Cover photographs:

Courtesy of Sean Kelly and Stephen W. Golladay,

J.W. Jones Ecological Research Center, Newton, Georgia.
SIMULATED EFFECTS OF GROUND-WATER PUMPAGE 

ON STREAM–AQUIFER FLOW IN THE VICINITY OF 

FEDERALLY PROTECTED SPECIES OF FRESHWATER 

MUSSELS IN THE LOWER APALACHICOLA–

CHATTAHOOCHEE–FLINT RIVER BASIN (SUBAREA 4), 

SOUTHEASTERN ALABAMA, NORTHWESTERN 

FLORIDA, AND SOUTHWESTERN GEORGIA

By Phillip N. Albertson and Lynn J. Torak 

___________________________________________________________________

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 02-4016

Water-Resources Investigations Report 02-4016

Prepared in cooperation with the

U.S. Fish and Wildlife Service

Atlanta, Georgia

2002
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Copies of this report can be purchased from:

State Representative

U.S. Geological Survey

Peachtree Business Center

3039 Amwiler Road, Suite 130

Atlanta, GA 30360-2824

http://www.usgs.gov

Copies of this report can be purchased from:

U.S. Geological Survey

Branch of Information Services

Denver Federal Center

Box 25286

Denver, CO 80225-0286
Contents iii

CONTENTS

Abstract 1

Introduction 2

Purpose and scope 2

Method of study 4

Description of the study area 4

Physiography 4

River and lake system 4

Precipitation 5

Geohydrology 6

Acknowledgments 6

Stream–aquifer relations 7

Simulation of stream–aquifer flow 10

Model representation of stream reaches 10

Sensitivity ranking procedure 11

Model limitations 11

Simulated effect of changing pumpage and boundary conditions on stream–aquifer flow 11

Simulated stream–aquifer flow in the vicinity of federally protected freshwater mussels 13

Summary and conclusions 22

References cited 22

Appendix A. Tables listing stream–aquifer flow, by reach, for simulated hydrologic and pumpage conditions 24

Appendix B. Graphs showing the simulated effect of pumpage on stream–aquifer flow for stream reaches 1–37 29

ILLUSTRATIONS

Figure 1. Map showing study area, model boundary, and physiographic districts in the lower Apalachicola–

Chattahoochee–Flint River basin 3

2. Graph showing average monthly precipitation for southwest Georgia, 1899–1998 5

3. Correlation chart of geologic and hydrologic units in the lower Apalachicola–Chattahoochee–Flint 

River basin 6

4. Cross-section showing conceptualization of stream-aquifer flow with a nearby pumping well in the lower 

Apalachicola–Chattahoochee–Flint River basin 7

5. Map showing potentiometric surface of the Upper Floridan aquifer in the lower Apalachicola– 

Chattahoochee–Flint River basin and location of U.S. Geological Survey monitoring wells, 

gaging station 02356000, and International Paper Company precipitation station near 

Bainbridge, Georgia 8

6. Stream stage for the Flint River at Bainbridge (02356000); water levels at U.S. Geological Survey 

monitoring wells 09F520, 09G001, and 10G313; and monthly total precipitation near 

Bainbridge, Georgia 9

7. Matrix showing six different hydrologic scenarios used in the Torak and McDowell (1996) simulations 10

Figures 8–9. Maps showing:

8. Model boundary and simulated stream reaches for Subarea 4, lower Apalachicola–Chattahoochee–

Flint River basin 12

9. Model boundary, reaches where at least one federally protected freshwater mussel species is 

located, and simulated stream reach sensitivities in the lower Apalachicola–Chattahoochee– 

Flint River basin 14
 iv

ILLUSTRATIONS–Continued

Figures 10–15. Maps showing model boundary and simulated stream reach sensitivities for the lower Apalachicola–

Chattahoochee–Flint River basin and sites containing federally protected mussel species: 

10. Shinyrayed pocketbook (Lampsilis subangulata) 16

11. Gulf moccasinshell (Medionidus penicillatus) 17

12. Oval pigtoe (Pleurobema pyriforme) 18

13. Purple bankclimber (Elliptoideus sloatianus) 19

14. Chipola slabshell (Elliptio chipolaensis) 20

15. Fat threeridge (Amblema neislerii) 21

Figures B1–B37. Graphs showing stream-aquifer flow for simulated pumpage scenarios, ground-water boundary 

conditions, and stream stage at October 1986, Q90, and Q50 levels for:

B1. Reach 1, Gum Creek, Georgia 30

B2. Reach 2, Cedar Creek, Georgia 31

B3. Reach 3, Swift Creek, Georgia 31

B4. Reach 4, Jones Creek, Georgia 32

B5. Reach 5, Abrams Creek, Georgia 32

B6. Reach 6, Mill Creek, Georgia 33

B7. Reach 7, Cooleewahee Creek, Georgia 33

B8. Reach 8, Chickasawhatchee Creek, Georgia 34

B9. Reach 9, Chickasawhatchee Creek, Georgia 34

B10. Reach 10, Chickasawhatchee Creek, Georgia 35

B11. Reach 11, Dry Creek, Georgia 35

B12. Reach 12, Spring Creek, Georgia 36

B13. Reach 13, Spring Creek, Georgia 36

B14. Reach 14, Spring Creek, Georgia 37

B15. Reach 15, Sawhatchee Creek, Georgia 37

B16. Reach 16, Cowarts Creek, Florida 38

B17. Reach 17, Marshall Creek, Florida 38

B18. Reach 18, Spring Creek, Georgia 39

B19. Reach 19, Dry Creek, Florida 39

B20. Reach 20, Ichawaynochaway Creek, Georgia 40

B21. Reach 21, Ichawaynochaway Creek, Georgia 40

B22. Reach 22, Muckalee Creek, Georgia 41

B23. Reach 23, Muckalee Creek, Georgia 41

B24. Reach 24, Muckalee Creek, Georgia 42

B25. Reach 25, Kinchafoonee Creek, Georgia 42

B26. Reach 26, Kinchafoonee Creek, Georgia 43

B27. Reach 27, Chipola River, Florida 43

B28. Reach 28, Chipola River, Florida 44

B29. Reach 29, Chipola River, Florida 44

B30. Reach 30, Flint River, Georgia 45

B31. Reach 31, Flint River, Georgia 45

B32. Reach 32, Flint River, Georgia 46

B33. Reach 33, Flint River, Georgia 46

B34. Reach 34, Flint River, Georgia 47

B35. Reach 35, Apalachicola River, Florida 47

B36 Reach 36, Apalachicola River, Florida 48

B37. Reach 37, Apalachicola River, Florida 48
 v

TABLES

Table 1. Stream-reach sensitivity to pumpage and reaches where federally protected freshwater mussel species 

are present 15

Tables A1–A4. Stream–aquifer flow, by reach, for hydrologic conditions and pumpage at:

 A1. 0.5 times October 1986 rates simulated in the Subarea 4 model 25

A2. October 1986 rates simulated in the Subarea 4 model 26

A3. 2 times October 1986 rates simulated in the Subarea 4 model 27

A4. 5 times October 1986 rates simulated in the Subarea 4 model 28

Well-Naming System

Wells used in this report are named according to a system based on the USGS index of topographic maps. Each 7.5-minute 

topographic quadrangle in Georgia has been given a number and letter designation beginning at the southwestern corner of 

the State. Numbers increase eastward and letters increase alphabetically northward. Quadrangles in the northern part of the 

area are designated by double letters. The letters “I,” “II,” “O,” and “OO” are omitted. Wells inventoried in each quadrangle 

are numbered consecutively beginning with 1. Thus, the 520th well numbered on the 09E quadrangle is designated 09E520.

Station-Identification Numbers

The system used by the U.S. Geological Survey to assign identification numbers for surface-water stations and for ground 

water well sites differ, but both are based on geographic location. Since October 1, 1950, the order of listing hydrologicstation records in USGS reports is in a downstream direction along the main stream. The station-identification number is 

assigned according to downstream order. The complete number for each station, such as 02356000 includes the two-digit 

part number “02” plus the downstream-order number “356000,” which can be from six to 12 digits.

Sea level: In this report “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)a geodetic 

datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly 

called Sea Level Datum of 1929. 

Abstract 1

SIMULATED EFFECTS OF GROUND-WATER PUMPAGE ON 

STREAM–AQUIFER FLOW IN THE VICINITY OF FEDERALLY 

PROTECTED SPECIES OF FRESHWATER MUSSELS IN THE 

LOWER APALACHICOLA–CHATTAHOOCHEE–FLINT RIVER 

BASIN (SUBAREA 4), SOUTHEASTERN ALABAMA, 

NORTHWESTERN FLORIDA, AND SOUTHWESTERN GEORGIA

By Phillip N. Albertson and Lynn J. Torak

ABSTRACT

Simulation results indicate that groundwater withdrawal in the lower 

Apalachicola-Chattahoochee-Flint River 

basin during times of drought could reduce 

stream–aquifer flow and cause specific 

stream reaches to go dry. Of the 37 reaches 

that were studied, 8 reaches ranked highly 

sensitive to pumpage, 13 reaches ranked 

medium, and 16 reaches ranked low. Of the 

eight reaches that ranked high, seven 

contain at least one federally protected 

mussel species. 

Small tributary streams such as Gum, 

Jones, Muckalee, Spring, and Cooleewahee 

Creeks would go dry at lower pumping rates 

than needed to dry up larger streams. 

Other streams that were ranked high may go 

dry depending on the amount of upstream 

flow entering the reach; this condition is 

indicated for some reaches on Spring 

Creek. A dry stream condition is of 

particular concern to water and wildlife 

managers because adequate streamflow is 

essential for mussel survival.
2 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

INTRODUCTION

Ground-water withdrawal for irrigation in southwest 

Georgia more than doubled between 1977 and 1981 (Hayes 

and others, 1983). Along with this increase in irrigation 

came an increase in concern over possible effects of further 

ground-water development on the water resources and biota 

of the lower Apalachicola–Chattahoochee–Flint (ACF) 

River basin (fig. 1). Of particular concern to water and 

wildlife managers is the potential for pumpage to cause 

unacceptable declines in water levels in wells and in 

discharge to streams. This concern led Federal, State, and 

local officials to conduct several studies with the U.S. 

Geological Survey (USGS) during the 1980’s and 1990’s to 

investigate the effects of increased ground-water development on the hydrologic system. These studies indicated a 

strong connection between pumpage and reduced 

streamflow in southwest Georgia (Hayes and others, 1983; 

Torak and others, 1996; Torak and McDowell, 1996).

An associated concern of State and Federal officials is the 

effect of pumpage in the lower ACF River basin on 

streamflow in reaches containing federally protected 

freshwater mussel populations. The most commonly cited 

cause of mussel extinction is habitat degradation (Havlik, 

1981; Layzer and others, 1993). Adequate streamflow is the 

hydraulic characteristic necessary to maintain mussel 

habitat (Richard J. Neves, Virginia Cooperative Fish and 

Wildlife Research Unit, Virginia Polytechnic Institute and 

State University, oral commun., 2001). Because of limited 

mobility (Layzer and Madison, 1995), short-term but often 

substantial fluctuations in streamflow can change hydraulic 

conditions faster than mussels can move, thus limiting the 

chance of survival under extreme low-flow conditions. 

Torak and McDowell (1996) indicated that simulated 

pumpage-induced changes in streamflow could cause some 

stream reaches to go dry. In addition to direct impacts on 

mussels, reduced streamflow could result in elimination of 

host fish populations, unsuccessful freshwater mussel 

fertilization, and failed attempts of glochidia to attach to 

host fish (U.S. and Wildlife Service, 1998).

