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MARCH 3, 2010

In this issue:
Rain and runoff
Current reservoir elevations
Historical reservoir elevations
Reservoir operations

Questions and answers about the spring fill
Special reservoir operations
More TVA information

Instead of publishing TVA River Neighbors, a quarterly electronic newsletter, TVA is now providing monthly updates on the operation of TVA-managed reservoirs by e-mail. 

To provide feedback, change your e-mail address, or opt out of receiving future e-mails, please send an e-mail request to reservoirupdate@tva.com.

 

Rain and runoff
Although rain in the eastern Valley was 3.7 inches above normal for the last three months of 2009, it seems to be tapering off in 2010. Rainfall was normal in January, and 1.6 inches below normal in February.

Runoff (the amount of water that reaches the river system when it rains instead of being absorbed into the ground) also is decreasing due to the drier weather, but it remains above normal. After reaching a high point of 4.65 inches in December 2009, runoff slowed to 3.89 inches in January and 3.65 inches in February. Normal runoff for February is 3.06 inches.

The higher runoff levels are the result of a combination of factors, including saturated ground conditions and the occurrence of several hard downpours, which tend to produce more runoff than extended periods of light rain.

 

Current reservoir elevations
All main-river reservoirs are within their seasonal operating ranges. Tributary reservoirs are at or very close to their targeted seasonal elevations, as shown in the chart below.

Reservoir

March 1, 2010
Observed Elevation

March 1
Flood Guide

June 1
Flood Guide

South Holston

1711.2

1710.3

1729

Watauga

1953

1952

1959

Cherokee

1044.3

1045

1070.9

Douglas

953.4

954

994

Fontana

1653

1653

1703

Norris

999.7

1000

1020

Chatuge

1917.9

1918

1926

Nottely

1762.1

1762

1777

Hiwassee

1486.5

1485

1521

Blue Ridge

1672.6

1672.3

1687

Tims Ford

878.1

877.8

888

Normandy

865.5

864

875

Flood guide levels show the amount of storage allocated for flood damage reduction during different times of the year. During the summer, TVA's goal is to meet downstream flow requirements while keeping the reservoir level at the dam as close to the flood guide level as possible to support reservoir recreation. From June 1 through Labor Day, reservoir levels fall below the flood guide only when rain and runoff are insufficient to meet flow requirements. During the rest of the year, the primary objective is to keep the reservoir level at or below the flood guide to ensure there is enough space in the reservoir to store the rain and runoff from flood events.

 

Historical reservoir elevations
Ever wondered what’s the highest your reservoir has been – or the lowest? The table below shows the maximum and minimum elevations since initial filling of the reservoirs listed.  Keep in mind, though, that TVA operated the Tennessee River system differently when all but one of the minimum reservoir elevations shown occurred. TVA’s current operating policy targets higher winter elevations on most of the tributary reservoir system, which makes it unlikely—barring an extreme drought or a deep drawdown for maintenance—that the minimum levels shown below will occur in the future.

