








TABLE 8, (Continued)

Caaini


I -------


Well
number

0818127.380



038-127-.44


038-145-380
D89-127-111


089-127-120



D39-127-321




389-127-844


B I i


I I I I I .1 1 1


P



P


D
I


1PM



I




I


1938


102-
1988
1946

1987


480
1,100
1,700

750


1938 11,072


1946

iagA


1946


1,840

1,073


1.820


2


2
26


8



26




26


x






X
R


R



R




R


DN



D


DS
I


Water levre
0 ;*
2.~






~d'd
__ k -_ a I I
%j 8"

isl S1 i s ^ t
Its1 IS C I II II


0.0 2.67
-- 2.64
5.05
1.46
5.46
13.0 40.9 P
-12.64


15
6.8


15



13.7




18.1


32.4
43.5


84.9



37.4




34.5


11-23-40
9- 8-55
11- 4-50
1-26-60
5-10-62
3-25-39
5-10-62

5- 9-62
3-15-39


11-80-40



3-15-39




3-15-39


30
28
62
38
33P
56

26
33
32
34
33 P


140

33P


168


MC


MC



MC




MC


S ,- I -. I


--75
75 1-


- 1,792F








1,880F


i1


I


Remarks






Cl, 4.T-48
CI, 10-T-48
Cl, 11-10-59


Cl, 2-15-38
CI, 6-31-62;
deepened to 1
1.700 ft ?
W.-84L .
CI, 4-1-59
Cl, 10-28-59 ;,
Cl, 5-31-62 .;
We-10, L,
Dr, Cl M
2-1-88
Cl, 5-7-62;
deepened
Wgl-12. L,
Dr; Cl
6-257 :
01, 541-82;
deepened :





!


g I


- -


I


I I i r







389-128-131 I 1942 1,065 650 26 0 R T I F 11 -OP MC W-690, ;CI,
32 5-80.50
CI, 5C.1-62
)89-128-241 I 1938 1,054 549 30 0 R T I F 8.8 42.6 3-15-39 34P MC 8,158F Wai-9, L, Dr;
CI, 1-19-88
,: 33 CI, 10-12-61
)89.181-281A P 1988 -- 0 X N DR F 9.8 25.4 1-17-40 .. 72-
5.58 9- ?-55
10.4 7-17-61
3.46 5-21-62 33
i8-131-381B P -- 3 3 0 X C DR F 10 5.05 11- 2-59 30
r 6.95 1-25-60 3
0.126382 P 1939 -- 3 0 X N DN F 20.4 29.5 P 3-28-89 33 72 -- CI, 4-T48
-24.58 6-10-62
127-211A 1 93 10 0 X N IN SR 5 -13.00R 3-10-61 MP -- r Pressurere- r
-11.4 5-28-62 colder in-
itaUed
8-9.61
14 27.211EB I 1987 900 680 24 0 R T I F 15 33P MP W 91, L, Dr;
iC, 11-12-56 ,,
46 CI, 5-17-62
40-127-12 I 100 80 6 O R C I SR 6 -10.86 3- 7-61 -- MP -
i0-1273-18 P 1925 -. 3 0 R N N F 6.87 43.0 6-19-39 78 -
.' : -26.61 9-14-55
-16.98 11- 5-59
-18.52 1-25-60
-14.01 7-17-61
-23.67 5-21-62
40-127-482A PM 1,100 -. 8 0 R T P FD 27.9 17 8-28-39 29P MC 72.5 Cl, 18.-24
26 Cl, 10.28-59
4O-127-482B PM 1,025 600 8 0 R T P FD -- 39P MC -._ 9-28-37
S36 C, 5-81-62
40-127-4820 PM 781 -- 8 0 R T P F C
i40-117.-42D PM 1958 1,205 650 12 0 R T P FD 24.9 --. -. .. C .. W-2918, L, Dr
1___------------------------------------0








TABsL 8, (Continued)


t v
fa
IJ


I 1936


I 1959



1959
I 1965

I 1930


040-188410


041-126-888A




041.126-88833B

041-127-142




041-127-322



041-127-430


041-1M7-220


F

0
t


500 --


2,100 1.450



1,961 1,328
1,408 550


753M




1,410


450


510




550


Caming







a


2


80




20

3




4


0




0



0


0


x


R




R

R




R




R


Fl c

o : -

p


I




I

I




IN



I


N


D




FD

F?




F




FD


F


F;

;o
g i
^B


19
19


- -I_______ I I


Water level










23.4 9-14.55
23.3 1-20-00
15.4 5-22-62








41.3 6-21-39
9.36 9-14-55
3.01 11- 5-59
1.24 1-25-60


-11.25R 11-18-60

-22.43 5-21-62




30.9 10- 9-58
26.1 6- 9-62


aa .
C..


20
35
33
80P



97
142P
165


36




36



02
95
20
34
33


I I I I _


- 72


MP --



C



76












75.5


90F


V I

.h a,,,, m


I I


CI, 11-22-40


Oeala Group
cased off;
Cl, 2-1-61;
A (5-ft.
Interval)
CI, 5-17-62
CI, 11-12--0
Cl, 6-17-62
This well may
not be corn-
pleted in
the Flor-
dan aquifer. w:"
CI, 5-2162
Float r-
corder In-
stalled 11-
18-60; E; ;
Cl, 6-21-62
CI, 10-7-61
CI, 2-13-62
Cl, -17-62
'''


1955


r


~---- --'~--''--------- -------------------- ------- ------- ----------


I I I


I


I


I


I I


I


I1C


90F




'.'.." .. 3 0 R N DN F 80.7 -21.54 6-19-44, u... re-
corder in-
stalled 6- :
19-44, re-
moved be-
tween 1953 -
1956
-26.24 1-20-60

41-165421 M 1955 821 448 10 0 R T P F 80 -- -- C W-3586, L;
chemical
analyies-
S*'4-2-59

041-155-424 M 1961 738M 520 16 0 R T P F 80 -.. 350P 10 2 L
l042-125-888 S 1988 800 550 4 0 R N PN F 7.8 48.1 P 8-27-39 82 72 270 W-891, L; Cl,
8.64 5-21-62 40 11-23-40

.042-127-884 S 800 584 4 0 X C PF F 7.5 44.3 8-27-49 28 72 270FM L, Dr; Cl, i
1-25-40
38 01, 5-15-59
82 Cl, ,11-459
84 Cl, 5-21-62

042-127-448 S 1938 800 520 4 0 X C PF F 6 42.7 3-27-39 30 72 245FM L, Dr; CI,
;;.:* 9-8-65- *
238.2 1-16-40 32 Cl, 5.15-59
32 Cl, 11-4-59 ,

(042-154-480 U 1960 700 405 8 0 R T PFA F 52 8.82 10-21-60 32 -- 0?
6.07 7-18-61 g;|
8.06 5.22-62 34

"643-187-441 I -- 3 0 X N D F 14 17.2 5- 8-62 37 -
,044-141-430 S 8 0 X C P F ? 15 32 C --- May not be
completed
in Floridan "
aquifer; Cl,.
4-10-59

044-156-100 P 1940 4,824 4,645 6% R N T FD 99.2 ---- 33,600 C W-336, L.
Analysis of
water sam- ,
pie taken
at 2205-2230
ft below land-
surface
datum. Cl,
8-24-37 co

04-158-800 P 450 8 0 X C D F 60 5.7 5- 9-62 46 -








TABLE 3. Stratigraphic units and aquifer systems in Duval, Nassau, and
and Baker counties.


Lithologic character


Aquifer
systems


Water-bearing properties


Recent and 0-150 Soil, muck, coarse to fine sand, Surficial sand yields small
Pleistocene shell, and some clayey sand amounts of water. Sand and
deposits 0 shell bed along coast yields
moderate quantities.

Pliocene or 20-110 Gray-green calcareous, silty j Limestone, sand, and shell bed
Upper Miocene clay and clayey sand; con- near base of deposits yield
deposits tains shell beds and white moderate to (locally) large
soft, friable limestone beds amounts.


Gray to blue-green calcareous
phosphatic, sandy clays and
clayey sands; contains fine to
medium phosphatic sand len-
ses and limestone and dolo-
mite beds, particularly near
the base of the formation


White to cream chalk, massive
fossiliferous marine lime-
stone.


SWilliston 20-100 Tan to buff granular, marine
Formation limestone
7a
0
Inglis 40-120 Tan to buff granular, calcitic,
Formation marine limestone; contains
thin dolomite lenses and
zones of Miliolidae foramin-
iferal coquina

Avon Park 50-250 Alternating beds of brown to
Limestone tan hard, massive dolomite,
brown finely crystalline dolo-
mite, and granular calcitic
limestone


-Lake City 425-500+ White to brown, purple-tinted
Limestone lignitic, granular limestone
and gray hard, massive dolo-
mite; contains lignite beds
and zones of Valvulinidae
foraminiferal coquina


Cream to brown massive to
chalky, granular limestone
and tan to brown massive
to finely crystalline dolomite


Recent and
Pleistocene



Pliocene?







Miocene


5 Massive dolomite beds restrict
S vertical movement of water.
*'



Limestone and porous dolomite
beds yield large to very large
quantities of water. Hard
dolomite and limestone beds
restrict vertical movement of
water within certain zones.
Potentially the greatest
source of water in the area.


Stratigraphic
unit


Approximate
thickness
(feet)


Hawthorn
Formation


Geologic
age


Relatively impermeable clays
and marls in both the late
Miocene or Pliocene depos-
its and the Hawthorn For-
mation confines the artesian
water in the Eocene lime-
stone and in the limestone
and shell beds above the
Eocene limestone. Yields
small to moderate supplies.


Marine limestone foamrtions
utilized as the primary
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Figure 5. Map showing the altitude of the top of the Crystal River lFormation
and the Avon Park Limestone and tho approximate depth below lanil surface
to the top of the Crystal River Formatiion, Duval and Nassau counties, Fla.


ERNANDINA
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EXPLANATION

. Area of ortesion flow
-50- -
Contour showing the altitude
of the piezometric surface, in
feet. Doshed where Inferred,
Contour interval 5 feet,
e50
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Number is the oltitute
of the piezometric surface
in May, 1962.


I


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C U N T Y


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Figure 12. Map of Duval and Nassau counties showing the piezometric
surface of the Florida aquifer system and the area of artesian flow in
May 1162.


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chloride content of water from artesian wells in 1940.


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EXPLANAT ION
CHLORIDE CONTENT IN
MAY 1962

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::' 20-30
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MORE THAN 40
* 12 Well ond control
number


PPM


FERNANDINA
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i
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C O U N T Y


ST JOHNS


COUNTY


Figure 19. Map of Duval and Nassau counties showing the approximate
chloride content of water froii aresian wells in May 1962.


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Ground water in Duval and Nassau Counties, Florida ( FGS: Report of investigations 43 ) CITATION SEARCH THUMBNAILS PDF VIEWER PAGE IMAGE ZOOMABLE

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STANDARD VIEW MARC VIEW Permanent Link: http://ufdc.ufl.edu/UF00001230/00001  Material Information Title: Ground water in Duval and Nassau Counties, Florida ( FGS: Report of investigations 43 ) Series Title: ( FGS: Report of investigations 43 ) Physical Description: 91 p. : illus. (in pocket) maps (1 col. in pocket) ; 23 cm. Language: English Creator: Leve, Gilbert W ( Gilbert Warren ), 1928- Geological Survey (U.S.) Publisher: s.n. Place of Publication: Tallahassee Publication Date: 1966  Subjects Subjects / Keywords: Groundwater -- Florida -- Duval County   ( lcsh ) Groundwater -- Florida -- Nassau County   ( lcsh ) Water-supply -- Florida -- Duval County   ( lcsh ) Water-supply -- Florida -- Nassau County   ( lcsh ) Genre: non-fiction   ( marcgt )  Notes Statement of Responsibility: by Gilbert W. Leve. Bibliography: Bibliography: p. 71-79. General Note: "Prepared by the United States Geological Survey in cooperation with the Division of Geology, and Duval County, and the City of Jacksonville."  Record Information Source Institution: University of Florida Rights Management: The author dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law and all related or neighboring legal rights he or she had in the work, to the extent allowable by law. Resource Identifier: aleph - 000957325 oclc - 01726783 notis - AES0061 lccn - a 67007462 System ID: UF00001230:00001

