Staff Photo by Dan Henry/Chattanooga Times Free Press
Chickamauga Dam had its spillways open until Thursday after last week's heavy rainfall.The Tennessee Valley Authority closed its floodgates on the Chickamauga, Nickajack and Watts Bar dams Thursday after more than a week of spilling water to lower the Tennessee River to more normal winter levels.
A two-day storm that dumped up to 6 inches of rain in parts of the Tennessee Valley early last week filled TVA reservoirs north of Chattanooga, despite the annual rainfall deficit.
Rainfall so far this year in Chattanooga is more than 10 inches below normal, according to the National Weather Service. But rains at the end of November and on Dec. 1 helped refill reservoirs and boost lake levels.
Winter levels are set lower to prevent spring flooding. Chickamauga Lake's level rose 31/2 feet after the heavy rains.
"Our reservoir levels jumped up and now we're recovering that flood storage space by both spilling water through the dams and running our turbines wide open around the clock," said Chuck Bach, TVA's general manager for reservoir operations.
Since Dec. 1, TVA has been spilling 300,000 cubic feet per second of water - or 13.5 million gallons per minute - through the Chickamauga Dam to draw down lake levels.
A half-dozen TVA mainstream dams were spilling in the past few weeks and TVA will begin today to draw down its upstream reservoirs by running power-generating turbines full time until lakes reach their winter levels, Bach said.
Last week, lake levels rose 7 feet in Fontana Lake in North Carolina and 6 feet in Norris Lake near Knoxville after heavy rains.
"This is a classic example of how we were able to handle a rainfall event that was higher than we predicted without any major flooding," TVA spokesman Travis Brickey said.