aquifer

Floridan

Lower

?

Upper Floridan aquifer

NORTH-WEST

SOUTH-EAST

GULFTROUGH

Discharge

Atlantic Ocean

Fernandina permeable zone

Surficial aquifer

Brunswick

Recharge area Recharge area

Water level about 65 feet above land surface

Flowing well

Upper Brunswick aquifer

Lower Brunswick aquifer

NORTH-WEST

SOUTH-EAST

Brunswick

Water level about 10 feet below land surfacePumping well

NORTH-EAST

SOUTH-WEST

Fracturein rock

Potentiometric surface

Well depth1,000 feetsemiconfining

Middle

unit

Upper confining unit

confining

Lower

unit

Atlantic Ocean

Brunswick Water level about 65 feet above land surface

Flowing well

UPPERBRUNSWICKAQUIFER

LOWERBRUNSWICKAQUIFER

UPPER CONFINING UNIT

Modified from Krause and Randolph, 1989

Predevelopment

LOWER FLORIDAN AQUIFER

Freshwater

Saltwater

Potentiometric surface

SURFICIAL AQUIFER

Well depth1,000 feet

Fracture in rock

Brunswick

Water level about 10 feetbelow land surface Pumping well

Modern day

UPPER FLORIDANAQUIFER

FERNANDINA PERMEABLE ZONE Transition zone

MIDDLE SEMICONFINING UNIT

LOWER CONFINING UNIT

Generaldirection of

ground-water flow

Flowingwell

Fres

hwat

ersp

rings

Saltw

ater

cond

uits

PortRoyalSound

CalibogueSound

SavannahSavannahHilton Head

IslandHilton Head

Island

Wells

Well depth250 feetSaltwater below 1,000 feet

Predevelopment

Modern day

CONFINING UNIT

General directionof ground-water flow

Potentiometric surface

?? ??

SURFICIAL AQUIFER

AQUIFERUPPER FLORIDAN

Water level about 30 feet above land surface

Water level about 110 feet below land surface

Area of flowing wells

Pumping well

Salt-water

Tran

sitio

n zo

ne

Freshwater

Area of flowing wells Area of flowing wellsFall Line

P L A I NC O A S T A L

Atlanta

G E O R G I A

FLORIDA

SOUTHCAROLINA

Imagearea

Brunswick

Savannah

Tu

rt

le

Ri

ve

r

Tu

rt

le

Ri

ve

r

OAndrewsIsland

AndrewsIsland

Norw

ich StreetM

artin Luther

King Jr Blvd

Martin Luther

King Jr Blvd

4th Ave

4th Street

17

New

castle Street

Norw

ich Street

4th Ave

4th Street

17

New

castle Street

Data from Wait and Gregg, 1973 Data from Peck and others, 1992

501002505001,0001,5002,0002,500

0 1 MILE

0 1 KILOMETER

Chloride concentration in Upper Floridan aquifer, in mg/L

501002505001,000

Downtown BrunswickChloride concentration

in Upper Floridan aquifer, in mg/L

0 1 MILE

0 1 KILOMETER

Downtown Brunswick

Bru

nsw

ick

Sava

nnah

Hilto

n He

ad Is

land

Sealevel

500

1,000

1,500

2,000

2,500

Surficial aquifer

Upper Brunswick aquifer

Semi-confining

unit

Lower Brunswick aquifer

Upp

er F

lorid

anaq

uife

rLo

wer

Flo

ridan

aqu

ifer

Fernandina permeable zone

VERTICAL SCALE GREATLY EXAGGERATED Modified from Krause and Randolph, 1989

Modified from Krause and Randolph, 1989

FLO

RID

AN A

QU

IFER

SYS

TEM

Freshwater

Transition

Saltwater

AquiferSand

Clay

Limestone

and

dolostone

Lithology

Confining unit

Solutioncavity

Feet

Overlying the Floridan aquifer system are layers of clay, thin limestone beds, and sand that yield small quantities of water that can be an alternative or supplemental source of water to the Upper Floridan aquifer. Uppermost of these units is the sandy surficial aquifer—present throughout the coastal area—supplying water mostly for domestic and small-scale irrigation uses.

