NASHVILLE, Tenn. (June 26, 2012) – The U.S. Army Corps of Engineers Nashville District announced today continued impacts due to drought conditions within the Cumberland River Basin.
A mild winter across the region, above average temperatures this spring, and insufficient rainfall in the Cumberland River Basin during the months of April and May set the stage for lower than normal lake levels at area reservoirs. Corps water managers rely on runoff from rainfall in April and May to fill the pools of reservoirs in the basin; however, this year those filling rains did not come. At J. Percy Priest Lake, the current reservoir level is about 3.5 feet below the elevation it should be for this time of year, and is 1.4 feet lower than it has ever been on this date. Likewise, Lake Barkley is approximately 1.4 feet lower than normal. The current Lake Barkley lake level is also at a new record low level for this date, approximately 0.5 feet lower than that observed during the 1988 drought. According to the National Weather Service, much of the Cumberland River Basin is considered to be in moderate drought and is approximately 5-6 inches behind in annual rainfall.
Lower lake levels combined with significantly reduced flow in area streams have resulted in impacts to a wide range of benefits that are dependent on the coordinated operation of the Cumberland River reservoir system. The current drought, while still in its early stages, is already creating taste and odor treatment challenges for area water treatment plants, impacting fish and aquatic life due to stressed environmental conditions, and significantly reducing hydropower generation capability. If conditions continue to worsen, the drought has the potential to disrupt the operation of coal-fired power plants, which rely on the Cumberland River for cooling water, and impact the availability of water for municipalities that rely on area reservoirs for supplies.
Mitigating potential impacts due to drought is largely 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 support the 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 mid-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 spring 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, has limited the Corps’ ability to respond to current low flow conditions. Without lake level restrictions, an adequate volume of cold water would normally 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.
(The public can obtain news, updates and information from the U.S. Army Corps of Engineers Nashville District on the district’s website at www.lrn.usace.army.mil
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