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September 2, 2010

In this issue:

Rain and runoff
Reservoir elevations
Reservoir operations
Barge transportation benefits us all
Sideview crew helps boaters navigate secondary channels safely
Project updates
More TVA information

TVA provides monthly updates on the operation of TVA-managed reservoirs by e-mail. To sign up for future updates, provide feedback, change your e-mail address, or have your address removed from this distribution list, please send an e-mail request to reservoirupdate@tva.com.

 

Rain and runoff

The generally dry weather pattern that prevailed across the Eastern Valley much of the summer eased in August thanks in part to several days of soaking rain in the middle of the month. Eastern Valley rainfall for the year totaled 28.06 inches at the end of August, which is 7.7 inches below normal.

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

Runoff (the amount of water that reaches the river system when it rains instead of being absorbed into the ground) is currently 88 percent of normal in the eastern Valley.

 

Reservoir elevations

Wet weather in mid-August helped TVA maintain the higher flows needed in late summer for water quality and other river system benefits while keeping tributary reservoir elevations near normal. At month’s end, tributary reservoirs also were generally in balance—that is, the elevations of most reservoirs were about the same in relation to their balancing guides and flood guides. Watauga was the only exception. Although TVA conserved as much water in Watauga as possible throughout the summer, it was still somewhat low relative to other tributary reservoirs because inflows weren’t sufficient to compensate for the water released to meet downstream minimum flow requirements and recreation flow commitments.

TVA began a special deep drawdown on Blue Ridge Reservoir in mid-July. The reservoir is being lowered to an elevation between 1620 and 1630 feet above sea level as part of a project to rehabilitate the 79-year-old dam. Get an update on this project below.

Tributary Reservoir Elevations¹

Reservoir

Sept. 1, 2010
Observed Elevation

Jan. 1
Flood Guide Elevation2

South Holston

1721.7

1708

Watauga

1951.6

1952

Cherokee

1059.8

1045

Douglas

983.7

954

Fontana

1693.9

1653

Norris

1012.4

1000

Chatuge

1922.1

1918

Nottely

1770.0

1762

Hiwassee

1510.4

1485

Blue Ridge

1645.3

1668

Tims Ford

887.3

873.1

Normandy

872.0

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

After the Labor Day weekend, tributary reservoir elevations begin dropping at a faster rate. Chuck Bach, manager of TVA River Scheduling, explains why.

“From June 1 through Labor Day, TVA restricts the drawdown of tributary storage reservoirs to provide higher levels for recreation,” he says. “During that period, under normal operations, just enough water is released from these reservoirs to meet downstream flow requirements. TVA generates hydroelectric power with the water released to meet those requirements, but we don’t release any extra water solely for the purpose of hydro generation.

“That doesn’t mean that reservoir levels stay steady. If there isn’t enough rain to replace the water released to meet minimum flow requirements, levels will drop. But the restrictions on releases help to provide the higher pool levels that everyone wants to see in the summer.

“After Labor Day, flow restrictions are lifted. We start releasing water from tributary storage reservoirs at a faster rate with the goal of lowering water levels to Jan. 1 flood-damage-reduction levels as efficiently as possible.

“We realize the importance of keeping reservoir levels up as long as possible. That was a key reason why TVA changed its reservoir operating policy in 2004. Based on extensive computer modeling and statistical analyses, we were able to delay the start of the annual unrestricted drawdown from Aug. 1 to after Labor Day and to increase winter pool levels on 11 tributary storage reservoirs by about 10 feet. But that same review showed that we cannot keep reservoir elevations up beyond Labor Day without jeopardizing flood-damage-reduction and other benefits that TVA’s system of dams and reservoirs was built to provide.

“If we held reservoir levels up through October or November and then got hit by a period of wet weather, for example, we’d be faced with the possibility of flooding low-lying land. Also, it’s likely that we wouldn’t be able to release the water fast enough through the turbines to recover the flood storage space we need that time of year. Instead, we’d have to spill it—that is, release it through the spillways or sluices at the dams—which would impact power rates since spilled water generates no electricity.

