Tennessee Valley Authority. Construction activities on a new generating unit in the new addition to TVA's hydroelectric plant at Wilson Dam. The walls and a portion of the intake can be seen. Located near Sheffield, Alabama, 260 miles above the mouth of the Tennessee River, the dam had an authorized power installation of 288,000 kilowatts, which can be increased to a possible ultimate of 444,000 kilowatts. The reservoir at the dam adds 377,000 acre-feet of water to controlled storage on the Tennesse River system