The fourteen river basins of Georgia are the Altamaha, Chattahoochee, Coosa, Flint, Ochlockonee, Ocmulgee, Oconee, Ogeechee, Satilla, Savannah, Suwanee, St. Marys, Tallapoosa, and Tennessee. The Savannah River, which begins at the confluence of the Seneca and Tugaloo rivers in the northeast part of the state, forms the border between Georgia and South Carolina.
Georgia has a vast diversity of surface and groundwater resources. The Environmental Protection Agency estimates that Georgia has 44,056 miles of perennial streams, 23,906 miles of intermittent streams,
Populations in the northern part of Georgia rely heavily on surface water supplies, and populations south of the fall line rely mainly on groundwater supplies. Both surface and groundwater sources are highly susceptible to contamination from runoff (known as nonpoint source pollution) from leaking landfills and underground storage tanks, as well as from industrial processes. Some of the critical issues for the state's long-term supply of groundwater and surface water supplies include saltwater intrusion in the upper Floridan aquifer of coastal Georgia, the equitable allocation of water with Alabama and Florida, and the growing demand on limited water resources in metropolitan Atlanta. Two additional issues facing southwest Georgia are the depletion of the Clayton aquifer and the reductions in flow through the Flint River basin resulting from surface and groundwater withdrawals for irrigation.
Savannah River Basin
The Savannah River forms the boundary between South Carolina and Georgia and begins at Lake Hartwell, in Hart County, at the confluence of the Seneca and Tugaloo rivers. From this point it flows southeast to Savannah, where it empties into the Atlantic Ocean. Above the junction of the Seneca and Tugaloo rivers, the major headwater streams of the Seneca River are the Keowee River and Twelve Mile Creek. The Tugaloo River is formed by the union of the Tallulah and Chattooga rivers. These headwater streams originate on the southern slopes of the Blue Ridge Mountains in North Carolina and Georgia.
In the late 1990s the federal Environmental Protection Agency (EPA) outlined significant man-made and natural threats to the Savannah River system. For example, the construction of dams to provide hydroelectric power and to reserve surface water to sustain municipal water requirements leads to releases of cold water with low dissolved oxygen, which can result in massive fish
Discharges and releases from the Savannah River Site, a nuclear materials processing center in South Carolina that was listed as an EPA Superfund site in 1989, also threaten the health of the Savannah. As the drought in Georgia continues, the water tables continue to drop farther beneath the surface. As the water tables drop, concerns increase over saltwater intrusion into groundwater supplies and the potential for an interaction with surface water supplies.
Coosa, Tallapoosa, and Tennessee River Basins
The Tallapoosa River originates west of Atlanta, in Paulding County. The Tallapoosa River basin occupies 4,680 square miles, of which 720 square miles (15 percent) lie in Georgia and 3,960 square miles (85 percent) lie in Alabama. The Tallapoosa supports cold- and warm-water fisheries as well as a rich diversity of species unique to this river. Species important to anglers include largemouth, spotted, and redeye bass; rainbow trout; black crappie; and channel catfish. The Tallapoosa is a free-flowing river in Georgia with no major impoundments until it reaches the Harris Reservoir in Alabama.
The Coosa, Tallapoosa, and Tennessee rivers are home to many threatened and endangered aquatic species. Two of the endangered species in these river basins are the Conasauga logperch, Percina jenkinsi, and the amber darter, Percina antesella. These species were once found throughout the Coosa, Tallapoosa, and Tennessee river basins and have been federally listed as
Chattahoochee and Flint River Basins
The headwaters of the Chattahoochee and Flint rivers occur north of the fall line in the Blue Ridge and Piedmont respectively. Water supplies in the headwater region derive primarily from surface waters. South of the fall line are the 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 groundwater discharge contributing to baseflow more in the Flint River than in the Chattahoochee River. Groundwater flow into the Chattahoochee River is one-fifth of that discharging into the Flint River.
Six percent of the surface waters sampled in the upper Flint River and 19 percent of those sampled in the lower Flint River are categorized as impaired by the Environmental Protection Agency. Nonpoint sources and urban/storm water runoff are the primary contributors to pollution in the Flint.
The highest impairment of surface waters in the Chattahoochee River occurs in the upper and middle reaches of the river, which flow through Atlanta. The upper Chattahoochee is ranked in the top 10 percent of the most polluted watersheds in the state of Georgia and in the top 20 percent in the nation. Significant contributions to this pollution include urban/storm water runoff, nonpoint and municipal point sources, and combined sewer outflows.
Four large reservoirs along the Chattahoochee River include Lake Lanier (38,000 acres in area and 540 miles of shoreline), West Point Lake (25,900 acres in area and 525 miles of shoreline), Lake Walter F. George (45,180 acres in area and 640 miles of shoreline), and Seminole (37,500 acres in area and 500 miles of shoreline).
Two hydropower dams located on the Flint River impound run-of-the-river reservoirs (which means that the amount of water flowing through the dam is the same amount flowing into the reservoir from the river upstream) and do not appreciably influence the monthly flow of the Flint River. The dams do alter the daily flow regime, however. The Flint River lacks impoundments for more than 200 river miles.