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FLRD GEOLOSk ( IC SUfRiW COPYRIGHT NOTICE [year of publication as printed] Florida Geological Survey [source text] The Florida Geological Survey holds all rights to the source text of this electronic resource on behalf of the State of Florida. The Florida Geological Survey shall be considered the copyright holder for the text of this publication. Under the Statutes of the State of Florida (FS 257.05; 257.105, and 377.075), the Florida Geologic Survey (Tallahassee, FL), publisher of the Florida Geologic Survey, as a division of state government, makes its documents public (i.e., published) and extends to the state's official agencies and libraries, including the University of Florida's Smathers Libraries, rights of reproduction. The Florida Geological Survey has made its publications available to the University of Florida, on behalf of the State University System of Florida, for the purpose of digitization and Internet distribution. The Florida Geological Survey reserves all rights to its publications. All uses, excluding those made under "fair use" provisions of U.S. copyright legislation (U.S. Code, Title 17, Section 107), are restricted. Contact the Florida Geological Survey for additional information and permissions. STATE OF FLORIDA STATE BOARD OF CONSERVATION DIVISION OF GEOLOGY FLORIDA GEOLOGICAL SURVEY Robert O. Vernon, Director REPORT OF INVESTIGATIONS NO. 43 GROUND WATER IN DUVAL AND NASSAU COUNTIES, FLORIDA By Gilbert W. Leve, Geologist Prepared by the UNITED STATES GEOLOGICAL SURVEY in cooperation with the DIVISION OF GEOLOGY and DUVAL COUNTY and the CITY OF JACKSONVILLE 1966 FLORIDA STATE BOARD OF CONSERVATION HAYDON BURNS Governor TOM ADAMS EARL FAIRCLOTH Secretary of State Attorney General BROWARD WILLIAMS FRED O. DICKINSON, JR. Treasurer Comptroller FLOYD T. CHRISTIAN DOYLE CONNOR Superintendent of Public Instruction Commissioner of Agriculture W. RANDOLPH HODGES Director LETTER OF TRANSMITTAL ilorida geological Survey 'Callakassee May 19, 1966 Honorable Haydon Burns, Chairman State Board of Conservation Tallahassee, Florida Dear Governor Burns: The Division of Geology, of the State Board of Conservation, will publish as Report of Investigations No. 43, a detailed report on "Ground Water in Duval and Nassau counties, Florida." This report was prepared by Gilbert W. Leve, Geologist with the U. S. Geo- logical Survey, in cooperation with this Division, Duval County, and the City of Jacksonville. It has been discovered that there are at least three aquifers in the area, a shallow ground-water aquifer and two distinctive aquifers in the Floridan aquifer system. Water under high pres- sure, but of less satisfactory quality, is available throughout the area, even though the pressures of the upper artesian aquifer have been reduced as much as 100 feet. About 200 million gallons of water per day is used from these aquifers in the vicinity of Jack- sonville. Some concern was felt that salt-water intrusion had be- :Tun, but the study shows that there is little danger of contamina- ion of these supplies and that Duval and Nassau counties have adequate water for the future, if properly managed and utilized. Respectfully yours, Robert O. Vernon Director and State Geologist Completed manuscript received January 31, 1966 Printed for the Florida Geological Survey By the E. O. Painter Printing Company DeLand, Florida iv CONTENTS Abstract ---------------------- --- ---.. .................... -- ........ 1 Introduction ----------..---............................... ....... ..... 2 Previous investigations ..---------.. -------------------.........-... -....-.. 3 Acknowledgments ---------------. --.......--------------.............. 4 W ell-numbering system ------------- ......... .................................. 5 geographyy -------- ---.-....... ------------............................... 5 Location and area --.-----------.- -... .-...-.................. .. 5 Climate ---.......-.. ..-.................................-------------------- 6 Population and industry ------------...... .........-----------------.....------- 7 Physiography .. ...-----------....-------------------------------------------........ ......--......... 8 Occurrence of aquifer systems ---......... --~~..-----------..... ..... ............ 10 General principles _.... ........... .------------------ --.. ..... ................. 10 Geologic setting ------.-.... -.---------------------------------------------. 11 Oldsmar Limestone .-------------....--..-..........--........... 12 Lake City Limestone -.---.------.. ..--... ---........ ......... 14 Avon Park Limestone ---------...-....... --...................-------- 15 Ocala Group ---------..--------------.. ..............---------------.. 16 Inglis Formation .---......... ------... .--....................- .......16 Williston Formation .- -....------. ----...----........ ---------- ..17 Crystal River Formation --...--..........------ --..... ................ 17 Hawthorn Formation ...--------......--------.---............... ------------------- 18 Upper Miocene or Pliocene deposits --...---..-------..-----.---------..- 18 Pleistocene and Recent deposits _-----..------.-- ----------- 19 Structure -.---------.... .............-------------------.... 19 Shallow aquifer system ....------.----.----. --.... ----------------..... 220 Aquifer characteristics ---.........------... ................------------ 21 Water supplies ------.-------------.......-.--....--- ----------. 23 Floridan aquifer system ..-----........--........ --------------------- ..... .. 24 Permeable zones .....-------.-------..----...--......... -------------- 24 Current-meter studies ---------------------.........------------. 28 Water supplies -----.--..... --.......-.. --------------------.. ... ...........31 Recharge and discharge ...----..... _-- ---------------............-................... 33 Area of flow ---------------------------------------------- _. 37 Water use --...---------------......- ....------..................................---. 38 Public'water use ...--------........ -------..-.--.-------. .. 38 Industrial water use ------------- --------------........... ..- ....... 39 Commercial and private water use ---.-------------------..............-. 39 Decline in artesian pressure ........--- .... .----...----..-- ...... .------------------.. 40 Quality of water ....----------------..... .-- -----------------46........... 46 Quality of water in the shallow aquifer system ----------------. 48 Quality of water in the Floridan aquifer system ..-.....--------.----.--.-- 48 Chloride ---------------...---------------------.-.--.---------............ 55 Dissolved solids --------..--------.-. -------------.........-_.-....... ...........---. --- 55 Hardness ---------------..-------- -.--------......-........- 55 Hydrogen sulfide gas ---.......-- --- --.---- --- ----------.. .... 56 Salt-water contamination ....-----------..-------........ ...--. 56 summary -....--..----.....-------------.......... -..-- ----........ ............ 65 uture studies .........-----......------- ----................. ............... 69 references -------- -_.------------.......-.......-...........- -......... ......... ... 71 ILLUSTRATIONS figuree Page 1 Map of peninsular Florida showing the location of Duval and Nassau counties and illustrations of well-location numbering system ------ -_--.._.____....._ .._..._...... ......_-- ................-------------.. 6 2 Map of Duval and Nassau counties showing the location of wells for which information was obtained -----.....--------....____---____ _- 7 3 Map of Duval and Nassau counties, Fla., showing the Pleistocene marine terraces _____--......In pocket 4 Geologic cross sections showing the formations penetrated by wells in Duval and Nassau counties, Fla. .----_---- -............. ..........-.... 13 5 Map showing the altitude of the top of the Crystal River Forma- tion and the Avon Park Limestone and the approximate depth below land surface to the top of the Crystal River Formation, Duval and Nassau counties, Fla __. -.._ ..-___----------- .... In pocket 6 Graphs showing rainfall at Fernandina Beach and Jacksonville and the water levels in well 040-127-211A, at Fernandina Beach, and 017-136-241B, near Jacksonville ___ _.. 22 7 Hydrographs and geologic data from wells 026-135-342A, B, and C, about 4 miles northeast of Jacksonville ____25 8 Diagrams showing geologic and current-meter data from wells in Duval County ___ 26 9 Diagrams showing geologic and current-meter data from wells in Duval and Nassau counties _. ---------- .............-.._........ ............ 27 10 Map of Florida showing the generalized piezometric surface of the Floridan aquifer _____ _--------------_..-..-_........- ..-. 34 11 Graphs showing relation of water levels in wells 019-140-421 and 033-150-242, to pumping and precipitation, Jacksonville area, Fla. _.... 36 12 Map of Duval and Nassau counties showing piezometric surface of the Floridan aquifer system and the area of artesian flow in May 1962 __ ______________________ In pocket 13 Hydrographs of selected wells in Duval County -----..--------.............. 41 14 Hydrographs of selected wells in Nassau County -- ---...--....... ... -......... 42 15 Map and cross sections of Duval and Nassau counties showing the change in artesian pressure during the periods July 1961 to May 1962 and 1940 to May 1962 ..-- ____ _...___........_-......--... ... 43 16 Graph showing annual discharge of artesian water by municipal wells in Jacksonville and average annual rainfall at three wea- ther stations in the recharge area ___ _........ ______ __ .. 44 17 Graphs showing the artesian pressure in two wells at Fernandina Beach _----___ ___. _.._....... _........... ..-------__--______--...... 45 18 Map of Duval and Nassau counties showing the approximate chloride content of water from artesian wells in 1940 -.-----. In pocket 19 Map of Duval and Nassau counties showing the approximate chloride content of water from artesian wells in May 1962 .-..... In pocket 20 Map showing the chloride content of water from deep wells at Fernandina Beach --..--------_--.....-- _--- __ .____. -.._ 53 21 Graphs of the chloride content of water from selected wells at Fernandina Beach that penetrate formations below the Ocala Group ------- -------------------.. ---_ -- .... 62 32 Graphs of the chloride content of water at different depths in wells in the Floridan aquifer system at Fernandina Beach ---- --64 TABLES Viable Page 1 Population of Jacksonville, Duval County, Fernandina Beach, and Nassau County, 1940-62 _..........____ .... __ __ __ ___....... 9 2 Nonagricultural wages and salaried employment in the Jack- sonville area ---........ -.........--......---....-...... ..- 9 3 Stratigraphic units and aquifer systems in Duval, Nassau, and Baker counties ------------.-------------- --...... -... ............ _.....k.. ..... In pocket 4 Artesian flow and pressure in five Jacksonville municipal wells before and after each well was deepened _-----_._ ---------------. 32 5 Analyses of water from aquifers overlying the Floridan aquifer system in Duval and Nassau counties _---_ -- ---. __ -_ 47 6 Analyses of water from the Floridan aquifer system in Duval, Nassau, and Baker counties -............... _- -.... .... ............ 49 7 Chloride content of water from wells in the Floridan aquifer system in Duval and Nassau counties ---------------------.......... ...... 59 8 Record of wells in Duval and Nassau counties --------_--- --_.. 74 GROUND WATER IN DUVAL AND NASSAU COUNTIES, FLORIDA By Gilbert W. Leve ABSTRACT This report describes an area of about 2,000 square miles in northeast Florida and extreme southeast Georgia. The topog- raphy is controlled by a series of ancient marine terraces, and sur- face drainage is through the St. Johns, Nassau, and St. Marys Rivers and through brackish-water streams that empty either into the intracoastal waterway or directly into the ocean. Practically all the water used in the area is supplied from the rock formations that underlie the surface. These formations, in ascending order, are the Oldsmar Limestone, the Lake City Lime- stone, the Avon Park Limestone, and the Inglis, Williston, and Crystal River Formations of the Ocala Group, all of Eocene Age; the Hawthorn Formation of Middle Miocene Age; deposits of late Miocene or Pliocene Age; and undifferentiated depos- its of Pleistocene and Recent Age. The formations of Eocene Age and the limestone at the base of the Hawthorn Formation compose the Floridan aquifer system. Surficial sand beds and a zone of limestone, shell, and sand at the base of the upper Miocene or Pliocene deposits are the most extensive aquifers in the shallow aquifer system. Increased pumpage from numerous wells in the shallow aqui- fers has caused a steady decline of water levels in these aquifers. However, additional water may be obtained from shallow aquifers by proper well construction and by artificial recharge. The principal source of fresh water in northeast Florida is the Floridan aquifer system. The top of this aquifer is between 300 and 550 feet below sea level and water is confined under artesian pressure in the aquifer by impermeable beds in the Miocene to Recent deposits. At least three permeable zones separated by lard, relatively impermeable zones, occur within the Floridan aquifer system. More water, possibly of less satisfactory quality mut under higher artesian pressure, can usually be obtained from he deeper zones than from the shallower zones in the aquifer. FLORIDA GEOLOGICAL SURVEY Most of the recharge of water to the aquifer is outside of Duvrl and Nassau counties where the overlying confining beds are thini or missing. Discharge is by seepage into the ocean and by number. ous wells throughout Duval and Nassau counties. Between 150 and 200 mgd (million gallons per day) is discharged by wells in the vicinity of Jacksonville, and between 50 and 70 mgd is dis- charged by wells at Fernandina Beach, causing depressions in the piezomentric surface in these areas. The piezometric surface has been depressed from less than 30 feet above sea level to more than 15 feet below sea level, and artesian pressures in wells declined between 50 and 60 feet at Fernandina Beach during the period 1939 to 1963 and between 12 to 22 feet at Jacksonville during the period 1916 to 1963. Water from both the shallow and Floridan aquifer systems is suitable for most uses. The chloride content of water from wells in the Floridan aquifer system ranges from less than 10 ppin (parts per million) to more than 40 ppm in wells less than 1,250 feet deep. and it exceeds 1,100 ppm in wells more than 1,250 feet deep at Fernandina Beach. The chloride content of water from most wells increased only 2 to 14 ppm during the period 1940 to 1962 except in some deep wells at Fernandina Beach, where it increased from 20 to 1,350 ppm during the period 1955 to 1962. At present serious salt-water contamination is limited to a few deep wells at Fernandina Beach, where salt water is migrating laterally from a highly mineralized zone within the fresh-water zone and vertically from highly mineralized zones below the fresh- water zones. Proper well construction and spacing controlled dis- charge. and careful development of the deeper water-bearing zones may retard. and prevent further, salt-water contamination. Future studies will include investigations of the shallow aquifer system, quantitative studies of the Floridan aquifer system, and detailed analysis of the spread of salt-water contamination in northeast Florida. INTRODUCTION Ground water is the principal supply of fresh water in north- east Florida. Practically all water for municipal, industrial, and agricultural use is obtained from wells. In recent years, expanding industry and increasing population in the area have considerably increased the use of ground water. To supply the increased need for water many new wells have been drilled, many existing wells have been deepened, and large-capacity pumps have been installed REPORT OF INVESTIGATIONS NO. 43 o wells that previously produced an adequate supply by natural 11i)W. Correlated with the increase in water use is the continued de- (line in artesian pressures. Records of water levels in northeast Florida show that since 1880 pressures have declined more than (t; feet in some parts of the area. In many parts of Florida and (eorgia, similar declines in artesian pressures have resulted in salt-water intrusion into the fresh-water supply. The constant decline in water pressure and the possibility of salt-water contami- nation of the aquifers pose a threat to the future development of the fresh water in northeast Florida. A shortage of fresh ground water could inhibit the area's economic growth and result in hard- ship for the population. Recognizing the need for a comprehensive appraisal of the ground-water resources of northeast Florida, an investigation was begun in 1959 by the U.S. Geological Survey in cooperation with the Florida Geological Survey. The purpose of this investigation was to provide the basic information necessary for the safe and cllicient development of ground water, one of the most important natural resources of northeast Florida. This report presents and interprets the information concerning the location and availability of ground water collected by the U.S. Geological Survey previous to and during this study. The report is a convenient reference for those persons charged with the re- splonsibility of developing and protecting water supplies and for those who use or control water in significant quantities in Duval and Nassau counties. The investigation was begun under the immediate supervision of M. I. Rorabaugh, the previous District Engineer, Ground Water Branch of the U.S. Geological Survey, and completed under C. S. ('onover, the present District Engineer. PREVIOUS INVESTIGATIONS The occurrence and quantity of ground water in northeast lorida are briefly mentioned in reports by Matson and Sanford 1913) and Sellards and Gunter (1913) as part of generalized in- estigations of ground water in Florida. A report by Stringfield 1936) includes maps of the Florida Peninsula showing the area ,f artesian flow, areas in which the artesian water contains more han 100 ppm of chloride, and the first published map of the piez- ,metric surface of the Floridan aquifer. Reports on ground-water sources in southeastern Georgia by Stewart and Counts (1958) FLORIDA GEOLOGICAL SURVEY and Stewart and Croft (1960) include information on ground- water discharge and maps of the piezometric surface in the Fer- nandina Beach area. Ground-water resources in northeast Florida are described in generalized reports by Stringfield, Warren and Cooper (1941), and by Cooper, Kenner, and Brown (1953). Chemical analyses of water from wells in northeast Florida are included in reports by Collins and Howard (1928), Black and Brown (1951) and the Florida State Board of Health (1960). A report by Black, Brown, and Pearce (1953) includes a brief dis- cussion on the possibility of salt-water intrusion in northeast Flor- ida. The surface-water resources of Baker County are described in a comprehensive report by Pride (1958). Geologic information on northeast Florida is included in re- ports by Cooke (1945), Vernon (1951), and Puri (1957). The reports by Vernon and Puri both contain generalized cross sec- tions that include northeast Florida, and the report by Vernon also contains a generalized subsurface structural map of northern Florida. Stratigraphic and paleontological studies of an oil-test well in Nassau County are described in a report by Cole (1944). Detailed studies of the ground-water resources and geology of northeast Florida were made by Pirnie (1927) and Cooper (1944). Eugene Derragon of the U.S. Geological Survey made a recon- naissance of the area in 1955. Many of the data collected by Cooper and Derragon were used in preparing this report. During this study preliminary reports of the ground-water re- sources of northeast Florida (Leve, 1961a) and the Fernandina Beach area (Leve, 1961b) were prepared to determine the extent of declines of water levels and salt-water intrusion in the area. Most of the data presented in these preliminary reports are in- cluded in this report. ACKNOWLEDGMENTS The author wishes to express his appreciation to Mr. D. M. French, Duval Drilling Co., who supplied drilling information and assisted in sampling and conducting tests on wells; to Mr. T. Oliver, power superintendent, Container Corp. of America; to Mr. H. G. Taylor, chief chemist, Rayonier Inc.; and to Mr. C. Washburn, chief engineer, and Mr. D. C. Hendrickson, associate engineer, Jacksonville Department of Electric and Water Utilities, all of whom provided valuable data and either permitted or assisted in conducting tests, sampling, and measuring of wells. REPORT OF INVESTIGATIONS No. 43 Appreciation is expressed to the many consultants, well drillers .nd members of the Florida State Board of Health who made available many valuable data included in this report. Special thanks are extended also to the many residents in the area who permitted access to their properties. WELL-NUMBERING SYSTEM Wells inventoried during this investigation were each assigned an identifying number. Figure 1 is a diagram illustrating the well- numbering system. As shown in the diagram, the first two seg- ments of the well number identify the 1-minute quadrangle of latitude and longitude in which the well is located. Thus, well 021-139 shown in the figure is located in a quadrangle bounded by latitude 30021'N on the south and longitude 81039'W on the east. The third segment of the well-location number is based upon dividing the 1-minute quadrangles into quarters, sixteenths, and sixty-fourths, which are numbered 1, 2, 3, 4 in the following order: northwest, northeast, southwest, and southeast. The first digit in the third segment of the well number locates the well within the quarter, the second digit locates the well within the quarter- quarter tract, and the third digit locates the quarter-quarter- quarter tract. If a well could not be located accurately within the smallest tract, then a zero is used for the third digit of the third segment of the well number. Similarly, a zero is used for the second and first digits of the third segment if the well could not be located more accurately within the 1-minute quadrangle. With this system, a well referred to by number in the text can be lo- cated on figure 2. GEOGRAPHY LOCATION AND AREA This report describes an area of about 2,000 square miles in he northeastern part of Florida and includes the bordering south- *astern part of Georgia (fig. 1). The area extends from 30o05' ,arallel north latitude northward into southern Georgia and from :2010' meridian of west longitude eastward to the Atlantic Ocean. t includes all of Duval and Nassau counties, eastern Baker, and northernn Clay and St. Johns counties, Florida, and the extreme southern portions of Camden and Charlton counties, Georgia. FLORIDA GEOLOGICAL SURVEY 81040 300 22f 1 2 3 -4 - 2 3 4 3021Wel -139- Well 021-139-443 ______-TF -' 25 0 25 50 75 100 miles Approximate scale Figure 1. Map of peninsular Florida showing the location of Duval and Nassau counties and illustrations of well-location numbering system. CLIMATE The climate of the area is humid subtropical. According to records of the U.S. Weather Bureau, the mean temperature i:D 69"F near the coast and about 68F inland. The lowest mean monthly temperature at Jacksonville is 55.90F, in January; the REPORT OF INVESTIGATIONS No. 43 Figure 2. Map of Duval and Nassau counties showing the location of wells for which information was obtained. highest mean monthly temperature is 82.60F, in July. The aver- ,ge annual precipitation in the area is about 52 inches, of which 0 to 70 percent falls between June 1 and October 31. POPULATION AND INDUSTRY Jacksonville, Jacksonville Beach, and Fernandina Beach are he three largest cities in the area. Most of the population is along he St. Johns River in and near Jacksonville and along the coast a- Duval County. Table 1 shows the population of Jacksonville and FLORIDA GEOLOGICAL SURVEY Duval County and of Fernandina Beach and Nassau County in 1940, 1950, 1960, and 1962 based on records of the U.S. Census Bureau. The table also shows the percentage increase in popular. tion between 1940 and 1962. The economy of Fernandina Beach and Nassau County is based upon the production of wood pulp and paper. Two large processing plants, Rayonier Inc. and Container Corp. of America, are located in Fernandina Beach, and their expansion has been a major rea- son for the population increase in Nassau County. Greater Jacksonville in Duval County is one of the major metro- politan areas in the southeastern United States. A natural harbor near the mouth of the St. Johns River and a vast network of transportation facilities make Jacksonville the distribution center for northern Florida and southeastern Georgia. A wide range of products are manufactured and processed in Jacksonville. Some of the major industries are paper manufacturing, shipbuilding and repair, processing and packaging of food products, manufacturing of cigars, chemicals and paint, building products, truck bodies, steel castings, and furniture. In addition, there are 18 home and regional offices of insurance companies and 3 major naval facili- ties in the area. An index of industrial growth of the Jacksonville area is the total nonagricultural wages and employment of salaried workers in the area as determined by the Bureau of Labor Statistics, U.S. Department of Labor. These figures are given in table 2 for every 2 years since 1950. PHYSIOGRAPHY The topography of northeast Florida is controlled by a series of ancient marine terraces (Cooke, 1945) which were formed -t times in the Pleistocene when the sea was relatively stationary at various higher levels than the present sea level. When the sea dropped to a lower level, the sea floor emerged as a level plain cr terrace and the landward edge of each terrace became an abandol- ed shoreline, which is generally marked by a low scarp. Seven terraces are recognized in northeast Florida; in descen.