Cover: Left photograph – Waterwheel powered by flowing artesian well at

Burnt Fork, Georgia, 1938. State Geologist Photographs and Negative Files, 

Department of Mines, Mining and Geology, RG 50-2-33, box 2, 

Camden County folder, Georgia Archives. Photograph by A.C. Munyon.

Right photograph – Production well at Durango Paper Mill, St. Marys, 

July 1999, Georgia. Photograph by Alan M. Cressler, U.S. Geological Survey.
Effects of Decreased Ground-Water 

Withdrawal on Ground-Water Levels 

and Chloride Concentrations in Camden 

County, Georgia, and Ground-Water 

Levels in Nassau County, Florida, 

From September 2001 to May 2003

By Michael F. Peck, Keith W. McFadden, and David C. Leeth

U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation with the

Georgia Department of Natural Resources

Environmental Protection Division

Scientific Investigations Report 2004-5295
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2005

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report.

Suggested citation:

Peck, Michael F., Keith W. McFadden, and David C. Leeth, 2005, Effects of decreased ground-water withdrawal on 

ground-water levels and chloride concentrations in Camden County, Georgia, and ground-water levels in Nassau County, 

Florida, from September 2001 to May 2003: U.S. Geological Survey Scientific Investigations Report 2004-5295, 36 p.
 iii

Contents

Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

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

Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Description of the Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Hydrogeologic Framework. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Methods of Investigation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Previous Investigations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Well-Numbering System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Ground-Water Withdrawal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Ground-Water Levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Confined Surficial Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Upper Brunswick Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Floridan Aquifer System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Upper Floridan Aquifer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Lower Floridan Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Interaquifer Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Chloride Concentrations in Camden County. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Selected References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figures

1. Maps showing location of study area and selected ground-water-level and chloride 

monitoring sites in Camden County, Georgia, and Nassau County, Florida and location of 

study area and selected ground-water-level and chloride monitoring sites in the 

St. Marys, Georgia, area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. Chart showing geologic and hydrogeologic units in the coastal area of Georgia. . . . . . . . . . . . . . . . . . . . .5

3. Map showing potentiometric surface of the Upper Floridan aquifer in the coastal area of 

Georgia, May 1998 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

4. Graphs showing estimated ground-water withdrawal in Camden County, Georgia, and 

Nassau County, Florida, 1938–2000, and monthly water use, in Camden County, Georgia, 2002 . . . . . .9

5–6. Hydrographs Showing:

5. Hydrographs for the St. Marys well cluster (33D071, 33D072, and 33D073) and nearby 

National Park Service well (33D069), Camden County, Georgia, 2000–2003 . . . . . . . . . . . . . . . . . . 12

6. Period-of-record for well 33D072 (confined surficial aquifer), Camden County, 

Georgia, 1998–2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7. Hydrographs and regional water-level trends for wells completed in the Upper Floridan 

aquifer, coastal Georgia and northeastern Florida, 1994–2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

8. Hydrographs showing Period-of-record for well 33D071 (upper Brunswick aquifer), Camden County, 

Georgia, 1998–2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
iv 

9–13. Maps Showing:

9. Potentiometric surface of the Upper Floridan aquiferin the coastal area of Georgia 

and Nassau County, Florida, 1942 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

10. Potentiometric surface of the Upper Floridan aquifer in Camden County, Georgia, 

and Nassau County, Florida, September 2001 and September 2002. . . . . . . . . . . . . . . . . . . . . . . . . . 18

11. Potentiometric surface of the Upper Floridan aquifer in Camden County, Georgia, and 

Nassau County, Florida, January 2003 and May 2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

12. Observed water-level change from September 2001 through May 2003 in wells completed

in the Upper Floridan aquifer in Camden County, Georgia, and Nassau County, Florida . . . . . . 22

13–19. Hydrographs Showing:

13. Period-of-record for well 33D069 (Upper Floridan aquifer), CamdenCounty, 

Georgia, 1994–2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

14. Period-of-record for well 33E007 (Upper Floridan aquifer), Camden County, 

Georgia, 1994–2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

15. Period-of-record for well 33E027 (Upper Floridan aquifer), Camden County, 

Georgia, 1980–2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

16. Period-of-record for well N-19 (Floridan aquifer system), Nassau County, 

Florida, 1986–y2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

17. Period-of-record for well N-62 (Floridan aquifer system), Nassau County, 

Florida, 1994–2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

18. Period-of-record for well 33D073 (Lower Floridan aquifer), Camden County, 

Georgia, 2000–2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

19. Chloride concentration in water from the Upper Floridan aquifer at well 33D061, 

Durango Paper Company, Camden County, Georgia, 1982–2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

20. Boxplots of chloride and sulfate concentration in water from the Upper Floridan 

aquifer in Camden County, Georgia, prior to and after the Durango Paper Company shutdown, 

September 2002–May 2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Tables

1. Location and construction information for wells used in this study, 

September 2001–May 2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2. Ground-water altitudes in selected wells in Camden County, Georgia, and Nassau County, 

Florida, September 2001–May 2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3. Water-quality data from selected wells in Camden County, Georgia, 

September 2002–May 2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
 v

Conversion Factors and Datum

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

acre 0.4047 hectare (ha)

acre 0.4047 square hectometer (hm2)

acre 0.004047 square kilometer (km2)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2)

Flow rate

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3/s)

Transmissivity*

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 x °C) + 32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C = (°F - 32) / 1.8

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88). Historical data collected and stored as National Geodetic Vertical Datum of 1929 have 

been converted to NAVD 88 for this publication.

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Historical data collected and stored as North American Datum 1927 have been converted to 

NAD 83 for this publication.

Altitude, as used in this report, refers to distance above the vertical datum.

*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times 

foot of aquifer thickness [(ft3/d)/ft2

]ft. In this report, the mathematically reduced form, foot 

squared per day (ft2

/d), is used for convenience.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25°C).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or 

micrograms per liter (μg/L).

NOTE TO USGS USERS: Use of hectare (ha) as an alternative name for square hectometer (hm2) 

is restricted to the measurement of small land or water areas. 

Effects of Decreased Ground-Water Withdrawal on 

Ground-Water Levels and Chloride Concentrations in 

Camden County, Georgia, and Ground-Water Levels in 

Nassau County, Florida, From September 2001 to May 2003

By Michael F. Peck, Keith W. McFadden, and David C. Leeth

Abstract

During October 2002, the Durango Paper Company 

(formerly Gillman Paper Company) in St. Marys, Georgia, 

shutdown paper-mill operations; the shutdown resulted in 

decreased ground-water withdrawal in Camden County by 

35.6 million gallons per day. The decrease in withdrawal 

resulted in water-level rise in wells completed in the Floridan 

aquifer system and the overlying surficial and Brunswick aquifer systems; many wells in the St. Marys area flowed for the 

first time since the mill began operations during 1941. 

Pumping at the mill resulted in the development of a cone of 

depression that coalesced with a larger adjacent cone of depression at Fernandina Beach, Florida. Since closure of the mill, the 

cone at St. Marys is no longer present, although the cone still 

exists at Fernandina Beach, Florida. Historical water-level data 

from the production wells at the mill indicate that the pumping 

water level ranged from 68 to 235 feet (ft) below North American Vertical Datum of 1988 (NAVD 88) and averaged about 

114 ft when the mill was operating. Since the shutdown, it is 

estimated that water levels at the mill have risen about 140 ft 

and are now at about 30 ft above NAVD 88. The water-level 

rise in wells in outlying areas in Camden County was less pronounced and ranged from about 5 to 10 ft above NAVD 88. 

Because of the regional upward water-level trend in the Upper 

Floridan aquifer that started during 1999–2000 in most of the 

coastal area, combined with a steeper upward trend beginning 

during October 2002, it was not possible to determine if the 

5–10 ft rise in water levels in wells away from St. Marys was due

to the mill closure. In addition to water-level rise of 22–26 ft in 

the Floridan aquifer system, water-level rises in the overlying 

surficial and Brunswick aquifer systems at St. Marys after the 

shutdown indicate upward leakage of water. Water levels had 

stabilized in the confined surficial and Upper and Lower Floridan aquifers by April–May 2003; however, the water level in 

the upper Brunswick aquifer was still rising as of May 2003.

Chloride concentrations in the Upper Floridan aquifer in 

Camden County do not exceed the State and Federal drinkingwater standard of 250 milligrams per liter (mg/L). With the 

exception of three wells located at St. Marys, all of the wells 

sampled during this study (from September 2002 to May 2003) 

had chloride concentrations ranging from 30 to 50 mg/L, which 

are considered within background levels for the Upper Floridan 

aquifer in this area. The three wells—two at the Durango Paper 

Company and the other an old unused City of St. Marys well— 

had chloride concentrations that ranged from 74 to 175 mg/L, 

which are above the background level, but were still below the 

250-mg/L drinking-water standard. The source has not been 

determined for the elevated chloride concentration in these 

wells; the chloride concentration in one of the wells has 

decreased slightly since the paper-mill shutdown. Chloride concentrations throughout Camden County showed little change 

after the paper-mill shutdown.

Introduction

In the coastal area of Georgia and northeastern Florida, the 

Floridan aquifer system, which consists of the Upper and Lower 

Floridan aquifers, is heavily used for water supply by the pulp 

and paper industry and local municipalities. From 1985 to 2000, 

industrial and municipal ground-water withdrawal in Camden 

County, Georgia, and Nassau County, Florida, ranged from 

about 81 to 90 million gallons per day (Mgal/d) primarily from 

the Floridan aquifer system (Frick and others, 2002). Concern 

about saltwater intrusion at Hilton Head Island, South Carolina, 

and Brunswick, Georgia, has resulted in restrictions on permitted ground-water withdrawal from the Upper Floridan aquifer 

by the State of Georgia. During 1997, the State Environmental 

Protection Division (GaEPD) issued an interim strategy (Georgia Environmental Protection Division, 1997) that capped withdrawal from the Upper Floridan aquifer at 1997 rates in Glynn 
2 Effects of Decreased Ground-Water Withdrawal

and Chatham Counties and parts of Effingham and Bryan Counties, and restricted additional permits in the other coastal counties 

to a total of 36 Mgal/d. The 36-Mgal/d limit was reached during 

2001, which effectively capped permitted withdrawal of the 

Upper Floridan aquifer in the entire 24-county coastal area, 

causing increased competition for the currently allocated permits.

During October 2002, the Durango Paper Company 

(formerly Gillman Paper Company) at St. Marys, Camden 

County, Georgia (fig. 1A and B), shutdown paper-mill operations, resulting in a 35.6-Mgal/d decrease in ground-water withdrawal from the Floridan aquifer system in Camden County 

(J.L. Fanning, U.S. Geological Survey, written commun., 

October 24, 2003). The decrease in withdrawal affected water 

levels in the Floridan aquifer system and in the overlying 

surficial and Brunswick aquifer systems (fig. 2), resulting in 

flow from many wells in the St. Marys area for the first time 

since the mill began operations during 1941. 

To assess the impact of the Durango Paper Company shutdown on ground-water levels and chloride concentrations in 

Camden County, Georgia, and ground-water levels in Nassau 

County, Florida, the U.S. Geological Survey (USGS)—in 

cooperation with the GaEPD—conducted an investigation from 

September 2002 to May 2003. Results of this investigation will 

provide water managers with information to help manage water 

resources in coastal Georgia.

Purpose and Scope

This report describes changes in ground-water levels in the 

Floridan aquifer system and overlying upper Brunswick and 

confined surficial aquifers and chloride concentration in the 

Upper Floridan aquifer, resulting from a large decrease in 

ground-water withdrawal because of closure of a paper mill at 

St. Marys, Georgia, during October 2002 (fig. 1A and B). As 

part of this study, synoptic water-level measurements were 

made during three time periods in 55 wells open to the Upper 

Floridan aquifer in Camden County, Georgia, and Nassau 

County, Florida, prior to the mill shutdown (September 2002) 

and after the shutdown (January and May 2003). Sixty-one 

water samples were collected from 31 wells in Camden County, 

Georgia, during the same three time periods, to evaluate possible changes in chloride concentration in the Upper Floridan aquifer. Potentiometric-surface maps were constructed for each time 

period to show changes in ground-water flowpaths and to help 

determine the areal extent of water-level rise. Hydrographs from 

six continuously monitored wells in Camden County, Georgia, 

and two wells in Nassau County, Florida (fig. 1A), were used to 

evaluate water-level trends and the effect of decreased groundwater withdrawal on a regional scale and to assess interaquifer 

leakage response. Water-use data for these areas were compiled 

and compared to water-level data from continuous recorders to 

evaluate the effects of industrial withdrawal.