The Floridan aquifer system consists of carbonate rocks of varying permeability; and in the coastal area, has been divided into the Upper and Lower Floridan aquifers. The Upper Floridan is the aquifer of choice in the coastal area because it lies at relatively shallow depth, has high water-yielding capabilities, and yields water of good quality. Although the Lower Floridan aquifer contains highly permeable zones, its utilization is limited by the excessive depth and locally poor water quality. In the southern part of the Georgia coastal area and in northeastern Florida, the Lower Floridan aquifer contains an extremely permeable water-bearing zone called the Fernandina permeable zone. The Fernandina permeable zone contains highly saline water in the southern part of coastal Georgia, and is the source of saltwater contamination in the Brunswick area.

VERTICAL SCALE GREATLY EXAGGERATED

VERTICAL SCALE GREATLY EXAGGERATED

VERTICAL SCALE GREATLY EXAGGERATED

Underlying the surficial aquifer are the sandy upper and lower Brunswick aquifers—present mostly in the Glynn County area—supplying water for irrigation, public, and some small industry use. Clay and other low-permeability strata confine the underlying Floridan aquifer system.

Sava

nnah

Riv

er

Port

Roy

al S

ound

Oge

eche

e Ri

ver

Alta

mah

a Ri

ver

Satil

la R

iver

St M

arys

Rive

r

MO

NTH

LY M

EAN

WAT

ER L

EVEL

ABO

VE A

ND

BEL

OW

(–)

SEA

LEVE

L, IN

FEE

T

1960

1950

1940

1970

1980

1990

1999

Well 33H133

Well 33H119

43

33

23

13

3

–7

–17

Wells cease flowing

Land surface

Brunswick

30

130

10

50

70

90

110

1950

1940

1960

1970

1980

1990

1999

Well 36Q008

Well 36Q005

MO

NTH

LY M

EAN

WAT

ERLE

VEL

BELO

W S

EA L

EVEL

,IN

FEE

T

800

600

400

200

01974 1976 1978 1980 1982

CH

LOR

IDE

CO

NC

EN-

TRAT

ION

, IN

mg/

L

Well BFT315

U.S. Environmental Protection Agency secondary

drinking-water standard

11,000

9,000

7,000

5,000

3,000

1,0001986 1988 1990 1992 1994 1996 1998

SPEC

IFIC

CO

ND

UC

TAN

CE,

INs/

cm A

T 25

DEG

REE

S C

ELSI

US

Well BFT1810Blank where data

are missing

ATL

AN

TIC

O

CE

AN

N

0

0 20 40 KILOMETERS

20 40 MILES

Oil exploration well

GLYNN

BRANTLEY

CHARLTON CAMDEN

NASSAU

TATTNALL

EVANS

BRYAN

LONG

WAYNE

LIBERTY

MCINTOSH

CHATHAM

JASPERBEAUFORT

EFFINGHAM

BULLOCH

CANDLER

DUVAL

COFFEEBACON

PIERCE

WARE

ATKINSON

CLINCH

WHEELER

TOOMBS

APPLINGJEFFDAVIS

MON

TGOM

ERY

JOHNSON

EMANUEL

TREUTLEN

JENKINS

SCREVENHAMPTON

ALLENDALE

BARNWELLBURKEJEFFERSON

DODGE

TELFAIR

LAURENS

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

–10

–80

0

0 010

10–10

–30

200

10

10

30

30

40

40

5060

80100

100120

120

150

150

250300

30030

0

200

200250

250

1030

200

–40

–60

–20

0

10

Saltwater interface from Bush and Johnston, 1988; May 1980 artesian flow from Krause and Randolph, 1989; May 1998 poten-tiometric contours from Peck and others, 1999