- ing level they are the Coharie, Sunderland, Wicomico, Penholoway, Talbot, Pamlico and Silver Bluff terraces. The original shorelines and the level plains of the terraces have been modified and des- troyed by stream erosion and only remnants of the original ter- races can be seen. The general configuration of these terrace. shown on figure 3 was mapped from topographic maps primarily . REPORT OF INVESTIGATIONS No. 43 9 ' WBLE 1. Population of Jacksonville, Duval County, Fernandina Beach, and Nassau County, 1940-62 Population unit .IJcksonville I)Ival County Flrniandina Bench NnIsau County 1940 178,065 210,143 3,492 10,826 204,517 304,029 4,074 12,811 1060 201,030 455,411 7.276 17,180 Percent increase 1962 1040-62 482,600 130 18,300 60 by their elevation above present msl (mean sea level) and from aerial photographs. The highest and oldest terraces, the Coharie, Sunderland and Wicomico, are in the western part of the area. They form an up- land that ranges in elevation from 70 to more than 200 feet above msl. The highest and most prominent surface feature is a high sandy ridge, called "Trail Ridge," that extends northward through eastern Baker County into Georgia. The ridge, a remnant of the Coharie terrace, ranges in altitude from 170 to more than 200 feet. The Sunderland terrace in eastern Baker County and extreme south- western Duval County is poorly developed and is modified by ero- sion. Remnants of this terrace consist of rolling, eroded hills that range in altitude from 100 to 170 feet. The most extensive occur- rence of the uplands in the western part of the area consists of an irregular flat plain from 70 to 100 feet above msl which is the 'I'BLE 2. Nonagricultural wages and salaried area. employment in the Jacksonville Total salaried workers employed in nonagricultural work 118,600 110,800 116,400 127,800 134,000 144,103 148,100 Percent increase 1 1950-1062 60.2 Year 1950 1952 1954 1956 1958 1960 1962 __ __ I__ _ILI_ --- - '-------- -- FLORIDA GEOLOGICAL SURVEY remnant of the Wicomico terrace. The outer boundary of this ter- race extends northwestward through south-central Duval County and western Nassau County into Georgia. The Penholoway and Talbot terraces in the area are not clearly defined in northeast Florida because they have been severely modi- fied by the numerous streams that drain the higher and older ter- races. Scattered remnants of these terraces occur in a belt that extends through central Nassau County, north-central Duval Coun- ty and southeastern Duval County east of the St. Johns River. They form a coastal ridge at altitudes from about 25 to 70 feet which is particularly well defined east of the St. Johns River in southeastern Duval County. Ancient dunes on the coastal ridge form a series of narrow sandy ridges and low intervening swampy areas which are elongate parallel to the coastline. The Pamlico and Silver Bluff terraces form a low coastal plain throughout most of the central and eastern part of northeast Flor- ida. The altitude of the plain ranges from slightly above sea level to 25 feet; however, some dunes along the present coastline are more than 50 feet above msl. In Nassau County and in northern Duval County, the plain slopes irregularly eastward toward the ocean. In central and southern Duval County, the plain slopes toward the St. Johns River west of the coastal ridge and toward the ocean east of the ridge. Adjacent and parallel to the present coastline, remnants of the Pamlico terrace form a series of offshore bars or islands. These bars range in width from less than a few hundred feet to about 2 miles and are separated from the mainland by a series of tidal lagoons and streams. Many of these tidal streams comprise the Intracoastal Waterway. Surface drainage in the western and central parts of the area is through the St. Johns, Nassau, and St. Marys rivers and their tributaries. East of the coastal ridge, drainage is primarily by numerous small brackish-water streams that empty either into the channel of the Intracoastal Waterway or directly into the ocean. Much of the relatively flat Pamlico, Silver Bluff, and Wicomico terraces is marshland because drainage is poor. OCCURRENCE OF AQUIFER SYSTEMS GENERAL PRINCIPLES Rainfall on the land surface may be returned directly to the atmosphere by transpiration and evaporation, drained off into sur- face bodies of water, or absorbed by the soil and rocks. Some (f REPORT OF INVESTIGATIONS No. 43 the water that is drained into lakes and streams or is absorbed lb the soil and rocks eventually moves downward through the ground to the zone in which the interstices of the rocks are com- pletely saturated with water, where it becomes a part of the ground-water body. Ground water moves laterally from zones of higher hydrostatic head, such as recharge areas where the water is replenished, to areas of lower hydrostatic head, such as dis- charging wells and springs. Ground water occurs under either nonartesian or artesian con- ditions. Nonartesian water is unconfined, so that its upper surface is free to rise and fall; artesian water is confined under pressure, so that its upper surface is not free to rise and fall. The height to which artesian water will rise above its confined surface in a tightly cased well is called the artesian pressure head. The imagi- nary surface coinciding with the altitude of such artesian pressure heads in wells is called the piezometric surface. Ground water occurs in rocks in the zone of saturation; how- ever, only aquifers transmit usable quantities of water to wells. An aquifer may be a formation, group of formations, or part of a formation that is porous and relatively permeable. Relatively im- permeable rocks that restrict the movement of water are called aquicludes. Thin, discontinuous, relatively impermeable zones that locally separate permeable zones are called confining beds. A ser- ies of similar aquifers or permeable zones together with associated confining beds and aquicludes constitute an aquifer system. In northeast Florida, ground water occurs in two separate aqui- fer systems: the shallow aquifer system and the Floridan aquifer system. Although both aquifer systems were studies during this investigation, the Floridan aquifer system is described in greater Detail in this report because it is the principal source of ground v'ater in the area. GEOLOGIC SETTING' Fresh-water supplies in Duval and Nassau counties are obtained itirely from wells drilled into the rock formations that compose 1 e aquifer systems. Therefore, an essential part of this study 'The stratigraphic nomenclature used in this report conforms to the usage 1 Cooke (1945) with revisions by Vernon (1951) except that the Ocala Smestone is referred to as the Ocala Group. The Ocala Group, and its divisions as described by Puri (1953), has been adopted by the Florida logical Survey. The Federal Geological Survey regards the Ocala as a Srmation, the Ocala Limestone. FLORIDA GEOLOGICAL SURVEY was to differentiate the formations and to determine their water- bearing properties. This was done by collecting rock cutting from a number of water wells drilled in the area and examining these cuttings to determine the texture, mineral composition, and fauna of the different formations. Additional geologic information was obtained from drillers' logs, and from lithologic and electric logs on file with the Florida Geological Survey. Current-meter tra- verses were made in a number of wells to locate the water-bearing zones and to determine the relative yield of water from the differ- ent formations. The rock formations that are tapped by water wells in the area include, in ascending order, the Oldsmar Limestone, the Lake City Limestone, the Avon Park Limestone, and the Inglis, Williston, and Crystal River Formations of the Ocala Group-all of Eocene age; the Hawthorn Formation, of middle Miocene age; deposits of late Miocene or Pliocene age; and, exposed at the surface, un- differentiated deposits of Pleistocene and Recent age. These rocks are listed in table 3 and their lithologic character and water- bearing properties are described briefly. Rock formations older than the Oldsmar Limestone have not been tapped by water wells in northeast Florida because sufficient water can be obtained from the overlying formations and the wa- ter from the deeper rocks is more highly mineralized. One deep oil-test well in northwestern Nassau County penetrated rocks deeper than the Oldsmar Limestone. In this well, marine dolomite and limestone beds of Eocene age are 2,235 feet thick and extend to a depth of 2,640 feet below msl. A sample of water collected between the depths of 2,100 and 2,130 feet below msl and analyzed for mineral content was found to contain 33,600 ppm of chloride which is about 11/ times the chloride content of sea water. The following discussion of the formations include only rocks penetrated by water wells in Duval and Nassau counties. The cross sections in figure 4 show these geologic formations. OLDSMAR LIMESTONE The Oldsmar Limestone of early Eocene age (Applin an. Applin, 1944, p. 1699) is the deepest and oldest formation utilize as a source of water in northeast Florida. The only well in the area that completely penetrates the Oldsmar Limestone is a deep oil-test well, 044-156-110, in north- western Nassau County (Cole, 1944). The top of the Oldsmar REPORT OF INVESTIGATIONS NO. 43 RECENT 200 A SEA tEZO- 400 600- BOO - 1000 - 1200- I . a teac s T DEPOSITS N ^L RIVER FM %t LIISTON FM. . AVON PARK LIMESTONE LAKE CITY LIMESTONE 0 5 tOmltl 4 ,ure 4. Geologic cross sections showing the formations in Duval and Nassau counties, Fla. S -200 A' SEA LEVEL -200 -<00 600 -800 -1000 -1200 penetrated by wells 'mestone is about 1,270 feet below msl in this well and the Srmation is 846 feet thick. Well 038-127-324, in Fernandina i 'ach (fig. 4), reached the top of the Oldsmar Limestone at 1,746 1 et below msl and penetrated more than 340 feet of the formation v 'thout reaching older formations. CRYSTAL RIVER SINGLIS AVON PA-RK --- LAKE CITY R MATIO UD DEPosns UPPER MIOCENE CR HAWTHORN FORMATION FORMATION LIMESTONE ----~ -- F 0 FLORIDA GEOLOGICAL SURVEY In wells in northeast Florida, the Oldsmar Limestone consists of a cream to brown, soft, massive to chalky granular limestone, and cherty, glauconitic, massive to finely crystalline, sugar- textured dolomite. The formation is lithologically similar to the overlying Lake City Limestone and is differentiated from the Lake City by its fossil content. The top of the Oldsmar Limestone is picked by the first occurrence of the foraminifer species Helicostegina gyralis Barker and Grimsdale. LAKE CITY LIMESTONE Lake City Limestone is the name applied by Applin and Applin (1944) to limestone of early middle Eocene age that conformably overlies the Oldsmar Limestone in peninsular Florida. Depths to the top of the Lake City Limestone in northeast Florida range from about 580 feet below msl in south-central Duval County to about 1,260 feet below msl at Fernandina Beach. Only a few wells in northeast Florida completely penetrate the Lake City Limestone. The Lake City is 486 feet thick in a well (044-156- 110) in northwestern Nassau County and 475 feet thick in a well (038-127-324) at Fernandina Beach. A well in southwestern Duval County (014-153-420) penetrates more than 490 feet of Lake City Limestone without reaching older formations. Lithologically, the Lake City Limestone consists of alternating beds of white to brown, purple tinted lignitic, chalky to granular limestone and gray to tan massive to finely crystalline, sugar- textured dolomite. It contains beds consisting entirely of cone- shaped (Valvulinidae) foraminifers and locally contains thin beds of lignite. The Lake City Limestone contains abundant fossil foraminifei s that are different from those in the underlying Oldsmar Limestore and overlying Avon Park Limestone. The most distinctive fossil of the Lake City Limestone is Dictyoconus americanus which w s selected by Applin and Applin (1944) as a guide fossil for the formation. The fossils most often found in well cuttings from th3 Lake City Limestone include Dictyoconus americanus (Cushman), Fabularia vaughani Cole and Ponton, Discorbis inornatus Col,' Fabiania cubensis Cushman and Bermudes, Archaias columbiensH Applin and Jordan. REPORT OF INVESTIGATIONS NO. 43 AVON PARK LIMESTONE Deposits of late middle Eocene age penetrated by wells in Polk countyy were named Avon Park Limestone by Applin and Applin (1944). Outcrops of the formation in Citrus and Levy counties were later recognized and described in detail by Vernon (1951, p. 95). The Avon Park Limestone ranges in thickness from 150 feet to more than 700 feet in central and southern Florida; however, it has been considerably thinned by erosion in northeast Florida. The geologic cross sections in figure 4 show that the formation averages only about 50 feet in thickness throughout the western and central parts of northeast Florida. It thickens toward the coast and is about 190 feet thick in a well (019-124-210) at Atlantic Beach and more than 250 feet thick in a well (038-127-324) at Fernandina Beach. The Avon Park Limestone unconformably overlies the Lake City Limestone and unconformably underlies the Ocala Group. Contours constructed on the irregular upper surface of the Avon Park Limestone in northeast Florida are shown on figure 5. As shown, the top of the formation is less than 500 feet below msl in south-central Duval County and more than 950 feet below msl in northeastern Nassau County. The lithology of the Avon Park Limestone varies both laterally and vertically throughout northeast Florida. In the western and central parts of the area where the formation has been consider- ably thinned by erosion, it consists predominantly of tan to brown, hard, massive dolomite beds containing thin zones of tan granular, fossiliferous limestone. In the eastern part of the area where the Information is thickest, it consists of alternating beds of tan hard, massive dolomite; brown to cream granular, calcitic limestone; and irown, finely crystalline, sugar-textured dolomite. The top of the formation usually can be detected during the STilling of wells because the hard dolomite beds in the upper part f the formation retard the drilling rate. In addition, the Avon ark Limestone can be identified and differentiated from the other -rmations of Eocene age by its fossil content. The following !agnostic foraminifers were identified in the Avon Park limestone from well cuttings in the area:Coskinolina, floridana ole, Dictyoconus cookei (Mobert), Dictyoconus gunteri Cole, ituonella floridana Cole, Spirolina coryensis Cole. FLORIDA GEOLOGICAL SURVEY OCALA GROUP Cooke (1915, p. 117; 1945, p. 53) defined all deposits of late Eocene age in Florida as one formation; the Ocala Limestone. These deposits were later redefined by Vernon (1951, p. 111-171) as two formations; the Moodys Branch Formation and the Ocala Limestone. More recently Puri (1953, p. 130; 1957, p. 22-24) divided the late Eocene limestone into three separate formations. These are, in ascending order, the Inglis, the Williston, and the Crystal River Formations. These three formations are now referred to collectively as the Ocala Group by the Florida Geological Survey. All three formations of the Ocala Group are fragmental marine limestones and were differentiated in cuttings from wells in northeast Florida by slight changes in lithology and on the basis of fossil content. However, in some wells from which cuttings were collected and examined, it was not possible to differentiate each of these formations because of lithological similarities and the absence of diagnostic fossils in the cuttings. INGLIS FORMATION The Inglis Formation lies unconformably on the Avon Park Limestone and ranges in thickness from about 40 feet to about 120 feet in northeast Florida. As shown on the geologic cross section in figure 4, it is thickest west of the St. Johns River in western and central Duval County. Lithologically, the Inglis Formation is a tan to buff granular, calcitic, marine limestone. It contains beds consisting entirely of a coquina of Miliolidae foraminifers. These coquina beds are loosely cemented and porous and have a mealy texture. Thin, discontinuous zones of gray to brown, hard, crystalline dolomite are prevalent near the base of the formation. The lithologies of the Inglis and the overlying Williston Formations are similar and in many sets of cuttings from wells in the area the upper contact of the Inglis is not clearly defined. However, in most cases it was possible to differentiate the forma- tions on the basis of changes in fossil content. The following diagnostic fossils were used as guide fossils (Puri, 1957, p. 48) t) identify the Inglis Formation in cuttings from wells in the area: Fabiana cubensis Cushman and Bermudez, Periarchus lyelli (Con- rad), Spirolocidina seminolensis Applin and Jordan, Spirolinu coryensis Cole. REPORT OF INVESTIGATIONS NO. 43 WILLISTON FORMATION The Williston Formation lies conformably between the under- lying Inglis and the overlying Crystal River Formations. It ranges in thickness from about 20 feet to 100 feet and has an average thickness of about 50 feet throughout northeast Florida. The lithology of the Williston Formation is similar to that of the underlying Inglis Formation, consisting of a tan to buff granular, marine limestone. However, the Williston is generally more indurated and does not contain the mealy-textured coquina beds that are found in the Inglis Formation. The Williston Formation can further be differentiated from the other formations in the Ocala Group by a distinct fossil assemblage. The following fossils were identified in well cuttings: Amphistegina pinarensis cosdeni Applin and Jordan, Operculi- itoides moodybcranchensis (Gravell and Hanna), Operculinoides willcoxi (Heilprin), Operculinoides jacksonensis (Gravell and Hanna), Nummulites vanderstoki Rutten and Vermunt, Heteroste- gina ocalana Cushman. Several of these species of fossils occur in the other formations of the Ocala Group but not as frequently nor in as great numbers as in the Williston Formation. The top of the formation was determined by the first appearance in well cuttings of Amphistegina pinarensis cosdeni, which is the most diagnostic fossil of the Williston Formation in northeast Florida. CRYSTAL RIVER FORMATION The Crystal River Formation is the youngest Eocene forma- lion generally penetrated by wells in northeast Florida. It conformably overlies the Williston Formation and unconformably underlies the Hawthorn Formation of middle Miocene age. The sickness of the formation varies considerably throughout the rea and, as shown by the geologic cross sections in figure 4, anges from less than 100 feet in central and western Duval county to 300 feet in well 038-127-324 at Fernandina Beach. Lithologically, the Crystal River Formation is a white to cream, halky massive fossiliferous, marine limestone. It is lighter in olor, less granular, and more friable than the underlying Williston 'ormation, and contains abundant Molluscan shells and relatively irge foraminifers that are not common in the underlying forma- ions of the Ocala Group. The fossils identified in well cuttings rom the Crystal River Formation include: Lepidocyclina ocalana FLORIDA GEOLOGICAL SURVEY Cushman, Lepidocyclina ocalana pseudomarginata Cushman, Oper- c~ulinoides ocalana Cushman, Operculinoides floridensis (Heilprin), Sphaerogypsina globula (Ruess), Nummulites vanderstoki Rutten and Vermunt, Heterostegina ocalana Cushman. HAWTHORN FORMATION Rocks of middle Miocene age in peninsular Florida were first named the Hawthorn Formation by Dall and Harris (1892, p. 107). The Hawthorn Formation lies unconformably on the eroded surface of the Ocala Group throughout all of northeast Florida. As shown in the geologic cross sections in figure 4, the thick- ness of the Hawthorn Formation ranges from about 250 feet in southern Duval County to about 500 feet in north-central Duval and central Nassau counties. Locally, the formation may vary in thickness by as much as 50 feet where it fills depressions in the irregular surface of the Crystal River Formation. The Hawthorn Formation consists of gray to blue-green calcareous, phosphatic sandy clays and clayey sands, interbedded with thin, discontinuous lenses of fine to medium phosphatic sand, phosphatic sandy limestone, and gray hard dolomite. The limestone and dolomite