Description of the Study Area

Camden County, Georgia, encompasses about 660 square 

miles (mi2) in the extreme southeastern part of the Coastal Plain 

physiographic province of Georgia (accessed October 17, 2003, 

at http://www.camdencounty-ga.com/). GaEPD defines the 

coastal area of Georgia as encompassing the 6 coastal counties 

and the adjacent 18 counties. GaEPD has further subdivided this 

area into three subareas, consisting of the northern, central, and 

southern areas; the latter encompass Camden County. Topographic relief is largely controlled by a series of relict shorelines 

formed during Pliocene-Pleistocene time as a result of global 

sea-level decline (Leeth, 1999; Leve, 1966). Relief ranges from 

0 feet (ft) along the coast to a maximum elevation of about 80 ft 

in the western part of the county. The climate in the Camden 

County area is humid subtropical, from about 52 to 54 inches of 

precipitation occurring annually, most of which falls from June 

through September (Leeth, 1999). Nassau County, Florida, has 

similar physiography and climate as Camden County and 

encompasses about 650 mi2 (accessed October 29, 2003, at 

http://www.nassauclerk.org/county/vitalstats.htm).

Hydrogeologic Framework

Hydrogeologic units underlying the study area in Camden 

County include the surficial aquifer system, Brunswick aquifer 

system, and the Floridan aquifer system (fig. 2). The surficial 

aquifer system in Camden County includes three water-bearing 

zones consisting of fine to medium quartz sand and coarse to 

very coarse quartz sand and gravel (Leeth, 1999). These three 

water-bearing zones are separated by layers of silt and clay, 

which form the unconfined water-table zone, the confined 

upper water-bearing zone, and the confined lower waterbearing zone (fig. 2). The Brunswick aquifer system consists of 

two water bearing zones: the upper Brunswick aquifer and the 

lower Brunswick aquifer (Clarke, 2003). The upper Brunswick 

aquifer consists of poorly sorted, fine to coarse, slightly phosphatic and dolomitic quartz sand and dense phosphatic limestone (Clarke and others, 1990; Leeth, 1999). The lower 

Brunswick aquifer consists of poorly sorted, fine to coarse, 

phosphatic, dolomitic sand (Clarke and others, 1990). In the 

coastal area of Georgia, the Floridan aquifer system is divided 

into the Upper and Lower Floridan aquifers (fig. 2). These 

aquifers consist of massive limestone and dolomite that are 

more than 2,000 ft thick in the Camden County area (Clarke 

and others, 1990). Because of the large ground-water withdrawal in the coastal area, cones of depression have developed 

in the potentiometric surface of the Upper Floridan aquifer at 

Savannah, Jesup-Riceboro, Brunswick, and St. Marys, Georgia 

(Peck and others, 1999) (fig. 3).
GEORGIA

Map

area

Atlantic

Ocean

FLORIDA

N-62

N-50

N-20

N-237

N-221

N-220 N-130

N-120

N-119

34F015

34F014

34F004

34E013

34E012

34E011

34E002

33F017

33F003

33F002

33E009

32F008

32E038

Location of

inset shown

on page 4

32E031

31F022

31E001

30E008

32E038

N-62

95

295

95

17

301

1

1

81o30'

30o30'

31o

82o

0 5 10 MILES

0 5 10 KILOMETERS

EXPLANATION

Observation well and site name

Continuous recorder well

Pumping center

Naval Submarine

Base Kings Bay

boundary

Jacksonville

St Marys

Fernandina

Beach

CAMDEN

CHARLTON

NASSAU

GLYNN

DUVAL

FL

GA

Atlantic Ocean

Base from U.S. Geological Survey 

1:100,000- and 1:250,000-scale digital data

Introduction 3

Figure 1A. Location of study area and selected ground-water-level and chloride monitoring sites in 

Camden County, Georgia, and Nassau County, Florida.
81o37'30" 81o33'45" 81o30' 81o26'15"

80o48'45"

30o41'15"

30o45'

St Marys

Yulee

Kingsland

Fernandina

Beach

Atlantic Ocean

FL

GA

Base from U.S. Geological Survey 

1:100,000 and 1:250,000-scale digital data

1

1

2

2

0

0

3 KILOMETERS

3 MILES

NASSAU

CAMDEN

17

95

N-19

N-121

34E014

32E032

33D069

33D055

33E117

33E115

33E055

33E053

33E052

33E051

33E050

33E049

33E046

33E034

33E007

33E006

33D073

33D074

33D071

33D072

33D054

32E033

33D004

33D050

33D061

33E027

33D051

33D058

33D063

34E010

34E003

34E001

33E054

Naval Submarine

Base Kings Bay

4 Effects of Decreased Ground-Water Withdrawal

Figure 1B. Location of study area and selected ground-water-level and chloride monitoring sites in the 

St. Marys, Georgia, area.

Aquifer-test data indicate that the Upper Floridan aquifer 

in the St. Marys area has the highest transmissivity in the 

coastal area of Georgia. Transmissivity ranges from 32,000 

to 40,000 feet squared per day (ft2/d) in the Savannah area 

(Warner and Aulenbach, 1999), from 33,000 to 40,000 ft2

/d 

in the Brunswick area (Clarke and others, 1990), and from 

98,000 to 170,000 ft2/d in the St. Marys area (Warner and 

Aulenbach, 1999). 

Hydrogeologic units underlying the study area in Nassau 

County, Florida, include the surficial aquifer system, an intermediate confining unit, and the Floridan aquifer system (fig. 2). 

The surficial aquifer system consists of sand, shell, and clay 

with some layers of dolomitic limestone and is divided into 

two water-bearing zones that range from semiconfined to 

unconfined (Phelps, 2001). The surficial aquifer system is 

underlain by the intermediate confining unit, which consists of 

varying layers of clay, silt, sand, dolomite, and limestone and 

contains ubiquitous phosphate that ranges in size from sand- to 

pebble-size particles (Phelps, 2001). In northeastern Florida, 

the Floridan aquifer system is divided into the Upper and 

Lower Floridan aquifers, as in southeastern Georgia; however, 

the Lower Floridan aquifer is further subdivided into two waterbearing zones. The transmissivity of the Upper Floridan aquifer in northeastern Florida ranges from 20,000 to 50,000 ft2/d 

(Phelps, 2001). Because of the large ground-water withdrawal 

in the Fernandina Beach area (fig. 1A), a cone of depression 

has developed in the potentiometric surface of the Upper Floridan aquifer (fig. 3).
Upper

Floridan

 aquifer

Floridan aquifer system

Lower Floridan aquifer 

1Modified from Randolph and others, 1991; Clarke and Krause, 2000 

2Modified from Phelps and Spechler, 1997

Confining

unit

Confining

unit

Upper

Brunswick 

 aquifer

Lower

Brunswick 

 aquifer

Satilla

Formation

Undifferentiated

surficial deposits

Surficial 

aquifer system

Intermediate

confining unit

Hawthorn

Group

Cypresshead

Formation

Holocene/

Pleistocene

Upper waterbearing zone

Lower

water-bearing zone

Water-table zone

Lower Middle Upper

Miocene

Quaternary

Tertiary

Eocene

Oligocene

Paleocene

Upper

Cretaceous

Cretaceous

Tiger Leap

Formation

Suwannee Limestone

Ocala

Limestone

Avon Park

Formation

 Oldsmar

Formation

Ocala

Limestone

Unit absent

Upper Floridan

aquifer

Avon Park

Formation

 Oldsmar

Formation

Cedar Keys

Formation

Sub-Floridan

confining unit

Fernandina

permeable zone

Semiconfining

unit

Upper zone 

Floridan aquifer system

Lower Florida

 aquifer

Middle semiconfining unit

Cedar Keys

Formation

Undifferentiated Undifferentiated Confining unit Fernandina permeable zone Confining unit

Confining

unit

Lazaretto Creek Fm

Parachucla Fm

Marks Head Fm

Confining unit

Coosawhatchie

Formation

Ebenezer

Formation

Georgia1

Geologic unit

Florida2

Geologic unit Hydrogeologic unit Hydrogeologic unit

System

Lower Middle

Surficial aquifer system Brunswick aquifer system

Upper

Series

Savannah St Marys

Pliocene

Introduction 5

Figure 2. Geologic and hydrogeologic units in the coastal area of Georgia (modified from Clarke, 2003; 

Clarke and others, 2004).
GEORGIA

SOUTH

CAROLINA

FLORIDA

Atlantic

Ocean

l l

l l l l l l

l

l l

l

l l

l l

l

l l l l l l l l l l l l l l l l l

l l

l

l l l l l l l l l l l l l l

l l l l

l l l l

l l

l l

l

l

l

l l l l l l l l l l l l

l l l l l l l l l l l l l l

l

l l l l l l l l l l l l l l l

l l l l l l l l l

l l l l l l l l l l l l

l l l l l l l l l l

l l l l l l l l l l l l l l l

l l

l l

l

l l l l l

l

l l l l

l l

l

l

l

l l l

l l l l l l l

l l l l

l l

l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l

Altamaha River

Savannah

River

Ogeechee

River

BACON

GLYNN

BRANTLEY

PIERCE

WARE

CHARLTON CAMDEN

NASSAU

TOOMBS

TATTNALL

EVANS

BRYAN

LONG

WAYNE

APPLING

LIBERTY

MCINTOSH

CHATHAM

EMANUEL

JENKINS

SCREVEN

EFFINGHAM

BULLOCH CANDLER

BURKE

Doctortown

Jesup

Brunswick

St Marys Fernandina

Beach

Savannah

–50

0

0

50

50

40

30

20

10

100

50

40

30

20

10

150

250

300

200

0

–30

–20

–10

0

10

0

34H125

34H125

34N089

GA

FL

SC

GA

33°

32°

31°

82°

81°

0

0 20 30 KILOMETERS 10

10 20 30 MILES

Atla

ntic

Ocean

EXPLANATION

Base from U.S. Geological Survey 

1:100,000-scale digital data

100

Axis of Gulf Trough—

Approximately located 

(Kellam and Gorday, 1990)

Potentiometric contour— 

Shows altitude at which water 

level would have stood in 

tightly cased wells during 

May 1–26, 1998. Hachures 

indicate depression. Contour 

interval 10 and 50 feet. 

Datum is NAVD 88

Continuous recorder well

6 Effects of Decreased Ground-Water Withdrawal

Figure 3. Potentiometric surface of the Upper Floridan aquifer in the coastal area of Georgia, May 1998 

(modified from Peck and others, 1999).
Introduction 7

Methods of Investigation

Continuous ground-water-level data were evaluated and 

compared to water-use data to determine the effect of the 

industrial shutdown and extent of water-level rise and changes 

in chloride concentration in the Upper Floridan aquifer, and 

to assess changes in water levels in the overlying surficial and 

Brunswick aquifer systems. Because water-level hydrographs 

typically show a strong seasonal component, the ability of the 

human eye to discern the central tendency or pattern inherent 

in long-term water-level hydrographs is poor; the range of 

data dominates visual impression (Helsel and Hirsch, 1992). 

A procedure for decomposing time series into a trend, a seasonal component and a remainder, has been used in this report 

to aid in discerning patterns in the long-term water-level 

hydrographs. This procedure, known as STL (Cleveland and 

others, 1990), has a simple design based on applying a 

sequence of locally weighted scatterplot smooths (LOESS) to 

the data. LOESS is a computationally intensive form of 

smoothing that involves fitting at least 2n

 weighted least 

squares (WLS) equations. At every X0, a - is computed from a 

WLS regression whose weights are a function of both the distance from X0 and the magnitude of the residual from the 

previous regression—an iterative procedure (Helsel and 

Hirsch, 1992). While more complex than traditional 

“smoothers,” LOESS allows the data analyst the opportunity 

to use various residual weights and window sizes according to 

the purpose for which the smooth is used. Because estimates 

for the trend and seasonal components from this procedure 

are robust, they are not distorted by aberrant behavior in the 

data and, thus, are preferable to smoothing techniques based 

on the mean or median.