GLYN

N

BRANTLEY

CHARLTON CAMDEN

NASSAU

TATTNALL

EVANS

BRYAN

LONG

WAYNE

LIBERTY

MCINTOSH

CHATHAM

JASPERBEAUFORT

EFFINGHAM

BULLOCH

CANDLER

DUVAL

COFFEE BACON

PIERCE

WARE

ATKINSON

CLINCH

WHEELERTOOMBS

APPLINGJEFF DAVIS

MON

TGOM

ERY

JOHNSON

EMANUEL

TREUTLEN

JENKINSSCREVEN

HAMPTON

ALLENDALE

BARNWELL

BURKEJEFFERSON

Savannah

DoctortownJesup

Brunswick

St Marys

Fernandina Beach Fernandina Beach

Jacksonville

GEORGIA

FLORIDA

GEORGIA

SOUTHCAROLINA

GEORGIA

FLORIDA

GEORGIA

SOUTHCAROLINA

ATL

AN

TIC

O

CE

AN

Hilton HeadIsland

Savannah

DoctortownJesup

Brunswick

St Marys

Jacksonville

Hilton HeadIsland

DODGE

TELFAIR

LAURENS

250

200

150

120

10090

80

70 60

50

40

30

20

20

10

Freshwater—Darker color shows area of artesian flow Transition zoneSaltwaterConfining unit

General direction of ground-water flow

Well and identification number

10 Potentiometric contour, Upper Floridan aquifer— Shows altitude at which water level would have stood in tightly cased wells. Dashed where approximately located. Hachures indicate depression. Contour interval variable

36Q005

Saltwater interface from Bush and Johnston, 1988; artesian flow and potentiometric contours from Krause and Randolph, 1989

GULF TROUGH

Maparea

Atl

anti

c O

cean

36Q00536Q008

BFT1810BFT315

33H13333H119

N

Savannah

Brunswick

HiltonHeadIsland

TybeeIsland

WassauIsland

OssabawIsland

SapeloIsland

St CatherinesIsland

St SimonsIsland

JekyllIsland

SkidawayIsland

Altamaha River

Ogeechee River

Savannah River

AT

LA

NT

I C

O

CE

AN

1965 Pumpage atBrunswick peaks atabout 105 Mgal/d

Ground-water developmentWater-quality informationScientific studies and State legislation

1943 Coastal area pumpage about 136 Mgal/d; Savannah pumpage is 42 Mgal/d, water level about 50 feet below sea level; Brunswick pumpage is 37 Mgal/d, water level about 28 feet above sea level; Union Camp Corporation pumpage is 18.2 Mgal/d

1958 Wells near center of pumping at Brunswick cease flowing; water level at Savannah is about 70 feet below sea level

2000199019801970196019501940193019201910190018901880

1990 Pumpage at Savannah peaks at about 88 Mgal/d

1980 Coastal area pumpage is 385 Mgal/d. Water level near Savannah is more than 100 feet below sea level, and near Brunswick is about 16 feet below sea level

1982 Voluntary pumping cutbacks result in water level recovery of 9 to 17 feet in Upper Floridan aquifer at Brunswick

1972 Georgia General Assembly passes Ground-Water Use Act requiring permitting of all non-agricultural users withdrawing 100,000 gal/d or more

1936 Union Camp Corporation begins operations at Savannah;daily pumpage is 3.4 Mgal/d

1938 Brunswick Pulp and Paper Company begins operation

1880 Potential for artesian flowing wells throughout coastal area; water level at Brunswick about 65 feet above sea level and at Savannah about 40 feet above sea level

1891 Savannah supplied by 25 wells

1888 Ground water (Upper Floridan aquifer) replaces Savannah River as principal water source for Savannah; daily pumpage is 7 Mgal/d

1885 First artesian wells drilled at Savannah and Darien

1987–89 In well BFT1810 on Hilton Head Island, specific conductance—an indicator of salt content in water—increases from about 2,000 to about 10,000 s/cm

1981–83 Chloride concentration in well BFT315, located at northern Hilton Head Island, becomes

greater than drinking-water standard of 250 mg/L in 1981 and increased to 600 mg/L by 1983

1962 Chloride contam-ination at Brunswick

covers a 0.4-square mile area near Bay Street.