lenses are thicker and more prevalent near the base of the formation than in the higher parts. They occasionally contain some poorly preserved mollusk casts and molds. The only other fossils in the formation are sharks' teeth, which are most often found in the clay beds. UPPER MIOCENE OR PLIOCENE DEPOSITS Deposits overlying the Hawthorn Formation in peninsular Florida were described by Cooke and Mossom (1929, p. 152) andi Cooke (1945) as being Pliocene in age. They have been more recently described by Vernon (1951, figs. 13,33) as late Miocene in age. Because their age has not been determined exactly, they are referred to in this report as Pliocene or upper Miocene deposits. Pliocene and upper Miocene deposits are the oldest rocks ex- posed at the surface in northeast Florida. They are exposed in roa( cuts, excavations, and the banks and beds of many streams in the area. As shown in the geologic cross sections (fig. 4), these deposits are about 100 feet thick adjacent to the St. Johns River in centra Duval County and in central and eastern Nassau County, and les: than 20 feet thick in western Duval and eastern Baker counties. REPORT OF INVESTIGATIONS No. 43 The Pliocene or upper Miocene deposits consist of interbedded ay-green calcareous silty clay and clayey sand; fine-to medium- grained, well-sorted sand; shell; and cream to brown soft, friable limestone. They differ from the underlying Hawthorn Formation in that they contain little or no phosphate. The limestone is most prevalent at the base of the deposits and together with sand and shell form a laterally extensive, continuous, relatively permeable zone which locally is as much as 40 feet thick. The contact between the Pliocene or upper Miocene deposits and the Hawthorn Formation is an unconformity generally marked by a course phosphatic sand and gravel bed. However, the contact between the Pliocene or upper Miocene deposits and the overlying Pleistocene and Recent deposits is not clearly defined. In some wells, particularly in the eastern and northern parts of the area, the contact appears to be gradational. PLEISTOCENE AND RECENT DEPOSITS Undifferentiated sediments of Pleistocene and Recent age blanket most of northeast Florida, except where they have been completely eroded by streams. As shown in the geologic cross sections (fig. 4), the deposits are more than 150 feet thick in eastern Baker County and average about 20 feet in thickness in central and eastern Duval and Nassau counties. The Pleistocene and Recent deposits in the western part of the area consist primarily of fine- to medium-grained, poorly sorted sand and clayey sand, locally stained yellow or orange by iron oxide. In the central and eastern parts of the area, the deposits are predominantly loose sand and gray to green clayey sand, containing some shell beds near the coast. STRUCTURE The structural contour lines in figure 5 reflect the eroded surface of the Avon Park Limestone and Crystal River Formation. At the contour interval shown in the figure, the small irregularities n the surface of the formations are not apparent and the configur- tion of the lines reflects the approximate subsurface structure *f the formations. As shown, the surface of the Avon Park .imestone strikes approximately northwest-southeast and dips northeast at about 9 feet per mile in the western part of the area, nd strikes northeast-southwest and irregularly dips northwest bout 16 to 20 feet per mile in the eastern part. FLORIDA GEOLOGICAL SURVEY Although the surface of the Crystal River Formation has been modified by erosion more than the surface of the Avon Park Limestone, the contour lines on the top of the Crystal River Formation in figure 5 generally reflect the configuration of the underlying Avon Park Limestone. The top of the Crystal River Formation ranges from less than 300 feet below msl in southern most Duval County to more than 550 feet below msl in north- central Duval County. The Crystal River Formation is the initial limestone of Eocene age penetrated by wells in the area, and in most areas it is also the top of the Floridan aquifer system. There- fore, these contour lines also show the top of the Floridan aquifer system in Duval and Nassau counties. The limestone formations of Eocene age in the western part of the area, sloping northeastward, and in the eastern part of the area. sloping northwestward, form an irregular trough or basin extending from south-central Duval County northeastward into northeastern Nassau County. A fault extends generally along the axis of this basin, the upthrown side to the west. In southern Duval County, the vertical displacement of the top of both the Ocala Group and the Avon Park Limestone by the fault is about 125 feet. The vertical displacement decreasess northward and the fault probably does not extend farther north than northern Duval County. The irregularities in the surface of the Eocene limestone formations were filled and blanketed by the thick series of post- Eocene sediments (fig. 4), and there is no surface reflection of the subsurface structural features in the area. SHALLOW AQUIFER SYSTEM The shallow aquifer system consists of the limestone and sand aquifers in the clayey sand and sandy clay confining beds in the upper part of the Hawthorn Formation, the shell, limestone, and sand aquifers in the Pliocene or upper Miocene deposits and the sand and shell aquifers in the Pleistocene and Recent deposits (table 3). The lithology of these deposits changes laterally as well as ver- tically and the aquifers and confining beds are discontinuous. Ir some part of northeast Florida, particularly in western Duval. Nassau, and eastern Baker counties, the shallow aquifer system may consist of a single, relatively thick aquifer extending down ward from the water table to the aquiclude in the Hawthorl REPORT OF INVESTIGATIONS NO. 43 F formation. In other parts of the area, particularly in central and e stern Duval and Nassau counties, the shallow aquifer system may consist of a series of relatively thin permeable zones separated ,locally by a number of relatively thin confining beds. The most laterally extensive aquifer in the shallow aquifer system occurs as either a limestone, a shell, or a sand bed near the base of the Pliocene or upper Miocene deposits. It is about 10 to 40 feet thick and is 50 to 150 feet below the surface throughout most of Duval and Nassau counties. AQUIFER CHARACTERISTICS Although ground water in the shallow aquifer system is generally under nonartesian conditions, some shallow wells located in low areas immediately adjacent to the St. Johns River and its tributaries yield artesian water. These local artesian conditions are caused by confining beds that confine water under pressure in an underlying aquifer, particularly in shell and limestone beds near the base of the Pliocene or upper Miocene deposits. The shallow aquifer system is recharged chiefly by local rainfall. Discharge from this system occurs by evaporation, transpiration by plants, seepage into surface bodies of water, leakage downward into the underlying rocks, and discharging wells. The fluctuations and seasonal trends of water levels in wells in the shallow aquifer system indicate the gain and loss of water to and from the system. The hydrographs in figure 6 show the fluctuations and seasonal trends of water levels in two wells in the shallow aquifer system in northeast Florida. Part A of the figure shows a hydrograph of the semi-daily water levels in well 040-127- 211A, at Fernandina Beach, and a bar graph of the daily rainfall ait Fernandina Beach in April 1961. The graphs show the effect 4o local rainfall on the water level in the well. For example, the :ise in water of more than 1 foot on April 15 reflects recharge o the aquifer from a rain of 2.70 inches the same day. The overall decline in the.water level between April 20 and 30 reflects depletion f water in the aquifer system by the pumping from other shallow ellss in the area and by the lack of rainfall after April 16. Part B of figure 6 shows a hydrograph of the water levels in ,-ell 017-136-241B and a bar graph of the monthly rainfall at acksonville between February 1961 and December 1962. As iown graphically, the water level in the well generally declined FLORIDA GEOLOGICAL SURVEY Daily rainfall ot Fernondino Beach r - I '5 6 7 8 9 10 2I I1 145 117 18 19 2 21 22 2324 25 26 2 28 29 APRIL 1961 SWELL 017-136-241B, Imile easl S i ol Jacksonville (Shallow a Ouler) -S I __ Monthly ralnfo ll ot Joclksonville -E MAWR APR MAY JUNE JULY AUG SEPT OCT NOV EEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC 1961 1962 Figure 6. Graphs showing rainfall at Fernandina Beach and Jacksonville and the water levels in well 040-127-211A at Fernandina Beach and welP 017-136-241B near Jacksonville. even during periods when the rainfall increased. For example rainfall during June and July 1962 was almost 7 inches greater than during the same period in 1961; however, the water level, in the well were about 2 feet lower in June and July 1962 thar during the same period in 1961. The decline in water level was irregular and generally months of greater rainfall resulted ir. REPORT OF INVESTIGATIONS NO. 43 slightly higher water levels. This general decline in water levels w-as partly a result of a deficiency in total rainfall during 1961 ltnd 1962 compared to rainfall in 1960. However, as indicated by (he lower water levels during periods of increased rainfall, the decline was caused partly also by increased pumping from more shallow wells in the area. WATER SUPPLIES Water in the shallow aquifer system is generally obtained from two separate aquifers: (1) from surficial sand beds and (2) from a limestone, sand, and shell zone near the base of the Pliocene or upper Miocene deposits. Some water for lawn irrigation, stock and domestic use is obtained from the surficial sand deposits by using "surface" sandpoint wells constructed of galvanized casing from 1/2 to 2 inches in diameter. The casing is either driven or jetted 10 to 30 feet below the surface to put the well screen below the water table. The yields of the surface wells differ in different parts of the area, primarily because of lateral changes in the water-transmitting character of the aquifer. In most of northeast Florida, typical surface wells 11/4 inches in diameter yield between 10 and 15 gpm (gallons per minute). However, some wells in relatively thick and permeable beach sands along the coast yield as much as 25 gpm. Most of the water from the shallow aquifer system is obtained near the base of the Pliocene or upper Miocene deposits. Water is obtained from this aquifer by "rock" wells, generally 2 inches in diameter and 50 to 150 feet deep. The casing is either driven or jetted to the top of the aquifer and the bottom of the casing is left open. An open hole is then drilled into the aquifer below the casing and water enters the well throughout the entire length of the open hole. Typical 2-inch "rock" wells throughout most of northeast Florida yield 15 to 20 gpm. Locally, where the aquifer !s relatively thick and composed of permeable limestone or shell, : 2-inch well may yield as much as 80 gpm. A few 4-inch rock wells n Jacksonville and a few 5-inch wells in Fernandina Beach yield )0 to 80 gpm. Water from the surficial sands generally contains iron (Fe), vhich gives it a pronounced taste and stains plumbing fixtures. surfacee wells .near brackish water are in danger of contamination 'y lateral encroachment of such water. Water from the "rock" vells is generally of good quality and suitable for most domestic, crigation," and industrial uses. FLORIDA GEOLOGICAL SURVEY The shallow aquifer system presently supplies only small to moderate amounts of water to small-diameter wells. However, properly constructed large-diameter gravel-packed wells in the shallow sand aquifers may be capable of supplying large amounts of water. The shallow aquifer in northeast Florida could become an important source of water to supplement the supplies that are presently obtained from the Floridan aquifer system. Although the areal extent of the relatively thick aquifer at the base of the upper Miocene or Pliocene deposits was not determined by this study, it appears to underlie most of the area. It is possible that this shallow aquifer could be artificially recharged locally with surface water. When the aquifer is not completely saturated, rainfall stored in shallow surface reservoirs could percolate down- ward into the aquifer to replace the water discharged from shallow wells. FLORIDAN AQUIFER SYSTEM The Floridan aquifer system is the principal source of fresh water in northeast Florida; therefore, most of the information collected and studied during this investigation was concerned with this aquifer system. It includes part or all of the Oldsmar, Lake City, and Avon Park Limestones, the Ocala Group, and a few discontinuous, thin aquifers in the Hawthorn Formation that are hydraulically connected to the rest of the aquifer system. The Floridan aquifer system is separated from the shallow aquifer system by the extensive aquiclude in the Hawthorn Formation and in the Pliocene or upper Miocene deposits. Water in the Floridan aquifer system is artesian. PERMEABLE ZONES The water-bearing zones within the Floridan aquifer system consist of soft, porous limestone and porous dolomite beds. Thte hard, massive dolomite and limestone are relatively impermeable and act as confining beds that restrict the vertical movement o'! water. Where the confining beds are continuous for a considerable( distance, they isolate these water-bearing zones. The Ocala Group is one homogeneous sequence of permeable hydraulically connected marine limestone beds that contain fev hard dolomite or limestone beds to restrict vertical movement of' water. The Avon Park Limestone consists almost entirely o2 REPORT OF INVESTIGATIONS NO. 43 h,rd, relatively impermeable dolomite beds that restrict the vertical movement of water between the overlying and underlying permeable zones. The Lake City and Oldsmar Limestones each contain alternating hard, relatively impermeable dolomite confin- ing beds and soft, permeable limestone and dolomite water-bearing zones. The separation of the permeable zones in the Floridan aquifer system in the vicinity of Jacksonville is indicated by the difference in artesian pressure at different depths in the aquifer system. Figure 7 shows hydrographs of three wells located within 40 feet of each other and drilled and cased to different depths within the Floridan aquifer system. The lowest artesian pressures were recorded in well 026-135-342C which is open to the top 250 feet of the Ocala Group. The highest artesian pressures were recorded in well 026-135-342B which is open to about 175 feet of the Avon Park and the Lake City Limestones. The water pressure in this well was between 0.5 and 1.5 feet higher than that in well 026-135- 342C between January 1960 and February 1963. This difference in pressure suggests that the zones supplying water to these wells are isolated from each other. Well 026-135-342A, drilled to 1,390 feet and cased to 584 feet below the surface, is open to permeable zones in both the Ocala Group and the Lake City Limestone. The artesian pressure 4811i IT I rr ri I I I I I i I i I I i I I I I I I II I I [-1 s, tha n 40 fl- leel B I M- 026-135-342B \AV / I A. !. v A 400- 4 -oductnd tore .......... j- -Cohl,.ng bed 200 f I 1600 0 0 i 200 0= 400 / Fow,m gallons p m 1 2 // 26-135-342A FLow DISIRIUTloN CL 026-135-342C\ J F MAM J J AS ON DJ FMAMJ J AS OND JF M A MJ J AS ON J FMAMJ 1960 1961 1962 1963 figure 7. Iydrographs and geologic data from wells 026-135-342 A, B, and C, about 4 miles northeast of Jacksonville. 26 FLORIDA GEOLOGICAL SURVEY measured at the well head reflects the pressure in the permeable zones in the Lake City Limestone modified by internal dissipation into the Ocala Group, where the pressure is lower. This internal dissipation of water within wells that penetrate more than one aquifer in the Florida aquifer system was indicated by current-meter traverses in wells 019-124-210, 021-141-423, 026- 135-342A, and 038-127-324, as shown in figures 8 and 9. Water moved from permeable zones of higher artesian head to those of lower head when the flow was shut off at the well head. In all wells the water moved upward, and, except in well 021-141-423, the water moved from lower formations into the Ocala Group. These zones -;;>^1!_ I ". hi I ;. 1- 7 F1 -1. I ';_- ^] 1 -.. -. ...-- 1 /- "" ~~s*rr~r ;n~ l1lrl0l iR,- Na :Ir ';i ~ l.s i,!. L~L---'~ r ,, ,, D---' y ~ I- C R -^ ~~, t,-ulr~J UCI~.C~r LI *i~YI.1(Iml n*l o _ci _pr\ ~p~~ IT"' Iri I - i I 1 c~ :: j Irr Ir ~~sn ~ -I~~clr- '' " -~ I~~llr, ~ I-- r S :I IIYUI"N~I c;rr ,r~ nOo Irl rlr '~3 .-r 40 YO La) U9 1~9 UO~OC I~a.nursn Dn mrul 200. C.. Figure 8. Diagrams showing geologic and current-meter data from wells in Duval County. t-f J~, ..,r ry VnF a~r;r~ ~I~R'F , i. in "` Vnmn nr brlr -.l.n~a~l~n~ r 5~~ i~.7'1 ~---- ' ( f ,.... .-.-I :'r-~ 'm or~r~ ..r I,.- r I - 'ji ii trf :~ !. E --i I LMp-A Eh IL- ell I j r REPORT OF INVESTIGATIONS NO. 43 27 A o1019-124-210 RevolutAi per mm ute of current meter S2W do d m r \ s |" i\ rru Ijw .I M o0 oCO a2 300 4000 5000(qpm) -000 0 L000 2000 3000 4P00 (2O Jp Maoluum flow between intervols, in D 0 CALIlBnATION C AIt glloIns per minute E 0oo /I- EXPLANATION i 100 lp 4g f M Dolomite W.ll 038.127.324. RW ao s p t1 olf WrI rI .l FrnoWnn Bmh 0 0 0O 300 400 o ____ 400. 2 Ob wyed I CtmI.td O Ier.d locir lcity lociy h o0 mma I __ .curveA, lkwo1) 00xgp 6' t .ad .. . 000 ..r .If 623 - S Dual and Nassau counties. rA L(8 y rlrpe>("locoflam623 apri (int 000l low) 00. CALIBRAT ram PH howi ing geologic and crr -memr flow between rinervals, i 400 gallons per m inuate 0z. 500 low 0l 0 2 1= ro er pIr FLORIDA GEOLOGICAL SURVEY containing water under different artesian pressure are separated by hard, relatively impermeable limestone and dolomite beds within the aquifer system. CURRENT-METER STUDIES In order to determine the depth, thickness, and relative yield of the different water-bearing zones or separate aquifers within the Floridan aquifer system, current-meter traverses of several wells in the area were analyzed by flow-distribution curves. The relative velocity of the water at different depths in a well was determined from current-meter traverses. The actual rate of flow of water at different depths is calculated by the formula q = av, in which q is the quantity of water per unit time, a is the cross- sectional area of the well at a given depth, and v is the mean velocity of water at that depth as indicated by the current meter. Because the cross-sectional area of a well bore is not the same at all depths below the casing, relative velocity graphs are insuffi- cient to determine q. The flow-distribution curve is constructed from the velocity graph by connecting the points of maximum velocity on the graph. The velocity is a maximum where the diameter is a minimum, which is generally where the resistant hard limestones and dolomites occur. Inasmuch as the minimum diameter of the well is about the diameter of the bit used in drilling the well, the diameter of these zones can only be equal to or greater than the diameter of the bit. The flows calculated at these hard zones using the bit diameter will be equal to or less than actual flow. Therefore, these zones, which are all assumed to have the same diameter, are utilized as markers in constructing flow-distribution curves. The configuration of the curves also depends on the geologic characteristics of the formations pene- trated by the well. Figures 8 and 9 show the geologic data, relative velocities, flow distribution, and relative yield or loss of water between regular intervals of the Floridan aquifer system for six wells in Duval and Nassau counties. The flow-distribution graphs were drawn by determining the rate of flow from the flow-distribution curves for each well at approximately 100-foot intervals below the casing. The increase or decrease in the rate of flow over each interval indicates the quantity of water that entered or left the well bore within that interval. The current meter was calibrated in each well to convert relative velocity to rate of flow by recording REPORT OF INVESTIGATIONS No. 43 he revolutions per minute of the meter while water flowed or ,was pumped at different rates, or by recording the revolutions per minute of the current meter in two casings of different diameters in each well while the rate of flow was kept constant. The flow-distribution curves and bar graphs for wells 021-139- 222, 021-141-423, 025-143-220, and 026-135-342A indicate at least two separate permeable zones in the Floridan aquifer system. One zone is in the Ocala Group at depths between the bottom of the casing in each well and about 800 feet below land surface. The other zone is in the Lake City Limestone at depths between about 950 feet and 1,200 feet below land surface. These two zones are separated by about 100 to 200 feet of hard limestone and dolomite, mostly in the Avon Park Limestone but also at the base of the Ocala Group and at the top of the Lake City Limestone. Within this impermeable zone little or no water enters the wells. A third permeable zone occurs within the Lake City Limestone between about 1,250 feet below the surface and the bottom of wells 021-141- 423 and 026-135-342A. This third permeable zone is separated from the overlying permeable zone by about 100 feet of imperme- able hard limestone and dolomite in the Lake City Limestone. As shown by the flow-distribution curves and the bar graphs in figures 8 and 9, the yield of water from the permeable zones in the Ocala Group is considerably less than that from the other, deeper zones. Generally, less than 30 percent of the total water produced from each well comes from the Ocala Group. In well 025-143-220, less than 200 gpm of the 4,800 gpm produced by natural flow is from the Ocala Group. The major water-bearing zone in the wells tested in the vicinity of Jacksonville is in the Lake City Limestone at depths between about 950 feet and 1,200 feet below land surface. As shown by the flow-distribution curves and the bar graphs in the figure, this zone yields 50 to 98 percent of the water produced by each well. In wells 021-141-423 and 026- 135-342A, the flow-distribution curves and bar graphs show that about 15 to 20 percent of the water from each of these wells comes from the aquifer in the Lake City Limestone at depths of more than 1,250 feet below land surface. In well 019-124-210 at Atlantic Beach, the water-producing zone between 1,100 feet and 1,290 feet below land surface in the Lake City Limestone can be correlated with the major water- producing zone in the Lake City Limestone in the vicinity of Jacksonville. In well 038-127-324, at Fernandina Beach, the water- bearing zone between 1,300 feet and 1,700 feet below land surface FLORIDA GEOLOGICAL SURVEY in the Lake City Limestone can be correlated with the two aquifer;: in the Lake City Limestone penetrated by the wells tested in the vicinity of Jacksonville. The confining beds separating the two zones in the Lake City Limestone in the vicinity of Jacksonville are absent in Fernandina Beach. The flow-distribution curves and bar graphs of well 038-127-324, at Fernandina Beach, show that there