Thurmond Lake, currently more than 15 feet low, is managed under a drought plan in which flows are reduced incrementally as water levels fall.
The current flow, 3,100 cubic feet per second, is the lowest allowed unless the lake falls to 312 feet above sea level, when releases would be limited to inflows.
The corps considered a further reduction – to 2,800 cubic feet per second – that would be in place on an experimental basis for the first few weeks of winter, enabling scientists to evaluate any effects on downstream water users and the environment.
“We had proposed to resource agencies that we could gather a lot of data on what the impacts would be if we went down to 2,800,” said corps spokesman Billy Birdwell.
However, the U.S. Fish & Wildlife Service – which has perennial concerns about the Augusta shoals segment of the river – and the South Carolina Department of Natural Resources rejected the idea with a “resounding no,” Birdwell said.
Had the change been affirmed, it would have been the first time releases had fallen below 3,100 cubic feet per second since the federal Drought Contingency Plan was approved in 1989, said Barb Shelley, a facilitator with the Friends of the Savannah River Basin stakeholder group.
The water management program for Thurmond Lake and the Savannah River downstream is based on “authorized purposes,” including flood-risk management, navigation, hydropower, recreation and fish and wildlife – in addition to providing drinking water and maintaining a river flow sufficient to assimilate treated industrial and municipal wastewater.
A full lake – with a pool of 330 feet above sea level – makes it possible to fulfill all those purposes. As water levels fall and flows into the river are reduced, water supply and water quality rise to the top of the priority list.
Augusta, North Augusta and Columbia County rely on the river as a drinking-water source and as a conduit for assimilation of treated wastewater. There are also nearly a dozen downstream industries, mostly in Richmond County, that use the river for process water or for waste assimilation, or both.