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TVA River Neighbors

August 4, 2011

In this issue:
Rainfall and runoff
Current reservoir conditions
Reservoir operations
The value of hydropower

Natural Resource Plan released
Lake info now available as Android app
More TVA information

TVA provides these monthly updates on the operation of the reservoir system by email. We sincerely welcome your comments and questions. To provide feedback, sign up for future updates, change your email address, or be removed from this distribution list, please contact riverneighbors@tva.com.


Rainfall and Runoff

July turned out to be drier than normal (monthly rainfall was just 75% of what it typically is) for the part of the Valley above Chattanooga. However, for the calendar year to date, this part of the river basin stands at 95% of normal.

Runoff numbers closely mimicked those of rainfall, with July coming in at 76% of normal. For the calendar year, runoff totals are, at 99%, about as close to normal as you can get.


Current reservoir conditions

TVA strives to keep reservoir elevations at or just slightly below flood guide levels. And that’s basically where we are, as of August 1. All the tributary reservoirs are below flood guide, with two exceptions. Nottely is 2.9 feet above flood guide, due to a unit forced outage, and Blue Ridge is well below flood guide, as a result of the dam rehabilitation project.

All the main river reservoirs are within their seasonal operating ranges.

Tributary Reservoir Levels
August 1, 2011
Observed Elevation1

August 1, 2011
Flood Guide2

South Holston



























Blue Ridge



Tims Ford






¹Elevations above mean sea level, as of 12:01 a.m. on this date

²Flood 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.


Reservoir Operations

The equation goes something like this:
The right amount of rainfall, in the right place, at the right time plus judicious management of the Tennessee River System by TVA equals more water in the tributary reservoirs, system-wide, than during any summer since 2005

David Bowling only wishes the "math" were that simple every year. As Senior Manager of TVA's River Forecast Center, Bowling and his colleagues feel pretty fortunate that their diligence has paid off: "The amount of rainfall we saw in early spring allowed us to sort of temporarily 'bank' that water. As the months passed, we were able to schedule releases at the most opportune times to maximize benefits." They certainly didn't have an overabundance of water with which to work, once the summer season began."That's the really amazing part: that we were able to do all this with what was essentially just a normal amount of rainfall," says Bowling. "A half-inch of rain doesn't seem like much, but if it comes at regular intervals and is pretty widespread in coverage, it adds up."

This summer, it's meant more water for hydropower, for improved environmental conditions in the tailwaters, for recreational activities, and for maintaining river temperatures below TVA's fossil and nuclear plants.

Things can change quickly, of course—and August is typically a hot, dry month. But for now, Bowling and his co-workers are just grateful that they've been able to keep elevations at or above the System Minimum Operating Guide, the measuring stick that TVA uses in its effort to maintain a minimum combined storage volume from all 10 large tributary reservoirs. "It's allowed us to maintain higher system minimum flows while keeping pool levels full for recreation. For this time of year, it doesn't get much better than that."


This time of year, TVA often finds itself
Turning to Hydropower

The mercury climbs steadily throughout the day. The Tennessee Valley is sweltering. Forecasters look expectantly at record high temperatures for this date, wondering which ones will be broken before nightfall.

GeneratorThe late afternoon wears on, and kids get home from school. Folks who worked 2nd shift aren’t far behind. Air conditioners get cranked up, in an attempt to get welcome relief from the relentless heat. The five o’clock hour approaches; demand for power edges ever higher.

Suddenly, an unforeseen mechanical problem causes Unit 1 at TVA’s Cumberland Fossil Plant to be forced offline. Just like that, 1,100 megawatts of capacity is drained from the system—at precisely the same time when it’s most needed.

At TVA’s System Operation Center in Chattanooga, the Coordinator of the Hydro Dispatch Control Cell picks up the phone to inform the River Forecast Center in Knoxville—and to try to determine how much generating capacity is available from which hydropower units.

The Lead Engineer immediately assesses the situation and provides a quick run-down of all available hydro production. Plans are implemented, and in a matter of five minutes or so, turbine blades begin to spin as water is passed through the generators at more than a half-dozen TVA dams across the Valley. The needed capacity has been successfully restored. Air conditioners continue to hum. Stoves and ovens are turned on in preparation for the evening meal. For the moment at least, demand for electricity has not exceeded the supply.

All because TVA was able to turn to hydropower.

Susan Jacks has seen it happen more times than she can remember. As a Senior Management Advisor in TVA’s River Scheduling organization, she’s had a front-row seat when it comes to witnessing just how often hydropower proves its value.

“This particular generating source is what you might call ‘multi-talented,’” she explains. “Hydro is low-cost, it’s clean, it’s renewable, it can be brought online to full capacity in a hurry, and it can be turned on and off to follow the demand for electricity. It’s hard to overestimate the advantage provided by hydropower’s almost instantaneous response time, when you consider how long it takes in comparison for fossil and nuclear plants to be powered up to capacity. Hydro makes up just 10% of TVA’s total capacity, but it’s a very important 10%--particularly during periods of peak demand.”

That translates into a truly impressive array of benefits:

Lower electric rates
Having hydropower to turn to often prevents TVA from having to turn to other generating sources that are more expensive to operate—or even from being forced to purchase power on the open market.

Improved air quality
TVA used conventional hydropower to produce 14,940 GWh of electricity during FY 2010, thereby offsetting the need to burn an equivalent six million tons of coal.

Additional environmental benefits
Hydropower provides waste assimilation and also helps ensure compliance with Federal standards by regulating water temperatures near fossil and nuclear plants.

CherokeeOf course, there are other renewable energy sources that are part of the generating mix for utilities across the United States—including wind power, geothermal, solar energy, etc. But none of these has proven as significant as hydro, when it comes to providing a substantial part of overall capacity.

That’s due, according to Jacks, to some unique attributes: “It really comes down to flexibility. You see, hydro is dispatchable, readily and consistently available in a way that most of these other sources are not. Breezes may die down and days may be overcast. But the water’s there when we need it, at the rate we need it. And what’s just as important, we can save it to use later—at exactly the right time to maximize the benefits it provides.”

Peak periods, whether they occur in summer or winter—present special challenges for the individuals charged with seeing to it that TVA has enough power on hand to meet what sometimes turn out to be record demands for electricity throughout the Valley. But when things get tricky, Jacks and her co-workers can breathe just a bit easier, knowing that hydroelectric power is part of the generating mix. “Regardless of how difficult it can sometimes be to try to follow the demand,” she observes, “it’s always good to have hydro in our back pocket.”


Final Natural Resource Plan Released

In a meeting later this month, the TVA Board of Directors will vote on the agency’s proposed Natural Resource Plan, designed to enhance stewardship of public recreation facilities, water resources, wildlife and plants, and historic and cultural sites on TVA-managed reservoir lands.

The Plan outlines public use policy over a 20-year period, while responding to the needs of communities and residents within TVA’s seven-state service territory. For more information, view the Natural Resource Plan and its accompanying Environmental Impact Statement at www.tva.com/nrp.


Lake Information App Now Available for Android-based Smartphones

AndroidNow users of mobile devices featuring the Android operating system can access the latest lake information, too.

The free application, available from the Android Marketplace, provides users with current information on lake elevations, water release schedules, years operating guides, and Google-based maps.

To learn more about the apps for both iPhones and Android devices, go to www.tva.com/river/mobile_app.htm.

Users of other types of smartphones can to http://m.tva.com for a mobile version of the lake information web page.


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.

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

Recreation release schedules: View the 2011 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, Upper Bear Creek 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 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.