Tennessee Valley Authority. Watts Bar Dam hydroelectric plant. An ironworker climbs a 16-foot by 60-foot stack at TVA's Watts Bar steam plant. This plant will supplement the big hydroelectric installations at Watts Bar Dam, which has an authorized output of 90,000 kilowatts, and a possible ultimate of 150,000 kilowatts. Each of the four big turbo-generators in the steam plant is rated at 60,000 kilowatts