Water Management on the Refuge
TVA reserved all rights on flood control, navigation, and power production for Kentucky Lake. Water management within refuge controlled impoundments is impacted by the water levels of the reservoir. Kentucky Lake has an annual water fluctuation which is exactly opposite of what is needed for water management within the refuge impoundments. Normal summer pool is 359' MSL with a drawdown to 354' MSL during the winter months. The reservoir drawdown begins July 5 gradually dropping to winter pool on December 1. The lake begins to rise again on April 1 reaching summer pool on May 1. Even though the water management schedule for Kentucky Lake presents difficulties in managing the water within the impoundments, the benefits of the habitats produced on the reservoir greatly outweigh the negative impacts.
A water management program is managed for 23 impoundments on the refuge. The primary purpose for managing the water levels within these impoundments is to enhance food production and to make it available to waterfowl during migration and wintering periods. Other migratory birds, such as shorebirds, herons, and rails greatly benefit from this management practice. The primary habitats that are managed for within these impoundments are agriculture and moist-soil. When an impoundment or portion of an impoundment is to be planted in row crops such as corn and soybeans the drawdown is planned to initiate in early March to allow sufficient drying time. Moist-soil drawdowns occur later during the growing season and vary from mid-April to mid-July. The drawdown timing and levels for each impoundment varies from year-to-year, as much as possible, to reduce the impacts of undesirable and invasive plants. Water management plans have to be altered during most years due to flooding from Kentucky Lake.
Three small impoundments, totaling about 50 acres are located on the Big Sandy Peninsula. These impoundments represent the only impounded waters on the Big Sandy Unit. The topography of this unit is too rolling to be conducive to large-scale impoundment construction. The existing impoundments are independent of one another and are solely dependant upon rainwater during flooding. These impoundments are managed in a moist-soil/agriculture rotation to provide a diversity of flooded habitats and to keep the fields in a early successional state.
There are fourteen impoundments in the Duck River Bottoms, totaling approximately 4,000 surface acres of water. These impoundments range in size from 10 to 1,200 acres. The existing impoundments are somewhat interconnected and water movement can and does occur between some of the impoundments. A 50,000 GPM electric pump that is located in the lowest end of the bottoms is available to pump water out (not into) of all of the impoundments. Typically, it is only used to pump water out of the lower six impoundments due to time and budget constraints. The water from the remaining impoundments is drained by gravity flow into Kentucky Lake prior to April 1 when the reservoir levels begin to rise towards summer pool. There are only a few impoundments small enough to be efficiently pumped using portable pumps. Flooding of the impoundments begins on a small scale in August in order to provide habitat for early migrating waterfowl and rails. For the most part, fall filling is dependant upon rainfall. Rarely can the refuge open Water Control Structures to move water from the reservoir into any impoundment because the reservoir water level has dropped to the winter pool.
There are four impoundments on the Busseltown Unit, totaling 300 acres. The drawdown of these impoundments generally occurs in early March. Fall filling of most of the unit occurs by rainfall. A few small impoundments are typically filled by the use of portable pumps.