The Tennessee Valley Authority (TVA) is set to pull the plug on Lake Blue Ridge during the late summer of 2010. Plans call for the lake to be drawn down to more than 60 feet below full pool.
TVA officials recently announced the final project plans for the deep-water drawdown necessary to repair and reinforce the intake tower, penstock and the upstream and downstream sides of the earthen dam, originally constructed in 1931. However, the exact date the drawdown will begin is still up in the air.
TVA Project Manager Wayne Oliver said a traffic issue with a road closure necessary to the project needs to be resolved before the drawdown start date will be announced. TVA officials have confirmed they hope to begin the drawdown in July, August or September of 2010.
Oliver said once the drawdown begins, it should take about two months to get the water to the lowest level necessary to begin work, which would be approximately 62 to 67 feet below full summer pool.
The drawdown will be comparable to the 2003 deep drawdown, used for penstock inspection.
While the water is low, Blue Ridge Marina will be the only location to launch a boat, Oliver said.
During the drawdown, the TVA will draw water through the penstock and generator “for as long as possible,” Oliver said. However, once the water reaches a certain level, draining the lake will be performed with the low-water discharge, Oliver said. This leads to the possibility of warm water being released into the Toccoa River tailrace, a premier Georgia trout fishery.
“There is some potential for some warm water to pass over into the tailwater,” Georgia DNR Fisheries Biologist John Damer said. “Weather will play a much bigger factor in this than anything the TVA does.
“Trout begin to stress, and we see some mortality once water temperatures reach much above 70 degrees,” Damer said.
Damer is currently involved in a long-term study of the trout fishery in the tailwater, but he said his study would be completed prior to the start of the drawdown, and his study would not be affected by it.
Once the water reaches its lowest point, Oliver said the crews will begin work on the upstream face of the dam and the penstock.
“The lake will probably be filling back up by the time we’re done on the upstream side,” he said.
Oliver said he expected the water to be held at the low level for four to six months.
In the lake, Damer said the DNR’s “only reservation is with the smallmouth population. We want to encourage people to harvest their limits of spots and release the smallies. If something does happen to the smallies, it’s more likely the invasive spots and blueback herring than the drawdown.
“During the drawdown the TVA will be monitoring conditions on the lake and the tailwater,” Damer said. “They’ll be relaying that information to us, and if we see any problems, we will try to address them to the best of our ability.”
While the fisheries in the lake and the tailwater could potentially suffer, Oliver said the TVA’s main objective was the safety of the public and of the construction crews. The work is being done to reinforce the dam because it could potentially liquefy if the region was to experience a large seismic event, Oliver said.
The project is likely to be finished by September 2012.