is another permeable zone in the Floridan aquifer system below the Lake City Limestone, in the Oldsmar Limestone. This zone, which is separated from the overlying zone in the Lake City Limestone by relatively impermeable dolomite beds in the Oldsmar Limestone, yields about one-third of the water produced in the well. It has not been penetrated by any of the wells tested in the vicinity of Jacksonville. Information obtained while wells 019-124-210, at Atlantic Beach, and 038-127-324, at Fernandina Beach, were being drilled indicates that in both wells the Ocala Group yielded water before the deeper water-bearing zones were reached. However, current- meter traverses made in both wells after they were drilled indicate that the Ocala Group does not yield any water to the wells, but instead, much water from zones of higher artesian pressure in the Lake City Limestone and Oldsmar Limestone flows through the well bore into zones of lower artesian pressure in the Ocala Group. As shown by the flow-distribution curves and bar graphs in well 019-124-210 when there was no flow of water at the surface, about 1,600 gpm entered the Ocala Group through the well bore from the zone in the Lake City Limestone; and when flow was 5,000 gpm at the surface, about 500 gpm entered the Ocala Group. In well 038-127-324, when there was no flow of water at the surface, about 700 gpm entered the Ocala Group through the well bore from the deeper zones; but when the well flow was 623 gpm at the surface, 650 gpm entered the Ocala Group; and when the well flow was 1,900 gpm at the surface, only about 350 gpm entered the Ocala Group. The great difference in artesian pressures within the Floridan aquifer system in well 019-124-210, at Atlantic Beach, and well 038-127-324, at Fernandina Beach, and to a lesser extent in wells in the vicinity of Jacksonville, indicate that in these areas the confining beds are extensive and the zones are separated and somewhat isolated from each other. Presently, the deeper zones yield more water, under higher pressure, than the zones in the Ocala Group. However, as additional wells are drilled or deepened into the deeper zones, internal leakage within the well bores and REPORT OF INVESTIGATIONS No. 43 withdrawall of water from the lower aquifers will probably equalize ihe pressures in the upper and lower zones. WATER SUPPLIES Wells in the Floridan aquifer are generally cased to the top of the aquifer, which in most areas is the top of the Crystal River Formation. The wells are then completed without casing into the Floridan aquifer system so that water may enter the open hole from the various water-bearing zones penetrated. The diameter of the casings ranges from 2 inches in small domestic wells to as large as 20 inches in some industrial wells. The approximate depth to the top of the Floridan aquifer system in Duval and Nassau counties is shown in figure 5. The figure also shows contours on the top of both the Crystal River Formation and the Avon Park Limestone. Exact depths to the top of the Floridan aquifer system can be computed for any specific locations in the area by using the contours on the top of the Crystal River Formation in figure 5 in conjunction with the land-surface altitude. The Ocala Group is the first permeable zone in the Floridan aquifer and its thickness may be determined at any specific location in the area by comparing the contours on the top of the Crystal River Formation and on the top of the Avon Park Limestone. This thickness added to the depth below land surface to the top of the Floridan aquifer system and the approximate thickness of the Avon Park Limestone, taken from the geologic cross sections (fig. 4), is the approximate depth to the major water-producing zone in the Lake City Limestone. The yield of wells in northeast Florida depends greatly on the depth of the wells. Wells drilled into the deeper zones in the Floridan aquifer system generally yield more water than those drilled only into the shallower zones. Table 4 shows the artesian flow and pressure in five Jacksonville municipal wells recorded before and after each well was deepened to penetrate the major water-producing zone in the Lake City Limestone. In each well there was a considerable increase in yield by natural flow and in artesian pressure after the wells were deepened. Wells 020-139-413 and 020-139-322, in central Jacksonville, originally penetrated about 520 feet of the Floridan aquifer system, which includes the permeable zones in the Ocala Group and the top of the permeable zone in the Lake City Limestone. After these wells were deepened TABLE 4. Artesian flow and pressure in five Jacksonville municipal wells before and after each well was deepened. Well number and location 018-189-281 Cedar St. between Flagler and Naldo Sts. 018-142-211 Corner of Plum and Shearer Sts. 020-189-822 Corner of Fourth and Pearl Sts. 020-189-418 Corner of Third and Silver Sts. 021-141-423 Corner of Fairfax and 20th Sts. Depth of well (feet) Before deepened After deepened 1,048 1.307 1,040 1,009 1,039 1,050 1,246 1,249 1,244 1,356 Amount deepened (feet) 259 206 240 205 306 Flow (thousand rpd) Before 1,985 1,914 468 647 1,732 After 3,420 4,338 1,00 1,988 2,707 Pressure (lb/ft2) Increase Before After 1,435 15 16 2,424 151/j 171 1,432 5 14 1,341 8 15 975 10 11% In crease 1 2 9 C 7 0 g r REPORT OF INVESTIGATIONS No. 43 1o penetrate about 750 feet of the aquifer system to include most ;f the second permeable zone in the Lake City Limestone, the ;'rtesian flow increased about 300 and 400 percent, respectively, a:nd the artesian pressure virtually doubled. The yield of wells in the Floridan aquifer system in Duval and Nassau counties depends upon well construction, the artesian pressure head, and the water-transmitting capacity of the zones penetrated by the well. The average yield by natural flow of typical small domestic wells between 2 and 6 inches in diameter is generally less than 500 gpm. However, some 6-inch wells yield as much as 1,000 gpm. The average natural flow of wells between 8 and 12 inches in diameter is generally less than 2,000 gpm. In some 10- and 12-inch-diameter wells in the deeper zones the natural flow may be as much as 5,000 or 6,000 gpm. Some industrial wells between 14 and 20 inches in diameter in Fernandina Beach and in the vicinity of Jacksonville are equipped with deep turbine pumps and continually yield 4,000 to 5,000 gpm. RECHARGE AND DISCHARGE The general areas of recharge and discharge and the direction of ground-water movement were determined by constructing a contour map on the piezometric surface. A piezometric surface is an imaginary surface to which water from an artesian aquifer will rise in tightly cased wells that penetrate the aquifer. The ground water moves from recharge areas, where the piezometric surface is relatively high, to discharge areas, where the piezometric surface is relatively low, in a direction approximately perpendicular to the contour lines. Figure 10 shows a generalized map of the piezometric surface of the Floridan aquifer in Florida. The principal recharge area of the aquifer system in northeast Florida is the area marked by a piezometric high in western Putnam and Clay counties and eastern Alachua and Bradford counties. Within this recharge area water enters the Floridan aquifer through breaches in the aquiclude caused by sinkholes, by downward leakage where the aquiclude is thin or absent, and directly into the aquifer where it is exposed at the surface. From this recharge area, the piezometric surface slopes toward discharge areas. In Duval and Nassau counties, water is discharged from the Floridan aquifer system primarily by numerous wells that penetrate the aquifer, system. There is FLORIDA GEOLOGICAL SURVEY 'V EXPLANATION -a- Contm u reprolsnts the hglh,. In fm referred to mm seo level. t khih wers wm d hIav risn in lightly cased mell that oanmm the maomr wrow.hbeaing formanlen in he Flordan oqulwer. July 6-17, 1961. Cantour intlal 10 and 20 kot. changing o meon I*o lev1. Ar e of e orian flow Extnt ande dlilnburion lo flew amnas vy wlih Iluctuations of rh p.ioamenic ufacoe. particularly in emO of heavy punrbo g. Relatlivly smait reas of wrtlan flow we not included i rMedldy adjocrl to and pamllellng the coast and many of the matir riv and sring*. 0 10 20 340 50 mele Taker. lrhe M Seri No.4 by H.G. Mealy, 191. e t &A. Figure 10. Map of Florida showing the generalized piezometric surface of the Florida aquifer. REPORT OF INVESTIGATIONS NO. 43 probably natural discharge from the aquifer system into the Atlantic Ocean off the coast of northeastern Florida. Artesian pressures rise in response to recharge and decline in response to discharge. Water levels in wells close to recharge areas show more response to rainfall than those further away. The reduction of artesian pressure induced by a discharging well decreases with distance from the well. The effect of variations in discharge on artesian pressure head in wells in Duval and Nassau counties is shown in figure 11. Well 019-140-421 is near the center of the discharge area at Jacksonville. The monthly municipal pumpage at Jacksonville compared with the hydrograph for well 019-140-421 shows that as the pumpage increases the artesian pressure in well 019-140-421 declines, and vice versa. Seasonal fluctuations of more than 10 feet are common, particularly during the late spring and summer when municipal pumpage is greatest. Well 033-150-242 is at Callahan, more than 20 miles from the heavily pumped areas at Jacksonville and Fernandina Beach. At this distance from the center of the discharge area, the seasonal fluctuations due to pumping are small and do not mask the fluctuations in response to recharge by rainfall. A comparison of the average monthly and annual rainfall at three stations in the recharge area with the hydrograph of well 033-150-242 shows that periods of relatively high and low artesian pressure in well 033-150-242 generally occur about 6 months after corresponding periods of high and low rainfall. This lag probably indicates the time necessary for the rainwater to leak into the Floridan aquifer system. The greatest declines in artesian head in well 033-150-242 occurred during the years of least rainfall and the greatest increases in head occurred during years of highest rainfall. It is possible that pumpage at Jacksonville and Fernandina Beach, both more than 20 miles from this well, also affect the rise and decline of artesian head to some extent. The effects of discharge in northeast Florida on the piezometric surface of the artesian aquifer system are shown in detail in figure 12. As artesian pressures are continually changing, the altitude and configuration of the piezometric surface in 1962 shown in this figure are only an approximate representation of the surface. The closed contour lines at Fernandina Beach and in the vicinity of Jacksonville (fig. 12) indicate depressions in the piezometric surface. These depressions, termed "cones of depres- sion," are a result of well discharge which lowers the artesian FLORIDA GEOLOGICAL SURVEY wt "~ a 28 " 4 2 Figure 11. Graphs showing relation of water levels in wells 019-140-421 and 033-150-242, to pumping and precipitation, Jacksonville area, Fla. - WELL 033-150-242, ao Collohon, more Ihon 20mies from cCetet of pmpin_ . .t--J^ -.-- ^ ^ --- - I I ________ ______ -___-___ ____-_____ REPORT OF INVESTIGATIONS NO. 43 head, thus creating a hydraulic gradient toward the points of discharge. In Jacksonville, the altitude of the piezometric surface within the center of the cone of depression is less than 20 feet above sea level and the hydraulic gradient toward the center of the cone is irregular. The slightly steeper gradient on the west side of the cone indicates recharge to the aquifer system from the west. The north-south elongation of the cone of depression may indicate that recharge from the west is partially blocked in the aquifer by the geologic fault. (See figs. 4 and 5). The cone of depression is partly prevented from expanding to the west of the fault and, therefore, expands to the north and south of the center of discharge. About 3 miles northeast of Jacksonville, at Eastport, with- drawals by industrial wells have created a relatively small cone of depression. In this area, the altitude of the piezometric surface has been depressed to about 30 feet above sea level. Along the coast, east of Jacksonville, discharge from municipal and private wells has lowered the piezometric surface to less than 40 feet above sea level. The most pronounced depression in the piezometric surface shown on figure 12 is at Fernandina Beach, where it is below mean sea level over an area of about 15 square miles and is more than 15 feet below sea level over about 3 square miles of the area. As shown by the configuration of the 40-foot contour line in central Nassau and north-central Duval counties, the piezometric surface has been depressed as far as 20 miles southwest of the center of the cone of depression by discharge from wells at Fernandina Beach. The steeper hydraulic gradient on the east side of the cone may indicate either recharge to the aquifer system from that direction or rocks with better water-transmitting properties east of the center of the depression. AREA OF FLOW Figure 12 also shows the approximate areas of artesian flow .n northeast Florida in May 1962. Artesian wells flow where the piezometric surface stands higher than the land surface. As shown )n the figure, artesian flow occurs principally .on the low coastal plain in eastern and central Duval and Nassau counties. Areas on the coastal plain in which the wells will not flow are on high sand ridges east of Jacksonville, where the land surface is higher than the piezometric surface, and in the vicinity of Jacksonville FLORIDA GEOLOGICAL SURVEY and Fernandina Beach, where the piezometric surface has been depressed below land surface by discharging wells. In the hilly uplands in western Duval and Nassau counties and in Baker County, artesian flow occurs only in wells along some stream valleys. Because the altitude of the piezometric surface is continuously changing, the area of flow shown on figure 12 is only an approxi- mation of the area of flow at other times. The greatest changes in the areas of flow occur in the vicinity of Jacksonville and Fernandina Beach, where the piezometric surface is about the same as the land surface. A slight decrease or increase in the altitude of the piezometric surface considerably reduces or increases the area of flow in these areas. WATER USE All the public water and most of the industrial and private water supplies in Duval and Nassau counties are obtained from wells developed in the Floridan aquifer system. PUBLIC WATER USE Jacksonville is one of the largest cities in the world to obtain its entire water supply from deep artesian wells. The city uses water from 46 wells whose depths range from about 1,000 to 1,500 feet. Water from seven well fields in the city is pumped into seven elevated reservoirs. In 1962 they produced an average of 38 mgd as compared to 27 mgd in 1950. In addition to municipal wells, there are about 100 privately owned water utilities in the vicinity of Jacksonville, each of which has at least one artesian well. Their combined yield is estimated to average 15 to 20 mgd. Jacksonville Beach uses an average of about 2 mgd of water that is obtained from seven wells ranging in depth from 600 to 1,000 feet. Each naval facility in the area has its own water system. U.S. Naval Air Station, Jacksonville, uses water from 12 wells between 400 and 1,096 feet deep, which produce an average of about 31/ mgd. Cecil Field Naval Air Station in western Duval County uses an average of about 700,000 gpd obtained from five wells that range in depth between 800 and 1,350 feet. U.S. Naval Station, Mayport, uses an average of 11/ mgd from two wells about 1,00Q feet deep. REPORT OF INVESTIGATIONS No. 43 Fernandina Beach uses about 1 mgd of water that is supplied Sy six wells ranging in depth between 700 and 1,200 feet. Other small towns in the area, such as Hilliard, Callahan, 1 .aldwin, Atlantic Beach, and Neptune Beach, each use water from at least one well drilled into the Floridan aquifer system. INDUSTRIAL WATER USE The greatest industrial use of ground water in Duval and Nassau counties is for the processing of wood pulp. In Fernandina Beach, Rayonier Pulp and Paper Inc. uses an average of 32 mgd from 11 wells that range in depth from 1,050 to 1,400 feet. Container Corp. of America uses an average of 21 mgd from six wells between 930 and 1,865 feet deep. In the vicinity of Jackson- ville, St. Regis Paper Co. uses an average of 18 mgd from eight wells between 1,350 and 1,400 feet deep. Other industries in the area that have their own water-supply system from the Florida aquifer system include chemical and paint manufacturing, dairies, laundries, icemaking, shipbuilding and food processing. Many of the larger industries use 5 to 10 mgd. COMMERCIAL AND PRIVATE WATER USE Many of the larger commercial buildings and stores have their own wells, which produce water for drinking, heating and cooling, kitchen and toilet, lawn irrigation, and washing. For example, May-Cohens Department Store and the Prudential Life Insurance Building in Jacksonville each uses an average of 60,000 to 80,000 gpd from wells about 750 feet deep. Numerous private wells, generally 6 inches or less in diameter and less than 750 feet in depth, are scattered throughout Duval and Nassau counties, particularly near Jacksonville and Fernandina Beach. These wells provide water for drinking, lawn irrigation, and swimming pools. The amount of water produced by all the wells in the Floridan aquifer system in Duval and Nassau counties was estimated on the basis of a general survey of the water used by municipal and private water utilities, major industries, large commerical build- ings, and individual well owners. It is estimated that an average of 150 to 200 mgd is discharged from wells in the vicinity of Jacksonville and 50 to 70 mgd from wells at Fernandina Beach. FLORIDA GEOLOGICAL SURVEY DECLINE IN ARTESIAN PRESSURE Artesian pressure has been measured periodically in northeast Florida in 7 wells since before 1934, in 18 wells since 1938, and in 4 wells since 1951. Hydrographs of a few selected wells in Duval and Nassau counties, shown in figures 13 and 14, show the seasonal fluctuations and the long-term trends of the artesian pressure head. All the hydrographs show an irregular but con- tinual decline in artesian head. The greatest declines in artesian pressure are in wells closest to the center of the cones of depression in Jacksonville and Fern- andina Beach. In wells 038-127-344 and 040-126-332 at Fernandina Beach, artesian pressure declined 50 to 60 feet between 1939 and 1963. In wells 018-143-234 and 018-140-123 at Jacksonville, artesian pressure declined about 12 to 22 feet between 1946 and 1963. Long-term changes in artesian pressure throughout northeast Florida from 1940 to 1962 and short-term changes from July 1961 to May 1962 are shown by contours and cross sections in figure 15. As shown by the contours in the figure, there has been a general decline in the piezometric surface throughout northeast Florida of about 10 feet to more than 25 feet between 1940 and 1962 and from less than 2 to more than 10 feet between July 1961 and May 1962. The cross section of the piezometric surfaces in the figure show that the general slope of the piezometric surface has remained approximately the same except in the vicinity of Jack- sonville and Fernandina Beach. In these areas the cones of depression in the piezometric surface have been deepened and considerably enlarged. The general decline in the artesian pressures in Duval and Nassau counties is attributed primarily to a great increase in the use of artesian ground water in the area and to a lesser extent to relatively long-term declines of rainfall on the recharge areas in northcentral Florida. Figure 16 shows the average annual rainfall at three stations in the recharge area and the annual discharge of artesian water by municipal wells in Jacksonville from 1940 to 1962. The annual discharge by the city wells is only a fraction of the total amount of artesian ground water discharged by all wells in the Jacksonville area. However, it serves as an index to determine the trend of ground-water discharge. As shown by. the bar graphs in the REPORT OF INVESTIGATIONS NO. 43 Zi iL2LL1 F1 ,4 3 miles soulhesl o Jocl, ille _ _l ----J -- .- --43- .L WELL OIB-140-123,-_ _I in Jocksonville 33 29 27 <25- 23 t34 in weslen pwT o Jack nill 18- 1 T I- Z/ -- /-' i- I . 14 24 WELL 028-137-334, 2 45 milem north of Jocksonvlle 14 4- 1940 1945 1950 1955 1960 196 Figure 13. Hydrographs of selected wells in Duval County. t-1 WELL 013-135-230, 5mlect Soullit" of jocnmille pj . . FLORIDA GEOLOGICAL SURVEY I I Ii II 36' -- 4 -i --- 32L..' 1 T- 28. T6T 16 8I 4LC--- W U C e o r r o a a ,- c w b' Q c w w r, r -I j: -I w c b3 i m r-454 CO- 95 1960IU Figure 14. Hydrographs of selected wells in Nassau County. I L1 .* i 1 i _I 1H ,F .. -i-- o E--- 0~- -- |WELL 37-136 122, 12 8 401 WELL 037-142-443, 36 .--l -- in cenlrol Nossou county ig ;__ ...-L- L-~- J_ .\ .. i |J- -\^ rjf~^\- - ^i iL_ L | -U, ,_, l__V< | I 40 32 .. _.. 1.5 miles south of SS | i1 i i I jFernondino Beach 1 _.__ of Fernndino Bech -28 i i 4 28 -4 -20'- A- Al-- + ,--- + J- .. + ++++ + + l l+ REPORT OF INVESTIGATIONS NO. 43 43 ..N COUNTY 4 + AA B A UVAU COUNTY BN I -- --- I I----o-,--.------ 5 -- I I -- -04 to o J 42 ;j Figure 15. Map and cross sections of Duval and Nassau counties showing the change in artesian pressure from July 1961 to May 1962 and from 1940 to May 1962. 