Chloride concentrations as high as 860 mg/L

1960 USGS and City of Brunswick initiate studies concerning source of saltwater contamination

1979 Oil explora-tion well, located about 55

miles offshore of St Marys, detects

freshwater in the upper part of the

Upper Floridan aquifer

1997 Coastal area pumpage is about 350 Mgal/d. Water level near Savannah is about 90 feet below sea level, and near Brunswick is about sea level. GaEPD develops and implements interim water management strategy for coastal Georgia. Water use in selected areas restricted to 1997 rates

2006 Final Water Management Strategy planned for coastal Georgia

1955 Salty taste noticed inBrunswick drinking water 1980 Colonels Island test well penetrates

Fernandina permeable zone at Brunswick. Chloride concentration is 33,000 mg/L at

2,700 feet below land surface

1991 Chloride contamination at Brunswick encompasses a 2.9-square mile area; concentration exceeds 2,500 mg/L at two locations

Phot

ogra

ph b

y R

icha

rd E

. Kra

use,

U.S

. Geo

logi

cal S

urve

y, 19

88

Phot

ogra

ph b

y Br

unsw

ick

Pulp

and

Pap

er C

ompa

ny, 1

985

Photograph by Richard E. Krause, U.S. Geological Survey, 1979

Phot

ogra

ph b

y U

.S. G

eolo

gica

l Sur

vey,

1942

1884 First artesian well drilled at Brunswick

1791 William Bartram made mention of a spring on Sapelo Island in his log of travels

1854 Savannah Water Works established; Savannah water supply obtained from Savannah River

1999 Coastal Georgia Sound Science Initiative begins. Information obtained while drilling offshore of Tybee Island, Georgia, is helping to better define the saltwater interface

Phot

ogra

ph b

y M

icha

el F

. Pec

k,U

.S. G

eolo

gica

l Sur

vey,

2000

TEXT COLORS USED IN TIMELINE

gal/d, gallons per daymg/L, milligrams per literMgal/d, million gallons per days/cm, microsiemens per centimeter

ABBREVIATIONS USED IN TIMELINE

Savannah

Hilton Head Island

Hilton Head Island

(GA, 1997, from Fanning, 1999; SC and FL, AWUDS, 1995)

Ground-water withdrawal, in Mgal/d

0 to 89 to 3031 to 8081 to 145

FLORIDA

GEORGIASOUTH

CAROLINA

IntroductionSaltwater contamination is restricting the development of ground-water supply in coastal Georgia and adjacent parts of South Carolina and Florida. The principal source of water in the coastal area is the Upper Floridan aquifer—an extremely permeable and high-yielding aquifer—which was first developed in the late 1800s. Pumping from the aquifer has resulted in substantial ground-water-level decline and subsequent saltwater intrusion of the aquifer from underlying strata containing highly saline water at Brunswick, Georgia, and with encroachment of sea-water into the aquifer at the northern end of Hilton Head Island, South Carolina. The saltwater contamination at these locations has constrained further development of the Upper Floridan aquifer in the coastal area and has created competing demands for the limited supply of freshwater. The Georgia Department of Natural Resources, Georgia Environmental Protection Division (GaEPD) has restricted permitted withdrawal of water from the Upper Floridan aquifer in parts of the coastal area (including the Savannah and Brunswick areas) to 1997 rates, and also has restricted additional permitted pumpage in all 24 coastal area counties to 36 million gallons per day above 1997 rates. These actions have prompted interest in alternative management of the aquifer and in the development of supplemental sources of water supply including those from the shallower surficial and upper and lower Brunswick aquifers and from the deeper Lower Floridan aquifer.

