U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY


MAP SERIES NO. 138


FLORIDA DEPARTMENT OF NATURAL RESOURCES
published by FLORIDA GEOLOGICAL SURVEY


890 88 870 860 850 840 63 82
II I I I I I I I


81i 800
I I 1--


EXPLANATION


POTENTIOMETRIC SURFACE OF THE
UPPER FLORIDAN AQUIFER IN
FLORIDA, MAY 1990

By
G.L. Barr

Prepared by the
U.S. GEOLOGICAL SURVEY
in cooperation with the
FLORIDA DEPARTMENT OF ENVIRONMENTAL REGULATION
and the
FLORIDA DEPARTMENT OF NATURAL RESOURCES
FLORIDA GEOLOGICAL SURVEY
Tallahassee, Florida
1992
ISSN 0085-0624


--- 20 POTENTIOMETRIC CONTOUR-Shows altitude
at which water level would have stood in
tightly cased wells. Dashed where
approximate. Hachures indicate depressions.
b ^ Contour interval 5, 10, and 20 feet. Datum is
0- O sea level. In this report, sea level refers to the
National Geodetic Vertical Datum of 1929
-20 (NGVD of 1929).

S O Note: The potentiometric contours are generally
to portray synoptically the head in a dynamic
30 hydrologic system taking due account of the
variations in hydrogeologic conditions such as
S differing depths of wells, nonsimultaneous
0 measurements of water levels, variable effects of
I30 pumping, and changing climatic influence. The
0'A potentiometric contours thus may not conform
exactly with individual measurements of water level.


ODt


290


28


270


250


INTRODUCTION
This report defines the potentiometric surface of the highly permeable
Upper Floridan aquifer of Tertiary age for May 1990 and describes changes in
this surface from May 1985 to May 1990. The potentiometric surface is the level
to which water will rise in tightly cased wells that tap the Upper Floridan aquifer.
The surface is mapped by determining the altitude of water levels in a network
of wells and is represented on maps by contours that connect points of equal
altitude. The potentiometric surface was constructed from water-level data
collected at more than 1,300 wells during May 1-29, 1990. Contours that
represent the potentiometric surface and the water-level data shown on the
hydrographs in figure 2 are referenced to sea level.
This report is the fifth in a series of map reports that describes the
potentiometric surface of the Floridan aquifer system in Florida (Healy, 1962;
1975; 1982; Barr, 1987). Most of the data used in the preparation of this and
previous map reports were collected as part of the continuing program of
monitoring the ground-water resources of Florida in cooperation with the Florida
Department of Environmental Regulation, the State water management districts,
and local government agencies. Major features of the potentiometric surface of
the Floridan aquifer system have previously been described by Cooper and others
(1953) and Stringfield (1966), and more recently by Bush and Johnston (1988).

FLORIDAN AQUIFER SYSTEM
The Floridan aquifer system consists of a thick, hydraulically connected
sequence of Tertiary carbonate rocks that extends throughout the southeastern
United States in Florida, southern Alabama, southeastern Georgia, and southern
South Carolina (Miller, 1986). The system consists of the Upper Floridan
aquifer, middle confining and semiconfining units, and the Lower Floridan
aquifer. According to Miller (1986), neither the boundaries of the (Floridan)
aquifer system nor of its component (aquifer) zones necessarily conform to either
- formation boundaries or time-stratigraphic breaks.
Limestone and dolomite rocks that constitute the aquifer system generally
range in age from middle Eocene to Oligocene in most of the State, although
units of early Miocene age occur locally in the Floridan aquifer system in the
central-coastal panhandle and in the Hillsborough and Pinellas County areas.
Changing depositional environments, karst development, and other erosional
processes during past geologic times have resulted in large variations in aquifer
system thickness. Thickness of the unit in the panhandle varies from about 100
feet or less (Escambia and Okaloosa Counties) to greater than 2,300 feet (Wakulla
County). Throughout the remainder of the State, thickness is variable, ranging
from about 100 feet to more than 1,500 feet (Miller, 1986, pl. 28). More detailed
descriptions of the Floridan aquifer system are in reports by Miller (1982; 1986).
Rocks that constitute the Upper Floridan aquifer generally crop out in a
50-mile-wide band along the western gulf coast from Wakulla County in the
northern part of the study area to Hillsborough County in the southern part where
the altitude of the top of the aquifer generally is less than 100 feet above sea level.
The altitude of the top of the Upper Floridan aquifer in northeastern Florida
ranges from near sea level to more than 500 feet below sea level. In northwestern
Florida (Escambia County), the altitude of the top of the Upper Floridan aquifer
ranges from 100 feet above sea level to more than 1,800 feet below sea level.
The altitude of the top of the Upper Floridan aquifer is near or above sea level
in an area along the gulf coast and most of central Florida between latitudes 30N
and 280N. South of latitude 280N, the altitude of the top of the Upper Floridan
aquifer gradually decreases from near sea level to more than 1,100 feet below
sea level.

