Low river flow means choices for Augusta Canal users

Lower flows into the Savannah River will require similar reductions in the volume of water diverted into the Augusta Canal.

“Now that they’ve gone down to 3,100 cubic feet per second, it does present some problems,” Augusta Utilities Director Tom Wiedmeier said.
The Army Corps of Engineers recently cut flows from Thurmond Dam into the river from 3,800 to 3,100 cubic feet per second to conserve water in the drought-parched reservoir.

The change means there is no longer enough flow in the river to fulfill the needs of the canal – a source of drinking water and hydropower – and also maintain a minimum flow in the river’s environmentally fragile shoals.

“We had been putting close to 3,000 cubic feet per second into the canal,” Wiedmeier said, “and we have indicated we would strive to keep between 1,000 and 1,500 cubic feet per second in the shoals.”

Without enough water for both purposes, officials want to reduce the canal’s intake by 500 cubic feet per second, which will require the Augusta Canal Authority to scale down hydropower production from its revenue-producing turbines at Sibley, King and Enterprise mills.

“We are working with (canal authority Director) Dayton Sherrouse, and we have been in touch with Georgia officials and the Corps of Engineers to let them know what we are working on,” Wiedmeier said.

The reduction will be accomplished by gradually adjusting the canal’s headgates, after which the velocity of the turbines will be scaled back.

“You can slow turbines by closing the wicket gates, and instead of using 100 percent water, they can move down to 80 percent,” Wiedmeier said. The slower movement of the generators will also reduce power, he said.

The canal is also used for Augusta’s drinking water and for hydromechanical power to pump raw water from the city pumping station on the canal to the treatment plant on Highland Avenue.

There are no plans to curtail raw water pumping or drinking-water production, although the city does have diesel pumps that could pump raw water to the treatment plant without using the canal’s flow.

Using those pumps, however, would cost about $10,000 a day, Wiedmeier said, so that would be done only in extreme emergencies.

The canal, built in 1845 and enlarged after the Civil War, allows much of the river’s flow to bypass the 4.5-mile stretch of rocky shoals.

Much of the diverted canal water is returned to the river through downstream spillways at the pumping station and the mills downtown.

The U.S. Fish and Wildlife Service and other resource agencies want Augusta to maintain minimum flows in the shoals to benefit the fish, plants and wildlife that live there.

The “bypass” area is the last remaining stretch of such habitat on the Savannah River. Similar areas were once abundant but were destroyed as the river was dammed into three major upstate reservoirs, starting with Thurmond Dam above Augusta.

Federal Energy Regulatory Commission’s Augusta Canal environmental assessment

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Sat, 12/03/2016 - 00:51

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