Currently (2001), the U.S. Fish and Wildlife Service 

(USFWS) protects seven species of freshwater mussels 

in the Apalachicola Region (U.S. Fish and Wildlife 

Service, 1998). Five species have been declared 

endangered and two species have been identified as 

threatened under the Endangered Species Act of 1973, 

as amended on March 16, 1998, due to significant 

reductions in the populations of these species (Brim Box 

and Williams, 2000) by habitat loss and alteration 

(Butler and Alam, 1999). The five endangered species are 

the fat threeridge (Amblema neislerii), shinyrayed 

pocketbook (Lampsilis subangulata), Gulf moccasinshell 

(Medionidus penicillatus), Ochlockonee moccasinshell 

(Medionidus simpsonianus), and oval pigtoe (Pleurobema 

pyriforme). The two threatened species are the Chipola 

slabshell (Elliptio chipolaensis) and purple bankclimber 

(Elliptio sloatianus). All these species—except for the 

Ochlockonee moccasinshell—reside in the lower ACF 

River basin. 

In August 1999, the USGS began a cooperative 

investigation with the USFWS to study the effect of 

ground-water pumpage on stream–aquifer flow in stream 

reaches containing federally protected mussel species in the 

lower ACF River basin. Stream reach sensitivity to changes 

in pumpage, stream stage, and ground-water level is of 

concern to the USFWS because the potential exists for 

stream reaches containing federally protected mussel 

species to go dry, thus eliminating mussel habitat under 

natural and anthropogenic hydrologic stresses. 

Purpose and Scope

This report describes the simulated effects of pumpage, 

climatic conditions, and hydrologic boundaries on stream–

aquifer flow between the Upper Floridan aquifer and 

streams containing populations of federally protected 

mussel species in the lower ACF River basin. Stream–

aquifer flow is the flow of water across the streambed 

between the aquifer and the stream that either increases or 

decreases streamflow. This project combined results from a 

previous USGS investigation (Torak and McDowell, 1996) 

with two sources of mussel-survey information (Brim Box 

and Williams, 2000; Paula M. Johnson, Jones Ecological 

Research Center, written commun., 1999). Changes in 

simulated stream–aquifer–flow rates determined by Torak 

and McDowell (1996) were used to rank stream reaches 

according to their sensitivity to hydrologic stress. Results 

were compared with known locations of federally protected 

mussel species identified from previous studies to assess 

possible effects of pumpage on mussel habitat.

Results presented herein are not intended to predict a 

pumping scenario or boundary condition under which a 

specific stream reach will go dry, although this information can be inferred from the illustrations; rather, the 

intent of this report is to indicate which stream reaches are 

more sensitive to imposed hydrologic stress than others, 

based on previous simulations. This information will 

assist the USFWS in managing current and future 

mussel populations.
Introduction 3

Figure 1. Study area, model boundary, and physiographic districts

in the lower Apalachicola–Chattahoochee–Flint River basin.

GADSDEN

DECATUR

MILLER

EARLY BAKER

MITCHELL

COLQUITT

WORTH

TURNER

CRISP

DOOLY

SUMTER

CALHOUN DOUGHERTY

TERRELL

LEE

GRADY

LIBERTY

GULF FRANKLIN

CALHOUN

JACKSON SEMINOLE

HOUSTON

84°

85°

32°

31°

30°

0

0

10

10

20

20

30 MILES

30 KILOMETERS

GA

FL

AL

FL

Lake 

Blackshear

Lake 

Seminole

EXPLANATION

UPPER FLORIDAN MODEL

INTERMEDIATE MODEL

SUBAREA 4 BOUNDARY

SURFACE-WATER GAGING STATION 

AND IDENTIFICATION NUMBER

Base from U.S. Geological Survey

1:100,000-scale digital files

Chattahoochee R

Flint

River

Apalachicola

Chipola River

River

Sumatra

Apalachicola Bay

DOUGHERTY PLAIN

FALL LINE HILLS

TIFTON UPLANDS

GULF COASTAL LOWLANDS

Pelham Escarpment

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin

02359170

02343801

02356000

02356000

Jim Woodruff

Lock and Dam
4 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Method of Study

Results of digital modeling from Torak and McDowell 

(1996) were utilized in this study to describe the effects of 

pumpage on stream–aquifer flow within the lower ACF 

River basin. These results were plotted and information on 

the graphs was used to quantitatively rank stream reaches 

according to their response to simulated pumpage and 

hydrologic boundary conditions. Locations of federally 

protected freshwater mussels determined from previous 

studies were superimposed on a map depicting ranked 

reaches to identify which mussel species may be threatened 

or in danger of becoming extinct because of their location 

in a highly sensitive stream reach. 

Stream-reach response to pumpage was simulated under six 

different hydrologic scenarios. Two conditions of aquifer 

and overburden head conditions (normal and dry), and 

three conditions of stream stage (October 1986, Q50, Q90) 

were used along with multiples of October 1986 pumping 

rates (n, n = 0.5, 1, 2, and 5) to evaluate the effect of 

pumpage and climate on stream–aquifer flow. Normal head 

conditions are long-term average ground-water levels over 

the period of record and refer to water levels used at model 

boundaries and in the overburden during simulation. Dry 

head conditions are water levels used at model boundaries 

and in the overburden in simulations representing dry 

(October 1986) conditions. Dry stream conditions were 

simulated using drought (October 1986) stream-stage 

conditions. Flow condition Q50 is the stage corresponding 

to discharge that is exceeded 50 percent of the time over 

the period of record (median flow), and Q90 is the stage 

associated with flow that is exceeded 90 percent of the time 

over the period of record (low flow). For some streams, 

surface-water records indicated that streamflow for October 

1986 represented a flow that was lower than Q98 (Torak 

and McDowell, 1996). Each scenario combined one head 

condition with one streamflow (stage) condition. Four 

simulations were conducted for each scenario: each 

scenario used four different pumpage multipliers of 

October 1986 rates. Simulated stream–aquifer flow for each 

reach was plotted and the data used to rank each reach. 

Maps showing ranked stream reaches were combined with 

maps depicting locations of federally protected mussels.

Description of the Study Area

The study area is located in the lower ACF River basin, a 

6,800 square-mile (mi2

) area including parts of 

southeastern Alabama, northwestern Florida, and 

southwestern Georgia (fig. 1). The area defined by the ACF 

and Alabama–Coosa–Tallapoosa (ACT) River basins was 

subdivided into eight subareas by the U.S. Army Corps of 

Engineers for a comprehensive study that began in January 

1992 under a Memorandum of Agreement among the States 

of Alabama, Florida, and Georgia; and the U.S. Department 

of the Army. The lower ACF River basin was identified as 

Subarea 4. The northern boundary of Subarea 4 (fig. 1) 

approximates the updip limit of the karstic Upper Floridan 

aquifer, which strikes in a northeast direction from 

southeastern Alabama to south-central Georgia. The eastern 

boundary extends south and southwest along a surfacewater divide called the Pelham Escarpment (Hayes and 

others, 1983)—also called the Solution Escarpment by 

MacNeil (1947)—into Florida. In Florida, the eastern 

boundary runs along a surface-water divide to the Gulf of 

Mexico. The southern boundary is the coastline along the 

Gulf of Mexico and forms a ground-water outflow 

boundary. A surface-water divide west of the Apalachicola 

and Chipola Rivers forms the western boundary of the 

study area.

Physiography

Subarea 4 is part of a larger region called the Coastal Plain 

physiographic province (Fenneman, 1938), an area in the 

southeastern, eastern, and northeastern United States where 

surface geology consists of formations of Cretaceous or 

younger strata sloping gently and thickening towards the 

sea. Within the study area, the Coastal Plain physiographic 

province is further subdivided into physiographic 

subdivisions, called districts, based upon similar geologic 

and geomorphologic characteristics (fig. 1).

Clark and Zisa (1976) described the Georgia region of 

Subarea 4 as three different districts: the Fall Line Hills, 

Dougherty Plain, and Tifton Uplands (fig. 1). In the Florida 

panhandle portion of the study area, there are three 

physiographic districts: the Dougherty Plain, the Tifton 

Uplands, and the Gulf Coastal Lowlands (Arthur and 

Rupert, 1989). For further descriptions of these districts, 

the reader is referred to Puri and Vernon (1964), Middleton 

(1968), White (1970), Sapp and Emplaincourt (1975), 

Brooks (1981), Hayes and others (1983), Wagner and Allen 

(1984), and Hicks and others (1995).

River and Lake System

Four principal rivers drain the study area—the 

Chattahoochee, Flint, Apalachicola, and Chipola (fig. 1). 

The Chattahoochee River drains approximately 1,800 mi2

of Coastal Plain sediments in Alabama and Georgia, enters 

the study area near Dothan, Ala., flows 50 mi south to Lake
Introduction 5

Seminole, and mixes with the Flint River. Few tributaries 

flow into the Chattahoochee River in Subarea 4. In this 

reach, the Chattahoochee River has cut into the limestone, 

and contours of the potentiometric surface intersect the 

river at acute angles pointing upstream, indicating a strong 

hydraulic gradient from the aquifer to the river (Torak and 

McDowell, 1996). Long-term median flow for the 

Chattahoochee River near Columbia, Ala. (USGS gaging 

station 02343801, fig. 1), is about 14,500 cubic feet per 

second (ft3

/s). Long-term minimum flow is about 1,350 ft3/

s, and long-term maximum flow is about 59,500 ft3/s.

The Flint River enters the northern part of the study 

area north of Lake Blackshear, and flows south-southwest 

along the base of the Pelham Escarpment to Lake 

Seminole, draining approximately 6,000 mi2

 of the Coastal 

Plain. Long-term median streamflow as of April 2001, for 

the Flint River at Bainbridge, Georgia (USGS gaging 

station 02356000, fig. 1), is about 11,900 ft3

/s. The longterm minimum and maximum flows are about 4,660 and 

50,310 ft3/s, respectively. Numerous major and minor 

streams flow into the Flint River along its extent in Subarea 

4. Most streams contributing flow to the Flint River 

originate to the northwest. The streams on the western side 

of the Flint River are longer and contribute more flow to 

the Flint River than streams on the east side. Most streams 

located east of the Flint River in the Dougherty Plain 

originate on the Pelham Escarpment. The Pelham 

Escarpment serves not only as a major surface-water divide 

but also as a ground-water divide between the Dougherty 

Plain and the Tifton Uplands. 

Lake Seminole is a 37,600-acre lake created in 1957 by the 

U.S. Army Corps of Engineers by the construction of the 

Jim Woodruff Lock and Dam across the Apalachicola 

River (fig. 1). The lake is located at the confluence of the 

Chattahoochee and Flint Rivers. Construction of the dam 

began in 1950, and subsequent filling of the reservoir 

occurred from 1954 to 1957. The structure was built for 

navigational and hydropower purposes and provides about 

30 ft of lift from the Apalachicola River to the lake surface, 

which maintains a normal pool altitude of about 77 ft. 

The Apalachicola River begins at the Jim Woodruff Lock 

and Dam and flows more than 100 mi south into 

Apalachicola Bay. The Apalachicola River and its major 

tributary—the Chipola River—drain almost 2,400 mi2 

(Elder and Cairns, 1982). Long-term median streamflow 

for the Apalachicola River at Sumatra, Fla. (USGS gaging 

station 02359170, fig. 1), is about 34,600 ft3

/s. Long-term 

minimum and maximum streamflow for the Apalachicola 

River at this station is about 12,800 and 87,100 ft3/s, 

respectively. The Apalachicola River is a wooded riverwetland system that produces and transports large amounts 

of detritus to Apalachicola Bay. Annual flushing of organic 

matter by seasonal high streamflow helps support 

economically viable offshore populations of blue crab, 

shrimp, and oysters (Elder and Cairns, 1982). 

The Chipola River originates in the southeast corner of 

Alabama and flows south to the Apalachicola River near 

Sumatra, Fla. Most tributaries of the Chipola River flow 

from the west and are longer than tributaries to the east.

Precipitation

Precipitation plays a critical role in recharging both surface 

and ground waters in Subarea 4. Average annual rainfall is 

approximately 46 inches per year in Crisp County (northern 

part of the study area) and increases southwesterly to 

Apalachicola Bay where it approaches 60 inches per year 

(Bush and Johnston, 1988). On average, rainfall is greatest 

during winter and mid-summer (fig. 2).

