Dedicated to the Conservation of Southeastern Fishes
Green Light On Fish Highway: Savannah River Flow Plan Aims To Aid Migratory Species
March 28, 2004
Augusta - For years, several large and small dams have impeded the Savannah River's flow to the sea - preventing shad, sturgeons and other migratory fish from reaching spawning grounds in the spring.
Atlanta Journal Constitution
Now, the U.S. Army Corps of Engineers and a national environmental group are testing a plan that puts more water into the lower river during the spring and mimics the stream's natural flow.
The goal: to bring back fish once numerous in the waterway, before the dams disrupted the natural flow.
"The conservation implications of this project are huge," says Amanda Wrona of the Nature Conservancy, the corps' partner in the effort.
To test the plan, last week the corps released nearly four times more water than usual from its massive J. Strom Thurmond Dam at Clarks Hill, S.C., about 30 miles upriver from Augusta.
Built in 1954, the dam controls flow in the 210-mile-long lower Savannah, the dividing line between Georgia and South Carolina.
To allow easy fish passage, the gates of another river barrier, the New Savannah Bluff Lock and Dam just downstream of Augusta, also were left open. The lock and dam were built to make the river navigable from the sea to Augusta.
The water was released from Thurmond Dam in pulses, similar to the surges of fresh water that meandered down the river in early spring in the years before the dams were built.
Similar releases are scheduled for early next month.
The corps said the additional water volume will not jeopardize Thurmond Dam's other functions - power generation, flood control and recreation. The agency had stored enough water behind the dam this winter to make the higher releases, officials said.
"We'll meet the human needs as well as the environmental needs," said Maj. Gen. Carl Strock, the corps' director of civil works, who came to Augusta from Washington last week to check on the project.
The corps and the Nature Conservancy hope that the project will be a model for other dammed-up rivers. Across the nation, they are testing at 13 other dams on nine other rivers - all part of the conservancy's Sustainable Waters program.
"We hope to set the stage for the ways dams are managed to more closely imitate the natural flows of rivers and restore their health," said Brian Richter, who heads the national program.
The natural pulses of fresh water - or spring freshets - that once surged unhindered down the Savannah to the Atlantic Ocean served many vital functions, biologists say.
The freshets were natural cues for migratory fish - Atlantic and shortnose sturgeons and American shad - to swim upstream nearly 200 miles from the sea to spawn in the Savannah's rocky shoals.
The freshets also provided enough water for large fish like sturgeons to maneuver their way upstream.
Downstream, near the river's mouth, the fresh water pushed back wedges of salt water, making conditions favorable for spawning fish like striped bass, whose eggs and larvae can tolerate only narrow ranges of salinity.
The freshets also recharged riverine swamps that are nursery grounds for bream and other fish.
But after the dams were built across the river, the fish no longer could reach spawning grounds. Swamps and shoals were left with little water, and salt water from the ocean crept higher up the waterway.
Similar scenarios unfolded in other rivers straddled by dams.
Consequently, migratory species have struggled to find suitable places to reproduce, biologists say.
American shad, which migrate to the North Atlantic before returning to the Savannah to spawn, are declining in numbers. The shortnose sturgeon is a federal endangered species.
Biologists with the Georgia Department of Natural Resources especially hope that the pulses of fresh water coming down the Savannah will help their efforts to re-establish a striped bass population in the lower stretches of the river.
Once plentiful in the lower river, "stripers" began to disappear from there in the 1970s after a tidal gate and diversion canal were installed in a tributary, where the fish once spawned, said DNR fisheries biologist Matt Thomas. The structures were built to aid commercial shipping at the Port of Savannah.
A moratorium on catching and keeping stripers from the river is in its 15th year.
"These fish now need all the help they can get," Thomas said.