44 FLORIDA GEOLOGICAL SURVEY ou. 70 -J A AVERAGEE RAINFALL LL 5 54.29 INCHES o S60- 1940-1962) _z6o-4 z -Z r 50- 40- 1940 1945 9SO 1955 1960 Figure 16. Graph showing annual discharge of artesian water by municipal wells in Jacksonville and average annual rainfall at three weather stations in the recharge area. figure, pumpage from city wells progressively increased from about 5 billion gallons in 1940 to almost 14 billion gallons in 1962. A comparison of the rainfall and discharge shown in figure 16 with water levels in wells shown in figures 13 and 14 indicates that between 1940 and 1957 artesian pressures declined even during years of above-average rainfall. This decline was probably due to the progressive increase in the use of ground water. A combi- nation of below-average rainfall and greatly increased discharge during 1954, 1955, and 1956 resulted in the rapid decline of artesian pressures during those years and the low artesian pressures ir 1956 and 1957. From 1957 to 1960, above-average rainfall anc nearly constant discharge resulted in a slight rise of artesiar pressure. However, a decrease in rainfall and steady increase in discharge during 1961 and 1962 caused a rapid decline of artesian pressure in 1962, to the lowest of record in most wellE in northeast Florida. The amount of decline in artesian pressure in northeast Florida varies in the different zones within the artesian aquifer system. Three wells near Jacksonville, 026-135-342A, B, and C, are within 40 feet of each other but product from three different zones. Well 1j aU -J REPORT OF INVESTIGATIONS NO. 43 C was developed in a shallow zone, well B was developed in a middle zYne, and well A was developed in both of these zones plus a third, (dep-lying zone (fig. 7). In these wells the trend of artesian pressures is the same, because the different zones are intercon- nected through well A, but the artesian pressure in well C, which is developed in the Ocala Group, is always considerably less than the pressure in the other two wells, which tap the deeper zones. In areas where there is little or no interconnection by wells between the zones in the artesian aquifer system, the difference in decline of artesian pressure in the different zones is even more pronounced. Figure 17 shows hydrographs of wells 038-127-324 and 038-127-142 at Fernandina Beach which are located about 2,000 feet from each other near the center of the cone of depression. The artesian pressures in both wells are drawn down by the many discharging industrial wells in the area, Well 038-127-142 taps only the permeable zone in the Ocala Group and well 038-127-324 taps that zone and the deeper zones in the artesian aquifer system. As shown by the figure, between November 1960 and October 1961 the artesian pressure in well 038-127-142 ranged from only 11 feet above msl to 3 feet below msl, -J _j 40 SWell 038-127-324,tapping permeable zones from the w Ocola Group to the Oldsmor Limestone 5 S30 0 Total depth=l,826 W -Delow ond surfccZ; M cosed to 567 0 w 0 20 LAND SURFACE 1I -LU S10 -- 1960 I 1961 Figure 17. Graphs showing the artesian pressure in two wells at Fernandina Beach. FLORIDA GEOLOGICAL SURVEY while during the same period the artesian pressure in well 038-127- 324 ranged from 40 to 22 feet above msl. In addition, water in well 038-127-324 remained higher than the land-surface datum while water in the surrounding shallower artesian wells was drawn down below the land surface. The use of artesian water can be expected to increase and the artesian pressure will continue to decline; however, the amount of decline within a specified period is beyond the scope of this report. The rate of decline will be faster during years of below- average rainfall than during years of normal or above-normal rainfall, and the pressure may even increase during years of above-average rainfall. However, if the rate of discharge in north- east Florida continues to increase, eventually the artesian pressure will probably decline even during cycles of above-average rainfall. The decline in artesian pressure in Duval and Nassau counties alone is not a serious threat to the availability of water in the area. At the present rate of decline, approximately 0.5 to 2.0 feet per year, it would take 100 to 400 years to lower the water 200 feet in most wells in the Floridan aquifer. This does not mean that the wells would then cease to yield water but merely that they would not flow at the surface, and that they would require pumping to yield water at the surface. A much greater danger than lowered pressure is that highly mineralized water would enter the zone of reduced pressure, either vertically from deeper highly mineralized zones in the aquifer system or laterally from the ocean, and contaminate the existing fresh-water supplies in the aquifers. QUALITY OF WATER The chemical character of ground water depends largely upon the type of material with which the water comes in contact and upon mixing with other water. Rainfall is only slightly-mineralized when it first enters the ground; but as it moves through the ground, it dissolves mineral matter from the rocks it contacts. Table 5 shows analyses of water from wells that do not pene- trate the Floridan aquifer system in the area and table 6 shows analyses of water from wells that do penetrate the Floridan aquifer. The dissolved chemical constituents are expressed in parts per million; 1 ppm is equivalent to a pound of dissolved matter in a million pounds of water; specific conductance is expressed in reciprocal ohms mhoss); hydrogen-ion concentration is expressed TABLE 5. Analyses of water from aquifers overlying the Floridan aquifer system in Duval and Nassau counties. Source of analysis: (1) Container Corp. of America; (2) Florida State Board of Health; (4) Southern Analytical Laboratory, Jacksonville. (Chemical analyses in parts per million except pH and color.) Hardness 40 i as CaCO, e O. 0 8 (total) * 1 W' V 0 | Well -S is I || number ^ i B______________ DUVAL COUNTY 014-148-180 1-18-58 185 .~ 0.8 44 9 .. 176 0 9 0.7 185 144 7.6 5 (2) 6-28-58 185 .. .1 46 10 ... 188 0 6 .7 210 158 7.5 5 (2) 016-187-100 10-30-58 70.100 .. 1.5 .. 52 6 .... .... 808 0 19 ..- 387 154 7.1 5 (2) 016-188-810 2-20-55 90 ...... -.. .. 84 0 .... 1.. 151 10 11 .05 159 124 7.1 5 (2) 018-185-840 7-20-68 80 -... 2.1 ... 68 11 .... 240 -.. 10 .4 280 202 7.2 5 (2) 019-185-480 6-17-58 200 ...... .... 89 7 .. .. .... 132 .... 18 .1 200 124 7.5 5 (2) 021-186-400 8-14-50 00 ...... 0.2 89 11 .... .. -.. 176 0 11 .1 195 142 7.6 5 (2) 021-142-100 6- 6-58 80 8.... 1 .0 .. 63 12 ............ 224 17 19 .25 280 216 7.3 100 (2) 028-129-880 4- 8-57 200 ...... 0.07 .... 86 5 .... .... .. 146 6 16 .15 146 112 7.5 5 (2) 2-20-59 200 ...... .06 .... 42 8 .. .. .... 180 2 15 .15 152 188 7.4 10 (2) 024-141-840 6-27-49 70 ...... ...... 46 12 .... .... .. 156 0 8 ...... 265 165 8.1 ..... (2) NASSAU COUNTY 028-1-1000 1 6- 8.87 028-156-100 6-28-87 040-127-211 11- 1-566 201 96 93 100 0.60 26 94 8.9 .... .... 0 0 17 ...... 840 96 .20 22 104 15 .... .... .... O 96 10 ...... 444 ...... .8 26 ...... ...... .... .... .... ...... 66 .... ...... 290 ..... (4) (4) 7.0 ...... (1) Na + K + CO, = 17 ppm Na + K + CO, = 29 ppm -------~---- --- - --- - -..------- ---- FLORIDA GEOLOGICAL SURVEY in standard pH units; and color is in units defined by the standard platinum cobalt scale. In all analyses determined by the Florida State Board of Health, the total dissolved-solids content was found by weighing the residue after the water had evaporated at 1030 to 1050 C and in all other analyses the total dissolved-solids content was found from the residue after evaporation of the water at 1800C. QUALITY OF WATER IN THE SHALLOW AQUIFER SYSTEM Water in the shallow aquifer system is generally not as hard and contains less dissolved mineral matter than water from the Floridan aquifer system in the same area. The sulfate content is generally negligible and the amount of magnesium is considerably smaller than the calcium content. The iron content of water from the shallow aquifers is generally greater than that from the Floridan aquifer system in the same area. In some parts of northeast Florida, the chemical composition of the water from both the shallow aquifer system and the under- lying Floridan aquifer system is similar. For example, the water in both the shallow and Floridan aquifers is similar in western Nassau County, where the Floridan aquifer is closer to the recharge area and the water is not as highly mineralized as in the central or eastern part of the area. The water in both aquifer systems is similar in sections of eastern Duval and Nassau counties, where water from the shallower aquifers has been mineralized by mixing with bodies of brackish surface water or sea water. Water from the shallow aquifers is generally suitable for domestic use and for most industrial uses. Because it contains relatively few impurities, it does not generally require treatment though it occasionally contains enough iron to impart a bad taste and to stain household equipment, clothes, and buildings. Iron can be removed from water by aeration or chlorination followed by filtration. QUALITY OF WATER IN THE FLORIDAN AQUIFER SYSTEM The chemical analyses of water from 50 selected wells that penetrate the Floridan aquifer system in the area (table 6) show that the quality of the water varies according to location, depth of the aquifer sampled, and date of sampling. TABLE 6. Analyses of water from the Floridan aquifer in Duval, Nassau, and Baker counties. Source of analysis: (1) U.S. Geological Survey; (2) Florida State Board of Health; (3) Black Laboratories Inc.; (4) Commercial Chemists, Inc.; (5) Southern Analytical Laboratory, Inc.; (6) St. Regis Paper and Pulp Co.; (7) Pittsburgh Testing Laboratory; (8) Rayonier Inc.; (9) Permuit Co. Dissolved solids: Residue at 1030C State Board of Health analyses. Residue at 1800C for all other analyses. (Chemical analyses in parts per million except pH and color.) Hardness as CaCOs g DUVAL COUNTY 0 V 4 DUVAL COUNTY -... 0.19 28 ...... 610 .10 ...... 71 87 880 .01 18 52 22 ........ .00 18 42 21 ...... .02 17 29 12 ...... .02 14 27 12 757 .... 68 6 757 .00 21 75 81 757 .00 ...... 68 82 I ........ ...... ...... 172 187 18 ...... ...... ........ ... ...... 162 188 21 ...... 8.8 2.4 0.00 138 101 10 0.5 0.1 9.7 2.8 .00 187 74 10 .6 .1 ........ ........ ..... 124 27 6.5 ..... 8.1 ...:... .00 124 22 6.0 .5 .0 ........ ... .... 158 165 15 14 2.3 .00 156 176 16 .8 .0 ........ ........ 00 161 184 8 ...... - (1) 2 (1) 3 (1) -. (3) 5 1) 5 2) ; 008-180-810 0: 18 185-1.400 018-140-414A 018-140-414B 018-158-240 015-188-280 6-16-25 6- 8-60 6-20-62 6-20-62 1942 1-18-54 10-10-49 6-18-62 1-17-68 858 610 1,005 708 990 990 1,187 1,187 1,187 NA + K = 7.6 ppm Crystal River Fm. cased off .__... .-.. -- -- - - I I I --------- TABaL 6. (Continued) 0" a a ON 605 7.7 S7.7 -_ 7.3 - 8.2 634 7.7 7.1 7.0 7.5 S7.5 631 7.8 7 .6 169 7.0 7.6 519 7.6 504 7.9 .. 7.6 Na + K = 87 ppm Na + K = 25 ppm Na + K = 9.0 ppm Na + K = 27 ppm 9 1 '-I iX U Well number 015.188-814 015.145-280 017-126-440 017-185418 017-1I8-142 017.158480 017-158-110 018.124-222 018.186.241 018-188-483 019-124.210 019-189-280 020-189-448 022-180-112 6-1342 2-2241 10. 8.56 6.13862 10-29-42 11- -50 1-164-3 9-2441 1-1042 5-20-50 8.3140 8- 742 9-27-41 9-8140 9-27.41 5-20-50 8.8-3140-60 8-2941 12 442 1,284 1,000 400 400 185 1,500 750 750 680 622 685 1,848 1,848 1,800 655 655 1,250 1,250 1,250 1,250 1.000 14 13 12 12 12 14 470 .00 460 .5 S.93 524 .008 - .00 433 - 483 - .. .1 382 .12 508 0.55 504 -. 504 - 407 .4 491 1.9 491 - 462 .2 22 74 1 35.7 ..-. 176 - 77 19,4 75 21 75 19 81 26 40 . 34 28 72 66 21 75 55" 21 0 27 61 . 60 20" 00 .. 64I 28 16.7 38 34 81 80 12 20. 14 35 28 81 26 318 13 23 22 13 22 26 i 2.0 1.9 8.4 . . 8.2 1.0 1.0- Hlardlnew ra CaCO, E 95 0e z 300 154 828 834 812 810 127 182 144 324 272 818 820 248 382 47 246 240 244 240 270 --. 188 _ 170 .00 1C3 .00 156 -187 205 129 .00 160 166 .. 167 0.00 164 - 188 .00 151 .00 71 -- 178 - 190 .00 188 .00 187 .... 190 154 34.6 193 193 210 168 22 18 12 190 146 184 158 209 96 A3 87 63 .7 2 .6 2.65 .76 .45 .8 .45 .7 0.65 .7 .7 .65 I --- ' I, j3 2; Y S i ..._.. ....,_..._ .__I---c~---- I I I r r -- - ' I q I ] 025-125-281 025.18s-2101 26.-13-342A 9-26-41 6- 3-41 1- 9-43 5-20-50 6-10-58 10-20-55 6-18-62 26-185-842B 10.20-55 6-18-62 26-185-842C 026-145.420 028-187.884 10-20-55 6-18-62 9.10.42 11- 8-52 840 450 .05 31 092 660 .02 .-. 992 660 .10 26 992 660 .08 27 992 660 .07 - 1,398 584 20 1,398 584 0.25 20 700 450 .0 27 700 460 .01 18 1,025 860 .5 28 1,025 850 .00 1.6 658 -- .5 81 500+ .1 80 --- 47 9n 17 17 9 3.4 1.2 ~ .00 186 142 104 .00 189 64 20 S197 72 4 - 204 98 22 - 168 63 26 .00 166 67 - .00 140 48 22 - 162 69 .00 200 48 21 .00 164 67 .00 54 0 - 200 84 2 - 188 2 18 .6 .45 .6 T .05 .. .05 .0 - .0 - NASSAU COUNTY 028-056-430 083149-140 087-186-122 088-126-820 9-20-50 9- 4-59 9.10-42 6-25-87 80-560 4-17-56 12- 6-56 8. 7-57 8-20-57 4- 1-59 038-127-324 4.17-46 12- 6.56 8. 7-57 3- 7-68 12. 1-58 8-10-59 6.18-59 90 3-59 6-13-62 650 600 800 1,000 1,208 1,208 1,208 1,208 1,208 1,208 1,208 1,826 1,826 1,826 1,826 1,826 1,826 1,826 1,826 1,100 83 88 - 61 685 10. 842 1.8 192 53 148 177 168 141 145 153 184 860 875 '855 864 879 372 382 403 400 22 25 28 388 30 34 23 24 27 29 644 687 770 790 865 860 960 864 1,150 3481 5031 4560 478 504 504 6791 471 4641 1,9551 2,475 2,805! 2.375 2,365 2,748 3,095 3.050 3,020' ! 132 7.8 10 - __ 7.3 - 7.2 7. ... 7.5 - 1388 7.4 5 158 7.3 5 793 4,490 7.6 Na + K = 25 ppm Na + K = 22 ppm Na + K = 87 ppm Na + K = 25 ppm (8) (8) (8) (8) i8) (8) (St (1) Plugged back, but plug leaking. , . 98 51 58 0 ... .. .... ... < t .. 15 (1) 7.2 (1) S 7.4 (1) 7.8 5 (2) S7.9 (6) 385 8.0 5 (1) - 7.7 (6) 438 8.0 5 (1) 7.9 (6) 165 8.0 5 (1) 7.25 (8) 7.8 (7) I I I -- Na + K = 5.2 ppm Na + K = 6.4 ppm Crystal River Fm. cased off Na + K = 18 ppm TABLE 6, (Continued) i Well number .g S i JS s g 0.6 .... -. . . .. .... --- 0. .7 .~ .~ . . . .' ii] , i9a I cav Hardness as CCO, T92 160 Na + K = 28 ppm Na + K = 41 ppm Na + K = 20 ppm - Ii I 4-17-56 1,700 12- 6-56 1,700 8- 7-57 1,700 38- 758 1,700 12- 1-58 1,700 8-10-59 1,700 6-18-59 1,700 9- 8-59 1,700 1- 8-24 750 4- 1-59 750 6-13-62 7560 4-17-66 1,820 12- 6-66 1,820 8- 1-57 1,820 8- 7-58 1,820 12- 1-58 1,820 8-10-59 1,820 6.18-59 1,820 9- 8.59 1,820 1. 8-24 1,065 8- 7-57 1,0685 8- 7-58 1,065 12- 1-58 1,085 3.10-59 1,065 6-18-59 1,065 9- 8-59 1,065 5-80-50 1,054 4.17-56 1,054 12- 6-66 1,054 -22 2 .2 1 088-127-120 039-127-44 083-128-241 169 168 152 177 184 172 184 177 178 168 144 190 185 197 206 197 198 208 182 167 145 181 156 152 152 149 161 152 126 44 88 47 47 52 50 51 50 81 38 80 107 99 112 112 127 121 126 125 29 85 82 40 35 87 84 30 82 30 676 7.5 5 7.6 6 I r --r I I --I -. -. . - ' I - - II--------- 040-127-482A 040.127-482B 040-127-432C 040-127-482D 041-126-388 041-165-421 042-125-888 042-127-844 042-127-443 044-141-480 8- 7-68 12- 1-58 3-10-69 6-18-591 9- 3-59 9-28-37 9-27-49 4- 2-50 5-16-59 9-27-49 4- 2-50 4- 1-659 9-28-37 4- 2-50 4- 1-59 4- 1-69 6-13-62 4- 2-59 5-15-59 5-15-59 5-15-69 4- 2-59 1,054 1,054 1,054 1,054 1,054 1,100 1.100 1,100 1,100 1,026 1,025 1,025 781 781 731 1,205 1,961 857 800 800 800 549 - 549 -- 5491 - 549- 549 - -- .32 .82 .0 .01 .04 500 0.10' 500 .0 500 .0 540 .31 540 .01 540 .06 550 .09 1,828 .04 .17 500 .06 550 .0 520 .06 .17 BAKER COUNTY 014-208-400 4-16-69 650 600 .. -. 40 28 .. 151 65 14 0.45 202 196 72 7.7 5 (2) '016-207-120 1-81.63 700 460 .. 6 17 ... 148 les 25 .5 217 10 88 7.6 (2) than _ ________o_ __-__ __,__o___-0 __ __ __ __ __t_ ___ _____________ 68 -- 65 -- 66 __ 65 22 60 -- 82 84 66 61 -80 34 69 -- 72 22 60 38 71 -- 72 - 77 32 88 _ 69 -- 76 7- 72 -- 72 -- 75 I-- --4 II 48 -- ...- .... .. - 2.7 - 157 - 161 168 165 182 195 159 205 162 204 160 192 224 205 161 204 168 190 158 195 159 1200 166 202 144 192 157 186 198 185 138 192 228 190 198 180 198 202 155 87 41 41 as 38 88 83 36 29 30 84 83 as 29 88 76 82 88 86 82 32 -- , 0.66 .65 .7 .56 .55 .65 .650 -- c ). -0 ..... 0.0 520 500 518 562 653 570 467 524 620 468 520 509 570 715 467 583 635 552, 501o Total 170 184 202 240 162 186 160 174 - (8) (8) 7.3 2)(8 7.8 7 2) -, 7.4 (2) ... 7.4 (2) S7.3 -1(2) _ 7.8 (2) S7.83 (9) i ( I 7-. 7-4 628 S7.3 5 (2) 928 7.7 5 (1) 7.4 6 (2) 7.6 5 (2) ._ 7.5 5 (2) 7.8 (2)j 7.4 10 (2) Na + K = 19 ppm Na + K = 14 ppm Na + K = 27 ppm Na + K = 16 ppm Na + K = 28 ppm Na + K = 19 ppm Ocala Group cased off FLORIDA GEOLOGICAL SURVEY Generally, water from wells closer to the recharge area is not as hard, and contains less mineral matter than water from wells farther away. As shown in table 6, except in the vicinity ot Fernandina Beach, the total hardness as CaCOQ of water from the Floridan aquifer system in the area ranges from 117 ppm in well 013-153-240, in southwestern Duval County to 336 ppm in well 008-130-310, at Bayard. The dissolved-solids content ranges from 90 ppm in well 026-135-342C near Jacksonville to 574 ppm in well 025-125-231 in eastern Duval County. In the vicinity of Fernandina Beach, in eastern Nassau County, the quality of water from wells in the Floridan aquifer system varies considerably with depth or with the aquifer sampled (Leve, 1961b). Water from the deeper wells is more mineralized than water from the shallower wells. In well 040-127-432C at Fernandina Beach, which is 731 feet deep, the water contained 300 ppm hardness as CaCO, and 509 ppm dissolved solids on April 1, 1959. In well 040-127-432D, which is 1,205 feet deep and about 100 yards away from well 040-127-432C, the water contained 360 ppm hardness as CaCO:, and 570 ppm dissolved solids on the same date. The date of sampling generally makes only a slight difference in the quality of the water, except in the deeper wells in the vicinity of Fernandina Beach where changes in the quality of water are caused by large variations in the piezometric head. As shown in table 6, water from well 038-127-324 at Fernandina Beach. 1.826 feet deep, ranged in hardness (as CaCOa) from 790 to 864 ppm and in dissolved-solids content from 1,960 to 3,100 ppm between April 17, 1956, and June 18, 1959. This well was plugged back to 1,100 feet in depth in 1962 and as shown in table 6, the hardness of the water increased to 940 ppm and the dissolved-solids content was 3,020 ppm. An indication of the quality of water below the Eocene forma- tions is given by the analysis of samples of water' from oil-test well 044-156-100 in western Nassau County. The well was drilled to 4,800 feet and samples of water were taken from 2,205 to 2,230 feet within the Cedar Keys Formation, of Paleocene Age. The hardness of the water was 9,660 ppm and the dissolved-solids content ranged from 64,300 to 100,900 ppm. The chloride content ranged from 33,600 to 60,200 ppm, which is 11 times to more than twice the chloride content of sea water. Except in a few deep wells in Fernandina Beach, water from the Floridan aquifer system in Duval, Nassau, and Baker counties REPORT OF INVESTIGATIONS NO. 48 is suitable for domestic use and for most industrial uses. However, locally, one or more of the chemical characteristics of the water exceed the maximum limit of concentration recommended by the U.S. Department of Health, Education, and Welfare (1962). Some of the more important of these chemical characteristics are discussed below. CHLORIDE Most of the water tested in the area contained less than 30 ppm of chloride, which is well below the maximum limit of concentra- tion suggested by the U.S. Department of Health, Education, and Welfare for public supplies. However, water from well 038-127- 324, in Fernandina Beach, contained between 644 and 1,150 ppm of chloride (table 6). Such large quantities of chloride in ground water in areas where the content is generally much lower indicate contamination by saline water, which will be discussed in detail in the section "Salt-Water Contamination." DISSOLVED SOLIDS The dissolved-solids content of water shown in tables 5 and 6 is the residue of mineral matter left after evaporation of the water and is an indication of the degree of mineralization of the water. Water that contains less than 500 ppm of dissolved solids is usually satisfactory for domestic use. In the wells sampled in Duval County, only well 025-125-231 contained water with more than 500 ppm of dissolved solids. Many wells in Nassau County contain water with more than 500 ppm of dissolved solids. However, only the deeper wells in Fernandina Beach contained water with extremely large amounts of dissolved solids. HARDNESS There are two types of hardness in water: (1) carbonate harness caused mainly by calcium and magnesium bicarbonates and (2) non-carbonate hardness caused primarily by sulfates, chlorides, and nitrates of calcium and magnesium. Water with a hardness of more than 100 ppm as CaCO., which is present in all wells tested in the area, may be classed as hard to very hard. Hardness of water retards the cleaning action of soaps and forms a precipitate or scale on plumbing fixtures, boiler pipes, and FLORIDA GEOLOGICAL SURVEY utensils when the water is heated. Carbonate hardness can easily be removed from the water by heating or by common soda-ash or lime-soda softening processes. Noncarbonate hardness is more difficult to remove, but it can be reduced by certain commercial softening processes. HYDROGEN SULFIDE GAS Although the water samples shown in table 6 were not analyzed to determine the amount of hydrogen sulfide gas present, most of the water from wells in the Floridan aquifer system in the area has the sulfur odor indicative of this gas. Hydrogen sulfide has a corrosive effect on plumbing and it is undesirable in drinking water. It can be removed easily from the water by simple aeration or by natural dissipation to the atmosphere from an open tank or pool. SALT-WATER CONTAMINATION Most of the water used in Duval, Nassau, and Baker counties is from the Floridan aquifer system, and hence the following discussion will include salt-water contamination of only that system. In northeast Florida as well as other parts of Florida, salt water is present within the Floridan aquifer system. In most areas this salt water entered the aquifer system during past geologic time when the sea stood above its present level, or the salt water was trapped within the rocks when they were deposited. Subsequently, fresh water entered the aquifer system and diluted or flushed out most of the salt water. The salt water that remains where the flushing was not completed is a source of contamination of the fresh ground water. About 91 percent of the dissolved-solids content- of sea water consists of chloride salts. The chloride content of ground water, therefore, is generally a reliable indication of the extent to which normally fresh ground water has become contaminated with sea water. Water samples were collected from most of the wells that were inventoried and were analyzed for chloride content. From many wells, water was sampled periodically to determine if the chloride content had changed. The maps of figures 18 and 19 shown the chloride content of water from wells in the Floridan aquifer system in northeast REPORT OF INVESTIGATIONS NO. 43 Florida in 1940 and in May 1962. As may be seen, the chloride content of the water is lowest close to the recharge area in southern Duval County and in Baker County, and progressively higher away from the recharge area toward the north. A comparison of both maps shows that the chloride content of the water from wells in the Floridan aquifer system has increased since 1940. In 1940, wells throughout all of southwestern Duval County and eastern Baker County contained water with a chloride content of less than 10 ppm, and the chloride content of water from wells sampled in Duval County did not exceed 20-29 ppm. In 1962, only one well in south-central Duval County contained water with a chloride content of less than 10 ppm, and wells near the mouth of the St. Johns River and near the center of the cones of depres- sion at Jacksonville and Eastport contained water whose chloride content was over 30 ppm. In 1940, the chloride content of water from wells sampled in Nassau County did not exceed 30-39 ppm, except possibly in wells north of Hilliard, In 1962, the chloride content of water from wells north of Hilliard and near the center of the cone of depression at Fernandina Beach was 40 ppm or more. Water in the deep wells at Fernandina Beach had the highest chloride content shown in figure 20, ranging from 53 to 1,180 ppm in May 1962 in wells more than 1,250 feet deep. A comparison of the maps in figures 18 and 19 with the map of change in artesian pressure in figure 15 shows that the increase in chloride content of water from the Floridan aquifer system in northeast Florida can generally be correlated with the decline of artesian pressure in the area. In most parts of eastern Baker County and western Duval and Nassau counties, where the artesian pressure has declined less than 15 feet since 1940, the increase in chloride content has been small. However, in the cones of depression at Jacksonville, Eastport, and Fernandina Beach where the piezometric surface has declined more than 15 feet since 1940, the increase is greater, particularly in the deep wells near the center of the cone of depression at Fernandina Beach. Table 7 shows the chloride content of water from wells that penetrate the Ocala Group and from wells that penetrate forma- tions deeper than the Ocala Group in Duval and Nassau counties between the years 1940 and 1962. In Duval County and in most of Nassau County, the chloride content of water from wells that penetrate the Ocala Group and from wells in deeper formations has increased only slightly, 2 to 14 ppm. However, in the vicinity of Fernandina Beach, the chloride content of water from wells FLORIDA GEOLOGICAL SURVEY EXPLANATION i n Well 404 165 Chloride contnt (ppm) 4140 j i404 ogh oB wI 1 AZ 0___ 2E miles Figure 20. Map showing the chloride content of water from deep wells at Fernandina Beach, May 1962. that penetrate formations deeper than the Ocala Group has increased at a faster rate. Between 1952 and 1962 the chloride content of water in wells 039-127-321 and 039-127-114 at Fernandina Beach approximately doubled, and that in well 038- 127-324 at Fernandina Beach increased to more than four times the amount measured in 1952. Figure 21 shows graphically the increase in chloride content of water from four wells at Fernandina Beach that penetrate formations deeper than the Ocala Group. The increase was only slight between 1955 and 1962 in well 039-128-241, which is 1,054 feet deep and penetrates the Ocala Group and the top of the Avon Park Limestone, and in well 039-127-114, which is 1,700 feet deep and penetrates the Ocala Group, the Avon Park Limestone, anc the Lake City Limestone. The chloride content of the water increased much more rapidly in well 038-127-324, which is 1,826 feet deep and penetrates the Ocala Group, the Avon Park Lime- stone, the Lake City Limestone, and a part of the Oldsmar Limestone, and in well 041-126-333A, which is 1,961 feet deep and open to the Lake City and Oldsmar Limestones. In well 038-127-324 it increased 1,820 ppm, from 550 to 1,800 ppm. TABLE 7. Chloride content of water, in parts per million, from wells in the Floridan aquifer system in Duval and Nassau counties. (ft) (feet) 1940 1948 1950 1952 1983 1954 1955 1956 1957 1958 19B60 1961 1962 WELLS IN THE OCALA GROUP Duval County 1 14 011-141-141 018-18-230 015-141-111 017-126-232 018-123-123 019-132411 019-140421 020-136-484 020-144430 021-123-133 023-125-142 024-16-136 024-144-320 025-141-300 026-126-423 026-145420 027-143-314 028-137-334 17 20 183 14 14 15 22 19 20 26 26 I-I 2 ~/ ----j _ri __ ----( _1 ___-_I 12 15-20 11 22 24 16 14-25 21 15 22 23 21 19 24 24 29 30- 17-19 - -- - ~ 17-22 14-18 24-87 - ---- -- 15-18 10 14-20 17-18 14 18 18 19 24 -I""' ----j 17-21 15 20 21 20 17 29 20 25 27 28 . .... ....0 nlr _... __.. ......... _- _ I ..........