“On the other hand, if October and November were dry, there would be less water available for discharge below Kentucky Dam. That would affect flows on the lower Ohio and Mississippi rivers and impact industries that rely on low-cost water transportation to ship the raw materials they use or supply to others. Water quality would be affected, too, because holding water behind tributary dams longer means higher surface-water temperatures, lower dissolved oxygen concentrations, and more algae—all of which can impact fish and other aquatic life.

“A lot of people don’t understand why we can’t wait to start releasing water until a big storm is in the forecast. Weather-forecasting technology has improved tremendously in recent years, but it still isn’t capable of providing reliable precipitation forecasts. Doppler radar allows us to watch weather systems as they form and move across the region. But when it comes to predicting when and where a front may stall and how many inches of rain it will produce before it starts moving again, it is educated guesswork.

“Another problem with waiting to release water is that it takes time to move water through the system efficiently. If we waited until the three- to five-day forecast calls for heavy rain, we’d have to draw the water level down very quickly, which could cause downstream flooding and waste the water’s hydroelectric potential. If the predicted rain doesn’t materialize—or we don’t get as much rain as predicted—we’d have released water needlessly. That means less water for recreation, navigation, water supply, and other purposes. Also, if dry weather sets in, refilling the affected reservoirs could be difficult.

“We balance a lot of different interests in operating the reservoir system, but this time of year flood damage reduction drives our operations. Our focus is on lowering the level of flood-storage reservoirs to make room to hold the runoff produced by winter storms so that we can provide the flood reduction benefits that TVA’s system of dams and reservoirs was designed to provide.”

Main-river reservoir operations
Main-river reservoirs don’t fluctuate as much as tributary reservoirs because they have less storage space and because of navigation requirements. Their drawdowns are staggered from July through November primarily to ensure that the released water can be used efficiently, generating electricity as it runs through the turbines at as many as nine dams downstream.

 

Barge transportation benefits us all

This article begins our series on the many ways the Tennessee River system touches our daily lives. In upcoming issues, we’ll highlight flood reduction, power generation, water supply, recreation, water quality, and other benefits.barge

“Were it not for barges moving up and down the river, we would be paying more for all kinds of products,” says Kelie Hammond, TVA program manager for navigation. “Anything that is made using commodities shipped in bulk quantities—grain, stone and gravel, iron and steel, lumber, coal, and chemicals, for example—would cost more.” These goods would have to be shipped by rail or truck, which experts estimate would cost about $500 million a year more than shipping by barge. The result would be higher prices for consumers.

The availability of the river as a competitive transportation option also helps to keep truck and rail prices down, providing an additional savings of about $486 million.

And those aren’t the only economic benefits, explains Hammond. “Navigation continues to contribute significantly to the economic development of the Valley. For example, the poultry industry in northeast Alabama would not have located where it did without river transportation. And the economies of cities like Decatur and Chattanooga would not be as dynamic as they are today, were it not for the Tennessee River.”

Just one eight-barge tow––fairly typical of what moves up and down the river––can transport as much tonnage as 464 18-wheelers, so water transportation also offers some important advantages in terms of energy efficiency and environmental protection, says Hammond. “Shipping goods by barge reduces fuel consumption, air pollution, and the number of tires going to landfills—not to mention the highway safety benefit of reduced truck traffic.”

River responsibilities
TVA, the U.S. Army Corps of Engineers and the U.S. Coast Guard work together to provide a safe and reliable passage for commercial and recreational vessels on the Tennessee River.

The TVA Act requires that TVA release water as needed to maintain a nine-foot navigation channel from Knoxville, TN to Paducah, KY and gives TVA ownership of and control over all physical structures in the water, including navigation locks. TVA also installs and maintains buoys, shoreline markers, and other navigation aids on about 375 miles of secondary, or recreational, waterways along the Tennessee River system.

The Corps of Engineers operates and maintains the locks and is responsible for periodic dredging to help maintain the depth of the commercial channel.

The Coast Guard has responsibility for ensuring the safety and security of commercial and recreational traffic on the main Tennessee River, including installing and maintaining navigation aids along roughly 800 miles of commercial channel.

