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Tailwater Improvements

Improving Water Quality Below TVA Hydropower Dams

Hydropower producers are faced with two environmental problems that can affect the area downstream from a dam (called the tailwater): low concentrations of dissolved oxygen in the water released through the dam during generation, and dry riverbeds that result when hydro generation is shut off.

Since the early 1990s, TVA has spent about $60 million to address these problems. In the first stage of the improvement effort, TVA installed equipment to increase dissolved oxygen concentrations below 16 dams. At the same time, TVA made operational changes and installed additional equipment to ensure minimum water flows through its dams.

TVA has since completed a second round of improvements. Oxygen systems have been installed or enhanced at nine projects, and two new autoventing turbines have been installed at Boone Dam. The additional oxygenation capacity will help offset the increased oxygen demands associated with delaying the seasonal drawdown of TVA reservoirs until Labor Day. The delayed drawdown is part of a new operating policy approved by the TVA Board in June 2004.

Link to the pages below to learn more about TVA’s reservoir-releases-improvement program.

Boosting oxygen concentrations
Learn why low-oxygen conditions can occur below hydropower dams and find out about the different technologies that TVA is using to address this problem at specific locations.

Maintaining a wetted riverbed
Learn how generating electricity can affect water flow below hydropower dams and find out what TVA is doing to maintain wetted habitat in the riverbeds below its dams.

Learn about how TVA’s reservoir-releases-improvement efforts have made a real difference in water quality and the health of the aquatic environment downstream of its hydropower dams.


Tributary dams

To see what TVA is doing about the problems of low oxygen concentrations and low flows at tributary dams, choose from the list below.

Main-river dams

View information on improvements at main-river dams.

Scientific papers

View papers and journal articles by TVA staff members on various topics, including the scientific and technical aspects of the agency’s reservoir-releases improvements.


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