Reservoir

Maximum Elevation

Date

Minimum Elevation

Date

Apalachia

1281.40

6/13/1953

1251.00

4/25/1971

Bear Creek

609.43

3/17/1973

547.00*

9/27/1976

Blue Ridge

1691.54

2/11/1946

1587.75

1/16/1956

Boone

1384.99

5/19/1964

1327.06

1/23/1956

Cedar Creek

587.43

5/8/1984

559.48

12/5/1980

Chatuge

1928.39

5/28/1973

1860.11

9/5/1947

Cherokee

1074.48

6/19/1989

980.77

1/7/1954

Chickamauga

687.13

5/7/2003

673.27

1/21/1942

Douglas

1002.45

5/9/1984

883.70

1/16/1956

Fontana

1710.20

5/28/1973

1472.00

1/29/1955

Ft. Loudoun

816.07

3/28/1994

805.54

1/18/1954

Ft. Patrick Henry

1263.80

2/11/1954

1223.86

12/4/2002

Great Falls

811.26

12/23/1990

761.98

1/10/1940

Guntersville

596.29

3/2/1944

590.65

11/12/1968

Hiwassee

1528.02

5/28/1973

1413.41

1/28/1948

Kentucky

369.99

5/11/1984

348.02

3/11/1961

Little Bear Creek

625.38

5/8/1984

599.30*

12/5/1977

Melton Hill

796.45

3/16/1973

784.10

2/9/1966

Nickajack

634.99

4/19/1969

630.82

2/20/1968

Normandy

880.12

2/20/1991

852.10

1/31/2008

Norris

1031.10

2/11/1937

909.35

1/24/1956

Nottely

1781.47

5/28/1973

1638.60

10/6/1947

Ocoee No. 1

835.20

2/16/1990

808.10

1/11/1940

Ocoee No. 3

1437.40*

4/28/1958

1381.00

10/18/1978

Pickwick

419.49

3/30/1944

407.12

12/18/1944

South Holston

1736.92

4/27/1987

1614.15

1/13/1956

Tellico

816.20

3/28/1994

806.96

1/14/1980

Tims Ford

894.55

12/10/2004

855.25

12/1/1997

Upper Bear Creek

802.73

12/23/1990

790.13

10/31/1982

Watauga

1963.34

9/19/2004

1813.47

1/13/1956

Watts Bar

747.35

5/7/2003

733.44

3/20/1945

Wheeler

557.32

3/1/1944

548.43

12/9/1962

Wilson

508.38

5/19/1983

502.98

7/9/1942


*Estimated

 

Reservoir operations
“We are right where we want to be.”

That's what Chuck Bach, TVA General Manager of River Scheduling had to say about the status of the TVA reservoir system on March 1.

“We started the year with a lot of water in storage due to all the rain in late 2009, and then we had a fairly significant rain or snow event about every week from January through early February.  In order to maintain flood storage space, we had to spill at most main-river dams and at some tributary dams through much of February. High flows also forced the closure of locks on the upper end of the river system, and barge traffic through the gorge below Chattanooga had to be suspended on several occasions.”

By the end of February, reservoirs were back to seasonal levels, according to Bach.

“Right now, we’ve got an optimal amount of water flowing through the reservoir system. We've got the flood storage space we need this time of year. But we still have plenty of water for other benefits. We've got the flow we need for hydroelectric power generation, but not so much that we have to spill water. And we've got the flow needed for commercial navigation, but not the high water levels that can restrict barge traffic through the locks on the river system or through the Tennessee River Gorge below Chattanooga.”

TVA's operating policy this time of year is to maintain reservoir elevations at or below seasonal flood guide levels, which is exactly what TVA is doing, says Bach.

“If we get a heavy rain, affected reservoirs could go above their flood guides temporarily to reduce downstream flooding. But we'll draw those reservoirs back down to seasonal levels as soon as that can be done without increasing downstream flood damage.

“Around the middle of March, flood guide levels start going up on tributary reservoirs, so—depending on rain—reservoir users can expect to see water levels start coming up soon. The forecast is for a wet spring, so we anticipate filling tributary reservoirs on schedule.”

To see your reservoir's flood guide and track its elevation, go to TVA's Reservoir Information Web page. Choose your reservoir from the pull-down menu on the right-hand side of the page and then select Operating Guide.

 

Questions and answers about the spring fill  
When will the water level in my reservoir start going up?
TVA begins aggressively storing water to fill tributary reservoirs in mid-March. This is because less flood storage space is needed in the spring when the roots of growing plants begin to intercept more of the rain that would otherwise run off into the reservoir system. In addition, weather patterns begin to change with less chance for larger, more organized storm systems.

Main-river reservoirs are kept at lower levels until mid-April or May because they have limited flood storage space compared to tributary reservoirs due to topography and the requirement in the TVA Act to provide a nine-foot waterway for commercial navigation on the main Tennessee River. However, since there is not as much difference between winter and summer levels on main-river reservoirs as on tributary reservoirs, it doesn’t take long to bring main-river reservoirs to summer elevations.

When will my reservoir reach “full pool”?
TVA tries to fill tributary reservoirs to summer levels by Memorial Day weekend. Most main-river reservoirs are targeted to fill by mid-April. Watts Bar, Chickamauga, and Fort Loudoun Reservoirs are targeted to fill by mid-May to help reduce the risk of flooding at Chattanooga, Tennessee.

When reservoirs actually reach targeted levels depends on rain and runoff. Beginning in mid-March, tributary reservoirs are allowed to fill as quickly as possible, as long as reservoir levels do not significantly exceed flood guide elevations (which allow for higher reservoir levels in the spring). If low rainfall prevents reservoirs from filling at the desired rate, TVA stores as much water as possible, allowing only minimum releases to meet downstream flow requirements.

What is full pool on my reservoir?
To see the targeted summer pool levels for TVA-managed reservoirs, go to TVA’s Reservoir Information web page. Choose your reservoir from the pull-down menu and then select Operating Guide.