Predevelopment Ground-Water Flow SystemPrior to development of the Floridan aquifer system in the 1880s, recharge to the aquifer system was roughly offset by natural discharge. The Floridan aquifer system was replenished (recharged) by rainfall in areas where aquifer sediments are at or near land surface, generally west and northwest of the coast. Ground water flowed from areas of recharge downgradient toward the coast. The aquifer system was under artesian conditions and the pressure in the aquifer system was great enough that wells flowed at land surface throughout most of the coastal area. In some areas, pressure was high enough to elevate water to multi-story buildings without pumping. The artesian water level was about 65 feet above sea level at Brunswick, and 35 feet above sea level at Savannah. Ground water discharged naturally to springs, rivers, ponds, wetlands, and other surface-water bodies; as diffuse upward leakage into overlying adjacent aquifers; and to the Atlantic Ocean. As water flowed coastward, low-permeability sediments in the vicinity of the Gulf Trough inhibited ground-water flow and produced a steep flow gradient.

Coastal Physical Setting

The coastal area of Georgia and adjacent parts of South Carolina and Florida is part of the Coastal Plain physiographic province of the Atlantic Coastal Plain. The area consists of barrier islands, marshes, plains, a series of terraces, and inland rolling hills and valleys. Land use is urban and industrial in cities such as Savannah and Brunswick; outside these areas, land use is a combination of forest, grazed woodland, cropland with pasture, and marsh and swampland. In 1997, ground-water sources served a population of about 526,600; surface-water sources served about 8,000 (Fanning, 1999). Average annual precipitation ranges from about 46 to 54 inches.

Modern-Day Ground-Water Flow System Ground-water pumping has caused the water level in the Upper Floridan aquifer to decline throughout the entire coastal area, resulting in the development of cones of depression in areas of heavy, concentrated pumpage, such as the Savannah, Brunswick, Jesup, and St Marys, Georgia–Fernandina Beach, Florida, areas. Wells have ceased to flow at land surface in much of the coastal area. Many freshwater springs and seeps have ceased to discharge; freshwater wetlands and ponds that prior to development were sustained by flow from the Upper Floridan aquifer are no longer sustained by that flow. Although the cones of depression are deep, they do not intercept the top of the Upper Floridan aquifer; thus, dewatering or mining of water is not occurring. The pressure reduction has caused saltwater that is under higher pressure to flow into and contaminate the freshwater part of the aquifer in at least two locations—Brunswick, Georgia, and Hilton Head Island, South Carolina.

Freshwater-Saltwater Interface Freshwater in the Floridan aquifer system flows seaward until it comes in contact with seawater along the freshwater-saltwater interface. Freshwater is less dense than saltwater and flows above the saltwater. The interface is not sharp and distinct, but is a diffuse zone where freshwater and saltwater mix through the processes of chemical diffusion and mechanical dispersion. Data from the offshore area, conceptual models, and results of simulation indicate that the freshwater-saltwater interface occurs near the coastline in the Hilton Head Island area, arcs eastward beneath the ocean floor, reaching a maximum distance of about 85 miles offshore, then arcs back westward to the coast south of Jacksonville, Florida.

Freshwater in the aquifer system along the coast also has an interface with saltwater at depth. Saltwater occurs naturally in aquifer-system sediments below the freshwater zone, extending landward from the freshwater-saltwater interface offshore, and underlying freshwater in the aquifer system in the lower part of the Fernandina permeable zone. In the Brunswick area, saltwater in the Fernandina permeable zone was detected at a depth of about 2,400 feet below sea level, and has a maximum chloride concen-tration of about 33,000 milligrams per liter at a depth of 2,700 feet.

Timeline of Ground-Water Development, Water Quality, and Scientific Studies and State Legislation

Saltwater contamination along the northern part of Hilton Head Island probably is a result of lateral encroachment of seawater, combined with some downward vertical leakage of seawater where the Upper Floridan aquifer is exposed or nearly exposed. In the vicinity of Port Royal Sound, and possibly other estuaries, downcutting by ancient river systems during periods of lower ocean levels that existed during the most recent ice age exposed rocks that form the Upper

Floridan aquifer, causing direct connection between seawater and fresh ground water.

Regional ground-water pumping, but most importantly, pumping on the island, has locally lowered the pressure in the Upper Floridan aquifer and reversed the natural hydraulic gradient, causing the encroachment of saltwater. Features that formerly were submarine springs prior to development, now are conduits for the encroachment of saltwater from the ocean, sounds, and estuaries.

