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Waterfowl Impoundments




Provide the resource and they will come! 

Waterfowl Impoundments

Wheeler NWR manages 16 impoundments to provide approximately 2,000 acres of waterfowl habitat in open water, moist soil, and in areas where agricultural crops can be flooded. Management consists of manipulating water flows through 20 water control structures (WCS) consisting of concrete and/or corrugated metal pipes with flash board riser or screwgate structures. By adjusting the height of the control mechanism (screwgates and riser stoplogs), water levels are set and gravity-induced water flows can be created. In addition, many of the impoundments are located within two large dewatering units (White Springs and Rockhouse Buckeye) that utilize mechanical pumps to remove water.

Generally, impoundments are filled in the fall by rainfall or through spring seepage. Rarely can the refuge open WCSs and allow water to flow from the Wheeler Reservoir into the impoundments because the reservoir's water level has dropped (early to mid-September) prior to the time when filling is needed (late September or early October). Impoundments are not filled with water until farmers harvest crops and just prior to the time birds begin to arrive at the refuge.
Most impoundments, with the exception of the Display Pool at the Visitor Center, can usually be drained or partially drained by gravity into the reservoir or its tributaries before the water level is raised in the spring (early to mid-April) by opening various WCS. A portable pump is used to empty the Display Pool. Impoundment drawdown is initiated after waterfowl leave, generally in late February or March, depending on the impoundment and yearly conditions. In typical years, water has to be pumped out of the impoundments after the reservoir is raised in mid-April.

In the spring, pumps are used to draw down the White Springs Dewatering Unit (Whiteside Pump Station) and the Rockhouse Buckeye Dewatering Unit (Rockhouse Pump Station). These pumps are operated by TVA in cooperation with the refuge and the State of Alabama (the pumps also affect management units on the Swan Creek Wildlife Management Area just west of the White Springs unit) via a cooperative agreement. The costs are paid by the Service or cost-shared as follows: Whiteside Pump Station - May 1 to September 1 - State 20 percent, TVA 50 percent, and Service 30 percent; Rockhouse Pump Station - May 1 to SeptemBuiber 1 - TVA 50 percent and Service 50 percent. The refuge pays 100 percent of pumping costs during the rest of the year when pumps are operated to dewater the units.

Impoundments and related structures are maintained annually as resources and conditions permit. When soil conditions are dry enough, unwanted vegetation (especially woody vegetation) is mowed, disced, or removed. Roadsides and the upper, dryer portion of the dikes are mowed annually. Areas that are farmed do not require as much maintenance.


Last Updated: Dec 09, 2013
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