For main-river reservoirs, you'll see a gray band showing the normal operating zone, which is highest during the summer months. For tributary reservoirs, you'll see a blue line representing the flood guide elevation, which is at the highest level on June 1. This line is set to support reservoir recreation from June 1 through Labor Day, while still preserving a small amount of flood storage capacity as a protection against a potential flood-producing summer storm.

Why isn’t my reservoir filling as fast as other reservoirs?
If your reservoir doesn’t seem to be filling as fast as a neighboring reservoir, it could be because your area isn’t getting as much rain. Rain amounts often vary widely even over adjacent watersheds, with direct impacts on the rate that reservoirs in each watershed fill.

Fill rates also can vary significantly from one reservoir to another due to differences in the size of the land area draining into each reservoir, the amount of ground cover, soil characteristics, and reservoir shape and surface area.


Special reservoir operations
Little Bear Creek – TVA is continuing to adjust the elevation of Little Bear Creek Reservoir to facilitate maintenance and repairs on the dam. TVA lowered the reservoir to its normal winter pool level (608 feet above sea level) in September to provide access to the dam. Work crews drilled a row of vertical holes into the foundation and are in the process of injecting grout to form a water-tight barrier. As this work nears completion, TVA is allowing the reservoir level to rise along its normal guide curve. TVA plans to hold the water level at 618 feet above sea level for several days to test the effectiveness of the repairs and then will allow the reservoir to fill to its normal elevation of 620 feet above sea level.

Shoreline cleanups – This time of year, TVA tries to accommodate requests from lake user groups to temporarily lower reservoir levels to help with shoreline cleanups. Shoreline property owners can also take advantage of the lower levels to make needed repairs to their docks. Upcoming cleanups include the Melton Hill River Rescue on March 27 and the Fort Loudoun River Rescue on April 10.


Get more information on TVA.com
The links below will take you to reservoir-related information on TVA’s Web site.

TVA’s reservoir operating policy:  Learn how TVA manages the flow of water through the Tennessee River system to provide navigation, flood damage reduction, power supply, water quality, water supply, recreation, and other benefits.

Reservoir information
:  Get detailed information about individual reservoirs, including observed and predicted elevations and releases at TVA dams, reservoir operating guides, water quality improvements, fish population survey results, and more.  To check reservoir information from your cell phone or other mobile device, go to http://m.tva.com.

Rainfall
and stream flows:  Get the latest information on daily rainfall and stream flows across the Valley.

Recreation release schedules
:  View the 2010 schedule for water releases for rafting, kayaking, and canoeing below these TVA dams:  Apalachia, Ocoee No. 1, Ocoee No. 2, Ocoee No. 3, Norris, Watauga/Wilbur, and Tims Ford.

Map of TVA reservoirs and power plants
:  Our interactive map is your guide to the entire TVA power system, including fossil and nuclear plants, dams and reservoirs, and visitor centers.  You’ll find interesting facts about each facility and learn how they work together for the purposes of power supply, river management, and economic development.

Water supply FAQs
:  Get answers to frequently asked questions about obtaining a water intake permit, improving water quality around intakes, inter-basin transfers, and more.

Dangerous areas around TVA dams
:  If you like fishing or enjoy swimming and boating on TVA-managed reservoirs, you need to be aware of the possible hazards around dams, locks, and powerhouses.

How to lock through
:  Find out what you need to do to safely approach a navigation lock, secure your boat in the lock chamber, and exit the lock.

Reservoir health ratings
:  See the latest monitoring results for TVA-managed reservoirs.

Campgrounds and day-use areas
:  Get information here about campground fees and amenities as well as picnic pavilion reservations.

TVAkids.com
:  TVA’s got a Web site just for kids!  Learn about how TVA makes electricity, reduces flood damage, protects wildlife, and more.  There’s a section for teachers, too.

TVA Heritage
:  Read about the people who founded TVA, shaped its purpose, and built its power plants.  TVA Heritage offers fascinating glimpses of the agency’s 76-year history.

Get more information by phone
For the latest information on reservoir elevations and stream flows, call TVA’s Reservoir Information Line from a touch-tone phone:

  • From Knoxville, TN:  865-632-2264
  • From Chattanooga, TN:  423-751-2264
  • From Muscle Shoals, AL:  256-386-2264
  • From all other locations:  800-238-2264 (toll-free)

For answers to questions on how your reservoir is operated, call TVA River Operations at 865-632-6065.
For answers to questions about recreation, permitting procedures, reservoir land management plans, and other environmental issues, call TVA’s Environmental Information Center at 1-800-882-5263.

 
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