POTENTIOMETRIC SURFACE
Data used to construct the May 1990 map of the potentiometric surface
shown on the large map were obtained from published reports (Knochenmus,
1990; Murray, 1990; Meadows, 1991a, b). For the area generally south of
latitude 270N, no interpretation was made because of a lack of water-level data
from wells open only to the Upper Floridan aquifer. Interpretations of the
potentiometric surface in reports prior to this map series for the area south of
latitude 27N used potentiometric-surface measurements that are now considered
to have been composite heads of the Upper Floridan aquifer and overlying flow
systems.
Net changes in the potentiometric surface of the Upper Floridan aquifer
that have occurred between May 1985 (Barr, 1987) and May 1990 are shown in
figure 1. Small to moderate changes (rises and declines of less than 10 feet) have
"" occurred in most of the study area. Changes are based upon both observed
differences in water levels in individual wells and manual and computer
techniques used to determine altitude differences between published
potentiometric-surface contour lines. Net changes were determined solely by
water-level differences in individual wells in areas where differences between
contour lines indicated unreasonable net changes that could not be related to
existing hydrologic conditions. Some isolated rises or declines, not representa-
tive of regional net changes in the potentiometric surface, are not shown in figure
1. Net declines of 10 feet or more have occurred in parts of Santa Rosa, Okaloosa,
Suwannee, and Hillsborough Counties due to the pumping of ground water for
public supply or crop irrigation. Santa Rosa, Okaloosa, and southeastern
Hillsborough Counties also had the most extreme water-level declines depicted
on the May 1985 map (Barr, 1987). Declines in the potentiometric surface,
although small throughout most of the State, are the result of rainfall deficits and
gradually increasing demands for almost all categories of ground-water supplies
(Marella, 1986; 1990). Rises in the potentiometric surface in the panhandle and
west-central parts of the State are due primarily to above normal rainfall
(National Oceanic and Atmospheric Administration, 1986-90) and recharge.
Hydrographs for selected wells in areas where regional ground-water
withdrawals have had appreciable effects on water levels are shown in figure 2.
One or two daily maximum water-level values for annual wet and dry seasons
were used to create the hydrographs. Generally, one daily maximum water level
in May and one in September were used. The hydrographs presented show net
water-level declines in wells that are open to the Upper Floridan aquifer since
the beginning of the record at each well for wells that are open to the Upper
Floridan aquifer.


SELECTED REFERENCES
Barr, G.L., 1987, Potentiometric surface of the Upper Floridan aquifer in
Florida, May 1985: Florida Geological Survey Map Series 119, 1
sheet.
Bush, P.W., and Johnston, R.H., 1988, Ground-water hydraulics, regional
flow, and ground-water development of the Floridan aquifer system
in Florida and in parts of Georgia, South Carolina, and Alabama:
U.S. Geological Survey Professional Paper 1403-C, 80 p.
Cooper, H.H., Kenner, W.E., and Brown, Eugene, 1953, Ground water in
central and northern Florida: Florida Geological Survey Report of
Investigations no. 10, 37 p.
Healy, H.G., 1962, Piezometric surface and areas of artesian flow of the
Floridan aquifer in Florida, July 6-17, 1961: Florida Bureau of
Geology Map Series 4.
----- 1975, Potentiometric surface and areas of artesian flow of the Floridan
aquifer in Florida, May 1974: Florida Bureau of Geology Map Series
73.
---- 1982, Potentiometric surface of the Floridan aquifer in Florida, May
1980: Florida Bureau of Geology Map Series 104.
Knochemnus, L.A., 1990, Potentiometric surface of the Upper Floridan
aquifer, west-central Florida, May 1990: U.S. Geological Survey
Open-File Report 90-556, 1 sheet.
Marella, R.L., 1986, St. Johns River Water Management District, annual
water use survey: 1985 Technical Publication SJ 86-5, 117 p.
----- 1990, Public supply water use in Florida, 1987: U.S. Geological
Survey Open-File Report 90-596, 39 p.
Meadows, P.E., 1991 a, Potentiometric surface of the Upper Floridan
aquifer in the Northwest Florida Water Management District, May
1990: U.S. Geological Survey Open-File Report 90-586, 1 sheet.
----- 1991b, Potentiometric surface of the Upper Floridan aquifer in the
Suwannee River Florida Water Management District, May 1990:
U.S. Geological Survey Open-File Report 90-582, 1 sheet.
Miller, J.A., 1982, Geology and configuration of the top of the Tertiary
limestone aquifer system, southeastern United States: U.S. Geological
Survey Open-File Report 81-1178, 1 sheet.
----- 1986, Hydrogeologic framework of the Floridan aquifer system in
Florida and in parts of GCccrgia, Alabama, and South Carolina: U.S.
Geological Survey Professional Paper 1403-B, 91 p., 28 pl.
Murray, L.C., 1990, Potentiometric surface of the Upper Floridan aquifer in
the St. Johns River Florida Water Management District, May 1990:
U.S. Geological Survey Open-File Report 90-557, 1 sheet.
National Oceanic and Atmospheric Administration, 1986-90, Climatologi-
cal data annual summary, Florida, 1986-90: published annually.
Stringfield, V.T., 1966, Artesian water in the Tertiary limestone in the
southeastern states: U.S. Geological Survey Professional Paper
517, 226 p.


~1
,kN)L.A


EXPLANATION

RISE, Less than 10

DECLINE, Less than 10

l DECLINE, Greater than 10

7 AREA NOT EVALUATED


E* SELECTED MONITORING WELL-
Letter indicates hydrograph
shown in figure 2


0 20 40 60 80 100 MILES
0 20 40 60 80100 KILOMETERS


0 0
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B. COLUMBIA 301031082381001
7 0 1 11' 1 1 .... I. r


C. DUVAL 122A 302304081383202


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0 0 0)


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- 1


E. POLK ROMP 60 275326081585801
9 0 1.1. 1 1 ... ...I .... I .. -. I .. I


3011, .. *. ,,,,m...
tO 0 0 10
10 (0 co (t

C(,C~' 2S8-0

-meto,4


Figure 1-Generalized net change in the potentiometric surface of
the Upper Floridan aquifer between May 1985 and May 1990.


Figure 2-Fluctuations and trends of ground-water levels
in selected wells in the Upper Floridan aquifer.


0 10 20 30 40 50 MILES


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