Water-level data were used to construct potentiometricsurface maps of the Upper Floridan aquifer and were compared 

to historical water levels to determine water-level change 

throughout the study area. Initially, the potentiometric surface 

for each measurement period was derived and modeled from the 

calculated water-surface altitudes (land-surface altitude minus 

depth to water) at each well location using ArcGISTM Spatial 

Analyst and Geostatistical AnalySt. The contours were used as 

a first draft of the potentiometric surface and then adjusted by 

hand. The data values were analyzed for spatial autocorrelation 

using a semivariogram to identify potential outliers. Values 

showing significant differences from the estimated surface 

trend were checked for validity and, in some cases, removed 

from further analysis. Potential causes for such outliers were 

traced to measurement errors, temporal differences from surrounding data, incorrect aquifer designations, well-construction 

flaws, or wells open to multiple aquifers. A tensioned-spline 

method was chosen to interpolate a raster-based prediction map 

of the water surface using a 100-meter grid cell size. This 

method was selected in order to maintain a surface that more 

closely adheres to the range of measured values, particularly at 

sampled locations. A weight factor of “2” with a 24-point 

neighborhood allowed for more distant points to have greater 

influence over the surface, particularly in areas with sparse coverage. The surface was interpolated to the county boundaries; 

however, areas beyond the geographic extent of the data points 

should not be considered as valid. The contours were derived 

from the surface model at 10-ft intervals. These contours were 

then adjusted by hand to produce the final potentiometric surface. A water-level difference map was derived by subtracting 

the September 2001 surface from the May 2003 surface. 

Water samples were collected from 31 wells in Camden 

County, Georgia, during September 2002 and January and 

May 2003, to determine if chloride concentrations changed 

in the Upper Floridan aquifer because of decreased withdrawal. 

The USGS Georgia District Laboratory analyzed water samples, and chloride concentrations were determined by ion 

chromatography using Environmental Protection Agency 

method 300.0 (Pfaff, 1999).

Previous Investigations

Detailed investigations of the geology and hydrology of 

the Floridan aquifer system in the southeastern Coastal Plain 

of Georgia have been compiled in a variety of previous publications. Warner and Aulenbach (1999) analyzed hydraulic characteristics of the Upper Floridan aquifer at sites in Savannah 

and at St. Marys, Georgia. Clarke and others (1990) described 

the surficial aquifer (confined and unconfined zones) and the 

upper and lower Brunswick aquifers throughout 13 counties in 

the coastal area of Georgia. Hughes and Henry (1995) conducted a review of all existing data for the Neogene surficial 

and upper and lower Brunswick aquifers in Glynn and Camden 

Counties. Leeth (1999) described the hydrogeology of the surficial aquifer at the Naval Submarine Base Kings Bay, Camden 

County. Brown (1984), Spechler (1994), Phelps and Spechler 

(1997), and Phelps (2001) described the geology and hydrogeology of northeastern Florida.

Warren (1944), Johnston and others (1980), Krause and 

Hayes (1981), Clarke (1987), Peck (1991), Peck and others 

(1999), and Peck and McFadden (2004) presented maps showing the potentiometric surface of the Upper Floridan aquifer in 

the coastal area of Georgia. Warren (1944) presented one of the 

earliest potentiometric surface maps of the Upper Floridan 

aquifer. Johnston and others (1980) presented an estimated 

potentiometric surface of the Upper Floridan aquifer prior to 

development during 1880. The maps by Clarke (1987) and Peck 

and others (1999) also included a discussion of water-level 

trends in the Upper Floridan aquifer, 1980–85 and 1990–98, 

respectively. Fanning (1999) compiled water-use data for 

coastal Georgia and evaluated trends in water use from 1980 to 

1997 and provided an update of total water use by county for 

2000 (Fanning, 2003). 

Several investigations have examined the potential for 

saltwater intrusion in the Floridan aquifer system because of 
8 Effects of Decreased Ground-Water Withdrawal

increased development in southeastern Georgia and northeastern 

Florida. Rose (2001, 2002) summarized existing data describing the potential for saltwater intrusion in Camden County, 

Georgia. Brown (1984) reported on the impact of development 

on the availability and quality of water from the Floridan aquifer system in Nassau County, Florida, and Camden County, 

Georgia. Spechler (1994) investigated the potential for saltwater intrusion in Nassau, Duval, and St. Johns Counties, Florida. 

Phelps (2001) documented the chemical and isotopic characteristics of water from different water-bearing zones in the Floridan aquifer system in northeastern Florida to determine the 

source of mineralized water detected in wells in Duval County.

Well-Numbering System

Wells in Georgia are given a well number according to a 

system based on the USGS index of topographic maps of 

Georgia. Each 71⁄2-minute topographic quadrangle in the State 

has been assigned a three- to four-digit number and letter designation (for example, 33D or 33E) beginning at the southwestern 

corner of the State. Numbers increase sequentially eastward 

and letters advance alphabetically northward. Quadrangles in 

the northern part of the State are designated by double letters: 

AA follows Z, and so forth. The letters “I,” “O,” “II,” and “OO” 

are not used. Wells inventoried in each quadrangle are numbered consecutively, beginning with 01. Thus, the fourth well 

inventoried in the 33D quadrangle is designated 33D004. In 

the USGS National Water Information System (NWIS) database, this information is stored under the field “Well Name” 

(http://waterdata.usgs.gov/ga/nwis/gw).

Wells in Florida are given a well number based on the 

county in which they are located. The USGS assigned local 

well numbers to wells in each county in northeastern Florida 

as each well was inventoried. The prefix N- in a well number 

denotes Nassau County and is followed by a sequential number 

that denotes the order in which the well was inventoried 

(Phelps, 2001).

Acknowledgments

The water-level and water-quality data collected during 

this study were obtained through the cooperation of the City 

of St. Marys, Durango Paper Company, St. Johns River 

Water Management District, and numerous private well 

owners throughout Camden County. Welby Stayton (USGS, 

Georgia) collected water levels and water samples in Georgia. 

Sandra Kinnaman, Darryl Williams, and Larry Thomas (USGS, 

Florida) provided water-level data for Nassau County, Florida. 

Richard L. Marella (USGS, Florida) provided water-use data 

for Nassau County, Florida.

Ground-Water Withdrawal

In Camden County, Georgia, and Nassau County, Florida, 

ground-water withdrawal increased from about 0.5 Mgal/d 

during 1938 to a total of about 105 Mgal/d during 1977 (Brown, 

1984). Much of the increase occurred during the 1940s when 

three major paper mills—one at St. Marys, Georgia, and two at 

Fernandina Beach, Florida—began operation (fig. 4A). By 

1980, total pumpage in this area decreased to about 91 Mgal/d 

(Brown, 1984), and from 1985 to 2000 ranged from about 81 to 

90 Mgal/d (Frick and others, 2002).

Most of the wells in the study area are completed in the 

Upper Floridan aquifer; however, some wells at the Durango 

Paper Company are completed in both the Upper Floridan 

aquifer and the upper part of the Lower Floridan aquifer (fig. 2; 

table 1). Miller (1986) reported that the top of the Lower Floridan aquifer in the St. Marys area is about 1,250 ft below land 

surface. Falls and others (2001), however, delineated the top of 

the Lower Floridan aquifer at about 1,185 ft below land surface. 

Four wells at the Durango Paper Company are completed to 

depths ranging between 1,199–1,259 ft below land surface 

(table 1). Falls and others (2001) interpretation of the top of the 

Lower Floridan aquifer is based on data obtained from two 

recently drilled test wells located about 0.2 miles (mi) southwest of the Durango Paper Company. 

In the 24-county coastal area of Georgia, ground-water 

withdrawal decreased from about 388 Mgal/d during 1980 to 

386 Mgal/d during 2000 (Fanning, 2003). During the same 

period, ground-water withdrawal in Camden County, Georgia, 

increased from 37.48 Mgal/d to 42.6 Mgal/d (fig. 4A), with 

most of the pumpage attributed to the Durango Paper Company 

at St. Marys, Georgia (Fanning, 2003). During 2000, the mill 

withdrew an average of about 35.6 Mgal/d from wells primarily 

completed in the Upper Floridan aquifer (fig. 4A). During 2002, 

the mill also pumped an average of about 35.6 Mgal/d, before it 

closed during early October (fig. 4B). The shutdown decreased 

total ground-water withdrawal in Camden County to 5.7 Mgal/d 

(J.L. Fanning, U.S. Geological Survey, written commun., 

October 24, 2003).

In Nassau County, Florida, ground-water withdrawal was 

about 46.3 Mgal/d during 2002, mostly for industrial and 

public supply. Industrial ground-water withdrawals in Nassau 

County decreased from the late 1970s to the present; this 

decrease is attributed to the overall decline in pulp production 

and more efficient use of water by the pulp and paper industry 

(R.L. Marella, U.S. Geological Survey, written commun., 

April 29, 2003). In addition, the St. Johns River Water 

Management District issued new regulations pertaining to 

withdrawal permits, limiting the amount of water consumed by 

major industrial users during the 1980s.
40

30

20

10

0

Durango Paper

 Company

2002

Cities of Kingsland 

 and St Marys and

 Naval Submarine

 Base Kings Bay

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

GROUND-WATER WITHDRAWAL, IN MILLION GALLONS PER DAY

0

20

40

60

80

100

19351940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

Camden County, Ga.

Camden County, Ga.

Nassau County, Fla.

A.

B.

Ground-Water Withdrawal 9

Figure 4. (A) Estimated ground-water withdrawal in Camden County, Georgia, and Nassau County, Florida, 

1938–2000 (modified from Frick and others, 2002), and (B) monthly water use, in Camden County, Georgia, 2002.
10 Effects of Decreased Ground-Water Withdrawal

Table 1. Location and construction information for wells used in this study, September 2001–May 2003.

[ID, identification; °, degree; ', minute; ", second; FAS, Floridan aquifer system; UF, Upper Floridan; LF, Lower Floridan; 

UB, upper Brunswick; GGS, Georgia Geologic Survey; —, data not available; *, no name]

Well ID Well name Latitude Longitude

Land-surface 

altitude 

(feet)

Well 

depth 

(feet)

Casing 

depth 

(feet)

Casing 

diameter 

(inch)

Aquifer Construction 

date

30E008 Lester Varn 30°49'53" 81°54'11" 13.34 460 235 4 FAS Feb. 16, 1982

31E001 E. Brown 30°48'31" 81°48'11" 21 500 400 3 UF Jan. 1, 1958

31F022 J. Van 30°56'24" 81°48'34" 18.89 650 422 3 UF May 1973

32E031 B&S Chicken Farm 30°49'23" 81°43'54" 19.84 750 504 3 UF —

32E032 E. Gross (1950) 30°48'08" 81°40'45" 27.02 516 466 3 UF Jan. 1, 1950

32E033 Georgia Welcome Center 30°45'17" 81°38'58" 17.1 600 420 6 UF Sept. 1974

32E038 J.D. Peeples 30°46'42" 81°42'32" 15.84 720 483 3 FAS Oct. 1968

32F008 H. Williams 30°58'05" 81°44'12" 4.87 872 399 3 UF Dec. 1965

33D004 E. Floyd 30°43'49" 81°32'38" 8.82 600 400 2 UF 1952

33D006 Gillman Paper Co. 8 30°44'27" 81°32'33" 7.81 1,199 560 — UF —

33D022 Gillman Paper Co. 3 30°44'02" 81°32'36" 9 860 517 20 UF Mar. 8, 1950

33D048 Gillman Paper Co. 9 30°44'07" 81°32'34" 8.82 1,183 530 — FAS —

33D049 Gillman Paper Co. 6 30°44'14" 81°33'24" 13.82 1,259 520 20 FAS Feb. 1956

33D050 Gillman Paper Co. 5 30°44'12" 81°33'18" 13.82 1,215 529 20 FAS Nov. 4, 1953

33D051 Gillman Paper Co. 4 30°44'08" 81°32'56" 8.81 1,220 519 18 FAS Oct. 1953

33D053 Gillman Paper Co. 1 30°44'12" 81°32'31" 8.81 1,063 516 18 UF Jan. 26, 1941

33D054 St. Marys Georgia 2 30°44'51" 81°33'33" 20.81 1,001 563 12 UF Jan. 1, 1965

33D055 St. Marys Georgia 1 30°43'31" 81°32'47" 9.82 761 500 6 UF July 1, 1953

33D058 Gillman Paper Co. 7 30°44'09" 81°32'34" 8.82 1,041 530 26 UF —

33D061 Gillman Paper Co. 11 30°44'02" 81°32'36" 8.82 1,088 550 26 UF Nov. 28, 1981

