Water Management Situation Report for Cumberland River Basin Reservoir System and Associated Waterways

J. Percy Priest - Fall 2009

Thermal stratification was already well underway at J. Percy Priest by April 2009 and proceeded rapidly reaching fully stratified condition by mid-May.  Water quality conditions in the lake are always quite stressful in this relatively shallow, nutrient enriched lake, so even though 2009 was a year that produced relatively poor water quality in Nashville District’s storage reservoirs, J. Percy Priest was not much worse than normal.

The big news at Percy Priest is the anticipated operation of a new, low flow maintenance structure called a Howell-Bunger valve.  This device will enable lake managers to provide a regulated flow into the tailwater during the warm summer months.  The Howell-Bunger valve will produce a spray across the stilling basin below the dam’s spillway area that should be fully oxygenated.  Most of the conduits and equipment for operating the valve were installed this summer.  However, some additional work must be completed before the valve can be put into use.

Within the lake, Tennessee Wildlife Resources Agency (TWRA) monitored white crappie numbers.  Prior to 2009, the last moderately strong white crappie year-class produced in J. Percy Priest Reservoir was 2003.  Angler success has declined in recent years but the stronger 2009 white crappie year-class will grow to harvestable size at approximately 2.5 years of age.  Therefore, fishermen will start harvesting more crappie starting in the fall, 2011, and spring 2012.  See “Main Stem Projects” for more information on sampling methods.

J. Percy Priest - Spring 2009

Because of its relative shallowness, J. Percy Priest Reservoir destratified by early December 2008. Over winter, lake levels remained higher than the normal winter pool. Wet weather systems moving through the area have resulted in J. Percy Priest attaining a very high pool level as of mid-May 2009. Thermal stratification had already been observed to be underway at the reservoir by the latter part of April 2009. Once the flood waters are evacuated, this process, which occurs every year, should proceed rapidly. The big news at Percy Priest is the installation of a new, low flow maintenance structure called a Howell-Bunger valve. This device will enable lake managers to provide a regulated flow into the tailwater during the warm summer months. The Howell-Bunger valve will produce a spray across the stilling basin below the dam's spillway area that should be fully oxygenated and improve conditions for aquatic flora and fauna. Pending completion of the upstream inlet structure, this valve will also be able to draw water from the upper, higher quality waters of J. Percy Priest.

The winter draw-down on J. Percy Priest provided Tennessee Wildlife Resources Agency (TWRA) the opportunity to make habitat improvements and build fish attractors on the exposed over-bank areas. Approximately 500 bald cypress trees were planted to enhance aquatic and terrestrial habitat. Many thousands of cypress trees have been planted through the years - some towering to 40 feet. They help stabilize the bank and prevent erosion, provide fish spawning habitat, and are good fish attractors for fishermen. They also benefit many wildlife species. Additionally, all stake beds (n = ~ 160) on J. Percy Priest Reservoir were enhanced and marker poles reset. New fish attractors were also constructed in the bank fishing cove at Stewart Creek ramp.

Approximately 100 spawning benches were also constructed in J. Percy Priest Reservoir to provide fish spawning structure. Many banks provide very good substrate but lack structure. The spawning benches enable males to more successfully protect the nest sites and increase spawning success.

Spillway releases at J. Percy Priest Dam are made to improve tailwater conditions and avoid the release of poor quality water through the turbine.