education: resources
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river basins of georgia
CHATTAHOOCHEE-FLINT RIVER BASIN
by Gretchen Loeffler and Judy L. Meyer
The Chattahoochee River, whose name is derived from Creek Indian words
meaning painted rock, drains an area of 8,770 sq mi and is the most heavily
used water resource in Georgia. Its headwaters begin at the southern edge
of the Blue Ridge Mountains at an altitude above 3,000 feet and flow 430
miles to its confluence with the Flint River. The Chattahoochee River
provides drinking water for more than half of all Georgians and recreation
for more than 25 million people each year. The Chattahoochee and Flint
Rivers are part of a larger Apalachicola-Chattahoochee-Flint (ACF) River
Basin, which flows through the states of Georgia, Alabama, and Florida.
The Flint River is approximately 350 miles long and drains an area of
8,460 square miles. Most of the larger tributaries in the ACF River Basin
are located in the lower reaches of the Flint River Basin.
Stream Flow
The following table lists stream flow data for the Chattahoochee and Flint
Rivers. The locations of the U.S. Geological Survey gauging stations are
denoted within the parentheses.
Table 1. Stream flow data from USGS. Stream flow is measured in units
of cubic feet per second (cfs) flowing past a point.
| |
Chattahoochee River
(Columbus, GA) |
Flint River
(Newton, GA) |
| Drainage Area (square miles) |
8,770 |
8,460 |
| Min Daily Flow (cfs) |
498 |
922 |
| Mean Daily (cfs) |
8,250 |
4,030 |
| Max Daily (cfs) |
191,000 |
47,000 |
| Years of Collection |
1977-1992 |
1977-1992 |
Land cover and land use patterns
Population within the metropolitan Atlanta area increased 97% from 1970
to 1995. In 1995, the estimated population was 3.1 million people in the
13 county metropolitan area. Table 2 lists the 1998 land cover percentages
for the Chattahoochee and Flint River basins. The Natural Resources Spatial
Analysis Laboratory (NARSAL) at the University of Georgia provided the
tabular data.
Table 2. 1998 land cover statistics.
| |
Chattahoochee River |
Flint River |
| Beach |
0.02% |
0.01% |
| Water |
3.34% |
1.44% |
| Suburban |
7.17% |
2.05% |
| Commercial |
3.75% |
1.57% |
| Clearcut |
7.61% |
5.54% |
| Mines, rock outcrops |
0.11% |
0.07% |
| Deciduous forest |
28.90% |
13.14% |
| Evergreen forest |
25.99% |
24.83% |
| Mixed forest |
6.93% |
5.14% |
| Agriculture |
12.64% |
35.27% |
| Wetlands |
3.55% |
10.94% |
Protected species
Classified as one of the nation's 20 most endangered rivers, the Chattahoochee
River provides valuable wildlife habitat for migratory birds, mammals
(including deer, beaver, otter), reptiles and amphibians. There are four
federally endangered and two federally threatened mussel species found
in the Chattahoochee-Flint river basin. The four endangered mussel species
are the fat threeridge (Amblema neislerii), shinyrayed pocketbook
(Lampsilis subangulata), Gulf moccasinshell (Medionidus penicillatus),
and oval pigtoe (Pleurobema pyriforme) have been federally listed
as endangered since 1997. Two threatened mussel species are the chipola
slabshell (Elliptio chipolaensis) and purple bankclimber (Elliptoideus
sloatianus). All six mussel species prefer main channel or large stream
sandy habitats with slow to moderate currents.
Impoundments in the Chattahoochee-Flint River Basin
The U.S. Army Corps of Engineers has constructed dams, which created large
impoundments for flood control, water supply, power, and commercial navigation.
Thirteen of 16 mainstem dams in the ACF River basin are along on the Chattahoochee
River. Over most of its length, hydroelectric plants release water for
production of hydropower and control the flow. Dam construction in the
basin began in the early 1800's on the Chattahoochee River above the Fall
Line at Columbus, GA to take advantage of natural elevation gradients
for power production. During low flow periods, stored water is used to
supplement the discharge of the river. There have been marked decreases
in the frequency of high and low flows since the start of operation of
Buford Dam in 1956, and river flows fluctuate daily below the reservoirs
along the Chattahoochee River. Lake Lanier provides 65 percent of the
water storage to regulate flows, yet it only drains 5 percent of the ACF
River basin.
Two hydropower dams located on the Flint River impound run-of-the-river
reservoirs and do not appreciably influence the monthly flow of the Flint
River, but do alter the daily flow regime. The Flint River has one of
only 42 free-flowing river reaches longer than 125 miles remaining in
the contiguous 48 states.
Four large reservoirs along the Chattahoochee River include:
| |
Area |
Shoreline |
| Lake Lanier |
38,000 acres |
540 miles |
| West Point Lake |
25,900 acres |
525 miles |
| Lake Walter F. George |
45,180 acres |
640 miles |
| Seminole |
37,500 acres |
500 miles |
Groundwater
The headwaters of the Chattahoochee and Flint Rivers occur north of the
Fall Line in the Blue Ridge and Piedmont Provinces. Water supplies in
the headwater region derive primarily from surface waters. South of the
Fall Line, one finds Providence aquifers and upper Cretaceous strata.
The Providence aquifer system is the deepest of the principal aquifers
in southern Georgia and consists of sand and gravel separated by clay
and silt confining beds. The lower reaches of both rivers are part of
the Floridan aquifer system, a karst limestone aquifer that is susceptible
to contamination. This aquifer is one of the most productive worldwide.
The hydrology connecting the Floridan aquifer and the Flint River results
in ground-water discharge contributing more to baseflow in the Flint River
than in the Chattahoochee River. Ground water flow into the Chattahoochee
River is one-fifth of that discharging into the Flint River.
Impaired Waters
Six percent of the surface waters sampled in the Upper Flint River and
19% of those sampled in the Lower Flint River are categorized as impaired
by the EPA. Nonpoint sources and urban/storm water runoff are the primary
contributors to pollution in the Flint. Unlike the Flint, the highest
impairment of surface waters in the Chattahoochee River occurs in the
upper and middle reaches of the river, which is flowing through the city
of Atlanta. The upper Chattahoochee is ranked in the top ten percent of
the most polluted watersheds in the state of Georgia and top twenty percent
in the nation. Significant contributions include urban/storm water runoff,
nonpoint and municipal point sources, and combined sewer outflows.
Additional Information
Benke, A.C. 1990. A perspective on America's vanishing streams. Journal
of the North American Benthological Society 9(1): 77-88.
Brown, F. and S.M. Smith. The Riverkeeper's guide to the Chattahoochee.
CI Publishing: Atlanta, Georgia.
Leitman, S.F., L. Ager, and C. Mesing. 1991. The Apalachicola experience:
environmental effects of physical modifications for navigation purposes.
Pages 223-246 in Livingston, R.J., editor. The Rivers of Florida. Springer-Verlag:
New York, NY.
Environmental
Defense Fund (watershed pollution)
NARSAL
maps
USGS
gauging stations
Environmental, Educational, and Community Action Organizations
American Rivers
Georgia
Adopt-A-Stream
Georgia Canoeing
Association
Georgia River Network
River Network
Nature
Conservancy of Georgia
Trust for Public Land
Alabama River
Alliance
Upper Chattahoochee
Riverkeeper
Chattahoochee
Riverkeeper
Apalachiola
Bay and Riverkeeper
Line Creek Association
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