33D062 Gillman Paper Co. 2 30°44'35" 81°32'31" 9 1,285 557 20 FAS Oct. 5, 1946

33D063 Gillman Paper Co. 10 30°44'33" 81°32'32" 8.81 1,099 560 26 UF —

33D069 National Park Service 30°43'14" 81°32'59" 7 575 467 4 UF Jan. 1, 1900

33D071 GGS Test Well 2 St. Marys 30°44'07" 81°33'04" 9 365 325 4 UB May 15, 1997

33D072 GGS Test Well 3 St. Marys 30°44'07" 81°33'04" 9 255 225 4 Surficial June 30, 1997

33D073 St. Marys Deep Test Well 30°44'06" 81°33'05" 8.82 1,500 1,360 8 LF Dec. 3, 1999

33D075 Durango Paper Co. 12 30°44'36" 81°32'48" 12.5 1,100 577 30 UF June 19, 1998

33E006 Finn and neighbor 30°46'09" 81°34'51" 10.83 750 — — FAS —

33E007 Huntly-Jiffy 30°45'12" 81°34'36" 16.82 760 552 3 UF Apr. 1, 1964

33E008 Crocked River State Park 30°50'38" 81°33'22" 15 470 261 4 UF —

33E009 American Legion St. Marys 30°50'46" 81°33'45" 10.83 565 250 4 FAS 1930

33E027 U.S. Navy, Kings Bay, test well 1 30°47'57" 81°31'10" 9.25 990 555 8 UF Feb. 8, 1979
Ground-Water Withdrawal 11

33E034 U.S. Navy Kings Bay 4 30°47'53" 81°31'11" 12.11 810 500 12 UF Aug. 1, 1955

33E046 Joiner-Green-Crocker-Onel 30°49'17" 81°36'06" 9 650 548 3 UF Nov. 11, 1983

33E049 Osprey Cove Inc. 30°45'15" 81°36'57" 13 840 522 12 UF Jan. 19, 1990

33E050 St. Marys Georgia 3 30°45'52" 81°34'28" 23 982 560 18 UF Apr. 3, 1986

33E051 U.S. Navy Kings Bay 6 30°47'55" 81°32'54" 17.29 900 560 18 UF Sept. 30, 1983

33E052 U.S. Navy Kings Bay No. 1 (1984) 30°47'41" 81°34'29" 30.57 900 590 18 UF Mar. 20, 1984

33E053 U.S. Navy Kings Bay No. 2 (1984) 30°47'43" 81°33'44" 23.33 900 570 18 UF Feb. 15, 1984

33E054 Rayland Company No. 1 30°48'51" 81°34'17" 27 640 381 10 UF 1900

33E055 Gillette 30°48'48" 81°34'20" 27 — — — FAS —

33E115 St. Marys Georgia No. 4 30°47'01" 81°35'39" 15 805 563 8 UF May 19, 1980

33E117 U.S. Navy Kings Bay Etowah Park 30°49'10" 81°32'39" 19 620 480 4 UF May 23, 1997

33F002 Union Carbide 2 30°55'15" 81°30'55" 8.85 806 513 12 UF Sept. 20, 1963

33F003 Union Carbide 3 30°57'11" 81°31'54" 18.86 847 508 12 UF Sept. 14, 1963

33F017 Union Carbide 4 30°55'39" 81°30'53" 10.86 832 534 24 UF Dec. 1, 1981

34E001 Cumberland Island GGS TW 1 30°45'23" 81°28'12" 16 645 540 4 UF —

34E003 Cumberland Island Greyfield 2 30°46'47" 81°28'08" 12.84 730 538 8 UF 1931

34E010 Cumberland Island Rockefeller 32 30°46'11" 81°28'08" 9 750 550 4 UF —

34E011 NPS Plum Orchard 30°51'23" 81°27'55" 11.86 — — 4 UF 1900

34E012 Reddick 30°50'33" 81°28'00" 10.85 — — — UF —

34E013 Yankee Paradise Trail Well 30°50'29" 81°26'50" 15.86 — — — UF —

34E014 Foster 30°48'52" 81°27'39" 25.85 — — — UF 1900

34F004 Mr. Botsford 30°56'31" 81°24'42" 7.9 743 571 3 UF Jan. 1, 1966

34F014 Squawtown Well 30°52'43" 81°26'33" 6.87 — — — UF —

34F015 Candler at water tower 30°54'53" 81°25'22" 13.89 — — — UF —

N-0220 Nassau County Fairgrounds 30°35'41" 81°49'48" 18.94 650 458 6 FAS Nov. 1, 1994

N-0221 * 30°46'59" 81°57'11" 20.4 812 539 6 FAS Nov. 8, 1994

N-0237 Carey State Forest 30°24'10" 81°55'15" 79.06 500 450 6 FAS —

N-119 Charles Allen 30°33'58" 81°29'55" 8.86 — — — FAS —

N-120 Humphreys Mining No. 2 30°44'23" 81°59'17" 95.14 923 525 12 FAS —

N-121 Baker Oil Test 30°40'06" 81°38'01" 20.89 645 460 4 FAS —

N-130 Amelia City, Florida 30°35'19" 81°27'49" 14.76 600 515 4 FAS —

N-19 Ft. Clinch State Park 30°42'11" 81°27'07" 7.26 710 — 5 FAS —

N-20 * 30°39'40" 81°31'25" 10.86 — — — FAS —

N-50 * 30°36'59" 81°42'25" 16.95 569 — 2 FAS 1938

N-62 ITT Rayonier No. 8 30°38'24" 81°27'32" 16.45 565 565 12 FAS —

Table 1. Location and construction information for wells used in this study, September 2001–May 2003.—Continued

[ID, identification; °, degree; ', minute; ", second; FAS, Floridan aquifer system; UF, Upper Floridan; LF, Lower Floridan; 

UB, upper Brunswick; GGS, Georgia Geologic Survey; —, data not available; *, no name]

Well ID Well name Latitude Longitude

Land-surface 

altitude 

(feet)

Well 

depth 

(feet)

Casing 

depth 

(feet)

Casing 

diameter 

(inch)

Aquifer Construction 

date
15

10

5

–5

0

–10

–25

–30

–20

–15

DAILY MEAN WATER LEVEL

ABOVE (–) AND BELOW NAVD 88, IN FEET

2000 2001 2002 2003

Upper Brunswick

aquifer, 33D071

Confined surficial

aquifer, 33D072

Blank where data missing

Lower Floridan 

aquifer, 33D073

Upper Floridan 

aquifer, 33D069

12 Effects of Decreased Ground-Water Withdrawal

Figure 5. Hydrographs for the St. Marys well cluster (33D071, 33D072, and 33D073) and 

nearby National Park Service well (33D069), Camden County, Georgia, 2000–2003.

Ground-Water Levels

Ground-water levels in the St. Marys area were affected 

substantially by the reduction in ground-water withdrawal at the 

Durango Paper Company. Continuous water-level data from 

wells completed in the confined surficial, upper Brunswick, 

Upper Floridan, and Lower Floridan aquifers show a pronounced water-level rise after the shutdown during early October 2002 (fig. 5). Data are not available for the lower Brunswick 

aquifer in the St. Marys area because during the study period 

there were no observation wells completed in this aquifer. 

Confined Surficial Aquifer

Water-level data for the surficial aquifer system in Camden 

County are sparse; and only the lower confined zone is monitored continuously at well 33D072 (fig. 6), located approximately 0.2 mi southwest of the Durango Paper Company (see 

location fig. 1B). In Camden County, most of the pumpage from 

the surficial aquifer system is either from the water-table zone 

or the upper and lower confined zones. The water-table zone is 

used by homeowners who install shallow-driven or jetted wells 

for landscape irrigation. At the Naval Submarine Base Kings 

Bay, located about 4.8 mi north of well 33D072, about 0.2 Mgal/d 

are withdrawn annually from the confined zones of the surficial 

aquifer system for irrigation (J.L. Fanning, U.S. Geological 

Survey, written commun, July 2003).

Water levels in the confined surficial aquifer at St. Marys 

have been monitored continuously in well 33D072 since early 

1998, and range from 5 to 8 ft below land surface for the period 

of record prior to the mill shutdown (fig. 6). A regional waterlevel rise that began during 2000 (fig. 7) in the deeper Brunswick and Floridan aquifer systems is not evident on the hydrograph for well 33D072. On October 6, 2002, the water level in 

well 33D072 began to rise from 6.38 ft below land surface and 

continued to rise through March 2003. A record high water level 

of 1.58 ft below land surface was recorded on March 13, 2003; 

by May 2003, the water level appeared to have stabilized, 

declining slightly to 2.5 ft below land surface on May 15, 2003. 

Overall, the water level in the confined surficial aquifer at 

St. Marys rose 4.8 ft from September 2002 to May 2003.
Ground-Water Levels 13

Upper Brunswick Aquifer

In the St. Marys–Camden County area, the Brunswick aquifer system is not heavily used; therefore, water-level and wateruse data are sparse. Water levels in the upper Brunswick aquifer are monitored continuously in only one well, 33D071 (fig. 8), 

located approximately 0.2 mi southwest of the Durango Paper 

Company (see location fig. 1B). Water levels in well 33D071 

have been monitored continuously since 1998 and range from 

about 7.3 to 12 ft below land surface for the period of record 

prior to the mill shutdown (fig. 8). Since late 2000, there has 

been a slight upward water-level trend in this well similar to the 

water-level rise in the Upper Floridan aquifer throughout the 

coastal area (fig. 7). On October 7, 2002, the water level in well 

33D071 began to rise at an accelerated rate, starting at 7.97 ft 

below land surface, and continued to rise through May 2003. 

On December 18, 2002, the water level in well 33D071 rose 

above land surface; and by mid-May, the water level was 5.0 ft 

above land surface, a record high. As of May 2003, the water 

level was still rising and did not appear to be stabilizing as was 

the case for the confined surficial aquifer. Overall, the water 

level in the upper Brunswick aquifer at St. Marys rose 12.9 ft 

from September 2002 to May 2003. The longer recovery period 

for the upper Brunswick aquifer is likely the result of low-permeability clays that confine the aquifer and inhibit the interaquifer flow of water.

Floridan Aquifer System

In the Camden County area, the Floridan aquifer system is 

deeply buried and far from its outcrop area; thus, water levels 

are not directly influenced by variations in precipitation and are 

primarily affected by industrial and municipal withdrawal 

(Clarke and others, 1990). Cones of depression have formed in 

the potentiometric surface of the Upper Floridan aquifer around 

the industrial pumping centers at Savannah, Jesup-Riceboro, 

Brunswick, and St. Marys, Georgia, and Fernandina Beach, 

Florida (Peck and others 1999) (fig. 3). 

Upper Floridan Aquifer

4

8

6

0

2

10

DAILY MEAN WATER

LEVEL BELOW LAND

SURFACE, IN FEET

1998 1999 2000 2001 2002 2003

Trend

Johnston and others (1980) estimated that the altitude of the 

predevelopment (prior to 1880) potentiometric surface of the 

Upper Floridan aquifer in Camden County ranged from about 

70 ft in the western part of the county to 60 ft along the coast. 

Warren (1944) published one of the earliest postdevelopment 

Upper Floridan potentiometric-surface maps (fig. 9), showing 

that the altitude of the water surface in 1942 Camden County 

ranged from 60 ft in the west to 50 ft along most of the coastal 

area of the county. This 1942 surface also shows large cones of 

depression centered at Savannah, Georgia, and Fernandina 

Beach, Florida, and includes a smaller cone at St. Marys, resulting from industrial withdrawal for the then-recently opened 

Gillman (now Durango) Paper Company. This configuration is 

typical of most potentiometric-surface maps of the Upper Floridan aquifer in coastal Georgia that have been constructed to the 

present (2004), with the exception of the addition of two other 

major cones of depression: one centered at Brunswick in Glynn 

County and the other centered at Jesup in Wayne County (fig. 3),

both owing to industrial withdrawal. The altitude of the 1998 

potentiometric surface of the Upper Floridan aquifer in Camden 

County is about 40 ft throughout most of the county, with the 

exception of St. Marys, where the altitude of the surface is 

about zero, indicating a decline of at least 50 ft since industrial 

withdrawal began during the early 1940s. 

The 1998 potentiometric surface does not depict the total

depth of the cone of depression at St. Marys because water-level 

measurements were not obtainable from production wells at the 

mill. Based on historical water-level measurements made in the 

active production wells during mill operation, however, the altitude of the cone of depression at the center of pumping at the mill 

was estimated to range from 68 to 235 ft below NAVD 88 and 

averaged about 114 ft below NAVD 88 during mill operation. To 

evaluate the effects of the Durango Paper Company shutdown, 

potentiometric-surface maps for the Upper Floridan aquifer were 

constructed for September 2001 and September 2002, prior to 

the Durango Paper Company ceasing operations, January 2003 

during the water-level recovery, and May 2003 when the water 

level had stabilized (table 2; figs. 10–11). 