Long-term monthly averages (fig. 2) indicate the study area 

receives more precipitation in July than in any other month 

of the year. Precipitation is lowest in October. Stream-stage 

records for the Flint River at Bainbridge, Ga. (gaging 

station 02356000, fig. 1), indicate mean-monthly stage is 

usually highest in February or March and lowest in summer 

or fall (U.S. Geological Survey, 1981–99). The Upper 

Floridan aquifer shows a pronounced response to climatic 

changes in the northwestern part of the study area where 

the aquifer and depth to water is shallow (Hayes and others, 

1983). During September through May, streamflow and 

ground-water levels respond quickly to precipitation; 

during June through August, evaporation is high and 

precipitation has less of an effect. Rainfall during summer 

tends to be short in duration and high in intensity; rainfall 

during winter tends to be long in duration and moderately

Figure 2. Average monthly precipitation for 

southwest Georgia, 1899–1998 (National 

Oceanic and Atmospheric Administration, 1998).

J F MA MJ J ASON D

0

1

2

3

4

5

6

7

AVERAGE MONTHLY PRECIPITATION, IN INCHES

4.99

3.95

4.93

5.67

4.44

3.32

2.18

3.23

4.42

5.15 5.41

3.69

MONTH
6 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

intense. Rainfall-induced changes in ground-water level 

and streamflow are subdued in the southern part of the 

study area where the depth to the aquifer is greater than in 

the north.

Geohydrology

The sequence of geologic units in southeastern Alabama, 

northwestern Florida, and southwestern Georgia constitutes 

a series of geohydrologic units having varying hydraulic 

characteristics that either restrict or transmit the flow of 

water. In Georgia, the principal source of water supply is 

the highly permeable, karstic Upper Floridan aquifer, 

which is confined below by the Lisbon Formation (Torak 

and others, 1996) and semiconfined above by 

undifferentiated overburden (fig. 3). In this area, streams 

are in direct connection with the Upper Floridan aquifer. In 

the Florida panhandle near the Gulf of Mexico, the Upper 

Floridan aquifer is hydraulically separated from the 

Intermediate system by a semiconfining unit (Torak and 

others, 1996). Streams in this part of the study area are in 

hydraulic connection with the Intermediate system. 

Additional details about the geohydrology in this area can 

be obtained from Torak and others (1996), Torak and 

McDowell (1996), Hayes and others (1983), Hicks 

and others (1995), Miller (1986), and Bush and 

Johnston (1988).

Acknowledgments

The authors extend sincere appreciation to all who have 

contributed to this report. The authors thank Amy Benson, 

USGS, Panama City, Fla., for providing coverages of 

federally protected mussel locations used in Brim Box and 

Williams (2000). The authors also thank Paula M. Johnson 

(Jones Ecological Research Center, Newton, Ga.) for 

survey results in the lower ACF River basin and for 

suggestions on improving this report. The authors greatly 

appreciate precipitation data supplied by Fred Haines of 

International Paper Company near Bainbridge, Ga. Caryl J. 

Wipperfurth, USGS, Atlanta, Ga., produced the 

illustrations in this report.

Figure 3. Correlation chart of geologic and hydrologic units in the lower Apalachicola–

Chattahoochee–Flint River basin (modified from Torak and McDowell, 1996).

Terrace and 

undifferentiated 

deposits

Terrace and 

undifferentiated 

deposits

GEOLOGIC UNIT GEOLOGIC UNIT HYDROLOGIC

UNIT

HYDROLOGIC

UNIT

SERIES

GEORGIA FLORIDA

HOLOCENE

AND

PLEISTOCENE MIOCENE EOCENE

Miccoskee

Formation

Suwannee

Limestone

Clinchfield

Sand

Ocala Limestone

Lisbon Formation

Tampa

Limestone

Hawthorn

Formation

Undifferentiated overburden

(residuum)

Semiconfining unit

Semiconfining unit

Underlying

semiconfining

unit

Upper

Floridan

aquifer

Lower

confining

unit

Sub-Floridan

confining

unit

Lisbon Formation

Ocala Limestone

Tampa Limestone

Suwannee Limestone

Intracoastal Formation

Jackson Bluff Formation

Citronelle Formation

Marianna Formation

Alum Bluff

Group

Intermediate

system

Upper

Floridan

aquifer

Chipola Formation

Hawthorn Formation

OLIGOCENE
Stream–Aquifer Relations 7

STREAM–AQUIFER RELATIONS

The connection between ground water and surface water in 

the study area is well documented. Hicks and others (1995) 

discussed the relation between ground water and surface 

water in the Albany, Ga., area. Large solution conduits 

transport water from the Upper Floridan aquifer to the Flint 

River. Numerous springs discharge ground water from the 

Upper Floridan aquifer to streams in the lower ACF River 

basin. Several modeling studies describe the connection 

between streams and the Upper Floridan aquifer (fig. 4) in 

all or parts of the study area and the effect of natural and/or 

anthropogenic stress on stream–aquifer flow (Hayes and 

others, 1983; Faye and Mayer, 1990, 1996; Torak and 

others, 1996; Torak and McDowell, 1996).

Stream–aquifer flow is the flow of water across the 

streambed that either increases or reduces streamflow 

(Torak and McDowell, 1996), and is the principal 

mechanism governing the amount of water at any point 

along a stream during periods of baseflow. Every point 

along a stream reach has a set of characteristics that 

determine the volumetric flow at that point. Stream–aquifer 

flow is a function of stream dimensions, hydraulic 

conductivity of streambed materials, streambed thickness, 

stage of the stream, and head in the aquifer. Of all the 

factors listed above, stream stage and aquifer head are the 

most dynamic; these two factors change frequently, if not 

continuously, to cause changes in stream–aquifer flow. 

The connection of ground water with surface water in the 

study area is further illustrated by equipotential contours on 

a potentiometric surface map constructed by Peck and 

others (1999) (fig. 5). Ground-water flow is from high 

hydraulic head to low hydraulic head in a direction 

perpendicular to potentiometric contours. Potentiometric 

contours bend upstream at acute angles indicating a 

substantial connection between ground water and streams; 

closely spaced contours indicate a large hydraulic gradient 

between the aquifer and the stream. Flow is from upland 

areas to streams.

Precipitation, ground-water levels, and stream stage vary 

seasonally (fig. 6). Although precipitation is highest during 

summer months, ground-water levels and streamflow are 

highest during winter months. These converse responses 

result from a combination of factors: (1) summer 

precipitation, while of high intensity is short in duration, 

resulting in high runoff and low infiltration; (2) 

evapotranspiration is high in summer, intercepting a 

percentage of precipitation before it can infiltrate to the 

ground-water system; and (3) irrigation pumpage during 

the summer months lowers ground-water levels and 

reduces ground-water discharge to streams.

Figure 4. Conceptualization of stream-aquifer flow with a nearby pumping well in the lower Apalachicola–

Chattahoochee–Flint River basin (modified from Torak and others, 1993).

LISBON FORMATION (confining unit, no vertical leakage)

UPPER FLORIDAN AQUIFER

Ground-water discharge

to stream (local flow)

Leakage from

overburden to aquifer

UNDIFFERENTIATED

OVERBURDEN Stream 

Regional flow

Pumping well

Water table

Potentiometric surface of 

Upper Floridan aquifer

NOT TO SCALE
8 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure 5. Potentiometric surface of the Upper Floridan aquifer in the lower Apalachicola– 

Chattahoochee–Flint River basin (modified from Peck and others, 1999), and location of 

U.S. Geological Survey monitoring wells, gaging station 02356000, and International 

Paper Company precipitation station near Bainbridge, Georgia.

60

80

100

100

120

120

140

160

180

180

200

200

200

220

220

60

80

100

260 280

280

300

300

260

240

220

200

180

160

140

120

100

80

AL

GA

GA

FL

FL

84°

85°

32°

31°

30°

10G313

09G001

09F520

02356000

EXPLANATION

 WELL AND IDENTIFICATION NUMBER

 MODEL BOUNDARY

SURFACE-WATER GAGING STATION 

 AND IDENTIFICATION NUMBER

INTERNATIONAL PAPER COMPANY

 PRECIPITATION STATION NEAR

 BAINBRIDGE, GEORGIA

100 POTENTIOMETRIC CONTOUR— 

Shows altitude at which water 

level would have stood in tightly 

cased wells during May 1–26, 

1998. Contour interval 20 feet. 

Datum is sea level

0

0

10

10

20

20

30 MILES

30 KILOMETERS

09F520

02356000

Base from U.S. Geological Survey

1:100,000-scale digital files

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin
Stream–Aquifer Relations 9

Figure 6. Stream stage for the Flint River at Bainbridge (02356000); water levels at 

U.S. Geological Survey monitoring wells 09F520, 09G001, and 10G313; and monthly 

total precipitation near Bainbridge, Georgia (see fig. 5 for location).

120

110

100

90

80

1998 1999 2000 2001

84

82

80

78

76

74

108

98

88

78

68

125

115

105

95

85

DAILY-MEAN WATER LEVEL, IN FEET ABOVE SEA LEVEL PRECIPITATION,

IN INCHES

STREAM STAGE,

IN FEET ABOVE

SEA LEVEL

0

4

8

12

16

J FMAMJ J ASONDJ FMAMJ J ASOND J FM J FMA AMJ J ASOND

Blank

where

data

missing

Blank

where

data

missing

Blank

where

data

missing

Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Winter Summer Fall

Well 09F520

Well 09G001

Well 10G313

International Paper Company near Bainbridge, Georgia

Effect of irrigation

Flint River at Bainbridge, Georgia (02356000)
10 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

SIMULATION OF STREAM-AQUIFER FLOW

Results of steady-state digital models of the Upper Floridan 

aquifer and Intermediate system, constructed by Torak and 

others (1996) and Torak and McDowell (1996), were used 

in this study to assess pumpage-induced changes in stream–

aquifer flow in stream reaches containing federally 

protected mussel species in the lower ACF River basin. The 

models utilized the USGS Modular Finite-Element model 

(MODFE) for ground-water flow (Cooley, 1992; Torak, 

1993a,b). Simulation results are presented in tables in 

Appendix A.

In the study by Torak and others (1996), two steady-state 

models were constructed to show the effect of groundwater pumpage on stream–aquifer flow during a period of 

drought. One of these two models, termed the Upper 

Floridan model, simulated ground- and surface-water 

interaction in the northern and central part of Subarea 4 

(fig. 1), where surface-water features are in direct hydraulic 

connection with the Upper Floridan aquifer. The second 

model, termed the Intermediate model, simulated groundand surface-water interaction in the southern part of 

Subarea 4, where surface-water features are not connected 

hydraulically with the Upper Floridan aquifer, but rather 

are connected with the Intermediate aquifer and surficial 

deposits.

In a second study (Torak and McDowell, 1996), the Upper 

Floridan and Intermediate models were utilized to show the 

effect of pumpage, stream stage, and ground-water level on 

stream–aquifer flow by combining six scenarios of surfacewater and ground-water conditions with four multiples (n) 

of the October 1986 pumping rate (n = 0.5, 1, 2, 5). Each 

scenario (fig. 7) consisted of a ground-water-level 

condition (“dry” October 1986 conditions or “normal” 

long-term average conditions), and a stream-stage condition (October 1986, Q90, or Q50). Stream-stage-condition 

October 1986 refers to the stage associated with measured 

streamflow in late October 1986. Stream-stage-condition 

Q90 is the stage associated with streamflow that is exceeded 

90 percent of the time, and stream-stage-condition Q50 is 

the stage associated with streamflow that is exceeded 50 

percent of the time. Simulations results provide computed 

values of stream–aquifer flow for 37 stream reaches in 

Subarea 4, based on given conditions of pumpage, groundwater level, and stream stage. Graphical results, by stream 

reach, are presented in Appendix B. For additional details 

pertaining to model input, the reader is referred to Torak 

and others (1996) and Torak and McDowell (1996).

