"It has been a wet year, and our river operations team took advantage of it," John McCormick, Tennessee Valley Authority's vice president for river operations, said in a statement. "As our cheapest energy source, all this hydro generation has helped lower our fuel cost to customers."
Scott Brooks, a Nashville-based TVA spokesman, told The Tennessean that the extra hydro power has allowed TVA to purchase less energy from more expensive sources, a pattern is expected to continue this month.
The rainfall this year has led to a record-setting year for TVA's 29 hydroelectric dams, which produced more energy in 2013 than at any other time in the past eight decades.
Total rainfall through October in Tennessee was 21 percent higher than average, but it was 31 percent higher than normal in the eastern section of the state, where many of TVA's hydroelectric dams are located, according to data from the National Oceanic and Atmospheric Administration.
Much of the rainfall came in July, which averaged just over 7 inches — about 58 percent more than usual.
TVA said U.S. Army Corps of Engineers dams on the Cumberland River that contribute to its system also generated more power than usual.
Hydroelectric power normally makes up between 8 and 10 percent of the power produced by TVA generation sites, but that increased to 13 percent this year, the agency said.
Brooks said energy prices usually jump during the last month of the year, but the cheap power supply this year will make December rates only slightly higher than last month.
TVA is the nation's largest public utility, supplying power to about 9 million people in Tennessee, Alabama, Mississippi, Kentucky, Georgia, North Carolina and Virginia.