Figure 6. Period-of-record hydrograph for well 33D072 (confined surficial aquifer), Camden County, 

Georgia, 1998–2003.
–10

10

0

40

20

30

DAILY MEAN WATER LEVEL, ABOVE (–) AND BELOW LAND SURFACE, IN FEET

Blank

where

data

missing

Blank

where

data

missing

Well 34H125 (Glynn County, Georgia, see well location fig. 3)

Well 34N089 (Liberty County, Georgia, see well location fig. 3)

10

0

20

30

40

Well N-19 (Nassau County, Florida, see well location fig. 1B)

10

0

–30

–20

–10

Well 33D069 (Camden County, Georgia, see well location fig. 1B)

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Trend

14 Effects of Decreased Ground-Water Withdrawal

Figure 7. Hydrographs and regional water-level trends for wells completed in the Upper Floridan aquifer, 

coastal Georgia and northeastern Florida, 1994–2003.
15

10

0

5

–5

–10

DAILY MEAN WATER LEVEL

ABOVE (–) AND BELOW

LAND SURFACE, IN FEET

1998 1999 2000 2001 2002 2003

Trend

Ground-Water Levels 15

Prior to the shutdown during October 2002, potentiometricsurface maps for September 2001 and September 2002 (fig. 10A

and B) show a small cone of depression centered at St. Marys 

(as indicated by the –10-ft contour) that coalesces with a larger 

cone of depression centered at Fernandina Beach, Florida. 

The maps indicate that the Fernandina Beach cone of depression (as indicated by the 30-ft contour extends about 4.7 mi 

west and 5.2 mi north of St. Marys). Although water levels in 

St. Marys began to rise from 24 to 48 hours after the shutdown, 

the cone of depression from Fernandina Beach remains, 

extending north and west of St. Marys (fig. 11A and B).

The most prominent changes in the potentiometric surface 

after the industrial shutdown are the disappearance of the cone 

of depression centered at St. Marys, Georgia, the decreased 

Fernandina Beach cone, and the development of the 40-ft 

ground-water mound northwest of St. Marys (fig. 11A and B). 

The water level in the Upper Floridan aquifer at St. Marys 

ranged from about 10 ft below land surface to 10 ft above 

during September 2001 (fig. 10A); by May 2003 (fig. 11B), the 

water level had risen to about 30 ft, which is 20 ft lower than 

the predevelopment potentiometric surface of Johnston and 

others (1980). A water-level change map was constructed by 

comparing water-level data for September 2001 and May 2003 

(fig. 12). The September 2002 water-level data were not used 

for the water-level change map because fewer paired well data 

were available for both time periods (table 2). Water levels 

during September 2001 were slightly lower than September 

2002; thus, the amount of recovery depicted on the map 

(fig. 12) is somewhat greater than would be expected between 

September 2002 and May 2003. Despite this difference, the 

general configuration of the September 2001 and 2002 potentiometric surfaces is similar; thus, the extent of water-level 

rises likely would be similar for September 2002 and May 2003.

The water-level changes resulting from the shutdown are 

greatest in the St. Marys area and are less pronounced and 

more difficult to distinguish from regional trends the farther 

away from the center of pumping. Analysis of continuous 

water-level data from wells in coastal Georgia and Nassau 

County, Florida, indicates a regional upward water-level trend 

in the Upper Floridan aquifer prior to the Durango Paper Company closing (fig. 7). Because of the high transmissivity of the 

Upper Floridan aquifer and the localized nature of the cone of 

depression centered at St. Marys, it appears that the groundwater withdrawal from the Durango Paper Company affected 

only wells located within several miles of the St. Marys area 

(based on the water-level data through May 2003). For wells 

located farther away in Liberty and Glynn Counties, Georgia, 

and Nassau County, Florida, the response to the mill shutdown 

is not discernible because of the overall regional water-level 

rise and the effects of ground-water withdrawal (fig. 7).

The USGS continuously monitored water levels in the 

Upper Floridan aquifer in four wells in Camden County, Georgia (three of which are discussed herein), and two wells in Nassau County, Florida (see locations, fig. 1B). Well 33D069 is 

closest to the Durango Paper Company wellfield, located 

about 1.1 mi south of the center of pumping. The water level 

has been monitored continuously since 1994 and ranged from 

about 8 ft below land surface to 9 ft above land surface for the 

period of record prior to the industrial shutdown, with an 

upward trend since early 2000 (fig. 13). After pumping ceased, 

the water level in the well rose to 2.12 ft above land surface on 

October 5, 2002, and continued to rise through April 2003. 

A record high water level of 23.62 ft above land surface was 

recorded on April 17, 2003; as of early May 2003, the water 

level appeared to have stabilized with a total rise of 21.5 ft 

from September 2002 to May 2003.

The water level in well 33E007, located about 2 mi 

northwest of the Durango Paper Company (fig. 1B), has 

been monitored continuously since 1993. Water levels 

ranged from about 7.5 ft below land surface to 5.5 ft above 

land surface for the period of record prior to the mill shutdown 

and showed an upward trend since early 2000 (fig. 14). 

Following the shutdown, the water level rose to 1.39 ft below 

land surface on October 6, 2002, and continued to rise through 

May 2003. A record high water level of 15.3 ft above land 

surface was recorded on April 12, 2003; as of early May, the 

water level had stabilized, with a total rise of about 18 ft from 

September 2002 to May 2003.

Figure 8. Period-of-record hydrograph for well 33D071 (upper Brunswick aquifer), 

Camden County, Georgia, 1998–2003.
l l l l l l l l l l l l

l

l l l

l l l l

l l

l l l

lllll

l l l l l l l l l l l l l l l l l l l l

l

l l l l l

l l l l

l

l l l l l

l l l l l l

GLYNN

BRANTLEY

PIERCE

CHARLTON

CAMDEN

NASSAU

TATTNALL

EVANS BRYAN

LONG

WAYNE

LIBERTY

MCINTOSH

CHATHAM

CANDLER BULLOCH EFFINGHAM

40

0

–10

–20

–30

30

20

30

20

10

70

60

5060

80

90

100

150

40

40

50

EXPLANATION

50 Potentiometric contour—Shows altitude at 

which water level would have stood in tightly 

cased wells during 1942. Hachures indicate 

depression. Contour interval 10 feet. Datum 

is NGVD 29

32°

82°

31°

81°

0 20 30 MILES 10

0 20 30 KILOMETERS 10

Atlantic Ocean

GA

FL

Base from U.S. Geological Survey 

1:100,000- and 1:250,000-scale digital data

16 Effects of Decreased Ground-Water Withdrawal

Figure 9. Potentiometric surface of the Upper Floridan 

aquifer in the coastal area of Georgia and Nassau County, 

Florida, 1942 (modified from Warren, 1944).

Table 2. Ground-water altitudes in selected wells in Camden County, 

Georgia, and Nassau County, Florida, September 2001–May 2003.

[ID, identification; –, indicates below NAVD 88; —, data not available; altitudes in feet]

30E008 31.18 31.60 32.08 34.26 37.00

31E001 34.1 33.65 37.31 37.88 39.95

31F022 34.7 34.41 40.63 41.69 41.29

32E031 34.83 33.7 37.76 37.9 40.76

32E032 34.03 33.14 31.33 35.24 38.44

32E033 30.71 29.85 29.32 35.89 38.22

32E038 27.07 25.9 26.76 30.06 33.52

32F008 35.55 33.97 37.61 38.43 40.63

33D004 — 6.72 — — —

33D050 — — — — 24.71

33D054 11.62 7.6 9.21 31.26 —

33D055 3.02 0.71 — 23.8 25.93

33D058 –2.93 –2.48 –2.51 — —

33D061 — — — — 22.71

33D063 –12.34 –11.21 –10.13 — —

33D069 7.18 6.79 7.16 26.97 28.28

33D073 — 8.46 10.08 — —

33E006 19.94 19.49 — 22.75 —

33E007 11.98 14.28 13.63 28.48 30.75

33E009 35.44 33.43 35.49 36.75 39.47

33E027 — 26.4 24.47 36.69 —

33E034 24.76 — — 35.79 36.94

33E046 35.02 31.81 39.08 44.99 45.02

33E049 28.22 26.46 26.63 32.65 35.71

33E050 18.4 15.81 17.18 30.75 30.9

33E051 25.04 33.69 28.21 28.51 35.74

33E052 27.47 27.67 — 32.65 35.14

33E053 26.69 25.01 23.54 29.55 35.41

33E054 — 27 33.17 39.24 —

33E055 — 30.89 33.88 39.5 43.8

33E115 23.56 26.59 25.89 27.62 30.89

33E117 31.75 30.12 29.82 39.02 40.92

33F002 32.37 35.65 30.89 35.87 38.47

33F003 28.73 32.27 25.94 31.57 34.06

33F017 34.15 37.57 32.92 35.57 40.48

34E001 18.62 17.02 16.11 18.5 29.92

34E003 23.06 — — — —

34E010 21.32 — — 28.23 31.46

34E012 30.11 — — 36.01 37.59

34E013 29.49 — — 35.12 36.8

34E014 29.47 — — 36.89 38.01

34F004 — — — — 41.52

34F014 32.98 — — 37.16 —

34F015 37 — — 41.31 43.55

N-119 28.73 28.03 28.53 34.67 34.67

N-120 36.51 — — — —

N-121 25.91 24.71 25.21 34.22 33.82

N-130 20.7 — 20.6 14.76 23.26

N-19 –10.61 –11.67 — –1.35 –2.27

N-20 2.93 0.99 3.02 9.75 10.42

N-220 37.64 37.44 38.24 41.95 44.45

N-221 36.52 35.75 34.43 40.13 42.78

N-237 36.14 34.56 34.76 40 41.24

N-50 33.14 32.44 33.94 — —

N-62 –13.1 –19.64 –14.17 –3.46 –8.42

Well ID 2001 2002 2003

Sept. May Sept. Jan. May
Interaquifer Leakage 17

The water level in well 33E027, located at the Naval Submarine Base Kings Bay about 4.6 mi northeast of the Durango 

Paper Company (fig. 1B), has been monitored continuously 

since 1979. Water levels ranged from about 10 to 25 ft above 

land surface for the period of record prior to the mill shutdown 

and showed an upward trend since early 2000 (fig. 15). After 

the shutdown, the water level rose to 16.66 ft above land surface 

on October 6, 2002, and continued to rise through May 2003. 

A record high water level of 29.77 ft above land surface was 

recorded on February 17, 2003; as of early May, the water level 

had stabilized with a total rise of 11.5 ft from September 2002 

to May 2003.

In Nassau County, Florida, the USGS continuously monitored water levels in two wells. Wells N-19 (fig. 16) and N-62 

(fig. 17)—located at Fernandina Beach, Florida, about 6.2 

and 8.5 mi, respectively, southeast of the Durango Paper 

Company (figs. 1A and B)—have been monitored continuously

since 1986 and 1994, respectively. Hydrographs for both 

wells show an upward water-level trend starting during early to 

mid-2000, which became more pronounced during October 

2002, similar to the trends observed in wells completed in the 

Upper Floridan aquifer throughout coastal Georgia (fig. 7). 

The water level in well N-62 in Nassau County, Florida, 

began rising during July 2002, about 3 months prior to the 

Durango Paper Company shutdown, and continued to rise 

through February 2003 when the water level began to decline. 

The water-level decline from February to late June 2003 at 

Fernandina Beach, Florida, is not evident on hydrographs of 

wells at St. Marys, indicating the decline resulted from 

increased local water use. The water level in well N-19 (fig. 16) 

began to rise in mid-September 2002 and rose steeply until midNovember 2002, when the water level stabilized. Statistical 

filtering of data from wells N-19 and N-62 (figs. 16 and 17) 

indicates that the higher water levels during 2003 are not 

directly related to the Durango Paper Company shutdown.

Lower Floridan Aquifer

Water levels in the Lower Floridan aquifer in well 33D073, 

located about 0.2 mi southwest of the Durango Paper Company, 

have been monitored continuously since 2000 (fig. 1B). Water 

levels in the well ranged from about 7 ft below land surface to 

10 ft above land surface for the period of record prior to the mill 

shutdown and showed a water-level rise since mid-2000 

(fig. 18). After the shutdown, the water level rose to 7.45 ft 

above land surface on October 5, 2002, and continued to rise 

through May 2003. A record-high water level of 25.67 ft 

above land surface was recorded on April 17, 2003; as of early 

May 2003, the water level appeared to have stabilized, with a 

total rise of 18.2 ft from September 2002 to May 2003.

