Parksville Lake News Article

November Reservoir System Update

River Neighbors

Rain and runoff

Rain for the first three weeks of October was only 24 percent of normal, but a series of fast-moving storms on Oct. 25 and 26 dumped two to four inches of rain across the Valley. The month ended with a rainfall total of 2.89 inches, which is 97 percent of normal.

Rainfall in the eastern Tennessee Valley for the year totaled 34.63 inches at the end of October, which is 7.47 inches below normal. Runoff (the amount of water that reaches the river system when it rains instead of being absorbed into the ground) was 86 percent of normal in the eastern Valley.

Eastern Valley Rainfall

Month

Observed rainfall

Normal rainfall

Percent of normal

January

4.51

4.6

98

February

2.68

4.23

63

March

2.79

4.82

58

April

2.69

4.17

65

May

4.50

4.23

106

June

2.91

4.28

70

July

3.96

4.97

80

August

4.01

4.28

94

September

3.68

3.38

109

October

2.89

2.99

97

Total
(year to date)

34.63

42.10

82


Reservoir elevations

The elevations of tributary storage reservoirs gradually dropped through the month of October as TVA continued the annual drawdown to winter flood-damage-reduction levels. Most reservoirs were at expected levels on Nov. 1, ranging from an average of 14 feet above Jan. 1 target levels on Douglas, Fontana, Hiwassee, and Tims Ford to an average of four feet above Jan. 1 target levels on South Holston, Cherokee, Norris, Chatuge, Nottely, and Normandy.

As in previous months, Watauga Reservoir was the exception. It fell below its winter flood-damage reduction level the end of August because there wasn’t enough rain in the surrounding watershed to compensate for the water released to meet downstream flow requirements. Because Watauga is still below its winter flood-guide elevation, TVA is continuing to limit releases to conserve water in Watauga, which may result in some increase in the reservoir’s elevation depending on local rainfall.

Blue Ridge Reservoir is also a special case. TVA began a deep drawdown on Blue Ridge in mid-July. The reservoir is being held at an elevation between 1620 and 1630 feet above sea level—compared to its normal winter flood-damage-reduction level of 1668—as part of a project to rehabilitate the 79-year-old dam. Get an update on this project below.

Reservoirs along the main Tennessee River—Fort Loudoun, Watts Bar, Chickamauga, Nickajack, Guntersville, Wheeler, Wilson, Pickwick, and Kentucky—were all within their normal operating ranges on Nov. 1.

Tributary Reservoir Elevations¹

Reservoir

Nov. 1, 2010
Observed Elevation

Jan. 1
Flood Guide Elevation2

South Holston

1712.1

1708

Watauga

1947.7

1952

Cherokee

1050.7

1045

Douglas

969.5

954

Fontana

1670.9

1653

Norris

1004.7

1000

Chatuge

1920.1

1918

Nottely

1766.3

1762

Hiwassee

1497.4

1485

Blue Ridge

1625.1

1668

Tims Ford

885.8

873.1

Normandy

868.5

864

1 Water elevation at the dam in feet above mean sea level
2 Flood-guide elevations show the amount of storage allocated for flood damage reduction during different times of the year. The amount of storage varies with the potential flood threat. Flood-guide elevations are lowest from Jan. 1 through mid March because winter storms are generally larger, occur more frequently, and produce more runoff. Flood-guide elevations increase between mid-March and June 1 as the risk of flooding decreases. They are highest from June 1 through Labor Day to support summer reservoir recreation. After Labor Day, TVA begins the unrestricted drawdown to Jan. 1 flood-guide elevations.

 

Reservoir operations

From September through

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