Effects of Impoundment of Lake Seminole on Water Resources in The

Effects of Impoundment of Lake Seminole on Water Resources in Study area, the Lower Apalachicola–Chattahoochee–Flint River Basin see maps GEORGIA in parts of Alabama, Florida, and Georgia facing page Study Chief Lynn J. Torak Cooperator Georgia Department of Natural Resources ALABAMA Environmental Protection Division Lower ACF River Basin FL Geologic Survey Branch OR ID Gu A Year Started 1999 lf of Mexico Problem Multiple uses of freshwater supplies in the lower or complete draining of the lake. If these events Apalachicola–Chattahoochee–Flint (ACF) River Basin are likely, then propose a data-collection system have been the concern of water managers in the States to monitor conditions that might lead to sudden of Alabama, Florida, and Georgia for many years. draining of Lake Seminole. Numerous studies have been conducted in an attempt to understand the complex relations that exist between Progress and Significant Results, 2001 hydrologic-system components and natural stresses, • Continued monitoring lake temperature, meteoro- and to answer questions regarding the effects on those logical conditions, and ground-water levels near the relations caused by human intervention. Although lake. Lake-temperature profiles can identify seasonal previous studies addressed important water-resource springflow variation to impoundment arms and along issues in the lower ACF River Basin, by design, none the lake bottom. provided a mechanism for collecting real-time hydro- • Completed sampling and chemical analysis of logic data necessary to develop and maintain an accurate surface and ground water during 1-year period to water budget for Lake Seminole and the stream-lake- evaluate lake-aquifer interconnection. Ground water aquifer flow system. None of these studies focused on and surface water have distinct chemical signatures investigating the hydrologic and hydrogeologic implica- that indicate complex inflow, outflow, and tions of impoundment of Lake Seminole by construction mixing processes. of Jim Woodruff Lock and Dam and the effect of the • Assisted U.S. Army Corps of Engineers dye-tracing lake on other components of the flow system. In evaluation of leakage in the vicinity of the Jim response to these needs, the U.S. Geological Survey Woodruff Lock and Dam by identifying temperature (USGS) has entered into a cooperative agreement with variations in dam pool and analyzing water samples the Georgia Department of Natural Resources to develop at dye-collection sites beneath the dam. Preliminary a water budget of the Lake Seminole area, to reasonably results indicate that lake water mixes with ground estimate the volume of water flowing into Florida before water beneath and downstream of the dam. and after construction of the dam, and to monitor the • Compiled geophysical-log information from Florida effects of any sinkhole collapse beneath the lake. and Alabama for developing hydrogeologic frame- Objectives work of Lake Seminole and vicinity. • Develop a water budget for Lake Seminole that will • Began development of automated methods for result in reasonable understanding of the effect of water-budget calculations and flow-cell analyses. the lake on the overall flow system in the lower ACF • Developed ground-water model approach for River Basin; evaluating pre- and post-impoundment flow and • Compare current (2001) and pre-Lake Seminole for computing ground-water inflow to and outflow ground-water and surface-water flow to determine from the lake. whether the volume of water flowing out of Georgia Automated real-time weather has changed significantly after construction of Jim station installed over water Woodruff Lock and Dam and filling of the lake; on piling to monitor atmos- • Evaluate the possibility of a substantial amount of pheric conditions at Sneads water entering the ground-water system from Lake Landing, Florida. The weather Seminole, flowing beneath Jim Woodruff Lock and station is part of the State of Dam, and entering Florida downstream of the dam; and Georgia’s Automated Environ- mental Monitoring Network • Assess the likelihood of failure of dissolution features accessed at URL: http://www. in the karst limestone of the lake bottom, such as georgiaweather.net. sinkhole collapse, and the likelihood of sudden partial

64 SELECTED GROUND-WATER STUDIES IN GEORGIA, 2001 Ground-Water Conditions and Studies in Georgia, 2001 EARLY BAKER DOOLY Colquitt

C SUMTER h a t t MILLER CRISP a Jakin h r MITCHELL o e o v Donalsonville i Lower ACF LEE c h R

e t e TERRELL n River Basin S TURNER F i Alabama l i p s F R h Iron r p i

Florida i n v o City g DECATUR e n

DOUGHERTY

C Brinson WORTH r d

r r

CALHOUN e e

e Bainbridge v

i k D

R r t a n i EARLY BAKER li n F MITCHELL SEMINOLE Climax

C MILLER HOUSTON h a t t SEMINOLE AL a h FL o DECATUR o Lake c h Seminole GRADY Attapulgus e JACKSON e Georgia a l JACKSON R N o Florida c i GA h c a r FL l e a v R p i GADSDEN A R a l o GADSDEN Base from U.S. Geological Survey 0 5 10 MILES c i h Area of 1:100,000-scale digital data CALHOUN c a enlarged map l a 0 5 10 KILOMETERS p N EXPLANATION A

LIBERTY Ground-water well

Location of Lake Seminole in the lower Apalachicola–Chattahoochee– GULF FRANKLIN Flint (ACF) River Basin in southwestern Georgia, northwestern Florida, and southeastern Alabama. The map above shows well network, impound- ment arms of the lake on the Chattahoochee and Flint Rivers, Fishpond Drain, Spring Creek, and the Apalachicola River.

Base from U.S. Geological Survey 1:5,000,000-scale digital data

Deployment of temperature A. B. probes in Lake Seminole: (A) attaching probes to weighted line at specified depths, (B) programming sampling interval and synchro- nizing start-up (launch) of probe, (C) probe array attached to C. D. cypress stump in lake, and (D) completed temperature- probe station marked with safety tape and medallion. Photos by Lynn J. Torak, USGS.

Ground-Water Conditions and Studies in Georgia, 2001 SELECTED GROUND-WATER STUDIES IN GEORGIA, 2001 65