During droughts, the corps must release a minimum weekly average of 3,600 cubic feet per second from the dam to meet downstream demands, including municipal drinking water, wastewater dilution and industrial uses. The annual average is more than 9,000 cubic feet per second.
The corps, acting on coordinated requests from Georgia and South Carolina, plans to reduce minimum flows even further– to 3,100 cubic feet per second beginning Nov. 1 and lasting through the end of February, corps spokesman Billy Birdwell said today.
The corps, which normally offers a 30-day public comment period on such matters, will accept public comments only through Oct. 27 because the two states have asked that the reduction take effect Nov. 1.
Through the proposed reduction, officials hope to conserve more water in the corps’ three reservoirs – Lakes Thurmond, Hartwell and Russell – while still meeting the needs of the downstream users and environment.
Currently, Thurmond’s pool is 314.67 feet above sea level, or more than 15 feet below its full pool of 330 feet above sea level. Forecasts indicate that the lake will continue to drop, despite the movement of more water from Hartwell into Thurmond to enable Thurmond to maintain its minimum flows to the river.
Although the proposed flow reduction could theoretically complicate Augusta’s ability to pump drinking water and dilute treated sewage, the main impact is likely to be less water in the Augusta shoals – home to many important fish and plants, according to Frank Carl, executive director of Savannah Riverkeeper Inc.
“It was first proposed last summer to let everyone get used to the idea that they’d drop to 3,100 around the turn of the year if lake levels didn’t pick up,” Dr. Carl said.
The city of Augusta, which diverts most of the river’s already-reduced flow into the Augusta Canal, might have some problems with the reduction, he said. “Right now the city is getting at least 75 percent of the flow and putting it in the canal.”
Although the canal provides much of the city’s drinking water, its flow is also used to power hydromechanical turbines that pump raw water to the Highland Avenue treatment plant, where it is transformed into drinking water.
Dr. Carl said it takes about 16 gallons of flow to pump 1 gallon of water to the treatment plant, but the city does have the alternative of using diesel pumps to provide such power in the event less water is available.
“What I would like to see is – in times of low flows like we have in this drought – we can use another source of energy to pump the water,” he said. “That could keep more water in the shoals.”
The corps, in its draft environmental assessment, concluded that the reductions would cause no significant environmental impact.
The proposal isn’t the first time such a reduction has been contemplated. In 2003, hoping to slow the lake’s decline, the corps proposed reducing minimum flows to 3,000 cubic feet per second but dropped the idea after objections were raised over the plan’s effect on fragile estuaries at the mouth of the Savannah.
The public may view the draft environmental assessment through the Savannah District home page at www.sas.usace.army.mil or may obtain a copy by contacting William Bailey at (912) 652-5781. The comment period expires Oct. 27.