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Restoring water quality and aquatic habitat are critical components of an intensive project on Rush Lake, a 3,000-acre prairie pothole in Winnebago County.
The project involves re-grading and dredging the outlet channel of the lake and replacing the existing dam with a more efficient structure that will allow a two-year drawdown of water levels. The drawdown is needed to stimulate the germination and establishment of aquatic vegetation that has severely declined on the lake over the past 20 years.
At the same time, non-native, invasive carp will be eliminated through winterkill and possible chemical treatment. These practices should restore the habitat for many species of wildlife and fish that use this wetland. In addition, the DNR and partners are restoring smaller wetlands and native grasslands in the surrounding watershed.
Partners in this project include U.S. Fish and Wildlife Service, Ducks Unlimited, the Rush Lake Watershed Restoration, Inc., and the Wisconsin Historical Society.
Among the activities accomplished to date, Ducks Unlimited completed engineering plans for the new water control structure and channel dredging, DNR completed an environmental analysis and hosted a public hearing, water regulation permits were issued and the Wisconsin Historical Society completed a thorough archaeological survey of the project site and recovered artifacts in construction areas.
In addition, a new dam has been installed and the outlet channel was dredged and regraded. The new outlet channel follows the natural channel meanders, and includes rock and gravel habitat features. The new dam has six gates and will allow much better water level control in the lake. The dam also includes a mechanical carp barrier to prevent these harmful fish from entering the lake.
Last year, the Bois Forte Band of Chippewa brought their "Swamp Devil" to Rush Lake to clear cattails from the outlet channel leading up to the dam.
Most recently, old culverts on the outlet stream were replaced with free-span bridges that improve stream flow and facilitate the drawdown while allowing public access to the lake. The dam gates were opened last summer, and with the drawdown, mudflats were exposed and are beginning to green up with new plant growth. Over 3,000 acres of shallow and deep marsh will be restored in Rush Lake by project completion and water clarity is excellent.
Natasha Kassulke is associate editor of Wisconsin Natural Resources magazine.