Model Representation of Stream Reaches

 Torak and others (1996) and Torak and McDowell 

(1996) divided streams in the lower ACF River basin into 

37 stream reaches (fig. 8) based on discharge measurements made in October 1986 at 94 points along streams in 

the basin (table 1 in Torak and others, 1996). Stream 

reaches were represented in digital models by using either a 

linear or nonlinear, head-dependent, Cauchy-type boundary 

(Torak, 1993a). The linear, head-dependent, Cauchy-type 

boundary either allows water from the stream to recharge 

the aquifer or allows ground water from the aquifer to 

discharge to the stream. This condition assumes the stream 

would not go dry under losing-stream conditions. The 

nonlinear, head-dependent, Cauchy-type boundary does 

not allow water from the stream to recharge the aquifer, 

as it is assumed that the stream would go dry under 

losing-stream conditions. Nineteen small stream reaches 

draining the upland areas of the lower ACF River basin 

(Upper Floridan model only) were represented with 

nonlinear, head-dependent, Cauchy-type boundaries, as 

some of these streams were observed to be dry or nearly 

dry during October 1986. Also, other streams were 

represented with the nonlinear boundary if the potential 

existed for them to go dry during simulation of increased 

pumpage from October 1986 rates (Torak and others, 

1996). Eighteen larger stream reaches that were not dry 

during October 1986 nor expected to go dry during 

simulation of pumpage increases from October 1986 rates 

were represented with the linear, head-dependent, Cauchytype boundary.

Figure 7. Matrix showing six different hydrologic 

scenarios used in the Torak and McDowell (1996) 

simulations.

Ground-water

boundary

condition

Stream stage for flow condition

 dashed where extrapolated

October 1986 1Q90 2Q50

Dry

(October 1986)

Normal

(Long-term 

average)

1 Streamflow equal to or exceeded 90 percent of the time 

 (low-flow condition)

2 Streamflow equal to or exceeded 50 percent of the time 

 (median streamflow condition) 
Simulation of Stream–Aquifer Flow 11

Sensitivity Ranking Procedure

Stream reaches were ranked according to their simulated 

response to pumpage. A ranking procedure was used to 

classify stream–aquifer response to pumpage and identify 

stream reaches that are sensitive to simulated pumpage. 

Stream-reach sensitivity to ground-water pumpage was 

ranked as either high, medium, or low, using simulated 

stream–aquifer flow for 37 reaches in the study area. The 

minimum pumpage multiplier (n) of October 1986 rates 

necessary to cause stream–aquifer flow to be zero was used 

to rank stream reaches. A high-sensitivity rank was 

assigned to reaches having zero simulated stream–aquifer 

flow at pumpage multipliers less than 5, regardless of the 

scenario of ground-water or surface-water boundary 

conditions that imparted this effect. A medium ranking was 

assigned to reaches in which a scenario produced a stream–

aquifer flow of zero between pumpage multipliers of 5 and 

10, and a low ranking was assigned to reaches for which a 

scenario produced zero stream–aquifer flow at pumpage 

multipliers greater than 10. 

Mathematical boundary conditions simulated in Torak and 

McDowell (1996) affect the stream-reach ranking procedure used in this study. One boundary condition 

represented gaining stream conditions; these reaches were 

expected to go dry under drought conditions. The other 

boundary condition represented gaining and losing stream 

conditions; this condition was applied to reaches that were 

not expected to go dry during drought conditions. Simulated stream reaches ranked high would go dry when 

stream–aquifer flow equals zero and when two conditions 

prevail: (1) the reach is simulated with a nonlinear Cauchytype boundary and (2) the reach does not receive inflow 

from upstream.

Stream reaches represented with a nonlinear Cauchy-type 

boundary that contained simulated stream–aquifer flow for 

one pumpage multiplier, but were simulated as having zero 

stream–aquifer flow for the next higher multiplier, would 

have zero stream–aquifer flow at a value of the pumpage 

multiplier that is between the two. For example, reduction 

of stream–aquifer flow to zero for reach 1, Gum Creek at 

Coney, Ga. (fig. B1), occurred for pumpage at a multiplier 

larger than two (n=2), but less than five (n=5). For cases 

such as this, linear extrapolation of a line depicting the 

reduction in stream–aquifer flow by pumpage multiplier 

was used to estimate the minimum pumping rate at which 

the reach would yield zero stream–aquifer flow. The 

estimate of the pumpage multiplier (n) corresponding to 

zero stream–aquifer flow was calculated using the previous 

two pumpage multipliers and finding the zero stream–

aquifer-flow intercept.

The sensitivity ranking procedure accounts for gaining and 

losing stream-reach conditions for stream reaches 

represented with a linear, Cauchy-type boundary. For 

reaches that contain pumpage multipliers corresponding 

first to gaining and then to losing reaches (fig. B23), the 

pumpage multiplier at which the reach changes from 

gaining to losing was used for ranking. Muckalee Creek 

near Leesburg, Ga. (reach 23, fig. B23), was ranked high 

because at least one scenario produced losing conditions at 

a pumpage multiplier less than 5.

Model Limitations 

Inaccuracy associated with measurement of ground-water 

level, parameterization, and model application combine 

with errors of numerical approximation to produce models 

that are not exact representations of the real system. 

Uncertainty is introduced into model results, which require 

interpretation in order to make meaningful application to 

real-world conditions.

In this application, pumpage in wells installed through 

1986 was simulated as occurring simultaneously at each 

well throughout the study area, a condition that does not 

occur, owing to the nonuniform schedules of irrigation 

pumpage. Also, streamflow measurements used to calibrate 

simulated stream–aquifer flow are instantaneous readings, 

taken at different times over a 6-day period. During this 

time, streamflow at any one station can vary significantly, 

and the measurements themselves contain errors of 

imprecision. Streamflow measurements along the 

Apalachicola River are long-term means for October 1986. 

These limitations are discussed in detail in Torak and 

others (1996) and Torak and McDowell (1996).

Model results can be used to show the effect of pumpage 

on stream–aquifer flow in Subarea 4 of the ACF River 

basin; however, the reader is cautioned that predictions of 

stream reaches going dry are based solely on computer 

simulation of steady-state conditions that might not actually 

occur in the stream–aquifer flow system.

Simulated Effect of Changing Pumpage and 

Boundary Conditions on Stream–Aquifer Flow

Model-derived values of stream–aquifer flow indicate that 

the 37 simulated stream reaches respond uniquely to 

changes in pumpage and boundary conditions (tables A1–

A4 in Appendix A). The effects of pumpage on stream–

aquifer flow for a specific reach are shown in plots of 

simulated stream–aquifer flow by pumpage multiplier of 

the October 1986 rates (figs. B1–B37 in Appendix B). The
12 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure 8. Model boundary and simulated stream reaches for Subarea 4, lower Apalachicola–

Chattahoochee–Flint River basin (modified from Torak and McDowell, 1996).

GADSDEN

DECATUR

MILLER

EARLY

BAKER

MITCHELL

COLQUITT

WORTH

TURNER

CRISP

DOOLY

SUMTER

CALHOUN DOUGHERTY

TERRELL

LEE

GRADY

LIBERTY

GULF FRANKLIN

CALHOUN

JACKSON

SEMINOLE

HOUSTON

84°

85°

32°

31°

30°

0

0

10

10

20

20

30 MILES

30 KILOMETERS

EXPLANATION

REACHES SIMULATED WITH A LINEAR 

CAUCHY-TYPE BOUNDARY

REACHES SIMULATED WITH A NONLINEAR CAUCHY-TYPE BOUNDARY

GEORGIA

FLORIDA

AL

FL

18

36

Base from U.S. Geological Survey

1:100,000-scale digital files

MODEL BOUNDARY

1

2

3

4

30

5

6

7

9

10

20

21

11

12

13

14

15

16

27

28

29

35

36

37

17

19

18

34

33

32

31

24

25

26

23

22

8

Chattahoochee R

Flint

River

Apalachicola

R

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin
Simulation of Stream–Aquifer Flow 13

effect of stream stage and lateral and vertical boundary 

conditions to the Upper Floridan aquifer on stream–aquifer 

flow can be observed by comparing values for a specific 

reach within a given table. 

Of the 37 stream reaches evaluated for sensitivity, 8 

reaches rank high, 13 reaches rank medium, and 16 reaches 

rank low in sensitivity to pumpage (table 1). Some reaches 

rank highly sensitive to pumpage even under normal 

climatic conditions. Streams ranking highly sensitive to 

pumpage are Gum, Jones, Cooleewahee, Spring, and 

Muckalee Creeks. The farthest downstream reach of the 

Flint River near Bainbridge, Ga. (reach 34, fig. B34), also 

exhibits high sensitivity to pumpage.

Stream reaches located near centers of agricultural 

pumpage, such as the Flint River and Dry and Spring 

Creeks, exhibit a large variation in stream–aquifer flow 

with pumpage change from October 1986 rates. Other 

stream reaches, such as the Apalachicola and Chipola 

Rivers exhibit little variation in stream–aquifer flow with 

pumpage change (see Appendix A, tables A1-A4 for values 

of stream–aquifer flow).

A reach exhibiting a high sensitivity to pumpage is 

Cooleewahee Creek at Newton, Ga. (reach 7, fig. B7), 

where stream–aquifer flow decreases for all simulations of 

increased pumpage from October 1986 rates for both dry 

and normal ground-water conditions. High sensitivity to 

pumpage means that stream–aquifer flow is zero at a 

pumpage multiplier (n) of less than 5. With stream–aquifer 

flow equal to zero, streamflow also is zero because there is 

no streamflow entering this reach from upstream. 

Simulation results indicate that under dry conditions, this 

stream would go dry with a minimal increase in pumpage 

from October 1986 rates.

In contrast, simulated stream–aquifer flows for reach 37 on 

the Apalachicola River near Sumatra, Fla. (fig. B37), 

indicate little effect of pumpage at any multiple of October 

1986. Consequently, this reach would not be expected to go 

dry. Reach 37 is located far from major pumping centers in 

Georgia and receives water from the Intermediate system, 

which is pumped very little in the study area (Torak and 

McDowell, 1996). 

Computed stream–aquifer response varied depending on 

whether dry or normal ground-water-flow boundaries were 

simulated. Normal boundary conditions produced higher 

stream–aquifer flow than simulations using dry boundary 

conditions. Simulation results indicate that stream–aquifer 

response is more sensitive to changes in ground-water 

levels than to changes in stream stage.

Simulations indicate that some stream reaches also are 

sensitive to pumpage during normal conditions. Reach 1, 

Gum Creek, may go dry under normal boundary conditions 

at a pumpage multiplier less than 5 times the October 1986 

rate (tables A1–A4). Other stream reaches sensitive to 

pumpage during normal conditions are 14 and 18 on Spring 

Creek; 22 and 23 on Muckalee Creek; and 34 on the Flint 

River. Reaches 14 and 18 may go dry under a pumpage 

multiplier of 5; reaches 22, 23, and 34 would change from 

gaining stream reaches to losing stream reaches.

SIMULATED STREAM–AQUIFER FLOW IN 

THE VICINITY OF FEDERALLY PROTECTED 

FRESHWATER MUSSELS

Two field surveys in the ACF River basin during the 

1990’s identified stream reaches containing federally 

protected mussels. The first survey was conducted during 

the summers of 1991 and 1992 to compare historical and 

present populations of mussels in the ACF River basin 

(Brim Box and Williams, 2000). The Joseph W. Jones 

Ecological Research Center, in Newton, Ga., conducted a 

second survey in 1999. From these data sets, the locations 

of six federally protected species found in the lower ACF 

River basin were compiled and projected on maps. 

Stream reaches where at least one federally protected 

mussel species lives are shown in figure 9 along with 

ranked stream reaches. Figures 10–15 show specifically 

where each of the six federally protected mussel species 

have been located in the lower ACF River basin and the 

sensitivity ranking of stream reaches.

Of the eight stream reaches ranked highly sensitive to 

pumpage, seven contain federally protected mussel species. 

Most reaches ranking highly sensitive to pumpage are near 

major pumping centers in the Dougherty Plain in Georgia. 

