NASHVILLE, Tenn. (May 9, 2012) – Developing drought conditions within the Cumberland River Basin could impact the coordinated operation of the Cumberland River reservoir system, the U.S. Army Corps of Engineers Nashville District said Tuesday.
A mild winter across the region, above average temperatures in March, and insufficient rainfall in the Cumberland River Basin during the month of April have resulted in lower than normal lake levels at area reservoirs. Corps water managers rely on runoff from rainfalls in April to fill the pools of reservoirs in the Basin. At J. Percy Priest Lake, the current reservoir level is 3.7 feet below the elevation it should be for this time of year. Likewise, Lake Barkley is approximately 2.8 feet lower than normal. According to the National Weather Service, much of the Cumberland River Basin is considered to be in moderate drought.
Lower lake levels combined with significantly reduced flow in area streams have the potential to impact a wide range of benefits provided by the coordinated operation of the Cumberland River reservoir system. Similar conditions during the recent severe drought in 2007 and 2008 resulted in interruptions to commercial navigation through Nashville, taste and odor issues at regional water treatment facilities, reduced hydropower generation, and impacts to fish and aquatic life. The most visible indication of the drought conditions are often lower lake levels, which may cause hazards for boating on some lakes in the Cumberland River Basin.
Mitigating potential impacts because of drought largely is dependent upon two primary factors: the volume of cold water stored in reservoirs and the occurrence of adequate rainfall. Management of the available cold water is important to the health of the aquatic ecosystem and to ensure normal operation of major power plants at Gallatin and Cumberland City, Tenn. Seasonal outlooks from the National Weather Service Climate Prediction Center are for normal rainfall and above normal temperatures this summer. While rainfall is forecast to be normal from June through August, the runoff from typical summer rain events is not sufficient to fully support the benefits the Cumberland River reservoir system is expected to provide. Normally, water stored during the spr ing at the tributary projects (Wolf Creek, Dale Hollow, Center Hill and J. Percy Priest) is used to supplement flows through the Cumberland River lock and dam projects (Cordell Hull, Old Hickory, Cheatham and Barkley) during this period. However, reduced water in storage at Wolf Creek and Center Hill Dams (two largest tributary projects in the Cumberland River system), where there are lake level restrictions in place because of dam safety concerns, will limit the Corps’ ability to respond to low flow conditions. Without lake level restrictions, an adequate volume of cold water would have been stored at these two projects in the spring for release to meet downstream requirements during summer and fall.
As particular impacts are known at specific reservoirs, the Corps of Engineers will keep the public informed.