Beginning Aug. 1, TVA increased the flow of water through Chickamauga Dam from 13,000 cubic feet per second to 25,000 cubic feet per second to continue to meet downstream flow requirements.
Increased flows at Chickamauga will continue at this rate until an unrestricted drawdown begins after Labor Day.
“As the river water gets warmer during the summer, we have to increase the flow to protect water quality and aquatic habitat and to provide cooling water for the power plants downstream,” said TVA Senior Vice President of River Operations Janet Herrin. “Unfortunately, this will result in lower water levels in the tributary reservoirs.”
TVA follows its “balancing guide” procedures to ensure that water is drawn equitably from the tributary reservoirs and that no reservoir loses a disproportionate amount of water. The reservoirs are currently about 10 feet below normal levels for this time of year because of continuing drought conditions.
TVA is not releasing water for the primary purpose of generating electricity at TVA’s hydroelectric dams, but more water moving through the system will enable TVA to generate some low-cost electricity, according to Mr. Herrin.
Mr. Herrin said that drought conditions are severely reducing how much low-cost electricity TVA can generate at its dams this summer. As a result, TVA must buy large amounts of electric power on the market. That power is typically generated from natural gas, making it very expensive, she said.
Low water conditions also create safety hazards on the reservoirs by exposing more boating hazards, including rocks, stumps, sandbars and shoals. Low water levels contribute to increased boat congestion and may make launching boats more difficult at some boat ramps.
Because of the hazards, boaters are urged to use caution at all times, especially if they are unfamiliar with the reservoir.
Tributary reservoirs that will see a change in elevation are Blue Ridge, Chatuge, Cherokee, Douglas, Fontana, Hiwassee, Norris, Nottely, South Holston and Watauga.
“Although reservoir levels are higher this year than last, rainfall and runoff are still well below normal for this time of year,” said Mr. Herrin. “We are managing the water we have to provide multiple benefits, but this effort has been made more difficult given the continued drought conditions.”
Information about current reservoir levels, a three-day forecast for levels and observed rainfall are posted daily on TVA’s web site at www.tva.com/river.
Last week, certain areas of the Tennessee Valley received some much needed rainfall. However, overall, precipitation remains well below normal for most of the Valley.
The eastern portion of the Valley − East Tennessee, southeastern Virginia, western North Carolina and northern Georgia − continues to experience extreme to severe drought conditions, and summer pool levels on the tributaries remain below normal. The region needs a sustained period of rainfall, which usually arrives at this time of year only with weather activity from the tropics, to break this three-year drought.
For the week ending Aug. 1, there was an average of 1.32 inches of rainfall recorded in the Valley. Runoff was 0.09 of an inch. (Note: All rainfall and runoff data included here is as of midnight July 31.)
Following a very hot and dry start to this week, a front is expected to move later this week, bringing a chance of scattered showers and thunderstorms, followed by clearing and dry conditions into this weekend.
Temperatures are expected to remain above average.
Below is information on the condition of the reservoir system as of the end of last week.
For the calendar year-to-date (Jan. 1-July 31), the Valley has received a total of 24.75 inches of rainfall and 10.67 inches of runoff. Rainfall for the calendar year-to-date is 78 percent of normal, and runoff, critical to filling the tributary reservoirs, is only 63 percent. Hydro production for the calendar year-to-date is 59 percent of normal.
Blue Ridge, Cherokee, Douglas, Fontana, Norris, Chatuge, Nottely and Hiwassee remain below their flood-guide levels. South Holston and Watauga are well below their flood-guide levels (23.5 feet and 12.7 feet, respectively).
TVA will schedule flows through the system to meet downstream flow requirements, maintain water quality, protect aquatic habitat and provide for commercial navigation.