Interaquifer Leakage

At St. Marys, water levels in the confined surficial, upper 

Brunswick, and Upper and Lower Floridan aquifers showed a 

pronounced rise following the Durango Paper Company shutdown, and continued to rise through May 2003, indicating interaquifer leakage (fig. 5). Clarke and others (1990) stated that the 

confining units in the coastal area above and below the Upper 

Floridan aquifer are not impermeable and may allow movement 

of water from the underlying and overlying aquifers. The rate of 

leakage of water from the Upper Floridan aquifer to the Brunswick and surficial aquifers systems depends on the thickness 

and hydraulic conductivity of the confining units and differences in hydraulic heads between water-bearing zones (Clarke 

and others, 1990; Gram and Parks, 1986). Leakage can occur in 

areas of heavy pumping where the cone of depression produces 

a steepened hydraulic gradient with adjacent aquifers. Hydrographs from wells completed in the confined surficial, upper 

Brunswick, and Upper and Lower Floridan aquifers at St. Marys

are shown in figure 5. Prior to the Durango Paper Company 

shutdown throughout most of Camden County, hydraulic head 

increased with depth, with an upward hydraulic gradient from 

the Floridan aquifer system to the overlying Brunswick and 

surficial aquifer systems, typical of an aquifer discharge area. 

At the center of pumping at St. Marys, however, the gradient 

was reversed. Water levels in the Upper Floridan aquifer during 

early October at the center of pumping were about 162 ft below 

NAVD 88 and at a site 0.2 mi west of the center of pumping, 

water levels in the overlying aquifers ranged from about 2 ft 

below to 3 ft above NAVD 88, resulting in a downward gradient 

and the potential for downward leakage from the surficial and 

Brunswick aquifers to the Upper Floridan aquifer. At present 

(2004), the rate of leakage has not been determined between the 

three aquifer systems in the St. Marys area.

Away from the center of pumping, the hydraulic gradient 

was less pronounced. The head in the upper Brunswick was the 

lowest observed, indicating the aquifer was a hydrologic “sink” 

that had the potential to receive flow from both the overlying 

confined surficial and the underlying Upper Floridan aquifers 

(fig. 5). Reasons are unclear for the depressed head in the upper 

Brunswick aquifer. Clarke and West (1998) reported a similar 

condition near the Savannah River site in Burke County, Georgia, and concluded that the anomalous low head might result 

from (1) subsurface pinch out of the aquifers, which influences 

flow patterns in the stream aquifer system; (2) hydraulic connection of the aquifers to river alluvium and associated high 

ground-water discharge rates that lowers heads; (3) water-level 

declines as a result of pumpage; or (4) any combination of these 

reasons. Because the upper Brunswick aquifer is deeply buried 

and not incised by nearby streams and is not utilized extensively 

in the Camden County area, the most likely cause of the lowhead condition is subsurface pinch out of the aquifer. Clarke 

(2003) reported the presence of discontinuous permeable layers 

in the Brunswick aquifer system in coastal Georgia.
GEORGIA

Map

area

Atlantic

Ocean

FLORIDA

81o30'

30o30'

31o

82o

l l

l l l l l l l l l l l

CHARLTON

NASSAU

CAMDEN

GLYNN

DUVAL

Atlantic Ocean

A. September 2001 

FL

GA

EXPLANATION

Observation well and site name

0 5 10 MILES

0 5 10 KILOMETERS

30 Potentiometric contour—Shows altitude at which water level 

would have stood in tightly cased wells during September 2001. 

Dashed were approximately located. Hachures indicate 

depression. Contour interval 10 feet. Datum is NAVD 88 

Base from U.S. Geological Survey 

1:100,000- and 1:250,000-scale digital data

St Marys

Fernandina

Beach

Pumping center

37

2.93

20.7

18.4

7.18

3.02

5.47

34.7

34.1

–13.1

33.14

36.52

37.64

36.14

36.14

25.91

36.51

28.73

32.98

29.47

30.11 29.49

21.87

21.32

23.06

23.27

18.62

34.15

28.73

32.37

31.75

23.56

35.22

39.65

26.69

27.47 25.04

28.22

35.02

24.76

27.94

35.44

11.98

19.94

–12.34

–2.93

11.62

35.55

27.07

30.71

34.03

34.83 31.18

–10.61

–10

–10

30

30

20

0

10

30

18 Effects of Decreased Ground-Water Withdrawal

Figure 10. Potentiometric surface of the Upper Floridan aquifer in Camden County, Georgia, and 

Nassau County, Florida, (A) September 2001 and (B) September 2002.
GEORGIA

Map

area

FLORIDA

Atlantic

Ocean

81o30'

30o30'

31o

82o

l l l l l l l l l l l l l l l l l l –10

–10

30

40

20

0

10

30

3.02

20.6

7.16

9.21

33.94

34.43

38.24

38.24

25.21

28.53

16.11

32.92

25.94

30.89

29.82

25.89

33.88

33.17

23.54 28.21

17.18

26.63

39.08

24.47

35.49

13.63

10.08

–10.13

–2.51

37.61

26.76

29.32

31.33

37.76

40.63

37.31

32.08

–14.17

34.76

CHARLTON

NASSAU

CAMDEN

GLYNN

DUVAL

Atlantic Ocean

FL

GA

EXPLANATION

Observation well and site name

B. September 2002

0 5 10 MILES

0 5 10 KILOMETERS

Potentiometric contour—Shows altitude at which water level would 

have stood in tightly cased wells during September 2002. Dashed 

were approximately located. Hachures indicate depression. 

Contour interval 10 feet. Datum is NAVD 88 

30

St Marys

Fernandina

Beach

Base from U.S. Geological Survey 

1:100,000- and 1:250,000-scale digital data

Pumping center

Interaquifer Leakage 19

Figure 10. Potentiometric surface of the Upper Floridan aquifer in Camden County, Georgia, and 

Nassau County, Florida, (A) September 2001 and (B) September 2002—Continued.
Pumping center

GEORGIA

Map

area

Atlantic

Ocean

FLORIDA

81o30'

30o30'

31o

82o

40

40

40

20

30

10

0

30

40

CAMDEN

CHARLTON

NASSAU

GLYNN

DUVAL

FL

GA

Atlantic Ocean

EXPLANATION

Observation well and site name

A. January 2003

0 5 10 MILES

0 5 10 KILOMETERS

Potentiometric contour—Shows altitude at which water level would 

have stood in tightly cased wells during January 2003. Dashed were 

approximately located. Contour interval 10 feet. Datum is NAVD 88 

40

St Marys

Fernandina

Beach

Base from U.S. Geological Survey 

1:100,000- and 1:250,000-scale digital data

9.75

18.5

39.5

23.8

37.9

–3.46

40.13

41.95

40

41.95

–1.35

14.76

34.22

34.67

41.31

37.16

36.89

35.12

36.01

28.23

35.57

31.57

35.87

39.02

27.62

39.24

29.55

32.65

28.51

30.75

32.65

44.99

35.79

36.69

36.75

28.48

22.75

31.26

38.43

30.06

35.89

35.24

41.69

37.88

34.26

26.97

20 Effects of Decreased Ground-Water Withdrawal

Figure 11. Potentiometric surface of the Upper Floridan aquifer in Camden County, Georgia, and 

Nassau County, Florida, (A) January 2003 and (B) May 2003.
GEORGIA

Map

area

FLORIDA

Atlantic

Ocean

81o30'

30o30'

31o

82o

CAMDEN

CHARLTON

NASSAU

GLYNN

DUVAL

FL

GA

Atlantic Ocean

EXPLANATION

Observation well and site name

B. May 2003

0 5 10 MILES

0 5 10 KILOMETERS

Potentiometric contour—Shows altitude at which water level would 

have stood in tightly cased wells during May 2003. Dashed were 

approximately located. Contour interval 10 feet. Datum is NAVD 88 

40

Base from U.S. Geological Survey 

1:100,000- and 1:250,000-scale digital data

St Marys

Fernandina

Beach

Pumping center

37 36.8

43.8

30.9

–8.42

42.78

44.45

44.45

10.42

–2.27

23.26

33.82

34.67

43.55

41.52

38.01

37.59

31.46

29.92

40.48

34.06

38.47

40.92

30.89

35.41 35.14

35.71

45.02

39.47

30.75

28.28

22.71

25.93

24.71

40.63

33.52

38.22

38.44

40.76

41.29

39.95

35.74

36.94

41.24

40

40

40

20

30

0 10

Interaquifer Leakage 21

Figure 11. Potentiometric surface of the Upper Floridan aquifer in Camden County, Georgia, and 

Nassau County, Florida, (A) January 2003 and (B) May 2003—Continued.
GEORGIA

Map

area

Atlantic

Ocean

FLORIDA

82o 81o30'

30o30'

31o

30

20

10

CHARLTON

NASSAU

CAMDEN

GLYNN

DUVAL

Atlantic Ocean

EXPLANATION

September 2001 through May 2003

0 5 10 MILES

0 5 10 KILOMETERS

10 Line of equal water-level change—Shows approximate change in 

water level in the Upper Floridan aquifer during September 2003 

through May 2003. Interval 10 feet. Datum is NAVD 88 

FL

GA

Base from U.S. Geological Survey 

1:100,000- and 1:250,000-scale digital data

St Marys

Fernandina

Beach

Observation well and water-level change

10

6.1

4.68 7.49

8.34

2.56

7.91

6.81

5.94

6.55

8.54

7.48 7.31

11.3

6.33

5.33

9.17

7.33 8.72

7.67 10.7

12.5

7.49

4.03

21.1

5.08

6.45

7.51

4.41

5.93

6.59

5.85

10.14

12.18

18.77

22.91

7.91

Pumping center

22 Effects of Decreased Ground-Water Withdrawal

Figure 12. Observed water-level change from September 2001 through May 2003 in wells completed in 

the Upper Floridan aquifer in Camden County, Georgia, and Nassau County, Florida.
–35

–25

–20

–15

–30

–10

–5

Trend

DAILY MEAN WATER LEVEL

ABOVE (–) LAND SURFACE, IN FEET

1980198219841986198819901992199419961998200020022003

Interaquifer Leakage 23

Figure 15. Period-of-record hydrograph for well 33E027 (Upper Floridan aquifer), Camden County, 

Georgia, 1980–2003.

10

20

0

–30

–20

–10

DAILY MEAN WATER LEVEL ABOVE (–) AND

BELOW LAND SURFACE, IN FEET

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Trend

Figure 13. Period-of-record hydrograph for well 33D069 (Upper Floridan aquifer), 

Camden County, Georgia, 1994–2003.

10

0

5

–20

–10

–5

–15

DAILY MEAN WATER LEVEL

ABOVE (–) AND BELOW

LAND SURFACE, IN FEET

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Trend

Figure 14. Period-of-record hydrograph for well 33E007 (Upper Floridan aquifer), Camden County, 

Georgia, 1994–2003.
10

0

20

30

40

DAILY MEAN WATER LEVEL

BELOW LAND SURFACE, IN FEET

1986 1988 1990 1992 1994 1996 1998 2000 2002 2003

Trend

24 Effects of Decreased Ground-Water Withdrawal

Figure 16. Period-of-record hydrograph for well N-19 (Floridan aquifer system), Nassau County, 

Florida, 1986–2003.

0

10

20

30

40

50

60

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

DAILY MEAN WATER LEVEL BELOW LAND SURFACE, IN FEET

Trend

Figure 17. Period-of-record hydrograph for well N-62 (Floridan aquifer system), Nassau County, 

Florida, 1994–2003.
Chloride Concentrations in Camden County 25

After the mill ceased operations during October 2002, water 

levels in all aquifers rose, changing vertical hydraulic gradients 

and direction of flow between the confined surficial and upper 

Brunswick aquifers. The head in the upper Brunswick aquifer 

rose above the head in the confined surficial, reversing the 

vertical hydraulic gradient between the two aquifers (fig. 5). 

Prior to the shutdown, water levels in the confined surficial 

were 2–4 ft higher than in the upper Brunswick aquifer; following the shutdown the water level in the upper Brunswick aquifer 

rose above the confined surficial aquifer and the head separation between the aquifers was about 10 ft. Thus, the distribution 

of hydraulic head following the shutdown is more typical of an 

aquifer discharge area, whereby head increases with depth. 