Saltwater Contamination at Brunswick, Georgia Saltwater contamination at Brunswick is the result of upward intrusion of saline water from the lower part of the Fernandina permeable zone into freshwater zones of the Lower Floridan, then Upper Floridan aquifers. Saltwater from the Fernandina permeable zone migrates upward through fractures and conduits in the limestone and dolostone confining units in response to reduced artesian pressure caused by pumping of water from the Upper Floridan aquifer. Upon reaching the aquifers in the southern part of Brunswick, the saltwater moves toward areas of ground-water pumping in the northern part of Brunswick.

Contamination of the Upper Floridan aquifer in the Brunswick area is not due to lateral encroachment nor downward intrusion of seawater because the Upper Floridan aquifer is deeply buried at Brunswick (greater than 500 feet deep); the freshwater-saltwater interface is far from the coastline (more than 50 miles offshore); and perhaps most importantly, pressure in the Upper Floridan aquifer was greater than sea level when saltwater contamination at Brunswick was first detected in the late 1950’s. Lateral encroachment or vertical infiltration of saltwater may be possible, however, in the shallower surficial aquifer or in the upper and lower Brunswick aquifers.

Ground-Water Management and Scientific StudiesWater-resource managers in Georgia and South Carolina are interested in minimizing further contamination of the Floridan aquifer system and allocating water from the aquifer system for current use and for future demands. To this end, the GaEPD released an interim strategy in April 1997, which is described in the document: "Interim Strategy for Managing Salt Water Intrusion in the Upper Floridan Aquifer of Southeast Georgia" (Georgia Environmental Protection Division, 1997). The intent of this Interim Strategy is to protect the Upper Floridan aquifer from saltwater contamination.

To better understand the processes of saltwater contamination and to monitor ground-water conditions in coastal Georgia, the USGS is participating in cooperative studies with the GaEPD, and the City of Brunswick and Glynn County, Georgia.

The Coastal Georgia Sound Science Initiative is a program of scientific and feasibility studies to support development of GaEPD’s final strategy to protect the Upper Floridan aquifer from saltwater contamination. Implementation of the final strategy is proposed for January 2006.

In support of the Sound Science Initiative, the USGS is working on a comprehensive program to evaluate ground-water conditions in the coastal area of Georgia and adjacent parts of South Carolina and Florida. The study is being conducted in cooperation with GaEPD. Other participants include the U.S. Army Corps of Engineers; Georgia Institute of Technology; The Georgia Conservancy; Georgia State University; Georgia Southern University; Skidaway Institute of Oceanography; The University of Georgia, Cooperative Extension Service; the South Carolina Department of Health and Environmental Control; and several private consulting firms.

Objectives of the Sound Science Initiative • Conduct expanded scientific and feasibility studies to

determine how to prevent saltwater from moving toward Hilton Head Island, South Carolina, and how to prevent the existing saltwater contamination at Brunswick, Georgia, from worsening.

• Develop a digital ground-water flow model to more completely simulate the flow system by incorporating additional layers in the surficial aquifer, the upper and lower Brunswick aquifers, and the Fernandina permeable zone. Use the calibrated flow model to simulate water-management scenarios and provide input data necessary to simulate chloride movement.

• Investigate paths and rates of ground-water flow and intrusion of saltwater into the Upper Floridan aquifer by developing solute-transport models for the Brunswick and Savannah–Hilton Head Island areas. Use the calibrated models to evaluate rates of saltwater contamination under a variety of water-management scenarios.

• Delineate areas where saltwater enters the Floridan aquifer system by constructing offshore test wells near Savannah– Hilton Head Island, and test wells onshore along the coast.

• Assess alternative and supplemental sources of water supply by conducting studies to evaluate the water-supply potential of (1) seepage ponds connected to the surficial aquifer; (2) the upper and lower Brunswick aquifers; (3) the Lower Floridan aquifer; (4) rivers and streams; (5) off mainstream impoundments; (6) reclaimed water; (7) reverse osmosis; and (8) conservation.