- 11- --- 1...... ................. -CI-l ~----~-i I ~1 ~ -I ~I II""' ""~~~l""i ---I -- -I 11111111 Il----L/I _II ==1 --- I ~' ,., ,i I-.. 11 ----- _____~/ I 1 I TABsL 7. (Continued) Well Well depth Ce number (teet) (feet) 1040 1948 1950 1952 1953 1954 1055 1956 1967 1958 1959 1960 1961 1962 Nassau County I I ,I I I a I 26 29 27 -- 29 30 54-58 62-56 23 28 - 80-32 30 26.31 27 36 39 28 30 33 29-32 24-27 32.33 - 30 33 32 35 36.40 3238 29.32 29-32 26-30 36 WELLS IN FORMATIONS DEEPER THAN THE OCALA GROUP Duval County S0-189.230 650 10 .15 2 013-141-441 1,015 318 9---..-- 1 1______ 16.. _- 4 81-32 31 30.31 28-30 34 883 40 34 23 - 26 28-20 25 26-31 082.12f142 088.150-242 085-127.310 : 085-127-830 S037.126-214 S087-129-242 0837-130.8380 087-142.480 089-127-120 089-131-231B 040-127-211B S040-138410 0i 42-125-888 042-127-448 28 28 24.26 i I I 'TABLE 7. (Continued) Well Well depth Cased number (feet) (feet) 1940 1948 1950 1952 1958 1964 1955 1966 1957 1958 1959 1960 1961 1962 .019.140-241 785 14-16 ---- -__________- 14-22 26-87 21 020.189448 1,250 17 -- -- --.-_____ _____ -- -- -- 22 24 021-188-121 1,060 548 18 28 21 S021-141 414 1,068 580 16. -- -- --- --- ._____--- ---- 18 19 026-185-842A 1,898 584 ----- --. _____ -- 24-26 24-27 24-29 Nassau County 087-186-122 1,000 460 80 28 ..... 2-0-80- 860 80-32 83 088-126-820 1,208 572 27 29-0 088-127-824 1,826 567 -_ .. 420-450 480-580 560-60 644-687 770 790-866 860-1,060 1,550-1,690 1,870-1,780 1,180-1,800 089-127-844 1,820 545 --104 106-127 -- 99-107 112 112-127 121-140 128-181 143-156 168 089-127-821 1,840 561 -- .---- 65-68 70-77 77-85 82-96 89-90 99 102-116 109-130 113-122 125-139 140 089-127-114 1,700 646 -- --- 82-88 86-43 40-43 37-48 38-44 47 47-52 50-55 66-60 51-58 56 089-128-131 1,065 550 80 80-32 30-32 35 32-40 33-37 34-40 82-37 32 089-128.241 1,054 549 80 -- 80-35 29.32 26 38-40 35-38 36-37 83-86 040-127-482A 1,100 29 36 ... .. 26-29 _____- -___ . 040-127-482B 1,025 500 80 8 34 ..-_ -3-5 ___ 35 041-126-888A 1,961 1,8281 74-89 91-97 i41-126-888B 1,404 560 --- --- -- 142-148 112-118 ..120 --- 152-161 150-165 FLORIDA GEOLOGICAL SURVEY 40 30. w oo 'i 600 S.400 S400 100 90 80 60 50 40 039-128-241 / Total on 1,054'- 039-127-114 Ca,d 567- -- -t-o-- 0-38-127-324 ~ . .Tal arit^ l826 ___ _____ rJP1u!d Coi7z t10ol,0 041-126-333 A- Total deplh 6' . coad IJ28' 9 i5 | 1956 1957 1958 1959 1960 1961 1962 Figure 21. Graphs of the chloride content from selected wells at Fernandina Beach that penetrate formations below the Ocala Group. The increase in chloride content of water from wells in the Floridan aquifer system and the decline in artesian pressure indicate that salt water is gradually moving into the zones of reduced pressure and contaminating the existing fresh-water supply. However, the relatively low chloride content of water samples from most wells in the area indicates that serious contamination is restricted at present to a few deep wells at Fernandina Beach. The rapid increase in these deep wells shows that the contamination is proceeding at a faster rate in the deeper aquifers in the Floridan aquifer system in this area. Water samples collected at depths between 2,205 and 2,230 feet in well 044-156-100 near Hilliard (p. 77), show that highly saline water is present in the deeper aquifers in Nassau County. The fresh water has a lower density than the saline water and will remain above the saline water if it is undisturbed. When thp fresh water is withdrawn from the aquifer system, the salt water REPORT OF INVESTIGATIONS NO. 43 will cone up and enter the zone of reduced pressure by vertical migration. However, analysis of water samples taken at different depths in wells at Fernandina Beach gives evidence that all or some of the contamination of water in deep wells is by lateral migration from a salt-water zone or zones within the upper part of the Floridan aquifer system. Figure 22 shows graphically the chloride content of water samples collected at various depths during the construction of wells 038-127-324 and 041-126-333A at Fernandina Beach. Water enters well 038-127-324 from the Ocala Group, and the Avon Park, Lake City, and Oldsmar Limestones, but in well 041-126-333A the Ocala Group, Avon Park Limestone, and part of the Lake City Limestone are cased off and water enters the well only from part of the Lake City and Oldsmar Limestones. The chloride content of water found in both wells in a zone at the bottom of the Avon Park Limestone and the top of the Lake City Limestone ranged from about 100 ppm to about 430 ppm. The water was considerably fresher immediately above and immediately below this zone, which indicates that water in this zone is isolated from water in the rest of the aquifer system. Although the maximum chloride content of the water in this zone was about 150 ppm in well 038-127-324 and 430 ppm in well 041-126-333A when the wells were constructed, the rapid increase with pumping (fig. 21) suggests that salt water is entering the zone. Therefore, this zone is probably a source of salt-water contamination of the fresh water in wells at Fernandina Beach. Discharging wells that are drilled into the Lake City and Oldsmar Limestones and are open to this zone may induce lateral migration of relatively saline water into the wells. Uncontaminated fresh water can be obtained from below if salt water is prevented from entering the well bore by casing off this zone. The graphs in figure 22 also show that the chloride content of water from both wells gradually increased below about 2,000 feet. This indicates that salty water is present below this depth also and wells drilled deeper than 2,000 feet in Fernandina Beach will probably encounter highly saline water. Except at Fernandina Beach, no wells in the area have been drilled sufficiently deep to encounter salt water, and none of the wells drilled into the Lake City Limestone have encountered the salt-water zone at the base of the Avon Park Limestone and the top of the Lake City Limestone. However, as more fresh water is withdrawn from the aquifer system and the artesian pressure CRYSTAL RIVER FORMATION )0- WILLISTON FORMATION INGLIS FORMATION )0- AVON PARK LIMESTONE LAKE CITY LIMESTONE )0- OLDSMAR LIMESTONE S0 0 60 120 180 240 300 360 420 scale CHLORIDE CONTENT, IN PARTS PER MILLION Well 038-27-324 swmles taken ItugQh drill stem durhg drilling Well 041-126.533A sormes oaken with ibaler during dinag Figure 22. Graphs of the chloride content of water at different depths in wells in the Floridan aquifer system at Fernandina Beach. REPORT OF INVESTIGATIONS NO. 43 continues to decline, more salt water may migrate either vertically or laterally, or both vertically and laterally, into the fresh-water zones in the upper part of the aquifer system. Then the fresh water will become progressively saltier until, eventually, it may become unsuitable for domestic and most industrial uses. It is possible to retard or even to prevent vertical and lateral encroachment of salt water by properly spacing wells and controlling discharge rates to avoid excessive drawdowns. The confining beds in the Avon Park, Lake City, and Oldsmar Limestones will retard or even prevent vertical movement of water in the aquifer system in most of the area. However, if these relatively impermeable beds are penetrated by a well, any salt water present will move upward at a faster rate. Therefore, caution should be taken in developing the deeper water-producing zones in the aquifer. More detailed information on the geologic and hydrologic characteristics of these deeper zones and the depth to salt water needs to be obtained before there is any extensive development of these zones. Such information will insure proper development of the deeper zones in the aquifer and lessen the possibility of salt-water contamination. SUMMARY Water supplies in northeast Florida are obtained almost entirely from ground-water sources. The rocks usually penetrated by water wells are thick limestone and dolomite beds of Eocene age which underlie the surface at depths ranging from 300 to 550 feet below msl. These rocks, in ascending order, are the Oldsmar Limestone; the Lake City Limestone; the Avon Park Limestone; and the Inglis, Williston, and Crystal River Formations which compose the Ocala Group. The limestones of Eocene age are ,verlain by the Hawthorn Formation, which is composed of beds 'f clay, phosphatic clay, sandy clay, phosphatic sand, limestone, :nd dolomite of early and middle Miocene age. The Hawthorn :ormation is overlain by beds of calcareous silty clay, limestone, .hell, and sand of late Miocene or Pliocene age and of Pleistocene :tnd Recent age. A fault extending along the St. Johns River in Duval County lisplaces the top of the limestones of Eocene age a maximum of .bout 125 feet. West of the fault the top of the Avon Park :imestone dips northeastward about 16 to 20 feet per mile. FLORIDA GEOLOGICAL SURVEY The shallow aquifer system, which is 300 to 550 feet thick in the area, extends from the surface into the Hawthorn Formation. The aquifers within the system consist of relatively discontinuous, porous limestone, shell, and sand lenses within the Hawthorn Formation, the upper Miocene or Pliocene deposits, and the Pleistocene to Recent deposits. The aquifers are recharged directly by local rainfall and by downward infiltration of water from shallower aquifers in the system. The aquifers in the shallow aquifer system most utilized by wells in the area are the surficial sand beds and a relatively continuous limestone, shell, and sand zone at the base of the upper Miocene or Pliocene deposits. As the thickness and lithology of these aquifers vary both vertically and laterally, the amount of water available from them depends on the location and depth of the well. Generally, the surficial sand beds yield about 10 to 25 gpm, and the aquifer at the base of the upper Miocene or Pliocene deposits yields between 15 and 20 gpm to small-diameter wells. As more information is obtained on these aquifers, it may be possible to determine the proper location and construction of wells to obtain more water. It may also be possible to recharge artificially one or more of the aquifers so that more water is available to wells. These aquifers may become a major source of ground water, particularly if the water in the underlying Floridan aquifer system becomes contaminated by salt water. The Floridan aquifer system, which is composed primarily of limestones of Eocene age, is the principal source of fresh water in northeast Florida. The top of the Floridan aquifer system, which ranges from 300 to 550 feet below msl, is overlain by an aquiclude of relatively impermeable clay, sandy clay, and dolomite beds in the Hawthorn Formation and in the upper Miocene or Pliocene deposits that separate it from the shallow aquifer system. Current-meter studies and information obtained while wells were being constructed indicate that there are at least three separate permeable zones within the Floridan aquifer system in northeast Florida. The first zone includes all the formations of the Ocala Group and, locally, limestone at the base of the Hawthorn Formation and at the top of the Avon Park Limestone. In the vicinity of Jacksonville, the second zone is in the top part of tie Lake City Limestone, and the third zone is within the Lake City Limestone, below a depth of about 1,200 feet. However, in Fernandina Beach, the Lake City Limestone contains only ore permeable zone, and a third zone is present below the Lake City REPORT OF INVESTIGATIONS No. 43 Limestone in the Oldsmar Limestone. These zones are separated by hard, relatively impermeable dolomitic limestone and dolomite beds. Water is generally under higher artesian pressure in the lower zones than in the Ocala Group. The deeper zones yielded 50 to 98 percent of the total amount of water from the wells tested in the vicinity of Jacksonville, and water was lost into the zone. in the Ocala Group from the deeper zones in the well tested at Fernandina Beach. The yield of water from wells in the Floridan aquifer system in the area depends largely upon the depth, the well construction, the artesian pressure, and the transmitting properties of the permeable zones. The natural flow of wells 2 to 6 inches in diameter is generally less than 500 gpm, and that of wells 8 to 12 inches in diameter is generally less than 2,000 gpm. As much as 4,000 or 5,000 gpm may be pumped from some wells larger than 12 inches in diameter that penetrate to the second or third permeable zones. Water enters the Floridan aquifer system in north-central Flor- ida through breaches in the aquiclude by sinkholes, by downward leakage from surface bodies of water or from shallower aquifers where the aquiclude is thin or absent, and directly into the aquifers where they are exposed at the surface. The water moves generally northeastward through the aquifer system into northeast Florida, where some of it is discharged artificially through numerous wells, and some is probably discharged naturally into the ocean off the coast. Cones of depression have formed in the piezometric surface in northeast Florida as a result of discharging wells which lower the artesian head and create a hydraulic gradient toward the discharging wells. Major cones of depression have developed in Duval County at Jacksonville and Eastport and in Nassau County at Fernandina Beach. The piezometric surface has been depressed to less than 30 feet above msl at Jacksonville and to riore than 15 feet below msl at Fernandina Beach. In parts of Duval and Nassau counties where the piezometric surface is higher than the land surface, the wells that penetrate t ie Floridan aquifer system will flow. The size of the area in Shich artesian flow will occur varies greatly with only slight c ranges in the elevation of the piezometric surface. Public water supplies in the vicinity of Jacksonville are c -tained from 46 municipal wells and more than 100 private utility 'vells that are drilled into the Floridan aquifer system. The smaller FLORIDA GEOLOGICAL SURVEY towns in the area and the three large Navy facilities also obtain water from the Floridan aquifer system. The three major paper manufacturers in the area, many other industries, and a number of the larger commercial buildings have wells in the Floridan aquifer system. Many private residences also obtain water from wells in this aquifer system. The total amount of water discharged by artesian wells is estimated to average from 150 to 200 mgd in the vicinity of Jacksonville and from 50 to 70 mgd at Fernandina Beach. Water-level records show an irregular but continual decline in artesian pressure in the area. The greatest decline is in wells in the shallower permeable zones in the Floridan aquifer system near the centers of the cones of depression. At Fernandina Beach, artesian pressure declined 50 to 60 feet during the period from 1939 to 1963, and at Jacksonville, artesian pressure declined 12 to 22 feet during the period 1946 to 1963. The piezometric surface declined 10 to 25 feet in all of northeast Florida during the period 1940 to 1962. During the period July 1961 to May 1962, the piezometric surface fell 1 to 10 feet because of below-normal rainfall and increased withdrawals of artesian water. Artesian pressure in the area will continue to decline if withdrawals of water continue to increase. However, the decline of artesian pressure does not pose an immediate threat to the availability of water in the area. A much greater danger is that highly mineralized water will enter the zone of reduced pressure and contaminate the existing fresh water in the aquifers. Water from most wells in the shallow aquifer system and in the Floridan aquifer system is suitable for domestic use and for most industrial uses. Water from wells in the shallow aquifer system is generally softer, contains less dissolved mineral matter and more iron than water from wells in the deeper Floridan aquifer system. Wells in the Floridan aquifer system closest to the recharge area in southwestern Duval County generally coritain softer water with less dissolved mineral matter than wells in the central and northern parts of the area. In the vicinity of Fernandina Beach, there is considerable variation in the quality of water from wel s of different depths in the Floridan aquifer system. Water from the deeper wells is harder and contains a higher dissolved-solics content than water from the shallower wells. The chloride content of water from wells in the Floridan aquifer system ranges from less than 10 ppm in the southwestern part of the area, where the piezometric surface is highest, to more REPORT OF INVESTIGATIONS NO. 43 than 40 ppm in wells less than 1,250 feet deep, and to more than 1,180 ppm in some wells more than 1,250 feet deep at Fernandina Beach, where the piezometric surface is the lowest. Except in some of the deeper weels at Fernandina Beach, the increase in chloride content of water from most wells in the area ranged from 2 to 14 ppm during the period 1940 to 1962. In many of the deeper wells at Fernandina Beach, the chloride content of water increased about 20 to 1,320 ppm between 1955 and 1962. The increase in chloride content of the water from artesian wells correlated with the decline of artesian pressure indicates that salt water is gradually moving into the zones of reduced pressure and contaminating the fresh-water supplies. At present, serious contamination is limited to a few deep wells at Fernandina Beach, where salt water is migrating laterally into the aquifer from a highly mineralized zone at the base of the Avon Park Limestone, and vertically from highly mineralized zones more than 2,000 feet below land surface. Contamination of the fresh water will increase in northeast Florida if the artesian pressure continues to decline. Further contamination can be retarded and even prevented if, in the future, wells are property spaced and their discharges controlled in a manner that prevents excessive lowering of the artesian pressure. The impermeable beds and the higher water pressure zones in the Avon Park Limestone, Lake City Limestone, and Oldsmar Limestone presently prevent upward coning of salt water from the lower part of the Floridan aquifer system. Careful well construction and proper development of these aquifers should be employed to keep these natural barriers effective. Contamination in some of the deep wells in Fernandina Beach may be retarded by casing off the highly mineralized zone at the base of the Avon Park Limestone. FUTURE STUDIES Many topics essential to completing the study of the ground- eater resources of northeast Florida are beyond the scope of this investigation. The findings from the following investigations to complete this study will be reported in the future. 1. A detailed investigation of the shallow aquifer system, particularlyy the aquifer at the base of the upper Miocene or )liocene deposits, to determine its potential as a primary or supplemental source of water. This investigation will include test FLORIDA GEOLOGICAL SURVEY drilling to determine the areal extent and thickness of the aquifers and pumping tests to determine their water-bearing properties. 2. Quantitative permeability investigations of each of the separate permeable zones in the Floridan aquifer system to predict the results of using water from the deeper zones and to determine the best method of developing these zones without causing salt- water intrusion. This investigation will include pumping tests to determine the water-transmitting and water-storing capacities of each of these zones and mathematical and graphic analyses of the aquifer system. 