No high or medium ranks were assigned to stream reaches 

simulating stream–aquifer flow in the Chipola or the 

Apalachicola Rivers in Florida, although these reaches 

contain federally protected mussel species (figs. B27–B29, 

Federally protected mussel species found in the lower 

Apalachicola–Chattahoochee–Flint River basin

 fat threeridge (Amblema neislerii)

 shinyrayed pocketbook (Lampsilis subangulata)

 oval pigtoe (Pleurobema pyriforme)

 Gulf moccasinshell (Medionidus penicillatus)

 Chipola slabshell (Elliptio chipolaensis)

 purple bankclimber (Elliptio sloatianus)
14 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure 9. Model boundary, reaches where at least one federally protected 

freshwater mussel species is located, and simulated stream reach sensitivities

in the lower Apalachicola–Chattahoochee–Flint River basin.

GADSDEN

DECATUR

MILLER

EARLY

BAKER

MITCHELL

COLQUITT

WORTH

TURNER

CRISP

DOOLY

SUMTER

CALHOUN DOUGHERTY

TERRELL LEE

GRADY

LIBERTY

GULF FRANKLIN

CALHOUN

JACKSON

SEMINOLE

HOUSTON

84°

85°

32°

31°

30°

0

0

10

10

20

20

30 MILES

30 KILOMETERS

EXPLANATION

MODEL BOUNDARY

SIMULATED STREAM REACH 

SENSITIVITY TO ADDITIONAL 

PUMPAGE AND REACH NUMBER 

Low

Medium

High

FEDERALLY PROTECTED FRESH-

 WATER MUSSEL(S) PRESENT

GA

FL

AL

FL

32

33

34

Base from U.S. Geological Survey

1:100,000-scale digital files

1

2

3

4 30

5

6

7

9

20

21

11

13

14

16

27

28

29

35

36

37

17

19

18

34

33

31

24

25

26

23

22

8

Chattahoochee R

Flint

River

Apalachicola

R

32

10 12

15

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin
Simulation of Stream–Aquifer Flow 15

Table 1. Stream-reach sensitivity to pumpage and reaches where federally protected freshwater mussel species are 

present

[Stream sensitivity rankings: High, stream–aquifer flow equals zero for n < 5; Medium, stream–aquifer flow equals zero between 

n = 5 and 10; Low, stream–aquifer flow equals zero for n >10; n, multiple of October 1986 pumping rate. Mussel species: sp, 

Shinyrayed pocketbook (Lampsilis subangulata); gm, Gulf moccasinshell (Medionidus penicillatus); op, Oval pigtoe (Pleurobema pyriforme); pb, Purple bankclimber (Elliptoideus sloatianus); cs, Chipola slabshell (Elliptio chipolaensis); ft, Fat threeridge (Amblema 

neislerii); leaders (—), federally protected mussel(s) not detected or reach not surveyed; do., ditto] 

Stream reach

(see figure 8, page 12)

Simulated sensitivity 

to pumpage Federally protected mussel(s) in reach

01 Gum Creek1/

1/Simulated as nonlinear leakage condition; zero-value entries may occur at pumpage multiplier (n) less than 

indicated on table.

High —

02 Cedar Creek1/ Medium —

03 Swift Creek1/ do. gm 

04 Jones Creek1/ High sp, op 

05 Abrams Creek1/ Medium sp

06 Mill Creek1/ do. sp, pb 

07 Cooleewahee Creek1/ High sp, op

08 Chickasawhatchee Creek1/ Low sp, gm, op

09 Do.1/ Medium —

10 Chickasawhatchee Creek1/ do. sp, gm

11 Dry Creek (Georgia)1/ do. —

12 Spring Creek1/ do. sp

13 Do.1/ do. —

14 Do.1/ High sp

15 Sawhatchee Creek1/ Low sp

16 Cowarts Creek1/ do. —

17 Marshall Creek1/ do. —

18 Spring Creek1/ High sp

19 Dry Creek (Florida)1/ Low —

20 Ichawaynochaway Creek do. sp

21 Do. do. —

22 Muckalee Creek High sp, gm, op, 

23 Do. do. sp

24 Do. Medium —

25 Kinchafoonee Creek2/

2/Stream–aquifer flow is negative for all values of n.

Low sp, op

26 Do. Medium sp

27 Chipola River Low op

28 Do. do. op, cs

29 Do. do. sp, cs

30 Flint River Medium pb

31 Do. Low pb

32 Do. do. gm, pb

33 Do. Medium pb

34 Do. High pb

35 Apalachicola River Low pb, ft

36 Do. do. pb, ft

37 Do. do. pb, ft
16 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure 10. Model boundary and simulated stream reach sensitivities for the lower Apalachicola–Chattahoochee–

Flint River basin (modified from Torak and McDowell, 1996) and sites containing federally protected mussel 

species Shinyrayed pocketbook (Lampsilis subangulata) (Amy J. Benson, U.S. Geological Survey, written 

commun., 2000; Paul M. Johnson, Joseph W. Jones Ecological Research Center, written commun., 1999).

GADSDEN

DECATUR

MILLER

EARLY

BAKER

MITCHELL

COLQUITT

WORTH

TURNER

CRISP

DOOLY

SUMTER

CALHOUN DOUGHERTY

TERRELL

LEE

GRADY

LIBERTY

GULF FRANKLIN

CALHOUN

JACKSON

SEMINOLE

HOUSTON

84°

85°

32°

31°

30°

0

0

10

10

20

20

30 MILES

30 KILOMETERS

EXPLANATION

MODEL BOUNDARY

SIMULATED STREAM REACH 

SENSITIVITY TO ADDITIONAL 

PUMPAGE AND REACH NUMBER 

Low

Medium

High

SITE CONTAINING FEDERALLY 

PROTECTED MUSSEL SPECIES 

SHINYRAYED POCKETBOOK 

(Lampsilis subangulata)

GA

FL

AL

FL

32

33

34

Base from U.S. Geological Survey

1:100,000-scale digital files

1

2

3

4

30

5

6

7

9

10

20

21

11

12

13

14

15

16

27

28

29

35

36

37

17

19

18

34

33

32

31

24

25

26

23

22

8

Chattahoochee R

Flint

River

Apalachicola

R

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin
Simulation of Stream–Aquifer Flow 17

Figure 11. Model boundary and simulated stream reach sensitivities for the lower Apalachicola–Chattahoochee–

Flint River basin (modified from Torak and McDowell, 1996) and sites containing federally protected mussel 

species Gulf moccasinshell (Medionidus penicillatus) (Amy J. Benson, U.S. Geological Survey, written commun., 

2000; Paul M. Johnson, Joseph W. Jones Ecological Research Center, written commun., 1999).

GADSDEN

DECATUR

MILLER

EARLY

BAKER

MITCHELL

COLQUITT

WORTH

TURNER

CRISP

DOOLY

SUMTER

CALHOUN DOUGHERTY

TERRELL

LEE

GRADY

LIBERTY

GULF FRANKLIN

CALHOUN

JACKSON

SEMINOLE

HOUSTON

84°

85°

32°

31°

30°

0

0

10

10

20

20

30 MILES

30 KILOMETERS

GA

FL

AL

FL

EXPLANATION

MODEL BOUNDARY

SIMULATED STREAM REACH 

SENSITIVITY TO ADDITIONAL 

PUMPAGE AND REACH NUMBER 

Low

Medium

High

SITE CONTAINING FEDERALLY 

PROTECTED MUSSEL SPECIES 

GULF MOCCASINSHELL

(Medionidus penicillatus)

32

33

34

Base from U.S. Geological Survey

1:100,000-scale digital files

1

2

3

4

30

5

6

7

9

10

20

21

11

12

13

14

15

16

27

28

29

35

36

37

17

19

18

34

33

32

31

24

25

26

23

22

8

Chattahoochee R

Flint

River

Apalachicola

R

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin
18 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure 12. Model boundary and simulated stream reach sensitivities for the lower Apalachicola–Chattahoochee–

Flint River basin (modified from Torak and McDowell, 1996) and sites containing federally protected mussel 

species Oval pigtoe (Pleurobema pyriforme) (Amy J. Benson, U.S. Geological Survey, written commun., 2000; 

Paul M. Johnson, Joseph W. Jones Ecological Research Center, written commun., 1999).

GADSDEN

DECATUR

MILLER

EARLY

BAKER

MITCHELL

COLQUITT

WORTH

TURNER

CRISP

DOOLY

SUMTER

CALHOUN DOUGHERTY

TERRELL

LEE

GRADY

LIBERTY

GULF FRANKLIN

CALHOUN

JACKSON

SEMINOLE

HOUSTON

84°

85°

32°

31°

30°

0

0

10

10

20

20

30 MILES

30 KILOMETERS

GA

FL

AL

FL

EXPLANATION

MODEL BOUNDARY

SIMULATED STREAM REACH 

SENSITIVITY TO ADDITIONAL 

PUMPAGE AND REACH NUMBER 

Low

Medium

High

SITE CONTAINING FEDERALLY 

PROTECTED MUSSEL SPECIES 

OVAL PIGTOE (Pleurobema pyriforme)

 

32

33

34

Base from U.S. Geological Survey

1:100,000-scale digital files

1

2

3

4

30

5

6

7

9

10

20

21

11

12

13

14

15

16

27

28

29

35

36

37

17

19

18

34

33

32

31

24

25

26

23

22

8

Chattahoochee R

Flint

River

Apalachicola

R

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin
Simulation of Stream–Aquifer Flow 19

Figure 13. Model boundary and simulated stream reach sensitivities for the lower 

Apalachicola–Chattahoochee–Flint River basin (modified from Torak and McDowell, 1996)

and sites containing federally protected mussel species Purple bankclimber (Elliptoideus 

sloatianus) (Amy J. Benson, U.S. Geological Survey, written commun., 2000).

GADSDEN

DECATUR

MILLER

EARLY

BAKER

MITCHELL

COLQUITT

WORTH

TURNER

CRISP

DOOLY

SUMTER

CALHOUN DOUGHERTY

TERRELL

LEE

GRADY

LIBERTY

GULF FRANKLIN

CALHOUN

JACKSON

SEMINOLE

HOUSTON

84°

85°

32°

31°

30°

0

0

10

10

20

20

30 MILES

30 KILOMETERS

GA

FL

AL

FL

Base from U.S. Geological Survey

1:100,000-scale digital files

1

2

3

4

30

5

6

7

9

10

20

21

11

12

13

14

15

16

27

28

29

35

36

37

17

19

18

34

33

32

31

24

25

26

23

22

8

Chattahoochee R

Flint

River

Apalachicola

R

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin

EXPLANATION

MODEL BOUNDARY

SIMULATED STREAM REACH 

SENSITIVITY TO ADDITIONAL 

PUMPAGE AND REACH NUMBER 

Low

Medium

High

SITE CONTAINING FEDERALLY 

PROTECTED MUSSEL SPECIES 

PURPLE BANKCLIMBER 

(Elliptoideus sloatianus)

32

33

34
20 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure 14. Model boundary and simulated stream reach sensitivities for the lower 

Apalachicola–Chattahoochee–Flint River basin (modified from Torak and McDowell, 1996)

and sites containing federally protected mussel species Chipola slabshell (Elliptio chipolaensis)

(Amy J. Benson, U.S. Geological Survey, written commun., 2000).

GADSDEN

DECATUR

MILLER

EARLY

BAKER

MITCHELL

COLQUITT

WORTH

TURNER

CRISP

DOOLY

SUMTER

CALHOUN DOUGHERTY

TERRELL

LEE

GRADY

LIBERTY

GULF FRANKLIN

CALHOUN

JACKSON

SEMINOLE

HOUSTON

84°

85°

32°

31°

30°

0

0

10

10

20

20

30 MILES

30 KILOMETERS

GA

FL

AL

FL

Base from U.S. Geological Survey

1:100,000-scale digital files

1

2

3

4

30

5

6

7

9

10

20

21

11

12

13

14

15

16

27

28

29

35

36

37

17

19

18

34

33

32

31

24

25

26

23

22

8

Chattahoochee R

Flint

River

Apalachicola

R

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin

EXPLANATION

MODEL BOUNDARY

SIMULATED STREAM REACH 

SENSITIVITY TO ADDITIONAL 

PUMPAGE AND REACH NUMBER 

Low

Medium

High

SITE CONTAINING FEDERALLY 

PROTECTED MUSSEL SPECIES 

CHIPOLA SLABSHELL 

(Elliptio chipolaensis)

32

33

34
Simulation of Stream–Aquifer Flow 21

Figure 15. Model boundary and simulated stream reach sensitivities for the lower 

Apalachicola–Chattahoochee–Flint River basin (modified from Torak and McDowell, 1996) 

and sites containing federally protected mussel species Fat threeridge (Amblema neislerii) 

(Amy J. Benson, U.S. Geological Survey, written commun., 2000).