Fast facts

  • The Tennessee River watershed has 800 miles of commercially navigable waterway, including 652 miles on the Tennessee River, 61 miles up the Clinch River, 29 miles up the Little Tennessee River, and 22 miles up the Hiwassee River.
  • Navigation locks are available at 10 TVA dams. Four of these dams—Pickwick, Wilson, Wheeler, and Guntersville—have both a main lock and an auxiliary lock.
  • Melton Hill, located on the Clinch River, is the only dam on a tributary reservoir with a navigation lock.
  • The largest lock, at Pickwick Dam, is 110 feet wide and 1,000 feet long.
  • The lock at Kentucky Dam is the busiest on the entire system, handling about 35 million tons of river freight per year.
  • More than 38,000 barges carry about 50 million tons of goods up and down the Tennessee River every year.
  • On average, locks along the Tennessee River provide passage for nearly 17,500 recreational craft annually.


Sideview crew helps boaters navigate secondary channels safely

Most people know that the U.S. Coast Guard is responsible for maintaining the buoys, shoreline markers, and other navigation aids on Tennessee River waterways deep enough for commercial barge traffic. But a lot of boaters may not know that the job of maintaining markers on secondary channels—waterways that are too shallow for commercial traffic—falls to TVA.sideview

More specifically, it falls to the four-man crew of the Sideview, TVA’s navigation service boat.

“We maintain about 2,500 buoys, directional signs, elevation gages, and hazard markers on secondary channels all along the Tennessee River,” says Tim Barkley, the crew leader. “We inspect each of these navigation aids at least twice a year.”

Run-ins with careless boaters, wave action and time take their toll, explains Barkley. Aids must be periodically repainted or replaced, and vegetation obscuring signs must be cut down.

Buoys are pulled completely out of the water on a three-year rotation so the crew can check their condition and make any necessary repairs.

The crew also checks the location of navigation aids using computerized charts and an enhanced Global Positioning System (GPS) which pinpoints the difference between the observed and original location of each marker.

“Buoys are held in place by a steel cable attached to a 150-pound concrete sinker that rests on the channel bottom,” says Barkley, “but they can still get pulled off station mainly by floating debris and people who use them to tie off their boats.”

The crew uses a crane to reset buoys if necessary.

It is illegal to tie your boat to a navigation buoy. The only exception is a mooring buoy. Mooring buoys have white bodies with a solid blue horizontal band across the center and are generally found only in areas designated for anchoring.

Barkley says that the hardest part of the job is the time spent away from home, coupled with the long hours of drive time from wherever the Sideview docks at the end of the workweek to the vessel’s home port in Muscle Shoals — and then back again in time to head out from the same location on Monday. But it’s worth it in his opinion: “We work hard, but we also enjoy our after-hours leisure time on the river,” he says. “There are a lot of guys out there that would pay to have my job.”

Report missing or damaged navigation aids online
You can help ensure safe travel on our waterways by using this form to report missing or damaged navigation aids.

 

Project updates

Blue Ridge Rehabilitation Project – TVA is continuing to lower the water level in Blue Ridge Reservoir with the goal of reaching an elevation between 1620 and 1630 feet above sea level by mid- to late-October depending on reservoir inflows. Workers can then begin repairing the penstock, a large underwater pipe which carries water from the reservoir to the turbines in the powerhouse. The penstock was damaged when the reservoir was filled after construction in 1931. The repairs are expected to take about six months. Barring construction delays due to heavy sustained rains, the reservoir should begin refilling by April 2011. The rehabilitation project also entails work to stabilize the water intake tower and earthen dam to prevent damage during a seismic event. This work is scheduled for completion in summer 2012. Old Highway 76 across the dam is closed for the duration of the project to protect motorists and workers on the construction site. Due to safety concerns, TVA Police are patrolling the area around-the-clock and issuing citations and/or fines to anyone who violates the road-closed signs. Read more about the project and sign up for regular e-mail updates.

Chickamauga Lock dewatering –The U.S. Army Corps of Engineers reopened Chickamauga Lock near Chattanooga, Tennessee, on August 14 after completing scheduled maintenance to the underwater components of the lock two days ahead of schedule.

 


Get more information on TVA.com

The links below will take you to reservoir-related information on TVA’s website.

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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