3. An investigation to determine the relation of water-level declines to the amount of water being discharged from the Floridan aquifer system in order to predict future declines. This investigation will include continued measurement of water levels and a detailed inventory of wells in the area to determine more exactly the amount of water being used. 4. An investigation to detect any increase or spread of salt- water contamination in the area. This will include continued sampling and chloride analysis of water from wells throughout the area. If possible, a deep well will be drilled near the center of the cone of depression at Jacksonville to locate the exact depth to salt water. This well will be sampled periodically at various depths to detect any vertical movement of salt water into the fresh-water zones in the upper part of the Floridan aquifer system. REPORT OF INVESTIGATIONS NO. 43 REFERENCES Applin, E. R. (See Applin, P. L) Applin, P. L. 1944 (and Applin, E. R.) Regional subsurface stratigraphy and structure of Florida and southern Georgia: Am. Assoc. Petroleum Geologists Bull., v. 28, no. 12, p. 1673-1753. Black, A. P. 1951 (and Brown, Eugene) Chemical character of Florida's waters, 1951: Florida State Board Cons., Div. Water Survey and Research Paper 6, 119 p. 1953 (Brown, Eugene, and Pearce, J. M.) Salt-water intrusion in Florida, 1953: Florida State Board Cons., Div. Water Survey and Research Paper 9, 38 p. Brown, Eugene (See Black, A. P., 1951, 1953, and Cooper, H. H., Jr., 1953) Cole, W. 1944 Stratigraphic and paleontologic studies of wells in Florida- No. 3: Florida Geol. Survey Bull. 26, 168 p. Collins, W. D. 1928 (and Howard, C. S.) Chemical character of waters of Florida: U.S. Geol. Survey Water-Supply Paper 596-G, p. 177-233. Cooke, C. W. 1915 The age of the Ocala. Limestone: U.S. Geol. Survey Prof. Paper 95-1, p. 107-117. 1945 Geology of Florida: Florida Geol. Survey Bull. 29, 339 p. 1929 (and Mossom, D.) Geology of Florida: Florida Geol. Survey 20th Ann. Rept., 1927-28, p. 29-227. Cooper, H. H., Jr. (See Stringfield, V. T.) 1944 Ground-water investigations in Florida (with special reference to Duval and Nassau Counties) : Am. Water Works Assoc. Jour., v. 36, no. 2, p. 169-185. 1953 (and Kenner, W. E., and Brown, Eugene) Ground water in central and northern Florida: Florida Geol. Survey Rept. Inv. 10, 37 p. Counts, H. B. (See Stewart, J. W.) Croft, M. G. (See Stewart, J. W.) D)all, W. H. 1892 (and Harris, G. D.) Correlation paper: Neocene: U.S. Geol. Survey Bull. 84, 349 p. )erragon, Eugene 1955 Basic data of the 1955 study of ground-water resources of Duval and Nassau counties, Florida: U.S. Geol. Survey open-file report. Florida State Board of Health 1960 Some physical and chemical characteristics of selected Florida waters: Florida State Board of Health, Bur. Sanitary Eng., Div. Water Supply, 108 p. hunter, Herman (See Sellards, E. H.) 'arris, G. D. (See Dall, W. H.) oward, C. S. (See Collins, W. D.) FLORIDA GEOLOGICAL SURVEY Leve, G. W. 1961a Preliminary investigation of the ground-water resources of northeast Florida: Florida Geol. Survey Inf. Circ. 27, 28 p. 1961b Reconnaissance of the ground-water resources of the Fernandina area, Nassau County, Florida: Florida Geol. Survey Inf. Cire. 28, 24 p. Matson, G. C. 1913 (and Sanford, Samuel) Geology and ground waters of Florida: U.S. Geol. Survey Water-Supply Paper 319, 445 p. Mossom, D. (See Cooke, C. W.) Pirnie, Malcolm 1927 Investigation to determine the source and sufficiency of the supply of water in the Ocala limestone as a municipal supply for Jacksonville: Hazen and Whipple, New York. Pride, R. W. 1958 Interim report on surface-water resources of Baker County, Florida: Florida Geol. Survey Inf. Circ. 20, 32 p. Puri, H. S. 1953 Z~nation of the Ocala group in peninsular Florida [abs.]: Jour. Sed. Petrology, v. 23, no. 2, p. 130. 1957 Stratigraphy and donation of the Ocala group: Florida Geol. Survey Bull. 28, 248 p. Sanford, Samuel (See Matson, G. C.) Sellards, E. H. 1913 (and Gunter, Herman) The artesian water supply of eastern and southern Florida: Florida Geol. Survey 5th Ann. Rept., p. 103-290. Stewart, J. W. 1958 (and Counts, H. B.) Decline of artesian pressures in the Coastal Plain of Georgia, northeastern Florida, and southeastern South Carolina: Georgia Geol. Survey Mineral Newsletter, v. 11, no. 1, p. 25-31. 1960 (and Croft, M. G.) Ground-water withdrawals and decline of artesian pressures in the coastal counties of Georgia: Georgia Mineral Newsletter, v. 13, no. 2, p. 84-93. Stringfield, V. T. 1936 Artesian water in the Florida peninsula: U.S. Geol. Survey Water-Supply Paper 773-C, p. 115-195. 1941 (Warren, M. A. and Cooper, H. H., Jr.) Artesian water in the coastal area of Georgia and northeastern Florida: Econ. Geology, v. 36, no. 7, p. 698-711. U.S. Department of Health, Education and Welfare 1962 Manual of individual water supply systems: Public Health Service Pub. 6, no. 24 Vernon, R. O. 1951 Geology and Citrus and Levy counties, Florida: Florida Geol. Survey Bull. 33, 256 p. Warren, M. A. (See Stringfield, V. T.) I ' TAsLE 8, Recoid of wells in Duval and Nassau counties. Well number: See figure 1 for explanation of well-numbering system. Owner: C, county; I, industry; M, municipality; 0, church; P, pri- vate; S, State; U, U.S. Government. Depth of well: Reported unless otherwise noted by M, measured by U.S. Geological Survey. Well finish: 0, cased to aquifer, open hole in aquifer; S, sand point. Method of drilling: C, cable tool; J, jetted; R, rotary; X, other or |; unknown. Type of pump: C, centrifugal; J, jet; N, none; T, turbine. Use of water: A, air conditioning; D, domestic; F, fire protection; I industrial; M, mining; N, none; P, public supply or municipal; irrigation; S, stock; T, test or, observation. uifer(s) : D, Floridan aquifer (deeper than Ocala only); F, Flor- idan aquifer (Ocala Group); FD, Floridan aquifer (Ocala Group 'and deeper than Ocala); Sr, shallow aquifer, rock well; Ss, shallow aquifer, surface well. Casing .--i *Wsi i &I b mbr I i: \ i^'**'' 5s s ooo < Altitude of land surface: To tenth of a foot if determined by precision leveling; otherwise, to nearest foot. Water level: To tenth of a foot if measured by wet-tape method or if taken from recorder chart. To nearest foot, if measured by pressure gage or air line. P, periodic measurement; R, recorder on well. Date of measurement applies also to temperature, chlor- ide, specific conductance, and hardness, unless otherwise noted in Remarks column. Chloride: P, periodic determination. Chemical analyses available: C, complete; D, complete and radio- chemical; M, multiple-complete and partial; P, partial. Yield and drawdown: Reported unless noted by M, measured by U.S. Geological Survey; F, yield by natural flow; P, yield by pumping. Remarks: W- or Wgi-, Florida Geological Survey well number. Logs available: A, chloride or conductivity; C, caliper; D, drilling time; Dr, driller's log; E, resistivity and/or spontaneous potential; L, geologists's log and/or samples; V, current meter. 'TABLE 8. (Continued) 008-180-810 P 008-184-120 P ?008-1i5-40 P 0016-244 0 1009-187-120 p |009-189-280 p |09-40-240 P 011ii1i-141 U C12-137-221 P TIl Only the earliest and latest measurements and chloride values are shown on table. 1960 1 500 D F D F D F Jr iji- -- 645 4 1961 1955 1936 1958 1946 1940 1956 200 337 500 457 425 252 0 0 0 0 0 0 0 0 0 O 0 0 0 0 O I 487 600 900 650 556 100 661 403 X N X N C N X N R N R - X N X C X C X N R C R N J N S' D D P DR DR DR N DR DF D F F FD F F F SR F F F 23.6 28.6 26 22 38 16.5 2.1 25 20 16.1 10 650 I I- 31.3 18.5 28.0 20.5 17.2 17.7 18.6 16.3 12.0 25.5 20.5 21.7 35.8 23.7 20.3 13.1 50.0 41.8 20.0 12.0 8.8 21.0 10.0 28.0 16.4 17.5 15.8 31.5 18.6 9-23-40 1- 4-60 9-27-40 1- 460 7-1161 5-14-62 1- 6-60 7-11-61 5-14-62 11- 1-61 5-14-62 1- 8-61 9-28-40 1- 7-60 7-11-61 5-14-62 9-28-40 1- 7-60 3- 1-61 5-14-62 3- 1-61 1- 5-61 5-14-62 8- 7-40 10-13-55 1- 4-60 5- 7-62 1- 5-61 5-14-62 0': : : mrl 0" 1 I.' 01 31 23 21 10 15 24 21 15 12 12 13 W-8464, L C1, 11-4-56 71 S2OFM TAsIL 8, (Continued) Cuing I ' 461 4 0 R N D 510 4 0 R C AFRI 380 12 0 R C PF -- 10 0 R C PF 318 12 R C PF 400 12 O R N - 10 0 R PF 286 8 0 -. DR - 0 X P 467 20 0 R N N 439 10 0 R N N 485 20 0 R T PF 520 18 0 R T MI F FD FD FD FD PD FD SR FD F FD Water level Iv a ^ - - j~i d - ++1 9 J 1 -=S~r l 25.2 28.6 P 7.4 -- 4 9.2 45.2 37.2 30.3 26.0 20.9 23.0 11.3 16-20 - 79.2 -16.23 16 - 79.8 -2S.72 -26.12 -29.54 80 - 85 -28 50 3.35 7-30-40 5- 1-12 3 5.40 1-1440 7-12-1 5-17-42 1-14-40 5-17-62 -- I 5-19-41 10613-0 5-1742 11- ?-V5 3- 1-61 I C C C I a f .8 76 3,000S M 4,JSOFM i--I--- 4,150rF 780P i--- 1,OOOP 1,i000P 2,000PF * 018135-230 S013.-1-400 013-140-414A 013-140-414B 013-141-441 013-142-214 013-158-240 014-141-220 4-143-130 014-153-111A 014-1053-l1B 014-153-20 01 -1334,1 1957 610 1940 1,005 - 708 1940 1.015 21 35 U 1942 U 1941 P 1922 P - U 1944 U 1942 U 1956 P 1957 988 990 669 185 1,005 780 1,305 1,246 Remwks L CI, 11-15-40 W-514, ; CL 11-15-40 V461, L W-561. L W.581,. L W-2T, L L W-731 W-4113, L t I -. : __ __ _ -- ----~-- 015-138-443 015-188-314 015-138.410 ' 16-5-141-111 015-145-230 015-145-330 i016-125-431 ;016-137-100 0 42-414 17-126-282 017-126-440 S017-180-442 oi7-134-210 '01 -134-31 017-135-413 017-186-124 P P P P P P P P P P M P P P P P C P 520 18 470 6 1967 1954 1949 1938 1961 1923 1924 1959 615 332 -_ 70-100 _ 1953 733 531 - 99 - 1928 729 476 1939 550 400 480 1960 1,004M 487 1939 675 -- 1939 785 524 56 O 0 R R 1,254 194 1,264 1,187 600 1,000M 1,920 1.690 T MI N DR T P N DN 757 470 460 800-1,000 0 R 0 X 0 R 0 X 0 R 0 X 0 X O X 0 X 0 X O X O R 0 R O R 0 J N- P N DR J ]N FD 5 FD 22 D 14 F 8.6 FD 33 FD 64.9 F 4 SR F SR F 16.2 F 11.6 F F 40 FD 13 F 24.1 P F N S 26.7 -10.3 -19.6 19 11.9 23 41 P 16.4 S 7.36 -3.6 R -17.16 383 29.4 11.7 Sl2 40 P 9.2 40.6 32.3 22.3 2-3 1.6 - 1.34 29.5 418 4.9 26.8 23 -14.76P I '-19.25 T P N T C P J DN C DA 3- 1-61 5.14-62 2-24-61 5-14-62 5-22-62 7- 5-40 5- 9-62 5-17-62 4-16-41 5.2-62 2-27-61 5-15-62 2-24-61 7-12-61 5-22-30 5- 9-62 9- 6-40 1- 7-60 5-15-62 12-19-61 5-15-62 6- 7-39 1- 5-60 5-14-62 6- 5-39 2-28-61 5-14-62 21 25 20 20 19 10 15 13 is 17 20 21 IS 24 22 15 13 74.5 _ 2,OOFM 950 400F C C - 2,00 71.5 4751 C C C L; Clf, jZ-,o0 Cl. 10-13-55 L, Dr; CI 11-15-40 2,600P 960 - 2,T00FM _ 450FM _ D PN D P DN Ocala Group csed of L Plugged at 1,920feet ReAord, record 14 a.r. CL 10-T-55 " s&; " " I rM TABLE 8, (Continued) Water level Casing 0 x 81 i j J 111K, sb. S .1 troiber 4 ^ S u a o j 017-136-241A 017-186241B 017-137-214 017-138-142 017-158-110 .017-158-480 018-123-128 018-124-222 018-131-240 018- 1-438 S1-136-241 777-aeu 1957 1957 2I. 245 1962 1,210M 1955 1,500 715 750 585 622 1,002 600.650 685 1957 1942 1934 1938 1959 515 200 530 500 465 433 357 382 427 508 1% 0 PN -* f=A a-l r 8 s 3 1 F 11. F 10 FD 42 F 17 F -- 803 9278 30.3 R 9-27-60 19.5 5-14-62 2-18-61 5.14-62 3- 6-57 1-11-61 5-1762 10.14-39 5-19-62 12-12-38 9-27-60 - 6.29P -13.18 1-35 -25.06 -29.4 42.4 P 21.6 40.3 19.2 R 4,$ 0 %. A' -- 3,501 3,25 .OFM C 4 .3 em Remairku SPressu re. border in- staled 9-2.6 60, removed 2.3-62 L V (incom- plete) W-4202 W-392, L L,Dr. Pressure r.- corder in- stalled 9 2760, re- moved 10- 31-61 0, 5< 3.ltoI~b 72.5 018-136411 P 1018-138-343 M 018-139-230 M (010-139-233 M 018-140-123 P 018-142-210 M f," :.. ', 018-143-234 M 08-145-140 P 019-124-210 M 19-182411 P O19-183-48 P 019-134-10 P 09-135430 P 019-18o-8 P 01-14-10 P -- 630 1939 1949 1935 1943 1939 1959 1931 1948 1937 1938 1962 1929 1929 1938 1,071 1,348 583 1,307 1,037 1,280 736 1,247 900 80 650 1,300M1 762 875 635 200 -- 3 505 10 500 10 508 10 3 18 5 6 S3 16 O 1 0 R 0 X 0 X 0 R 0 X 0 X 0 X 0 R 0 X 0 X 0 x 0 C C D T P T P T P N D C P N PN J DA N R DR DN FD 20.5 FD 7 FD 5.1 F 4.5 F 14 FD FD 24.6 SR - F 12.6 F 10 FD 12 F 38.4 53.04 24.1 27.9 14 1 30 17 16.9 43.9 39.1 35.3 43.2 P 18.2 30.7 P 10.1 41.5 32.6 20 42.9 34.8 30 17.7 7.3 1.8 P -21.94 31.5 20.2 9.5 2-22-39 1- 5-60 5-15-62 3-23-39 1-12-60 7-13-.61 I---- 3-23-39 1-12-60 7-13-60 11-26-34 5- 9-62 11-28-40 5- 9-62 2-25-39 1- 7-60 5-15-62 2-25-39 1- 7-60 6- 4-62 6- 7-39 11-18-60 6-10-39 5- 9-62 6- S-39 1- 6-60 5-1662 75 1,700F 5,000FM CI, 10-7.-5 CI, 10-14-5 i _I CI, 10-6-55 -22, L; CI. 11-7-40 11-T-40 W CI, 5-21-41 , W-169, L CI, 104-55 Q A. C, E. L. V, packer li testsA C CI, 2119-40 ( TAsLN 8. (Continued) - 019.188.820 1i9.189.124 019-189-230 19-140421 19.1242111 119-143-181 119-146-40 '. 9-.147-210 10-134-34 20-183-.240 Cuinir 4 I I I I I 1 1942 1961 1939 1954 1,074 753M 655 760 785 1911 1,075 1938 1929 1,.060 1936 765 1932 O 0 O 0 0 0 0 0 0 O O O 0 O O O O s 8.20 Ii I(DI I DA DR PRA T PN I DR D DR DR FD 4 F 22.1 F 3.5 F 4 F 8.3 FD 22.8 F 21.9 F 44.1 59 30.3 34.2 Water I1p 3L; a J 42 -0.1 30.3 19.5 82.1 PR 13.3 39.2 P 13.2 36.8 25.5 15.1 4.45 3.97 1.88 3.1 30.8 10.7 11.8 5.67 23.5 12.8 2.1 level -o LI f ^ i : I l 7-20-42 11-25.38 5- 9-62 8-13-30 5- 9-62 7-16-40 1-13-60 7-2340 1- 3-60 12-2240 7-14-61 7- ?-29 6- 8-39 1- 640 7-1241 5-1642 6-11-39 1- 6-60 515-62 2,000F 1501FM 72.5 - 76.5 - I I I I I I W449. L L, D L, Dr L. Dr CI, 10-1530 CI, 10-12-5 Cl, 10-12-55 W.116, L CI, 10-14-5 I ~---~------ I f I I i-_~ L -- P ,h;r ~ t I n r -~ L I i I 1 I a'd 0 0 d ? Remarks || I s ,i i 4020-1368-44 P 1940 020-187-340 P nlaa.1-132 M '1911 l020-1394223 :i2O-139-448~ ,020.140-430 P 020-144-430 P id21428-183 P 021-125-421 021-182-410 021-183-220 '0-186-4800 .021-188-121 1936 1907 1923 6UO 5d0 1,016 1,035 980 1,260 - 1,150 630 1937 575 1961 703M 1987 540 1963 610 1938 90 1,060 396 475 522 543 3 4 10 10 10 6 6 8 3 4 10 O X 0 X 0 X 10 10 N It F 29.4 C I F 14.7 N PN FD 5.9 C P C P N I N DR N R X x x x x R X J X 5.5 4 24.1 24.7 9.1 7.0 17.0 15 16.7 23.5 15.5 9.2 6.8 40.0 34.5 18.0 36.8 30.3 18.3 35.5 49.0 36.8 33.5 34.2 27.3 25.2 14.6 25.9 18.6 11.9 48.6 34.4 26.3 32.3 26.5 37.7 21.3 81.4 23.3 39.5 27.2 16.1 8-23-40 1- 6-60 7-12-61 5-15-62 2-16-34 7- 4-40 5-21-62 6-16-39 1-12-60 5-24-62 9-28-36 6-13-39 1-12-60 7-18-61 5-24-62 2- 0-89 1-11-60 5-17-62 7-23-40 1-18400 5-18-62 2-25-39 1- 7-60 5-15-62 5-19-61 5-16-62 8-24-40 1- 6-60 9-28-40 5-16-62 2- 7-39 1-12-60 5-21-62 14 21 20 18 23 13 16 21 24 17 17 22 24 17 18 11 16 18 17 15 18 22 29 22 22 20 22 20 24 13 23 21 76 S77 77 S1,135iP 83 - 83 200-300F 81 - 72 - - 930FM SI- - 78 2,160F --- -ii CI, 11-4-65 CI, 118-55 CI, 11-740 CI, 5-21-41 W-304, L CIL 11-740 C, 10- -55 : CEl 11-1-40 CI, 10-7-55 , z* , , D CI, 10-14-55 CI, 11-13-40 /'- N DR J DR C R TAra 8, (Continued) ;: .. .. .. Cu*ing 31.2 24 14.4 23.0 35.2 27.7 18.9 40.8 26 20.11 32.9 7.2 37.7 26.8 15.3 37.3 25.9 22.5 15.7 26 19 7- 1-40 1-12-60 5-21-62 2- 8-62 7- 1-40 1.11-60 5-2162 &-14-39 1-12-60 5-24-62 6-14-39 9-25-60 2- P-39 1-12-60 5-21-62 2-11-39 1-12-60 7.1.-61 521-62 1-12-60 6524-62 Water lIvel Sa- 4 I ji ~ '~: JA 111 'Sii i +.i 1 5 J . Pg I emrk 78 80 78 76 1.900FM 1,500FM 900F 2,000P 473 550 530 513 462 510 469 I 7Y ^JS CI, 10-5-55 L, V Cl, 10.5-5 CI, 5-2141: W-830,.L L V '" L. Dr1 ' Cl, 10-5-5 CI, 10.5-55 W-532, L 0214,-1,20 :02149-424 0214141414 021-141423 021-142-100 022-180-112 ,.A' : ' 022-188-400 022-189244 p22-140-10 022-148-320 4222 loe at,.,: 1939 1962 1939 1939 1941 1959 1923 1915 1951 1940 780 1,803M 1,053 1,055 1,356 800 1,076 700 1,303 690 0 0 0 0 0 0 0 0 0 0 O -. --I. 1,020F .. - N N D C P _ R 21.8 20 19.0 16.4 24.4 89 19.2 16.4 FD 22.4 F 10.5 .. . I____I___ --- -~- ' 1 |022-147-240 "028-125-142 023-129-830 S';: '. . i -1: 22 0S4-128.233 04-136-130 0p4-141-340 ,024-144820 o2-126-281 025-132-444 025-186.220 '0251810 026.13z8-l 210i 1953 1962 1,001 . 1939 510 1930 1925 200 905 435 - 570 1940 700 560 -- 70 1939 625 1930 840 1910 1942 556 942 c- 500 450 660 630 3 18 6 2 4 8 3 38% 6 2 3 8 4 8 8 0 0 0 0 0 0 0 0 0 0 0 0 0 O O O O O O O O O O O O N S X R X X X X X X X X X X X X X J DRF N R N C N N N R DR D F 23 24.5 10-19-40 18.6 5-17-62 FD 6.7 30.3 5-16-62 F 8.0 41.3 6- 9-39 36.4 1- 7-60 SR ____- F 3.12 53.2 P 6-12-39 FD I 14.9 F F F SR F 6.0 4 29.2 20.7 DR IFD 15.7 DR F IN F PRI FD 4.2 8.8 19.9 32.2 47.0 PR 23.7 43.8 P 28.8 28 28.0 P 3.4 35.3 23.3 17.0 45.2 P 25.8 42.3 36.2 44.5 P 18.3 21.7 23.6 18.5 5- 9-62 6-22-30 5-10-62 7-27-40 5-10-62 5-21-62 6-25-40 5-18-62 7-24-40 1-18-60 5-18-62 8-19-30 5-10-62 1-21-60 5-21-62 3-22-51 5-10-62 1-20-60 7-13-61 5-18-62 22 23 21 16 16 15 18 18 19 20 90 122 35 25 25 28 25 C CD - 2,500F 73 - 73.5 75 - - 80-- PF N sj 1929 800 19290 800 W-5823 Flowing wld; Cl, 11-19-40 Cl, 10-7-55 ; Trit'dmn, ,ta 1-edl-60 - 62, 0-12removed 26-82; ,j, 5-20-41; Tritium CI, 1-7-80 Flowing wild Cl, 10-12-55 ' Cl, 11-21-40 Cl, 19-601 CI, 3-8-60 00' TAPLI 8. (Continued) 1, Cuasing It - i Well '' number 03*288888 1 02141400 026-185-842A 26.185-42C .02614110 .& S-i4t-i ,ii&13 ', ', O1 8P Ia - Water level c S, 14.5 31.15 29.5 24.5 17.7 39.2 26.8 25 .. 12.2 42.1 36.5 30.0 0 X C PRI FD 0 X N R F O R C P FD O X C D F O R N T FD O R N T D 37.0 P 22.5 33.1 P 23.2 32.9 P 22.2 28.8 27.72 17.8 1-20460 7-18-61 5.18-42 6-12-40 1-18-60 0.12-40 1-19-60 5.21-62 6-12-51 5-10-62 1-13-54 6-10-62 1-13-54 5-10-62 5-81-56 4-20-56 5-24-62 C., a a a i a - 1,830F 1,830F 4,800FM 930F 6,700 456F '5- 'a YI be 17.3 16.96 16.87 16.2 14.1 25.2 1941 1982 1962 1921 1,019 725 1,280M 455 IT 1951 1,393 1,025 700 1,878 1,390 700 1956 1956 1952 Reasrksu W-M44, L Cl, 11.14.40 CI, 10.-35 L, V Cl, 11-21-40 C,. 6-20-41 CI, 10.25-55 w.-60 L, v, E; Cl, 1-7-60 L4 Dr; Oeala Group eased off;: C, L, Dr;CI, 12-9-0 W-8974, L W-3869 :, 1 . W-2410,' '. . 02145-100 026-145420 027-184-220 ; I : :. 027-148-314 I28-187-884 J 141-888 142-240 p032-1837-410 0 , 1954 1917 1936 P _19 __ 8 P 1985 485 -- 3 750 658 642 610 0 0 0 0 0 0 0 0 O 25 23.6 20.8 21.8 34.8 22 27.2 27.8 84.3 21.1 15.0 35.0 P 18.4 35.1 16.2 22.2 P 5.58 18 12.7 22.8 16.4 11 530F 1-11-56 1-18-60 7-24-40 1-18-62 5-18-62 6-26-40 5-10-62 6-24-40 1-18-60 7-2440 5-10-62 4-25-62 4-25-60 1-16-40 10-25-55 1-18-60 028-156.100A P .. 96 96 1% S X D SS 66 1 4-9-34 70 - 08-i6-100B P 1928 201 100 2 0 X D SR 68 2.5 4- 9-34 C 70 028-166-480 P 1900 650 6 0 X J D F 69 0.0 3- 1-51 C -- 0-148-120 P 500 -- 8 0 X N D F 20 22.7 5- 9-62 - s -12-142 P 1937 680 4 0 X N D F 13.70 41.75P 3-24-39 23 72 01,11-23-40 18.8 5-10-62 26 CI, 3-8-60 28 CI, 9-19-60 82150-300 P 500 3 0 X N DS F 20 27.7 1-12-61 31 - -149-140 M -- 600-800 0 X P F 20 -- --. C -- 150-242 P 1938 580 2 O X D F 18.8 40.2 P 1-18-40 26 ..- 72 C1, 11-22-40 25.2 5-10-62 31 W-3345 CI, 11-14-40 CI, 10-12-55 CI, S-8-60 CI. 9-19-60 CI, 11-1440 CI, 10-12-65 5 c01, 5-18-62 CI, 11-1440 Flowing wild; ' CI, 11-14-40 ;,B>1 3 1^ a' CW 00 TABB 8. (Continued) Si number S I: i __ 0( a ____ 084.-11.438 084-186.288 0365-127.810 685-127.3o0 0835-127.410 08-1855-811 087.126-214 807-180-330 f';^.' P 192 800 ... 8 0 X P 192- 480 2 0 X 1982 1932 1953 1989 1927 1940 580 540-40 580 905 578 540 850 850 480 8 504 8 8 3 16 3 2 2 N N N N N N N N D D R D R I DR DRS D F SR F F F F F F F ,1i lag .s8 9.9 14.7 15.4 25 16.9 6.0 12.6 Water level 00ii sa(^ 22.2 P 10.0 41.1 P 19.8 89.7 38.5 21.8 36.8 4.0 2.5 3.77 - 0.67 46.3 4.9 8.8 7.4 4.55 26.7 P 9.3 5- 8-62 5. 8-62 3-23.39 5-10-62 8-22-89 3-23-39 1-25-60 8-25-89 9- 8-55 11- 4-59 1-25-60 5-21-62 3-28-89 9-15-55 11- 5-59 1-25-60 6-21-62 6-26-40 5-10-62 k U 9d R rIs 0 -s .g g I ^5 JlItemarka 3J 71.4 72.6 73 865F 72.5 - 71.5 May be Flori- dan aquifer, leak in easin Cl, 11-28-40 CLI 12-9-40 Cl, 9-555 Cl. 9-7-55 : O W-2964,'L CI. 11.28-40 Cl, 11-23-40 C 11-2-40 .112 'i !! r u" ,, 087-142-480 088-126-820 *, 088-127-142A 012' i * 'i . 038-127-142B '7/i , I1 P M I I P M 1988 11,208 1940 12,130 X X C N T T N I DR P 34.8 17.8 15 19.1 19 8.22 P 11- 1-60 19.2 P - 2.34 40.3 P 20.9 R R 1-16-40 5-10-62 1-18-40 5-10-62 28 33 24 81 27 29 80 1,680 1,180 26 27 29 29 74.5 71.5 -- S 1,284P S1.900F 1946 1962 1940 1,826 1,100 1,100 3.72 -22.2 P -24.66 10- 5-61 11-10-59 5-10-62 BC MC iLIC ---------------------- -- C1, 9-10-42 Cl, 1-8-62 Cl, 11-23-40 W-4810, L, Dr; Cl, 8-20-57, : . CI, 4-1-59 Cl, 10-28-59 W-890, L, A,:, E, V; packer teets i completee'.& ' analmsa, artesian, head and flow mea- sureuients : . made at: ' different' ', depths while the, weU was being drilled in ' 1940. Pack-.,: er tests and' current-, meter tra- venes made, P 1 In 1945. Plugged at , 1,826 ft, CI, ' 5-862 Plugged at 1,100 ft Cl, 11-29-40 Cl, 105-42 Cl, 12-27-60 Cl, 9-662 : ; ' I I I r I n I -- . .~.. TABLm 8, (Continued) Well number 08127.3380 08-127.344 08-,1456 30 89-127-111 039-127-120 '039-127-821 39-i ,27-44 o80-127-844 I A Casing I : I I I -1 1* 1 -1 -1 1 P P D I 1PM 1938 192- 1988 1946 1987 480 1,100 1,700 750 1988 11,072 1946 I 1938 1946 1,840 1,073 1.820 ;iL--. --~-- 2 2 26 8 26 26 x X R R R R DN D DS I Water levre 0 ;* 2.~ %j 8" I__ I s I 4:11 ~ CI O- P 9.9 2.67 -- 2.64 5.05 1.46 5.46 13.0 40.9 P -12.64 15 6.8 15 13.7 18.1 32.4 43.5 34.9 37.4 34.5 11-28-40 9- 8-55 11- 4-50 1-25-60 5-10-62 8-25-39 5-10-62 5- 9-62 8-15-39 11-80-40 3-15-39 3-15-39 30 28 62 38 33P 56 26 33 32 34 33 P 140 33P 168 MC MC MC MC I I I -" I" -- I- 75 1- - 1792F 1,880F Remarks Cl, 4.T-48 Cl, 10.T-48 Cl, 11.10-59 Cl, 2.15-38 Cl, 561-62; deepeed to rr 1,700 ft W-.343,L CI 4-1-59 Cl, 10-28549 Cl, 5-31-62 Wgl-10, L, Dr. C, 2-15-88 Cl, 5-7-62; Wgl-12. L, Dr; CI, , 6-2M87 l, 541-62; deepened I ! i - - I I I i r ' 16 b Ao to bzo, to go"-4 t 1 toP to to toZ to to to ~ Ii~ t __4 J4 -4. o .410 to-to to V co- to -t t. oAf to o cc Go a*o & ct tGo 0 to' tO to I to I I to to E ra -3 C) OO o" to I O co 1 0. qO C. 0 .0 co I M 0 to to t a* t to to to to o to C-a W Got o Cp CA 00 0 0 00 0 0 0 0 0 0 0 u tj ti ti to Z Z m m P4 Ilibi0) c ft h ft N ft to cn I to 42 t to 0 1. to goto W.-W M CD -i0 Dot toI to t aq to ba 66 tR o .3..) toFlo a 8 r -1 til 1 1 IbI Ito V V b C mt oto -1 r o o p 7 1,O6 to I ~ P~ OtloC toto 00.o to -tttotlM toG oo aloao t 34 CA co to to Io P. c o Wc c c o fm ot Mot tot C"t to wc I- to . 0 0 34 34 34 0 0 co N0 1~ UOO ~g Ii Oa CI I W ~ ~ I I C H~~ IIH I Q ca g$ g g ma B! II I I I I I I I lii II I I I I I pa' to 914 a D. 9 r_ tot ---tot *0 to3'r 99~ 68 Q O6r SN9Th tIaSAI &OMa -J - TABsL 8, (Continued) t v fa IJ I 1936 I 1959 1959 I 1965 I 1930 040-188410 041-126-888A 041.126-88833B 041-127-142 041-127-322 041-127-430 041-1M7-220 F 0 t 500 -- 2,100 1.450 1,961 1,328 1,408 550 753M 1,410 450 510 550 Caming a 2 80 20 3 4 0 0 0 0 x R R R R R Fl c o : - p I I I IN I N D FD F? F FD F F; ;p i B4 'S.8 19 19 - -I_______ I I Water level 23.4 9-14.55 23.3 1-20-00 15.4 5-22-62 41.3 6-21-39 9.36 9-14-55 3.01 11- 5-59 1.24 1-25-60 -11.25R 11-18-60 -22.43 5-21-62 30.9 10- 9-58 26.1 6- 9-62 aa . C.. 20 35 33 80P 97 142P 165 36 36 02 95 20 34 33 I I I I _ - 72 MP -- C 76 75.5 90F V I .h a,,,, m I I CI, 11-22-40 Oeala Group cased off; Cl, 2-1-61; A (5-ft. Interval) CI, 5-17-62 CI, 11-12--0 Cl, 6-17-62 This well may not be corn- pleted in the Flor- dan aquifer. w:" CI, 5-2162 Float r- corder In- stalled 11- 18-60; E; ; Cl, 6-21-62 CI, 10-7-61 CI, 2-13-62 Cl, -17-62 ''' 1955 r ~---- --'~--''--------- -------------------- ------- ------- ---------- I I I I I I I I I I1C 90F '.'.." .. 3 0 R N DN F 80.7 -21.54 6-19-44, u... re- corder in- stalled 6- : 19-44, re- moved be- tween 1953 - 1956 -26.24 1-20-60 41-165421 M 1955 821 448 10 0 R T P F 80 -- -- C W-3586, L; chemical analyies- S*'4-2-59 041-155-424 M 1961 738M 520 16 0 R T P F 80 -.. 350P 10 2 L l042-125-888 S 1988 800 550 4 0 R N PN F 7.8 48.1 P 8-27-39 82 72 270 W-891, L; Cl, 8.64 5-21-62 40 11-23-40 .042-127-884 S 800 584 4 0 X C PF F 7.5 44.3 8-27-49 28 72 270FM L, Dr; Cl, i 1-25-40 38 01, 5-15-59 82 Cl, ,11-459 84 Cl, 5-21-62 042-127-448 S 1938 800 520 4 0 X C PF F 6 42.7 3-27-39 30 72 245FM L, Dr; CI, ;;.:* 9-8-65- * 238.2 1-16-40 32 Cl, 5.15-59 32 Cl, 11-4-59 , (042-154-480 U 1960 700 405 8 0 R T PFA F 52 8.82 10-21-60 32 -- 0? 6.07 7-18-61 g;| 8.06 5.22-62 34 "643-187-441 I -- 3 0 X N D F 14 17.2 5- 8-62 37 - ,044-141-430 S 8 0 X C P F ? 15 32 C --- May not be completed in Floridan " aquifer; Cl,. 4-10-59 044-156-100 P 1940 4,824 4,645 6% R N T FD 99.2 ---- 33,600 C W-336, L. Analysis of water sam- , pie taken at 2205-2230 ft below land- surface datum. Cl, 8-24-37 co 04-158-800 P 450 8 0 X C D F 60 5.7 5- 9-62 46 -

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