Normandy Reservoir - Optimization of Water Releases

Bedford, Coffee, Marshall, and Maury Counties, Tennessee

Updated March 28, 2025

Tennessee Valley Authority (TVA) has completed an Environmental Assessment (EA) and issued a finding of no significant impact (FONSI) addressing its proposal to modify how TVA measures flow targets of water releases from Normandy Dam into the Duck River. Under the Proposed Action, TVA would release water to meet a target at the Shelbyville, TN gage (28 miles downstream of the dam) that is based on the average flows at Shelbyville over the course of a week (through 2400 hours on Sunday) rather than releasing flows to maintain the Shelbyville flow target instantaneously (i.e., measured during one instant in time).

Notably, TVA would not modify the reservoir guide curve of Normandy Reservoir or change the minimum flows released from the dam.

In addition, TVA would maintain a new minimum instantaneous flow requirement to augment the weekly average flow target. TVA would be required to meet this minimum instantaneous flow requirement even if the average flow for any day or combination of days of the week was considerably higher than the weekly target.

TVA plans to begin modified water releases from Normandy Dam in mid-2025.

Optimization of Normandy Reservoir Releases

Under current operation of Normandy Reservoir, TVA has provided minimum instantaneous flow of 155 cfs from June through November, and 120 cfs from December through May, 28 river miles downstream at Shelbyville. In addition, TVA guidelines for Normandy Reservoir stipulate pool elevations of 875 feet from June through November, and 864 feet for flood control from December through May. TVA also maintains a minimum flow from Normandy Dam of 40 cfs year round.

Following severe drought conditions in the watershed in 2007 and 2008, TVA and the Tennessee Duck River Development Agency (TDRDA), which represents seven water utilities serving approximately 250,000 people and industries in the region, worked collaboratively with numerous consulting agencies and stakeholders to reduce the potential negative effects of drought conditions in the future. In 2013, the TDRDA issued an Optimization of Normandy Reservoir Releases (ONRR) report to assess water release modifications to precisely meet flow targets at Shelbyville, with the goal of preserving water and storage in Normandy Reservoir. A main recommendation of the ONRR was to implement a weekly average flow target at Shelbyville, instead of the current instantaneous flow targets. This recommendation served as the basis for the proposed action in the EA.

Under the Proposed Action, TVA would revise its flows as follows:

• Weekly average flow of 120 cfs (measured at midnight on Sunday) for the period of December 1 through May 31, with a minimum instantaneous flow threshold of 100 cfs during this period;
• Weekly average flow of 155 cfs (measured at midnight on Sunday) for the period of June 1 through November 30, with a minimum instantaneous flow threshold of 135 cfs during this period.

The Proposed Action would provide TVA with greater flexibility to meet operational goals during normal conditions while continuing to meet key operational goals related to water quality, aquatic habitat, and water supply. The proposal also has the potential to assist TVA and its partners in addressing drought conditions in the watershed that may affect water supply in the region.

Public Involvement

In 2018, TVA held a public scoping period regarding the ONRR proposal and a drought management plan. Subsequent to the scoping period, TVA began its environmental review of the ONRR, while continuing to discuss the drought management plan with its partners.

TVA released the draft EA on the ONRR proposal for a 30-day public comment period in May 2024.  During the period, TVA received 18 comment letters from the public. TVA considered this input in finalizing the EA and provided responses to the comments in the final EA.

TVA hosted a virtual webinar on June 13, 2024, to provide information about the proposal. A recording of the virtual webinar can be viewed by clicking the link below.

Public Virtual Webinar - Recording (6/13/2024)