GADSDEN

DECATUR

MILLER

EARLY

BAKER

MITCHELL

COLQUITT

WORTH

TURNER

CRISP

DOOLY

SUMTER

CALHOUN DOUGHERTY

TERRELL

LEE

GRADY

LIBERTY

GULF FRANKLIN

CALHOUN

JACKSON

SEMINOLE

HOUSTON

84°

85°

32°

31°

30°

0

0

10

10

20

20

30 MILES

30 KILOMETERS

Base from U.S. Geological Survey

1:100,000-scale digital files

GA

FL

AL

FL

1

2

3

4

30

5

6

7

9

10

20

21

11

12

13

14

15

16

27

28

29

35

36

37

17

19

18

34

33

32

31

24

25

26

23

22

8

Chattahoochee R

Flint

River

Apalachicola

R

ALABAMA

GEORGIA

Gulf of Mexico

FLORIDA

Apalachicola–

 Chattahoochee–

 Flint River basin

EXPLANATION

MODEL BOUNDARY

SIMULATED STREAM REACH 

SENSITIVITY TO ADDITIONAL 

PUMPAGE AND REACH NUMBER 

Low

Medium

High

SITE CONTAINING FEDERALLY 

PROTECTED MUSSEL SPECIES FA

THREERIDGE (Amblema neislerii)

 

32

33

34
22 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

and B35–B37); these stream reaches are far removed from 

major pumping centers in Georgia.

Model simulations indicate increased pumpage would 

substantially effect mussel habitat in stream reaches ranked 

highly sensitive to pumpage and that have no inflow from 

upstream. Long-term, pumpage-induced, stream–aquifer 

flow reductions would cause small tributary streams such 

as Gum, Jones, and Cooleewahee Creeks to go dry, because 

these reaches have no inflow from upstream. These 

streams, except for Gum Creek, provide habitat for 

federally protected mussel species. Other stream reaches 

with high rankings could go dry depending on the upstream 

flow entering the reach. Drying conditions in these streams 

would reduce available habitat; and thus contribute to 

further declines in federally protected mussel species (U.S. 

Fish and Wildlife Service, 1998; Richard J. Neves, Virginia 

Cooperative Fish and Wildlife Research Unit, Virginia 

Polytechnic Institute and State University, oral commun., 

2001).

SUMMARY AND CONCLUSIONS

Simulation results indicate that ground-water withdrawal in 

the lower Apalachicola–Chattahoochee–Flint (ACF) River 

basin during times of drought could reduce stream–aquifer 

flow and cause specific stream reaches to go dry. Of the 37 

reaches that were studied, 8 reaches ranked highly sensitive 

to pumpage, 13 reaches ranked medium, and 16 reaches 

ranked low. Of the eight reaches that ranked high, seven 

contain at least one federally protected mussel species. 

Model simulations indicate small tributary streams such as 

Gum, Jones, Muckalee, Spring, and Cooleewahee Creeks 

would go dry at lower pumping rates than needed to dry up 

larger streams. Other streams that were ranked high may go 

dry depending on the amount of upstream flow entering the 

reach; this condition is indicated for some reaches on 

Spring Creek. A dry stream condition is of particular 

concern to water and wildlife managers because adequate 

streamflow is essential to mussel survival (Dick Neves, 

Virginia Cooperative Fish and Wildlife Research Unit, 

Virginia Polytechnic Institute and State University, oral 

commun., 200l; U.S. Fish and Wildlife Service, 1998).

Besides being sensitive to dry conditions, some streams 

exhibit a high sensitivity to pumpage under normal 

conditions. Reach 1, Gum Creek, may go dry under normal 

boundary conditions at a pumpage multiplier less than 5 

times the October 1986 rate. Other stream reaches sensitive 

to pumpage during normal conditions are 14 and 18 on 

Spring Creek; 22 and 23 on Muckalee Creek; and 34 on the 

Flint River. Reaches 14, 18, 22, 23, and 34 in the 

simulation would switch from gaining to losing stream 

conditions.

Stream reaches in Florida show low sensitivity to pumpage 

because nearly all simulated pumpage occurs in Georgia, 

far from stream reaches in Florida that were expected to 

show pumpage-induced streamflow reductions. Stream 

reaches 36 and 37 simulated in the Intermediate model 

ranked low because they are far from pumpage in Georgia 

and also because they are in hydraulic connection with the 

Intermediate system, not the Upper Floridan aquifer in 

which most pumpage occurs.

Limitations posed by the modeling process and 

measurements used to calibrate the models prevent 

definitive statements from being made about the exact 

pumpage required to cause streams containing federally 

protected mussels to go dry. The ranking of stream reaches 

conducted in this study, however, can be used as an 

indicator of the degree to which pumpage affects change 

stream–aquifer flow in streams containing federally 

protected mussel species.

REFERENCES CITED

Arthur, J.D., and Rupert, F.R., 1989, Selected geomorphic features 

of Florida, in The lithostratigraphy and hydrostratigraphy of 

the Floridan aquifer system in Florida, field trip guide-book 

T185, Tampa to Tallahassee, Florida, July 1–7, 1989: 

American Geophysical Union, no. T185,

p. 10–14.

Brim Box, Jayne, and Williams, J.D., 2000, Unionid mollusks of 

the Apalachicola Basin in Alabama, Florida, and Georgia: 

Tuscaloosa, Ala., Bulletin of the Alabama Museum Natural 

History, University of Alabama, 144 p.

Brooks, H.K., 1981, Physiographic divisions of Florida: 

Gainesville, Fla., Institute of Flood and Agricultural 

Sciences, University of Florida, 6 p.

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.

Butler, R.S., and Alam, S.K., 1999, Technical/Agency Draft 

Recovery Plan for Endangered Fat Threeridge (Amblema 

neislerii), Shinyrayed Pocketbook (Lampsilis subangulata), 

Gulf Moccasinshell (Medionidus penicillatus), Ochlockonee 

Moccasinshell (Medionidus simpsonianus), Oval Pigtoe 

(Pluerobema pyriforme) and threatened Chipola Slabshell 

(Elliptio chipolaensis), and Purple Bankclimber 

(Elliptoideus sloatianus): Atlanta, Ga., U.S. Fish and 

Wildlife Service, Southeast Region, 107 p.

Clark, W.Z., and Zisa, A.C., 1976, Physiographic map of Georgia: 

Georgia Geologic Survey, SM-4, 1 plate, scale 1:2,000,000. 
References Cited 23

Cooley, R.L., 1992, A MODular Finite-Element model (MODFE) 

for areal and axisymmetric ground-water-flow problems, part 

2: derivation of finite element equations and comparisons 

with analytical solutions: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 6, chap. 

A4, 108 p.

Elder, J.F., and Cairns, D.J., 1982, Production and decomposition 

of forest litter fall on the Apalachicola River flood plain, 

Florida: U.S. Geological Survey Water-Supply Paper 

2196–B, 42 p.

Faye, R.E., and Mayer, G.C., 1990, Ground-water flow and 

stream–aquifer relations in the northern Coastal Plain of 

Georgia and adjacent parts of Alabama and South Carolina: 

U.S. Geological Survey Water-Resources Investigations 

Report 88-4143, 83 p., 7 plates.

____ 1996, Simulation of ground-water flow in southeastern 

coastal plain clastic aquifers in Georgia and adjacent parts of 

Alabama and South Carolina: U.S. Geological Survey 

Professional Paper 1410-F, 77 p., 16 plates.

Fenneman, N.M., 1938, Physiography of eastern United States: 

New York, N.Y., McGraw-Hill, 714 p.

Havlik, M., 1981, The historic and present distributions of the 

endangered naiad mollusk, Lampsilis higginsl: Bulletin 

American Malacology Union Inc., 1980, p.19–22

Hayes, L.R., Maslia, M.L., and Meeks, W.C., 1983, Hydrology 

and model evaluation of the principal artesian aquifer, 

Dougherty Plain, southwest Georgia: Georgia Geologic 

Survey Bulletin, 93 p.

Hicks, D.W., Gill, H.E., and Longsworth, S.A., 1995, 

Hydrogeology, chemical quality, and avail-ability of ground 

water in the Upper Floridan aquifer, Albany, Georgia: U.S. 

Geological Survey Water-Resources Investigations Report 

87–4145, 52 p.

Layzer, J.B., Gordon, M.E., and Anderson, R.M., 1993, Mussels: 

the forgotten fauna of regulated rivers. A case study of the 

Caney Fork River: Regulated Rivers, v. 8, 63-71

Layzer, J.B., and Madison, L.M., 1995, Microhabitat use by 

freshwater mussels and recommendations for determining 

their instream flow needs in Regulated Rivers—Research 

and Management: John Wiley & Sons, Ltd., p. 334-350.

MacNeil, F.S., 1947, Geologic Map of the Tertiary and Quaternary 

Formations of Georgia: U.S. Geological Survey Oil and Gas 

Inventory (Preliminary) Map 72, 

scale 1:506,880.

Middleton, R.G., 1968, Soil survey of Dougherty County, 

Georgia: U.S. Department of Agriculture, Soil Conservation 

Service, 64 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.

National Oceanic and Atmospheric Administration, 1998, 

Climatological Data, Annual Summary, Georgia, 22 p.

Peck, M.F., Clarke, J.S., Ransom III, C.R., 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 plate, scale 1:100,000

Puri, H.S., and Vernon, F.O., 1964, Summary of the geology of 

Florida and a guidebook to the classic exposures: Florida 

State Geological Survey, Special Publication 5 Revised, 312 

p.

Sapp, D.C. and Emplaincourt, Jacques., 1975, Physiographic 

regions of Alabama: Geological Survey of Alabama Map, 

SM 168.

Torak, L.J., 1993a, A MODular Finite-Element model (MODFE) 

for areal and axisymmetric ground-water flow problems, part 

1: model description and user’s manual: U.S. Geological 

Survey Techniques of Water-Resources Investigations, 

Book 6, Chapter A3, 136 p. 

____ 1993b, A MODular Finite-Element model (MODFE) for 

areal and axisymmetric ground-water flow problems, part 3: 

design philosophy and programming details: U.S. Geological 

Survey Techniques of Water-Resources Investigations, Book 

6, Chapter A5, 243 p.

Torak, L.J., Davis, G.S., Strain, G.A., and Herndon, J.G., l993, 

Geohydrology and evaluation of water-resource potential of 

the Upper Floridan aquifer in the Albany area, southwestern 

Georgia: U.S. Geological Survey Water-Supply Paper 2391, 

59 p.

____ 1996, Geohydrology and evaluation of stream–aquifer 

relations in the Apalachicola–Chattahoochee–Flint River 

Basin, southeastern Alabama, northwestern Florida, and 

southwestern Georgia: U.S. Geological Survey WaterSupply Paper 2460, 95 p.

Torak, L.J., and McDowell, R.J., 1996, Ground-water resources of 

the lower Apalachicola–Chattahoochee–Flint River basin in 

parts of Alabama, Florida, and Georgia–Subarea 4 of the 

Apalachicola–Chattahoochee–Flint and Alabama–Coosa–

Tallapoosa River basins: U.S. Geological Survey Open-File 

Report 95-321, 145 p.

U.S. Army Corps of Engineers, 1998, Water allocation for the 

Apalachicola–Chattahoochee–Flint (ACF) River basin, 

Alabama, Florida, and Georgia, Document Overview, Draft 

Environmental Impact Statement: Mobile, Ala., U.S. Army 

Corps of Engineers, v. 1, 394 p., with appendices.

U.S. Geological Survey, 1981–1999, Water Resources Data, 

Georgia: U.S. Geological Survey Water Data Reports, 

published annually, variously paged.

