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TVA River Neighbors

Reservoir system update

Thunderstorms and showers this spring and summer have brought relief from the longstanding dry conditions in the Tennessee Valley.

photo

Fort Loudoun Reservoir

For the calendar year to date (Jan. 1-Sept. 1), the Valley has received about 34 inches of rain, which is 94 percent of normal. Runoff is 89 percent of normal.

Rainfall in the eastern Valley — the area above Chattanooga — also has returned to near normal for the year (97 percent), but runoff amounts are only 83 percent of normal, indicating that groundwater is still recharging after several years of drought conditions.

Runoff is important to reservoir elevations because it is a measure of the water that reaches the river system when it rains instead of being absorbed into the ground. Runoff is affected by soil conditions and by the intensity, amount, and duration of rainfall.

Because rainfall has been near normal since Jan. 1, TVA was able to fill the reservoir system to target levels on schedule and to keep reservoirs within their targeted elevation ranges through the summer.

Tributary reservoir elevations

Reservoir

Observed Elevation*

Flood Guide Elevation*

Sept. 1, 2008

Sept. 1, 2009

Sept. 1

Jan. 1

South Holston

1698.9

1723.6

1729

1708

Watauga

1943.6

1953.6

1959

1952

Cherokee

1050.9

1062.4

1069

1045

Douglas

970.3

985.9

991.5

954

Fontana

1675.4

1696.7

1702.5

1653

Norris

1000.4

1012.4

1020

1000

Chatuge

1920.4

1922.6

1923.4

1918

Nottely

1765.5

1770.8

1772

1762

Hiwassee

1498.7

1511.3

1513

1485

Blue Ridge

1675.4

1680.9

1682

1668

*In feet

On Sept. 1, 2009, the 10 largest tributary storage reservoirs were an average of 12 feet above their level on the same date in 2008.

 

“Reservoir levels dropped gradually in August, but that’s typical,” says TVA’s Chuck Bach, manager of River Scheduling. “Our system flow requirement goes up on August 1 because river temperatures gradually increase as the summer progresses. Providing more flow in late summer helps to keep the water from becoming too warm, which, in turn, helps to protect aquatic habitat and water quality. In years with normal rainfall and runoff, there’s enough inflow to make up for much of the water released to meet the higher flow requirement, so there’s less impact on reservoir elevations. But this year, the drop in reservoir levels was more noticeable because we’re still catching up on runoff.”

Even so, August elevations were within the targeted range and much higher than they were in 2007 and 2008, according to Bach.

“After three years of drought, we’ve had a little more water to work with this summer,” he says. “We’ve been able to keep reservoir elevations up for recreation, and we’re in a much better position to supply hydro generation this fall.”

 

 

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Now available: reservoir information site for mobile devices

TVA.com has a new mobile site that allows users to check key recreation information from their cell phones or other mobile devices.

The address for the site is: http://m.tva.com.

The initial version of the site has links to information on reservoir levels, recreation release schedules, and stream flows in a format that loads quickly and displays neatly on mobile devices.

New information will be added as it becomes available.

 

 

           
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