Digital flow modeling could be used to estimate confining unit 

leakance rates and to study local interaquifer connection.

Chloride Concentrations in 

Camden County

10

0

–30

–20

–10

DAILY MEAN WATER LEVEL ABOVE (–)

AND BELOW LAND SURFACE, IN FEET

2000 2001 2002 2003

Trend

Chloride concentrations in the Upper Floridan aquifer have 

been monitored periodically in the Camden County area since 

the 1960s and annually since 1994 (Leeth and others, 2003). 

Chloride concentrations in the Upper Floridan aquifer in 

Camden County do not exceed the State and Federal drinkingwater standard of 250 mg/L (Georgia Environmental Protection 

Division, 1997; U.S. Environmental Protection Agency, 2000). 

Chloride concentrations in water samples collected from a 

recently drilled deep test well at St. Marys, Georgia, indicate 

that the chloride concentration in the Floridan aquifer system 

remained near background levels (from 30 to 50 mg/L) to a 

depth of 2,060 ft below land surface, at which point the 

chloride concentration increased to 350 mg/L (St. Johns River 

Water Management District, 2002). Water samples from 

Upper Floridan aquifer wells collected during this study (from 

September 2002 to May 2003) (table 3) had chloride concentrations that ranged from 23 to 43 mg/L, which is considered in the 

background, or uncontaminated, range (Rose, 2001; 2002). 

Water from three wells, however—two at Durango Paper 

Company and one unused City of St. Marys well—had chloride 

concentrations above the background range, but were still 

within the drinking-water limit of 250 mg/L (table 3). The 

chloride concentration in well 33D061 (Durango Paper Company well) ranged from 48.7 mg/L during1988 to 184 mg/L 

during 2000 (fig. 19). The other two wells with elevated 

chloride concentrations could be only sampled once during 

the study period. The unused City of St. Marys well 33D055 

had a chloride concentration of 156.4 mg/L, and the Durango 

Paper Company well 33D048 had a chloride concentration of 

74.9 mg/L. The source has not been determined for the 

elevated chloride concentrations in these wells. 

Saltwater intrusion into the Upper Floridan aquifer is a 

major concern in the coastal area. At Brunswick, Georgia, 

saltwater intrusion is the result of upward movement of 

highly saline water from deeper zones (Clarke and others, 

1990); on the north end of Hilton Head Island, South Carolina, 

saltwater intrusion is the result of lateral encroachment of sea 

water attributed to the reduction of pressure in the freshwater 

zones (Clarke and others, 1990). The depth of the aquifer 

(about 560 ft) and the presence of freshwater in the aquifer as 

far offshore as 70 mi make lateral saltwater encroachment 

unlikely (Johnston and others, 1982). Although it is possible 

that the saltwater is derived from deeper zones, at St. Marys, 

the presence of freshwater in the aquifer to a depth of 2,060 ft 

makes upward movement of saline water unlikely. A possible 

mechanism for elevated chloride concentration is vertical 

movement along the annular space of the well bore, whereby 

saline marsh water moves downward into the Upper Floridan 

aquifer. Changes in chloride concentration in well 33D061 

(fig. 19) support the hypothesis of saltwater movement along 

the annular well space.

Figure 18. Period-of-record hydrograph for well 33D073 (Lower Floridan aquifer), 

Camden County, Georgia, 2000–2003.
26 Effects of Decreased Ground-Water Withdrawal

Table 3. Water-quality data from selected wells in Camden County, Georgia, September 2002–May 2003.

[mg/L, milligrams per liter; μS/cm, microseimens per centimeter at 25 degrees Celsius; do., ditto; UF, Upper Floridan aquifer; 

FAS, Floridan Aquifer system; LF, Lower Floridan; —, data not available]

Well name Date sampled Chloride dissolved 

(mg/L)

Specific conductance

(μS/cm)

Sulfate dissolved 

(mg/L) Aquifer code

31E001 Jan. 30, 2003 31.76 731.72 30.30 UF

do. May 15, 2003 29.92 741.69 162.51 UF

32E031 Jan. 30, 2003 35.85 725.82 36.22 UF

32E033 Sept. 17, 2002 30.23 534 — UF

do. Jan. 30, 2003 34.02 443.4 72.07 UF

do. May 12, 2003 41 387 77 UF

do. May 13, 2003 42.37 403.41 83.67 UF

32F008 Jan. 30, 2003 42.8 707.9 57.7 UF

do. May 15, 2003 37.12 692.96 133.11 UF

33D006 Jan. 29, 2003 33.15 728.72 22.04 UF

33D048 Jan. 29, 2003 74.91 857.71 14.46 FAS

33D050 Jan. 29, 2003 32.01 689.44 25.19 FAS

do. May 13, 2003 34.73 733.25 166.13 FAS

33D054 Sept. 16, 2002 30.88 709 — UF

do. Jan. 29, 2003 31.27 692.14 15.94 UF

do. May 13, 2003 33.31 723.34 160.64 UF

do. May 14, 2003 32 718 160 UF

33D055 Jan. 29, 2003 156.42 569.51 4.8 UF

33D058 Jan. 29, 2003 31.65 728.14 17.7 UF

33D061 Sept. 17, 2002 175.29 1150 — UF

do. Jan. 29, 2003 128.65 1026.29 4.81 UF

do. May 14, 2003 110 988 170 UF

do. May 14, 2003 143.3 1027.46 182.51 UF

33D073 Sept. 12, 2002 30.16 971.93 50 LF

do. Sept. 12, 2002 27.23 829.83 50 LF

do. Sept. 12, 2002 26.9 926.62 50 LF

do. Sept. 12, 2002 26.72 855.27 50 LF

do. May 16, 2003 29.24 629.43 212.48 LF

33E008 Jan. 30, 2003 23.34 679.67 43.75 UF

33E027 May 12, 2003 32.37 674.7 146.22 UF

33E046 Jan. 29, 2003 37.47 731.82 28.62 UF

do. May 14, 2003 35.33 673.91 161.18 UF

33E049 Sept. 17, 2002 31.19 704 — UF

do. Jan. 30, 2003 32.33 637 21.2 UF

do. May 12, 2003 33.00 720.00 160.00 UF

do. May 12, 2003 37.43 747.13 170.47 UF

33E050 Jan. 29, 2003 34.07 724.09 27.18 UF
Chloride Concentrations in Camden County 27

33E051 Jan. 27, 2003 34 714.88 30.43 UF

do. May 12, 2003 35.13 719.76 149.12 UF

33E052 Jan. 27, 2003 35.28 726.66 26.66 UF

do. May 12, 2003 35.62 736.02 161.98 UF

33E053 Sept. 16, 2002 33.32 698 — UF

do. Jan. 27, 2003 34.89 713.63 34.12 UF

do. May 12, 2003 36 711 150 UF

do. May 12, 2003 36.11 739.93 163.62 UF

33E115 Jan. 29, 2003 34 729.25 24.12 UF

do. May 14, 2003 33.39 712.65 170.91 UF

33F002 Jan. 27, 2003 38.4 673.35 59.46 UF

do. May 14, 2003 36.16 501.4 92.24 UF

33F003 Jan. 27, 2003 39.51 481.49 71.08 UF

do. May 14, 2003 43.6 471.66 79.95 UF

33F017 Jan. 27, 2003 39.5 674.67 52.92 UF

do. May 14, 2003 41.6 690.97 139.11 UF

34E001 Jan. 28, 2003 31.82 738.48 19.79 UF

do. May 13, 2003 33 723 160 UF

do. May 13, 2003 30.61 732.56 160.07 UF

34E003 Jan. 28, 2003 31.51 740.41 219.42 UF

do. May 13, 2003 31.7 697.9 157.91 UF

34E010 Jan. 28, 2003 32.27 731.75 11.94 UF

34E011 Jan. 28, 2003 35.92 612.4 46.45 UF

34E012 Jan. 28, 2003 36.09 697.59 49 UF

34E013 Jan. 28, 2003 35.93 710.05 40.11 UF

do. May 12, 2003 33.66 738.12 177.52 UF

34E014 Jan. 28, 2003 34.91 711.75 31.44 UF

do. May 13, 2003 37.99 711.86 149.71 UF

34F014 Jan. 28, 2003 36.88 700.17 40.6 UF

Table 3. Water-quality data from selected wells in Camden County, Georgia, September 2002–May 2003.—Continued

[mg/L, milligrams per liter; μS/cm, microseimens per centimeter at 25 degrees Celsius; do., ditto; UF, Upper Floridan aquifer; 

FAS, Floridan Aquifer system; LF, Lower Floridan; —, data not available]

Well name Date sampled Chloride dissolved 

(mg/L)

Specific conductance

(μS/cm)

Sulfate dissolved 

(mg/L) Aquifer code
28 Effects of Decreased Ground-Water Withdrawal

During 1982–2001, concentrations generally increased in well 

33D061, a period during which the vertical hydraulic gradient 

was downward due to pumpage at the Durango Paper Company. 

Since 2001, concentrations in this well generally decreased, corresponding to changes in the direction and magnitude of the 

hydraulic gradient between the Upper Floridan aquifer and 

overlying unconfined surficial aquifer. The unconfined surficial 

aquifer is in contact with saline water from the nearby salt 

marsh. As the hydraulic gradient decreased, less saline water 

moved vertically along the annular space and into the Upper 

Floridan and, thus, concentrations decreased. Borehole geophysical data could verify the integrity of the grout seal in the 

annular space of the wells; however, it may be difficult to obtain 

access to these wells because of installed turbine pumps and 

high borehole flow rates. In addition, water-chemistry data 

could be used to determine the source of the saltwater.

Boxplots of water samples collected prior to (1969–September 2002) and after the mill shutdown (January–May 2003) are 

shown in figure 20. Except for wells 33D061, 33D055, and 

33D048, chloride and sulfate concentrations have not changed 

appreciably since the reduction in ground-water withdrawal.

Figure 19. Chloride concentration in water from the Upper 

Floridan aquifer at well 33D061, Durango Paper Company, 

Camden County, Georgia, 1982–2003.

CHLORIDE CONCENTRATION, IN MILLIGRAMS PER LITER

50

40

45

35

30

25

152

152

56

46 56

SULFATE CONCENTRATION, IN MILLIGRAMS PER LITER

PRESHUTDOWN

POSTSHUTDOWN

250

150

200

100

50

0

EXPLANATION 

75th percentile

90th percentile

Number of

 samples

Median

25th percentile

10th percentile

A.

B.

0

40

80

120

160

200

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2003

CHLORIDE CONCENTRATION,

IN MILLIGRAMS PER LITER

Figure 20. Boxplots of (A) chloride and (B) sulfate 

concentration in water from the Upper Floridan 

aquifer in Camden County, Georgia, prior to and after 

the Durango Paper Company shutdown, September 

2002–May 2003.
Summary and Conclusions 29

est in the Lower Floridan aquifer followed by the Upper Floridan aquifer, the confined surficial aquifer, and the upper Brunswick aquifer. After the mill ceased operations during October 

2002, the hydraulic head separation between the aquifers 

increased and the head in the upper Brunswick rose above the 

head in the confined surficial, reversing the vertical hydraulic 

gradient. Digital modeling could be used to estimate confining 

unit leakance rates and to study local interaquifer connection.

Chloride concentrations in water from the Upper Floridan 

aquifer in Camden County do not exceed the State and Federal 

drinking-water standards of 250 milligrams per liter (mg/L). 

Concentrations in most of the wells sampled during this study 

(from September 2002 to May 2003) ranged from 30 to 50 mg/L, 

which is considered as the range for background concentrations 

in the Upper Floridan aquifer. Three wells in the St. Marys area, 

however, had chloride concentrations above the background 

range. Well 33D061 (Durango Paper Company well) has had an 

increase in chloride concentration since sampling began during 

1982; however, these concentrations are below the drinkingwater limit of 250 mg/L. The source has not been determined for 

the elevated chloride concentrations in this well, and chloride 

concentrations have decreased slightly since the Durango Paper 

Company shutdown. The depth of the aquifer (about 560 ft) and 

the presence of freshwater in the aquifer as far offshore as 70 

miles makes lateral saltwater encroachment unlikely. In addition, the presence of freshwater in the aquifer to a depth of 2,060 

ft makes upward movement of saline water unlikely. A possible 

mechanism for elevated chloride concentration is vertical 

movement along the annular space of the well bore, whereby 

saline marsh water moves downward into the Upper Floridan 

aquifer. Changes in chloride concentration in well 33D061 support the hypothesis of saltwater movement along the annular 

well space. Overall chloride concentrations in the Upper Floridan aquifer did not change appreciably after the reduction in 

ground-water withdrawal, and the sulfate concentration 

remained about the same. Borehole geophysical logging techniques could be used to determine if saltwater is entering the 

wells from the marsh.

