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TVA says dams, reservoirs averted $800M in flood damage in January

staff report • Feb 6, 2013 at 10:27 AM

KNOXVILLE — The Tennessee Valley Authority, through its system of dams and reservoirs, said it was able to avert more than $800 million in flood damage to communities along the Tennessee River and its tributaries in January.

According to TVA numbers, $17.4 million in flood damage was averted in Kingsport following storms in mid-January that drenched the city with approximately 5 inches of rain in four days, immediately followed by nearly 6 inches of snow.

Elsewhere in Tennessee, TVA estimated it averted $710 million in flood damage in Chattanooga; $61 million in Lenoir City; $7 million in Knoxville; $5.5 million in South Pittsburg; $2.9 million in Elizabethton; $812,000 in Clinton and $73,000 in Savannah.

TVA is using its 49 dams to store and then gradually release water after what was the third-largest recorded rainfall and runoff for a January in TVA history.

During the month of January, the eastern part of the Tennessee Valley, including Knoxville and the Tri-Cities area, received approximately 10 inches of rain, and the area below Chattanooga and West Tennessee averaged about 8 inches of rain.

“We hold water behind the dams in order to minimize downstream flood impacts. After the high water crested on the Tennessee River and its tributary rivers, we started gradually releasing water out of the tributary reservoirs to recover storage space and to prepare for the next rain event,” said John McCormick, senior vice president, River Operations and Renewables.

TVA engineers use computer flood modeling, water elevation calculations and property value assessments along the Tennessee River and its tributaries to determine floodwater impacts if TVA dams didn’t exist.

During an average year, TVA’s reservoir operations avert approximately $250 million in flood damage. TVA estimates it has averted nearly $7 billion in flood damage since it completed its first dam, Norris Dam, in 1936.

TVA continues to release water to recover flood storage space at most of its dams, including all nine dams on the Tennessee River. Excess water is also being released using spillway gates or sluice gates along with generators operating at maximum capacity at all 29 hydro generating dams, producing about 3,300 megawatts of electricity. That is enough to power about 1.8 million homes.

“We try to avoid spilling water because it’s low-cost power generation, but when we have a lot of water our No. 1 priority becomes reducing flood damage risks. This is a perfect example of why TVA lowers the reservoirs to their lowest elevations during the fall and winter months,” McCormick said.

The Tennessee Valley Authority, a corporate agency owned by the U.S. government, provides electricity for business customers and distribution utilities that serve 9 million people in parts of seven southeastern states at prices below the national average. TVA, which receives no taxpayer money and makes no profits, also provides flood control, navigation and land management for the Tennessee River system and assists utilities and state and local governments with economic development.

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