A habitat restoration project is underway by the U.S. Fish and Wildlife Service (Service) that will dramatically improve conditions for fish and wildlife at Swan Lake, a 2,600-acre backwater area in Calhoun County, Illinois. As part of the restoration project, the agency this summer will temporarily lower the water level of the lake, an action that is expected to limit boater access to the lake and result in mortality of a large number of the lakes fish, mostly carp and buffalo. The Service, which manages Swan Lake as part of Mark Twain National Wildlife Refuge, predicts tremendous benefits for the lakes fish and waterfowl populations once the lake is flooded again this fall.
We are excited about the prospects of a greatly improved Swan Lake, both for fish populations and the large numbers of waterfowl that use this lake, said Howard Phillips, manager of the Mark Twain National Wildlife Refuges Brussels District. But in order to gain those benefits in the long term, we must undergo a short period of rebuilding, and that includes the temporary lake drawdown and resulting impacts on the fish population and boater and angler access to the lake.
Phillips says the lake drawdown is needed to dry out the lake bed, which over the years has filled with sediment, making the lakes bottom unsuitable for growth of aquatic vegetation needed by fish and wildlife for feeding, resting, and shelter. Excessive sedimentation also contributes to turbid, or cloudy, water, further inhibiting the growth of desirable aquatic plants.
Swan Lake is one of the largest remaining backwater areas on the Illinois River, and with this restoration, can again become one of the premiere areas for fish and wildlife habitat along the river, Phillips said. Were looking at a project here that will provide phenomenal results for waterfowl once aquatic vegetation is reestablished.
Phillips also expects to see a vast improvement in the lakes fishery, which currently supports mostly rough fish, mainly carp and buffalo. This project should make the lake more attractive to a variety of species, including game fish such as bass, bluegill, and crappie.
Because high mortality is expected among the lakes current fish populations, Phillips is encouraging commercial anglers to work the lake as much as possible to remove as many commercial species as possible as the lakes level drops. Phillips has contacted traditional commercial users of the lake to notify them of this opportunity.
This summers restoration effort follows completion of a joint project with the U.S. Army Corps of Engineers and the Illinois Department of Natural Resources that allows managers to control water levels in the lake and reduce sedimentation. Using water control structures installed as part of the project, the lakes managers can imitate the seasonal variations in water levels which no longer occur naturally. By periodically drawing down the water level of the lake, the bottom can be solidified to improve aquatic plant production and turbid water conditions can be reduced.
Phillips expects such drawdowns will not be necessary more frequently than every several years to maintain optimum habitat conditions. The lakes fish populations will be naturally restored by fish entering the lake from the Illinois River.