• Develop and maintain an expanded monitoring network to assess ground-water levels and quality.

• Conduct feasibility studies and assessments of engineered and non-engineered methods that could be used to prevent saltwater intrusion.

• Provide scientific rationale to support development of a final strategy to protect ground water in coastal Georgia from saltwater intrusion.

Geology and Ground-Water Resources

The coastal area of Georgia and adjacent parts of Florida and South Carolina is blanketed and underlain by sand, clay, and other clastic rocks that overlie limestone and dolostone at varying depth. The sequence of sedimentary strata is thickest and most deeply buried in the Brunswick area and southward into northeastern Florida, where more than 500 feet of sand

and clay overlie more than 2,000 feet of limestone and dolostone. The sequence is thinner and at shallower depths toward the north in the Savannah, Georgia, and Hilton Head Island, South Carolina, areas where the carbonate rocks are 50–150 feet below land surface and are less than 500 feet thick.

By Richard E. Krause and John S. Clarke

Design and layout by Caryl J. Wipperfurth

Water-Resources Investigations Report 01-4107Prepared in cooperation with the Georgia Department of Natural Resources, Georgia Environmental Protection Division, Georgia Geologic Survey; the City of Brunswick, and Glynn County

For information concerning USGS products and services please contact:State Representative phone (770) 903-9100U.S. Geological Survey fax (770) 903-9199Peachtree Business Center url http://ga.water.usgs.gov3039 Amwiler Road Atlanta, GA 30360-2824 USGS url http://www.usgs.gov

For information concerning Georgia Geologic Survey products and services please contact:Georgia Geologic Survey phone (404) 657-612719 Martin Luther King Jr. Dr., SW Room 400 GGS url http://www.georgianet.org/dnr/envrion/Maps and Publications Atlanta, GA 30334

Bush, P.W., and Johnston, R.H., 1988, Ground-water hydraulics, regional flow, and ground-water development of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama: U.S. Geological Survey Professional Paper 1403-C, 80 p.

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.

Garza, Reggina, and Krause, R.E., 1992, Water-supply potential of major streams and the Upper Floridan aquifer in the vicinity of Savannah, Georgia: U.S. Geological Survey Water-Supply Paper 2411, 36 p.

Georgia Environmental Protection Division, 1997, Interim strategy for managing saltwater intrusion in the Upper Floridan aquifer of southeast Georgia, April 23, 1997: Atlanta, Ga., Georgia Environmental Protection Division, 19 p.

Krause, R.E, and Randolph, R.B., 1989, Hydrology 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.

Peck, M.F., Clarke, J.S., Ransom III, Camille, 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.

U.S. Environmental Protection Agency, 1990, Secondary maximum contaminant levels, National secondary drinking-water regulations: U.S. Code of Federal Regulations, section 143.3, title 40, parts 100-149, revised July 1990, p. 674.

Peck, M.F., Joiner, C.N., and Cressler, A.M., 1992, Ground-water conditions in Georgia, 1991: U.S. Geological Survey Open-File Report 92-470, 137 p.

Wait, R.L., and Gregg, D.O., 1973, Hydrology and chloride contamination of the principal artesian aquifer in Glynn County, Georgia: Georgia Department of Natural Resources Hydrologic Report 1, 93 p.

Data for all water-level and chloride-concentration graphs from the U.S. Geological Survey National Water Information System.

1995 water-use data for South Carolina and Florida from the U.S. Geological Survey Aggregate Water-Use Data System (AWUDS).

Saltwater Contamination at Hilton Head Island, South Carolina

Selected References, Sources of Information, and Contacts

Coastal Ground Water at Risk—

U.S. DEPARTMENT OF THE INTERIORGale A. Norton, Secretary

U.S. GEOLOGICAL SURVEYCharles G. Groat, Director

Image from Nickolas L. Faust, Coastal Georgia LANDSAT TM Image, Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia, 1998

Saltwater contamination at Brunswick, Georgia and Hilton Head Island, South Carolina