U.S. Fish and Wildlife Service, 1998, Endangered and threatened 

wildlife and plants; Determination of endangered status for 

five freshwater mussels and threatened status for two 

freshwater mussels from the Eastern Gulf Slope drainages of 

Alabama, Florida, and Georgia, Federal Register: March 16, 

1998, v. 63, no. 50, 84 p.

Wagner, J.R., and Allen, T.W., 1984, Ground water section: in 

1984 water assessment for the Apalachicola– 

Chattahoochee–Flint River basin water management study: 

U.S. Army Corps of Engineers, and States of Alabama, 

Florida, and Georgia, v. 3, appendix III, section 3, 

129 p.

White, W.A., 1970, Geomorphology of the Florida Peninsula: 

Florida Geological Survey Bulletin 51, 164 p.
24 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

APPENDIX A

TABLES LISTING STREAM–AQUIFER FLOW, BY REACH, FOR SIMULATED 

HYDROLOGIC AND PUMPAGE CONDITIONS
Appendix A 25

Table A1. Stream–aquifer flow, by reach, for hydrologic conditions and pumpage at 0.5 times October 1986 

rates simulated in the Subarea 4 model

[Do., ditto; negative values indicate recharge to aquifer by streamflow; Oct 86 is October 1986 streamflow; Q90 is 

streamflow that is exceeded 90 percent of the time, and Q50 is streamflow that is exceeded 50 percent of the time; 

streamflow conditions calculated using recorded measurements for period of record ending 1993; dry is October 1986 

conditions of lateral boundary and semiconfining-unit head; normal is long-term-average conditions of lateral boundary 

and semiconfining-unit head]

Stream reach

(see figure 8, page 12)

Computed net stream–aquifer flow (in cubic feet per second)

Hydrologic condition

Oct 86 

Dry

Oct 86 

Normal

Q90

Dry

Q90

Normal

O50

Dry

Q50

Normal

1 Gum Creek1/

1/Simulated as nonlinear leakage condition.

4.5 6 5.3 7 4.3 6

2 Cedar Creek1/ 1.4 1.9 1.4 1.9 1.1 1.5

3 Swift Creek1/ 4 5.3 4 5.3 3.4 4.6

4 Jones Creek1/ 2.6 3.4 2.8 3.6 2.6 3.2

5 Abrams Creek1/ 2.9 3.7 2.9 3.7 2.8 3.6

6 Mill Creek1/ 7.3 9.4 7.3 9.4 7.0 8.8

7 Cooleewahee Creek1/ 0.8 4.6 0.6 4.2 0.2 3.1

8 Chickasawhatchee Creek1/ 4 5.7 4 5.6 3.6 5.3

9 Do.1/ 0.5 4 0.3 3.9 0.2 3.4

10 Do.1/ 3.1 10.5 2.9 10.4 2.8 9.7

11 Dry Creek (Georgia)1/ 3.1 4.6 2.9 4.5 3.1 4.6

12 Spring Creek1/ 3.9 6 3.9 5.9 4 6

13 Do.1/ 24.9 36.4 23.8 35.4 25.2 36.8

14 Do.1/ 4 6.8 3.6 6.3 4.6 7.4

15 Sawhatchee Creek1/ 9.7 15.6 9.7 15.6 9.1 14.9

16 Cowarts Creek1/ 20 26.8 19.8 26.6 19 25.8

17 Marshall Creek1/ 31.7 46.1 31.4 46 30.2 44.7

18 Spring Creek1/ 52.9 59.9 51.5 58.3 54.8 61.7

19 Dry Creek (Florida)1/ 42.2 74.1 41.6 73.3 39.2 70.1

20 Ichawaynochaway Creek 53.7 78.9 52.3 77.4 50.1 75.2

21 Do. 24.4 35.7 24.1 35.4 23.7 34.8

22 Muckalee Creek 23.2 29.7 20 26.2 19 25.2

23 Do. 5.7 7.3 5 6.3 4.6 6

24 Do. 15 18 11.1 14.1 10.1 13

25 Kinchafoonee Creek -2.3 -2.3 -2.3 -2.3 -2.3 -2.3

26 Do. 6.7 7.3 7 7.4 6.7 7.4

27 Chipola River 115.1 171.3 113.7 169.9 108 164.2

28 Do. 339.8 387.3 361.6 409 448.9 496.3

29 Do. 359.2 388.7 455.9 485.4 678.4 708

30 Flint River 7.3 8.4 7.4 8.5 7.3 8.4

31 Do. 629.8 708 630.3 708.3 616.5 694.2

32 Do. 564.5 644.2 558.9 638.6 534.6 613.6

33 Do. 396.5 501.8 391.5 496.9 376.3 481.4

34 Do. 394.3 452.8 393.2 451.5 377.1 435

35 Apalachicola River 282.1 334.7 268.3 321.1 256.6 309.3

36 Do. 165.6 210 148.4 197.2 116.1 160.5

37 Do. 522.6 534.2 480.6 480.8 92.7 181.5
26 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Table A2. Stream–aquifer flow, by reach, for hydrologic conditions and pumpage at October 1986 rates simulated in 

the Subarea 4 model

[Do., ditto; negative values indicate recharge to aquifer by streamflow; Oct 86 is October 1986 streamflow; Q90 is streamflow 

that is exceeded 90 percent of the time, and Q50 is streamflow that is exceeded 50 percent of the time; streamflow conditions 

calculated using recorded measurements for period of record ending 1993; dry is October 1986 conditions of lateral boundary 

and semiconfining-unit head; normal is long-term-average conditions of lateral boundary and semiconfining-unit head]

Stream reach

(see figure 8, page 12)

Computed net stream–aquifer flow (in cubic feet per second)

Hydrologic condition

Oct 86 

Dry

Oct 86 

Normal

Q90

Dry

Q90

Normal

O50

Dry

Q50

Normal

1 Gum Creek1/

1/Simulated as nonlinear leakage condition.

3.6 5.1 4.2 5.7 3.4 5

2 Cedar Creek1/ 1.2 1.7 1.2 1.7 0.9 1.5

3 Swift Creek1/ 3.9 5 3.9 5 3.2 4.3

4 Jones Creek1/ 2.3 2.9 2.5 2.9 2.2 2.9

5 Abrams Creek1/ 2.6 3.4 2.6 3.4 2.5 3.2

6 Mill Creek1/ 7 8.8 6.8 8.8 6.3 8.4

7 Cooleewahee Creek1/ 0.5 4 0.5 3.7 0 2.6

8 Chickasawhatchee Creek1/ 4 5.7 4 5.6 3.6 5.3

9 Do.1/ 0.3 4 0.3 3.9 0.2 3.2

10 Do.1/ 2.8 10.1 2.6 9.7 2.5 9.3

11 Dry Creek (Georgia)1/ 2.8 4.3 2.6 4.2 2.8 4.3

12 Spring Creek1/ 3.6 5.7 3.4 5.6 3.6 5.7

13 Do.1/ 19.5 31.3 18.6 30.3 20 31.6

14 Do.1/ 1.1 3.1 0.8 2.6 1.4 3.6

15 Sawhatchee Creek1/ 9.6 15.3 9.6 15.3 8.8 14.7

16 Cowarts Creek1/ 20 26.6 19.7 26.5 18.9 25.7

17 Marshall Creek1/ 31.6 46.1 31.3 45.8 30 44.6

18 Spring Creek1/ 42.2 49.5 40.7 48 44.3 51.2

19 Dry Creek (Florida)1/ 42.1 74 41.6 73.3 39 70.1

20 Ichawaynochaway Creek 52.6 77.8 51.2 76.4 49.1 74.1

21 Do. 23.7 35 23.4 34.7 22.9 34.2

22 Muckalee Creek 17.8 24.3 14.5 21.0 13.6 20

23 Do. 3.9 5.6 3.1 4.6 2.8 4.3

24 Do. 14.2 17.3 10.4 13.5 9.4 12.4

25 Kinchafoonee Creek -2.3 -2.3 -2.3 -2.3 -2.3 -2.3

26 Do. 5.9 6.7 6.2 6.8 6 6.7

27 Chipola River 114.7 170.8 113.3 169.4 107.5 163.7

28 Do. 339.5 387 361.2 408.7 448.6 496

29 Do. 359 388.7 455.7 485.4 678.2 707.8

30 Flint River 6.3 7.4 6.5 7.6 6.3 7.3

31 Do. 604.7 683.2 605.4 683.5 591.4 669.4

32 Do. 537.1 616.8 531.7 611.2 507.3 586.3

33 Do. 363.3 469.5 358.5 464.5 343.4 449.1

34 Do. 352 411.9 351 410.8 335.5 394.8

35 Apalachicola River 281.5 334.2 267.7 320.5 255.9 308.7

36 Do. 165.4 209.8 148.1 197 115.9 160.3

37 Do. 522.6 534.2 480.6 480.8 92.7 181.5
Appendix A 27

Table A3. Stream–aquifer flow, by reach, for hydrologic conditions and pumpage at 2 times October 1986 rates 

simulated in the Subarea 4 model 

[Do, ditto; negative values indicate recharge to aquifer by streamflow; Oct 86 is October 1986 streamflow; Q90 is streamflow 

that is exceeded 90 percent of the time, and Q50 is streamflow that is exceeded 50 percent of the time; streamflow conditions 

calculated using recorded measurements for period of record ending 1993; dry is October 1986 conditions of lateral boundary 

and semiconfining-unit head; normal is long-term-average conditions of lateral boundary and semiconfining-unit head]

Stream reach

(see figure 8, page 12)

Computed net stream–aquifer flow (in cubic feet per second)

Hydrologic condition

Oct 86 

Dry

Oct 86 

Normal

Q90

Dry

Q90

Normal

O50

Dry

Q50

Normal

1 Gum Creek1/

1/Simulated as nonlinear leakage condition.

1.7 3.2 2.2 3.7 1.5 2.9

2 Cedar Creek1/ 0.9 1.4 0.9 1.4 0.8 1.2

3 Swift Creek1/ 3.4 4.6 3.2 4.5 2.8 3.9

4 Jones Creek1/ 1.5 2.2 1.5 2.2 1.4 2

5 Abrams Creek1/ 1.9 2.6 1.9 2.6 1.5 2.5

6 Mill Creek1/ 5.9 7.7 5.9 7.7 5.6 7.3

7 Cooleewahee Creek1/ 0.2 3.1 0.2 2.8 0 2

8 Chickasawhatchee Creek1/ 4 5.7 3.9 5.6 3.6 5.1

9 Do.1/ 0.3 3.7 0.3 3.6 0.2 2.9

10 Do.1/ 2.3 9.1 2.2 8.8 2 8.4

11 Dry Creek (Georgia)1/ 2.2 3.9 2.2 3.7 2.3 3.9

12 Spring Creek1/ 2.6 4.8 2.5 4.6 2.6 5

13 Do.1/ 9.1 20.4 8.4 19.7 9.4 20.9

14 Do.1/ 0 0.2 0 0 0 0.2

15 Sawhatchee Creek1/ 9.1 15.2 9.1 15 8.5 14.4

16 Cowarts Creek1/ 19.7 26.5 19.3 26.3 18.6 25.5

17 Marshall Creek1/ 31.4 46 31.1 45.6 30 44.4

18 Spring Creek1/ 15.3 25.5 14.1 24.1 18 28

19 Dry Creek (Florida)1/ 41.9 73.8 41.3 73 38.8 69.9

20 Ichawaynochaway Creek 50.3 75.7 48.9 74.1 46.7 72

21 Do. 22.1 33.6 21.7 33.1 21.4 32.8

22 Muckalee Creek 7 13.5 3.9 10.2 2.8 9.1

23 Do. 0.2 1.9 -0.6 0.9 -0.8 0.8

24 Do. 12.5 15.9 8.8 12.1 7.9 11

25 Kinchafoonee Creek -2.3 -2.3 -2.3 -2.3 -2.3 -2.3

26 Do. 4.3 5.3 4.6 5.4 4.6 5.3

27 Chipola River 113.6 169.9 112.2 168.5 106.6 162.8

28 Do. 338.7 386.4 360.4 408.1 447.8 495.3

29 Do. 358.9 388.6 455.6 485.3 678.1 707.8

30 Flint River 4.3 5.6 4.5 5.6 4.3 5.4

31 Do. 554.6 633.7 555.2 634.1 541.5 619.9

32 Do. 482.2 562 476.8 556.5 452.8 531.7

33 Do. 294.9 403.1 290.1 398.3 275.3 383.2

34 Do. 259.4 323.9 258.4 323.0 243.9 307.8

35 Apalachicola River 280.2 333 266.5 319.2 254.9 307.5

36 Do. 165 209.4 147.8 196.4 115.3 159.9

37 Do. 522.6 534.2 480.6 480.8 92.7 181.5
28 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Table A4. Stream–aquifer flow, by reach, for hydrologic conditions and pumpage at 5 times October 1986 rates 

simulated in the Subarea 4 model

[Do., ditto; negative values indicate recharge to aquifer by streamflow; Oct 86 is October 1986 streamflow; Q90 is streamflow 

that is exceeded 90 percent of the time, and Q50 is streamflow that is exceeded 50 percent of the time; streamflow conditions 

calculated using recorded measurements for period of record ending 1993; dry is October 1986 conditions of lateral boundary 

and semiconfining-unit head; normal is long-term-average conditions of lateral boundary and semiconfining-unit head]

Stream reach

(see figure 8, page 12)

Computed net stream–aquifer flow (in cubic feet per second)

Hydrologic condition

Oct 86 

Dry

Oct 86 

Normal

Q90

Dry

Q90

Normal

O50

Dry

Q50

Normal

1 Gum Creek1/

1/Simulated as nonlinear leakage condition.