Ocmulgee, Oconee, and Altamaha River Basins
A major continental divide occurring between the Ocmulgee and Flint rivers causes the Altamaha River basin to drain into the Atlantic Ocean. The Altamaha River basin is the largest watershed in the state of Georgia and the third largest in the United States draining into the Atlantic Ocean.
Three distinct groundwater aquifers influence the Altamaha River basin. In the northern headwaters of the Ocmulgee and Oconee rivers, crystalline-rock aquifers dominate. In the lower reaches of these rivers, cretaceous aquifer systems lie beneath the surface. The Altamaha River is part of the large Floridan aquifer system. Groundwater aquifers that occur near the fall line are exposed
A total of 137 river miles marks the distance between the convergence of the Oconee and Ocmulgee rivers and the entry of the Altamaha into the Atlantic Ocean near Darien. The tidal estuary at the mouth of the Altamaha functions as a linkage between the freshwater habitats of the river basin with the saltwater system of the Atlantic Ocean. During the 1800s the Altamaha River was a major route for shipping to the Georgia coast.
Agriculture dominates the landscape of the Ocmulgee, Oconee, and Altamaha basins and has a direct impact on the health of the watershed. The Ocmulgee River officially begins southeast of Atlanta, where the Yellow, Alcovy, and South rivers converge at Lake Jackson. Downstream the Ocmulgee's watershed is dominated by agriculture and forested areas. The Oconee River headwaters arise in a highly forested region, but the presence of agriculture increases as the Oconee flows southeastward toward the Altamaha River. The ninety-mile coastal flood plain of the Altamaha River is covered with dense timber and underbrush.
The upper reaches of both the Oconee and Ocmulgee watersheds have been particularly affected by a combination of pollutants from urban runoff, storm sewers, municipal point sources, and combined sewer outflows. In the Altamaha River watershed, nonpoint source pollution contributes
The National Dam Inventory documents 276 dams in the upper Oconee River watershed, while a detailed scale analysis found more than 5,400 impoundments in the watershed. These figures demonstrate that the majority of the reservoirs in this watershed are unaccounted for and that their environmental impacts can be underestimated. Two large dams (greater than twenty-five-feet high) were built along the mainstem of the Oconee River, creating Lake Sinclair and Lake Oconee. Neither the Ocmulgee River nor the Altamaha River has large dams built along its mainstem.
More than 100 rare and endangered aquatic species are found in the Altamaha. The watershed provides habitats for nesting and breeding migratory birds as well as for common game species. In 1991 the Nature Conservancy initiated an ecological survey to assess the biological resources and potential threats to the integrity of freshwater species diversity in the Altamaha River. This fragile watershed sustains several imperiled pearly mussel species, some of which are found nowhere else in the world.
Blackwater River Basins
Each of these rivers drains sandy soils that lack the ability to retain dissolved organic matter leached from terrestrial vegetation. For that reason their water is tea-colored, and they are referred to as blackwater rivers. Even though there are high concentrations of dissolved organic matter in the blackwater river basin, the suspended sediment levels are low. Extremely low concentrations of dissolved oxygen occur in blackwater rivers during the warmer months of the year.
Historically, large amounts of woody debris and snags created an intricate patchwork of blackwater rivers and riparian zones. These stream bottoms consist primarily of constantly shifting sand, and woody debris and snags provide a stable habitat for insects and thus are vital to the secondary production of aquatic insects. Snagging operations at the turn of the twentieth century changed
Flooding plays an important role in the exchange between the surrounding watershed and the main channel of each blackwater river. The highest concentrations of total organic carbon occur during these flooding periods, and the lowest concentrations are measured during low flow periods. This exchange between the mainstem and the floodplain occurs because of the lack of impoundments and the low gradient of these rivers.
A. C. Benke, "A Perspective on America's Vanishing Streams," Journal of the North American Benthological Society 9, no. 1 (1990): 77-88.
Fred Brown and Sherri M. L. Smith, The Riverkeeper's Guide to the Chattahoochee River: From Its Origin at Chattahoochee Gap to Apalachicola Bay (Atlanta: CI, 1997).
Thomas W. Hodler and Howard A. Schretter, The Atlas of Georgia (Athens: Institute of Community and Area Development, University of Georgia, 1986).
S. F. Leitman, L. Ager, and C. Mesing, "The Apalachicola Experience: Environmental Effects of Physical Modifications for Navigation Purposes," in The Rivers of Florida, ed. Robert J. Livingston (New York: Springer-Verlag, 1991), 223-46.
Michael Duane Merrill, "Local and Watershed Influences on Stream Fish Biotic Integrity in the Upper Oconee Watershed, Georgia, USA" (master's thesis, University of Georgia, 2001).
Judy L. Meyer, "A Blackwater Perspective on Riverine Ecosystems," Bioscience 40 (1990): 643-51.
Judy L. Meyer, "Seasonal Patterns of Water Quality in Blackwater Rivers of the Coastal Plain, Southeastern United States," in Water Quality in North American River Systems, ed. C. Dale Becker and Duane A. Neitzel (Columbus, Ohio: Battelle Press, 1992), 250-76.
Judith L. Meyer, University of Georgia
Gretchen Loeffler, University of Georgia
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