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Home / Susan Thrasher / Understanding the Elk River Generation Schedule

Understanding the Elk River Generation Schedule

February 28, 2017
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Tailwaters give opportunities in Middle Tennessee to fish for trout throughout the year. However, given the sudden changes in water elevations, it can be extremely dangerous if you are not familiar with the water release schedules.

The River Forecast Center is a division within the Tennessee Valley Authority (TVA) charged with modeling, evaluating and controlling the water release on 29 power generating dams and 19 non-power dams in Tennessee.

Hydropower, created from the release of water through turbines, creates electricity for customers. Hydropower is a supplemental power source and serves primarily to offset the cost of delivering power from other sources of electricity such as natural gas and coal.

TVA controls 109 hydro units throughout the Valley. The primary focus for management of the river system is power generation, flood control and commercial navigation. These three objectives were specifically called out in the TVA Act of 1936. Although not explicitly called out in the Act, but also important, is water supply, quality and recreation.

Tims Ford Dam on the Elk River, is one of the 29 power generating facilities controlled by TVA.   The River Forecast Center daily monitors the reservoir elevation, temperature, water quality, water in flow and outflow, weather prediction and power needs. This data is used within a complex modeling process to determine the water release schedule. Once determined, the schedule is given to the hydro dispatch center in Chattanooga where the dams are controlled remotely.

In 2004, the Reservoir Operation policy was updated to reflect information obtained from an environmental agency review as well as public input. Specifically of interest to fishermen, is the adopted recreational strategy. In complying with this policy, TVA does not utilize the large turbine on the weekends from Memorial Day through the last weekend in September. In addition, the Mondays on Memorial Day, July 4th weekend, and Labor Day follow the same policy to allow for water recreation.

Tims Ford reservoir has three forms of water release: a sluice gate, spillway and a turbine. The sluice and turbine both pull water from the bottom of the lake, while the spillway comes from the top. During the months of April through November, no power is generated or water released through the turbine. This is in cooperation with the U.S. Fish and Wildlife Service (FWS) in an effort to protect the Boulder Darter, a warm water species that was placed on the endangered species list due to the large amount of cold water introduced by the turbine. Instead, TVA utilizes the sluice gate, which results in less volume of cold water entering the river. Since 2008, TVA has closely monitored the water temperature on the river to protect the boulder darter as well as protect the trout fishery. Efforts are made to maintain a water temperature below 70 degrees to ensure the survival of trout. TVA has had success with blending water from both the sluice gate and spillway to maintain acceptable water temperatures.

Another area closely monitored by TVA is the amount of dissolved oxygen in the river. The goal is to maintain 6 milligrams/liter. During the summer, the surface temperature of the lake is between 70 and 80 degrees, while the lake bottom averages 50 degrees. The stratification of the lake holds steady until fall when the temperature begins to become uniform from top to bottom. As the warm water cools, it becomes more dense and sinks to the bottom forcing the water and debris at the bottom of the lake to rise and mix with the water layers above. This change is commonly known as “lake turn over.” This phenomena results in low dissolved oxygen. As this water is released into the river, it can be lethal to trout without a process in place to counter the low oxygen levels. Beginning in mid summer through late fall, TVA uses two systems to introduce oxygen into the water. Mechanical blowers are used, as well as a system which converts liquid oxygen into gas and then bubbles out slowly into the river.

This coordinated effort between TVA, FWS and TWRA results in a healthy fishery for anglers. Coupled with the recreation policy, the Elk River provides opportunities for anglers to enjoy this resource for the majority of the year.

TVA provides a generation release schedule, which is updated periodically throughout the day. The next day release schedules are typically available by 6 p.m. of the current day. The schedule for Tims Ford may be viewed at the link below. A flow of 250cfs or less provides for safe and comfortable wading. Flows higher than 250 cfs should be avoided.

https://www.tva.com/Environment/Lake-Levels/Tims-Ford

As with all tailwaters, it is important to check the schedule before entering the water. Since the schedule is subject to change at any time, you should be aware of your surroundings, keep an eye on the current for any changes in flow or water level and have an escape route in place just in case.

Special thanks to James Everett, Manager, River Forecast Center Operations Support Tennessee Valley Authority for his valuable input.

 

 

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About Susan

Susan Thrasher

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My Bio

Susan Thrasher, an FFF certified instructor, is the owner and operator of Southern Brookies Fly Fishing in Lancaster, Tennessee. For over a decade her teaching passion has extended into leading Casting for Recovery in Middle Tennessee and as a staff instructor at the Joan Wulff School of Fly Fishing in the New York Catskills.  In 2007, Susan and Nikki Mitchell founded the Music City Fly Girls, a Nashville based women's fly fishing club with over 40 active members.