Selected References

Brown, D.P., 1984, Impact of development on availability and 

quality of ground water in eastern Nassau County, Florida, 

and southeastern Camden County, Georgia: U.S. Geological 

Survey Water-Resources Investigations Report 83-4190, 

113 p.

Clarke, J.S., 1987, Potentiometric surface of the Upper 

Floridan aquifer in Georgia, May 1985, and water-level 

trends, 1980–85: Georgia Geologic Survey Hydrologic 

Atlas 16, 1 sheet, scale 1:1,000,000.

Clarke, J.S., 2003, The surficial and Brunswick aquifer systems—alternative ground-water resources for Coastal Georgia, in Proceedings of 2003 Georgia Water Resources conference, Athens, Georgia, April 23–24, 2003, K.J. Hatcher, ed., 

The University of Georgia, Institute of Ecology, CD–ROM.

Summary and Conclusions

During October 2002, the Durango Paper Company 

(formally Gillman Paper Company) at St. Marys, Georgia, shutdown paper-mill operations; the shutdown resulted in decreased 

ground-water withdrawal in Camden County by 35.6 million 

gallons per day. The reduction in withdrawal affected water levels in the Floridan aquifer system and the overlying surficial and 

Brunswick aquifer systems. As a result, many wells in the St. 

Marys area began to flow for the first time since the mill began 

operations during 1941. 

The most prominent changes in the potentiometric surface 

of the Upper Floridan aquifer since the mill shutdown have 

been the disappearance of the cone of depression centered at 

St. Marys, Georgia, the decreased Fernandina Beach cone, and 

the development of the 40-foot (ft) ground-water mound northwest of St. Marys. The water level in the Upper Floridan aquifer 

at St. Marys ranged from about 10 ft below land surface to 10 ft 

above land surface during September 2001, and by May 2003 

had risen to about 30 ft, which is 20 ft lower than predevelopment water levels. The water-level changes resulting from the 

mill shutdown are greatest in the St. Marys area and are less 

pronounced and more difficult to distinguish from regional 

trends the farther away from the center of pumping. Analysis of 

continuous water-level data from wells in coastal Georgia and 

Nassau County, Florida, indicates a regional upward water-level 

trend in many wells in the Upper Floridan aquifer beginning during 1999–2000. This trend became more pronounced during 

early October 2002 and continued through May 2003. Waterlevel rises resulting from the Durango Paper Company shutdown are easy to discern in wells located at St. Marys; however, 

for wells located farther away in Glynn County, Georgia, and 

Nassau County, Florida, the response to the mill shutdown is not 

discernible because of the overall regional water-level rise and 

the effects of ground-water withdrawal. Since the shutdown, 

water levels at the mill have risen about 140 ft and are now at 

about 30 ft above NAVD 88. 

At St. Marys, the water levels in the Lower Floridan, Upper 

Floridan, upper Brunswick, and confined surficial aquifers 

began rising during early October 2002 after the mill shutdown 

and continued rising through May 2003, indicating interaquifer 

leakage. Throughout Camden County, the vertical hydraulic 

gradient is upward from the Floridan aquifer system to the overlying Brunswick and surficial aquifer systems. When the mill 

was operating, however, water levels in the Upper Floridan 

aquifer at the center of pumping ranged from 68 to 235 ft below 

NAVD 88, and water levels in the overlying aquifers ranged 

from about 2 ft below to 3 ft above NAVD 88, reversing the vertical hydraulic gradient within the cone of depression. This 

reverse in vertical gradient causes decreasing upward leakage 

from the Upper Floridan aquifer and creates the potential for 

downward leakage from the surficial and Brunswick aquifers to 

the Upper Floridan aquifer. At present (2004), the rate of leakage has not been determined for the three aquifer systems in the 

St. Marys area. Typical head relations in the four different zones 

being monitored at St. Marys were: the hydraulic head was high-
30 Effects of Decreased Ground-Water Withdrawal

Clarke, J.S., Hacke, C.M., and Peck, M.F., 1990, Geology and 

ground-water resources of the coastal area of Georgia: Georgia Geologic Survey Bulletin 113, 106 p.

Clarke, J.S., and Krause, R.E., 2000, Design, revision, and 

application of ground-water flow models for simulation of 

selected water-management scenarios in the coastal area of 

Georgia and adjacent parts of South Carolina and Florida: 

U.S. Geological Survey Water-Resources Investigations 

Report 00-4084, 93 p.

Clarke, J.S., Leeth, D.C., Taylor-Harris, DáVette, Painter, J.A., 

Labowski, J.L., 2004, Hydraulic properties of the Floridan 

aquifer system and equivalent clastic units in coastal Georgia 

and adjacent parts of South Carolina and Florida: Georgia 

Geologic Survey Information Circular 109, 50 p.

Clarke, J.S., and West, C.T., 1998, Simulation of ground-water 

flow and stream-aquifer relations in the vicinity of the Savannah River Site, Georgia and South Carolina, predevelopment 

through 1992: U.S. Geological Survey Water-Resources 

Investigations Report 98-4062, 134 p.

Cleveland, R.G., Cleveland, W.S., McRae, J.E., and Terpenning, I.J., 1990, STL: A seasonal-trend decomposition 

procedure base on loess: Journal of Official Statistics, v. 6, 

no. 1, p. 3–73.

Cleveland, W. S., 1979, Robust locally weighted regression and 

smoothing scatter plots: Journal of American Statistical 

Association, v. 74, p. 829–836.

Cooper, H.H., and Warren, M.A., 1945, The perennial yield of 

artesian water in the coastal area of Georgia and northeastern 

Florida: Economic Geology and the Bulletin of the Society of 

Economic Geologists, v. 40, no. 4, p. 263–282.

Falls, W.F., Harrelson, L.G., Conlon, K.J., and Petkewich, 

M.D., 2001, Hydrogeology and water quality of the Lower 

Floridan aquifer, coastal Georgia, 1999–2000, in Proceedings of 2001 Georgia Water Resources Conference, Athens, 

Georgia, March 26–27, 2001, K.J. Hatcher, ed., The University of Georgia, Institute of Ecology, p. 652–655.

Fanning, J.L., 1999, Water use in coastal Georgia by county 

and source, 1997; and water-use trends, 1980–97: Georgia 

Geologic Survey Information Circular 104, 37 p.

Fanning, J.L., 2003, Water use in Georgia by county for 2000 

and water-use trends for 1980–2000: Georgia Geologic 

Survey Information Circular 106, 176 p.

Frick, E.A., Gregory, M.B., Calhoun, D.L., and Hopkins, E.H., 

2002, Water quality and aquatic communities of upland wetlands, Cumberland Island National Seashore, Georgia, April 

1999 to July 2000: U.S. Geological Survey Water-Resources 

Investigations Report 02-4082, 72 p.

Gram, D.D., and Parks, W.S., 1986, Potential for leakage 

among principal aquifers in the Memphis area, Tennessee: 

U.S. Geological Survey Water-Resources Investigations 

Report 85-4295, 46 p.

Georgia Environmental Protection Division, 1997, Secondary 

maximum contaminant levels for drinking water: Environmental Rule 391-3-5-19, revised October 1997: Official 

Code of Georgia Annotated Statutes, Statute 12-5-170 

(Georgia Safe Drinking Water Act), variously paginated.

Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in 

water resources: Elsevier, New York, N.Y., 529 p.

Hughes, J.P., and Henry, V.J., 1995, Compilation and review 

of information on Neogene aquifers in Camden and Glynn 

Counties, Georgia: Georgia Geologic Survey Project 

Report 23, 56 p.

Johnston, R.H., Bush, P.W., Krause, R.E., Miller, J.E., and 

Sprinkle, C.L., 1982, Summary of hydrologic testing in the 

tertiary limestone aquifer, Tenneco offshore exploratory 

well—Atlantic OCS, Lease-Block 427 (Jacksonville NH 17-5): 

U.S. Geological Survey Water-Supply Paper 2180, 15 p.

Johnston, R.H., Krause, R.E., Meyer, F.W., Ryder, P.D., 

Tibbals, C.H., and Hunn, J.D., 1980, Estimated potentiometric surface for the Tertiary limestone aquifer system, southeastern United States, prior to development: U.S. Geological 

Survey Open-File Report 80-406, 1 sheet.

Kellam, M.F., and Gorday, L.L., 1990, Hydrogeology of the 

Gulf Trough–Apalachicola Embayment area, Georgia: 

Georgia Geologic Survey Bulletin 94, 75 p.

Krause, R.E., and Hayes, L.R., 1981, Potentiometric surface 

of the principal artesian aquifer in Georgia, May 1980: 

Georgia Geologic Survey Hydrologic Atlas 6, 1 sheet, 

scale 1:1,000,000.

Krause, R.E., Mathews, S.E., and Gill, H.E., 1984, Evaluation 

of the ground-water resources of coastal Georgia—Preliminary report on the data available as of July 1983: Georgia 

Geologic Survey Information Circular 62, 55 p.

Krause, R.E., and Randolph, R.B., 1989, Hydrogeology of the 

Floridan aquifer system in southeast Georgia and adjacent 

parts of Florida and South Carolina: U.S. Geological Survey 

Professional Paper 1403-D, 65 p.

Leeth, D.C., 1999, Hydrogeology of the surficial aquifer in the 

vicinity of a former landfill, Naval Submarine Base Kings 

Bay, Camden County, Georgia: U.S. Geological Survey 

Water-Resources Investigations Report 98-4246, 28 p.

Leeth, D.C., Clarke, J.S., Craigg, S.D., and Wipperfurth, C.J., 

2003, Ground-water conditions and studies in Georgia, 2001: 

U.S. Geological Survey Water-Resources Investigations 

Report 03-4032, 96 p.

Leve, G.W., 1966, Ground water in Duval and Nassau, Florida: 

Florida Geological Survey Report of Investigations 43, 91 p.

Miller, J.A., 1986, Hydrogeologic framework of the Floridan 

aquifer system in Florida and parts of Georgia, Alabama, 

and South Carolina: U.S. Geological Survey Professional 

Paper 1403-B, 91 p.

Peck, M.F., 1991, Potentiometric surface of the Upper Floridan 

aquifer in Georgia and adjacent parts of Alabama, Florida, 

and South Carolina, May–June 1990: U.S. Geological 

Survey Open-File Report 91-206, 3 p.

Peck, M.F., Clarke, J.S., Ransom, Camille, III, and Richards, C.J.,

1999, Potentiometric surface of the Upper Floridan aquifer in 

Georgia and adjacent parts of Alabama, Florida, and South 

Carolina, May 1998, and water level trends in Georgia, 1990–

98: Georgia Geologic Survey Hydrologic Atlas 22, 1 sheet.
Selected References 31

Peck, M.F., and McFadden, K.W., 2004, Potentiometric surface 

of the Upper Floridan aquifer in the coastal area of Georgia, 

September 2000: U.S. Geological Survey Open-File Report 

2004-1030, http://ga.water.usgs.gov/pubs/galist-gw.html

Pfaff, J.D., 1999, Method 300.0: Determination of inorganic 

anions by ion chromatography, Revision 2.2, U.S. Environmental Protection Agency, EPA-821-R-99-015, 28 p.

Phelps, G.G., 2001, Geochemistry and origins of mineralized 

waters in the Floridan aquifer system, northwestern Florida: 

U.S. Geological Survey Water-Resources Investigations 

Report 01-4112, 64 p.

Phelps, G.G., and Spechler, R.M., 1997, The relation between 

hydrogeology and water quality of the Lower Floridan aquifer in Duval County, Florida, and implications for monitoring 

movement of saline water: U.S. Geological Survey WaterResources Investigations Report 96-4242, 58 p.

Randolph, R.B., Pernick, Maribeth, and Garza, Reggina, 1991, 

Water-supply potential of the Floridan aquifer system in the 

coastal area of Georgia—a digital model approach: Georgia 

Geologic Survey Bulletin 116, 30 p.

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Prepared by U.S. Geological Survey, Water Resources 

Discipline, Georgia District, Atlanta, Georgia. 

Figure design and production by Bonnie J. Turcott and 

Caryl J. Wipperfurth. 

Editing and page layout by Patricia L. Nobles.