 0 0 0 0 0 0

2 Cedar Creek1/ 0.2 0.6 0.2 0.6 0.2 0.5

3 Swift Creek1/ 2.2 3.2 2 3.2 1.5 2.6

4 Jones Creek1/ 0 0.2 0 0.3 0 0.2

5 Abrams Creek1/ 0.2 0.8 0.2 0.8 0.2 0.5

6 Mill Creek1/ 3.1 5.0 2.9 4.8 2.6 4.3

7 Cooleewahee Creek1/ 0 1.1 0 0.9 0 0.5

8 Chickasawhatchee Creek1/ 3.9 5.6 3.9 5.4 3.4 5.0

9 Do.1/ 0.3 2.9 0.2 2.6 0.2 2.2

10 Do.1/ 0.8 5.9 0.8 5.7 0.6 5.3

11 Dry Creek (Georgia)1/ 0.5 1.7 0.5 1.5 0.5 1.9

12 Spring Creek1/ 0.5 2.2 0.5 1.9 0.5 2.2

13 Do.1/ 0.8 2.2 0.6 1.9 0.8 2.2

14 Do.1/ 0 0 0 0 0 0

15 Sawhatchee Creek1/ 7.9 13.8 7.9 13.8 7.3 13.2

16 Cowarts Creek1/ 18.9 25.8 18.7 25.5 18.0 24.8

17 Marshall Creek1/ 30.9 45.3 30.6 45 29.4 43.9

18 Spring Creek1/ 0 0 0 0 0 0

19 Dry Creek (Florida)1/ 41.3 73 40.7 72.4 38.2 69.2

20 Ichawaynochaway Creek 42.7 68.7 41.3 67.3 39.3 65.1

21 Do. 16.6 28.6 16.2 28.3 15.9 27.9

22 Muckalee Creek -17.5 -12.5 -21.8 -17.6 -22.6 -18.7

23 Do. -8.0 -6.7 -9.1 -8.0 -9.1 -8.4

24 Do. 8.7 12.1 5 8.0 3.9 7

25 Kinchafoonee Creek -2.3 -2.3 -2.3 -2.3 -2.3 -2.3

26 Do. 0.9 1.2 0.8 0.8 0.6 0.6

27 Chipola River 110.2 166.8 108.8 165.4 103.2 159.7

28 Do. 336.4 384.2 358.1 405.9 445.5 493.2

29 Do. 358.4 388.1 455.1 484.7 677.6 707.2

30 Flint River 0.2 0.9 0.2 0.9 0.2 0.6

31 Do. 403 484.5 403.6 485 390.4 471

32 Do. 314.9 396.8 309.8 391.4 286.7 367.1

33 Do. 74.6 190.6 69.9 185.7 56.2 171.3

34 Do. -76.1 -2.5 -77.2 -3.9 -89.8 -15.9

35 Apalachicola River 275.9 328.8 262.1 315.1 250.4 303.3

36 Do. 163.6 208 146.4 195 113.9 158.5

37 Do. 522.6 534.2 480.6 480.8 92.7 181.5
Appendix B 29

APPENDIX B

GRAPHS SHOWING THE SIMULATED EFFECT OF PUMPAGE ON STREAM–AQUIFER FLOW FOR 

STREAM REACHES 1–37
30 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B1. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 1, Gum Creek, Georgia (see fig. 8 for location).

012345

0

1

2

3

4

5

6

7

8

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

2.83

Ground-water

boundary

condition

Stream stage for flow condition—

 dashed where extrapolated

October 1986 1Q90

2Q50

Dry

(October 1986)

Normal

(Long-term 

average)

1 Streamflow equal to or exceeded 90 percent of the time (low-flow condition)

2 Streamflow equal to or exceeded 50 percent of the time (median streamflow 

 condition) 

EXPLANATION FOR FIGURES B1–B37

NOTE: Graph scales vary
Appendix B 31

Figure B2. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 2, Cedar Creek, Georgia (see fig. 8 for location).

Figure B3. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 3, Swift Creek, Georgia (see fig. 8 for location).

0123456789

0.0

0.5

1.0

1.5

2.0

5.6

Normal October 1986

and normal Q90

Dry October 1986

and dry Q90

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

0

1

2

3

4

5

6

8.75

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
32 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B4. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 4, Jones Creek, Georgia (see fig. 8 for location).

Figure B5. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 5, Abrams Creek, Georgia (see fig. 8 for location).

01234567

0

1

2

3

4

3.67

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345678

0

1

2

3

4

5.27

Normal October 1986

and normal Q90

Dry October 1986

and dry Q90

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
Appendix B 33

Figure B6. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 6, Mill Creek, Georgia (see fig. 8 for location).

Figure B7. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 7, Cooleewahee Creek, Georgia (see fig. 8 for location).

0 1 2 3 4 5 6 7 8 9 10 11 12

0

1

2

3

4

5

6

7

8

9

10

7.68

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND) STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345678

0

1

2

3

4

5

1.00
34 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B8. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 8, Chickasawhatchee Creek, Georgia (see fig. 8 for location).

Figure B9. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 9, Chickasawhatchee Creek, Georgia (see fig. 8 for location).

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

012345678

0

1

2

3

4

5

6

7

8

9

10

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

0123456789

0

1

2

3

4

5

8.00
Appendix B 35

Figure B10. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 10, Chickasawhatchee Creek, Georgia (see fig. 8 for location).

Figure B11. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 11, Dry Creek, Georgia (see fig. 8 for location).

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

0 1 2 3 4 5 6 7 8 9 10 11

0

1

2

3

4

5

6

7

8

9

10

11

12

6.33

0123456789

0

1

2

3

4

5

5.75

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
36 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B12. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 12, Spring Creek, Georgia (see fig. 8 for location).

Figure B13. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 13, Spring Creek, Georgia (see fig. 8 for location).

012345678

0

1

2

3

4

5

6

7

5.64

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345678

0

10

20

30

40

5.24
Appendix B 37

Figure B14. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 14, Spring Creek, Georgia (see fig. 8 for location).

Figure B15. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 15, Sawhatchee Creek, Georgia (see fig. 8 for location).

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345

0

1

2

3

4

5

6

7

8

9

10

11

12

1.14

012345678

0

5

10

15

20

25

Dry October 1986

and dry Q90

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

S
38 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B16. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 16, Cowarts Creek, Florida (see fig. 8 for location).

Figure B17. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach17, Marshall Creek, Florida (see fig. 8 for location).

0123456

0

4

8

12

16

20

24

28

32

36

40

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345678

0

10

20

30

40

50

60

70
Appendix B 39

Figure B18. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 18, Spring Creek, Georgia (see fig. 8 for location).

Figure B19. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 19, Dry Creek, Florida (see fig. 8 for location).

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345

0

10

20

30

40

50

60

70

2.53

0123456

0

10

20

30

40

50

60

70

80

90

100

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
40 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B20. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 20, Ichawaynochaway Creek, Georgia (see fig. 8 for location).

Figure B21. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 21, Ichawaynochaway Creek, Georgia (see fig. 8 for location).

0123456

0

10

20

30

40

50

60

70

80

90

100

110

120

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

0123456

0

10

20

30

40

50
Appendix B 41

Figure B22. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 22, Muckalee Creek, Georgia (see fig. 8 for location).

Figure B23. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 23, Muckalee Creek, Georgia (see fig. 8 for location).

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345678

–30

–20

–10

0

10

20

30

40

2.33

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345678

–10

–8

–6

–4

–2

0

2

4

6

8

10

1.72

Interpolated zero streamaquifer flow intercept

Gaining stream reach

Losing stream reach
42 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B24. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 24, Muckalee Creek, Georgia (see fig. 8 for location).

Figure B25. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 25, Kinchafoonee Creek, Georgia (see fig. 8 for location).

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

0 1 2 3 4 5 6 7 8 9 10

0

5

10

15

20

25

30

7.88

012345678

–5

–4

–3

–2

–1

0

1

2

3

4

5

Dry October 1986, normal October 1986,

dry Q90, normal Q90, dry Q50

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

, normal Q50

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
Appendix B 43

Figure B26. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 26, Kinchafoonee Creek, Georgia (see fig. 8 for location).

Figure B27. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 27, Chipola River, Florida (see fig. 8 for location).

012345678

0

1

2

3

4

5

6

7

8

5.40

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

0123456

0

50

100

150

200

250

300

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
44 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B28. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 28, Chipola River, Florida (see fig. 8 for location).

Figure B29. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 29, Chipola River, Florida (see fig. 8 for location).

0123456

0

100

200

300

400

500

600

700

800

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

0123456

0

100

200

300

400

500

600

700

800

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
Appendix B 45

Figure B30. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 30, Flint River, Georgia (see fig. 8 for location).

Figure B31. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 31, Flint River, Georgia (see fig. 8 for location).

012345678

–1

0

1

2

3

4

5

6

7

8

9

5.11

Dry October 1986

and dry Q50 results

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

0123456

0

100

200

300

400

500

600

700

800

900

1,000

Normal October 1986

and normal Q90

Dry October 1986

and dry Q90

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
46 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B32. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 32, Flint River, Georgia (see fig. 8 for location).

Figure B33. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 33, Flint River, Georgia (see fig. 8 for location).

0 1 2 3 4 5 6 7 8 9 10 11

0

100

200

300

400

500

600

700

10.18

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345678

0

100

200

300

400

500

600

5.77

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
Appendix B 47

Figure B34. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 34, Flint River, Georgia (see fig. 8 for location).

Figure B35. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 35, Apalachicola River, Florida (see fig. 8 for location).

012345678

–100

0

100

200

300

400

500

4.19

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

Normal October 1986

and normal Q90

Dry October 1986

and dry Q90

0123456

0

90

180

270

360

450

540

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES
48 Simulated effects of ground-water pumpage on stream–aquifer flow in the vicinity of Federally protected species of 

freshwater mussels in the lower Apalachicola–Chattahoochee–Flint River basin (Subarea 4), southeastern Alabama, 

northwestern Florida, and southwestern Georgia

Figure B36. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 36, Apalachicola River, Florida (see fig. 8 for location).

Figure B37. Stream-aquifer flow for simulated pumpage scenarios, groundwater boundary conditions, and stream stage at October 1986, Q90, and Q50

levels for reach 37, Apalachicola River, Florida (see fig. 8 for location).

012345678

0

50

100

150

200

250

300

350

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

012345678

0

100

200

300

400

500

600

700

800

STREAM–AQUIFER FLOW (CUBIC FEET PER SECOND)

PUMPAGE MULTIPLIER (n) x OCTOBER 1986 RATES

Dry and normal Q90