TVA hydroelectric dams running at maximum capacity


Tennessee Valley Authority

The following is a press release from the Tennessee Valley Authority.


KNOXVILLE, Tenn. - Higher than normal rainfall in 2009, along with recent rain and snow have filled TVA reservoirs above seasonal levels.

All nine hydroelectric dams on the Tennessee River and most of the 20 power-producing tributary dams are generating at maximum capacity. The hydroelectric system's currently available output is about 3,100 megawatts. That is enough to power about 1.8 million homes.

In mid-January, all 29 TVA hydroelectric dams generated at the same time for the first time in three years. Hydro power, TVA's least cost form of electricity, has been running above normal this fiscal year because of the precipitation, though it remains less than 10 percent of TVA's total generation mix.

An estimated 1 million gallons per second is moving through the Tennessee River at Chattanooga. TVA is spilling or releasing excess water at all main river and some tributary dams in the TVA system to reduce the potential for flooding.

"We try to avoid spilling, but when we have a lot of water our No. 1 priority becomes reducing flood damage. With all of the recent rain and snow we need to bring down the reservoir levels to prepare for anticipated rain in the weeks ahead," said Chuck Bach, TVA general manager for river scheduling. "This year is beginning like last year ended, with a lot of precipitation. During the last three months of 2009, rainfall and runoff totals were significantly above normal, and now in 2010, we are getting a significant rain or snow every week."

On Feb. 8, the 10 largest tributary reservoirs were all above the flood guide. The flood guide is a seasonal elevation guide that shows the amount of space in a reservoir available to store water. The operating objective is to keep the reservoir level at the dam at or below the guide to be ready for heavy rains, so extra water can be stored to reduce the risk of flooding downstream.

Even with the current abundance of water and the immediate need to reduce reservoir levels to recover flood storage space, TVA will begin holding water in the tributary reservoir system in mid-March in order to reach targeted summer water levels by June 1.

TVA sets a target to fill most main-river reservoirs to summer levels by mid-April. However, Watts Bar, Chickamauga and Fort Loudoun reservoirs are scheduled to reach summer levels by mid-May to help reduce the risk of flooding at Chattanooga. When reservoirs actually reach targeted levels depends on rainfall, runoff and stream flows.

The Tennessee Valley Authority, a corporation owned by the U.S. government, provides electricity for utility and business customers in most of Tennessee and parts of Alabama, Mississippi, Kentucky, Georgia, North Carolina and Virginia - an area of 80,000 square miles with a population of 9 million. TVA operates 29 hydroelectric dams, 11 coal-fired power plants, three nuclear plants and 11 natural gas-fired power facilities and supplies up to 36,000 megawatts of electricity, delivered over 16,000 miles of high-voltage power lines. TVA also provides flood control, navigation, land management and recreation for the Tennessee River system and works with local utilities and state and local governments to promote economic development across the region. TVA, which makes no profits and receives no taxpayer money, is funded by sales of electricity to its customers. Electricity prices in TVA's service territory are below the national average.