Rush Lake is located within the Wisconsin DNR?s Glacial Habitat Restoration Area. It is the largest prairie-pothole lake east of the Mississippi River, and formerly held hardstem bulrush beds more than 1,500 acres in extent. In recent years, the bulrush beds have declined greatly in acreage due to artificially high water levels, degraded water quality, and carp infestation. Restoration of the emergent marsh and bulrush acreage is underway, and a non-profit organization has been formed to oversee management and restoration activities. The lake has extensive submergent vegetation composed of chara, pondweeds, coontail, and common water milfoil; the emergent marsh is dominated by cattail and hardstem bulrush, but there are areas of sedge meadow, wet prairie, and shrub-carr as well. Some oak savanna and oak forest are found in the uplands.

Ornithological Summary

The large size, high productivity, and shallow depth (only 1.5 to 6 feet) of Rush Lake make it extremely valuable as waterbird and waterfowl habitat. Grebes, terns, herons, bitterns, rails, and ducks all breed here. Even with recent population declines, Rush Lake is the foremost nesting site for Red-necked Grebe in Wisconsin. Breeding records of Western Grebe attest to this site being one of the few in Wisconsin with habitat attractive to this rare species. Other wetland breeders include Least Bittern, American Bittern, Common Moorhen, and large numbers of American Coot, Forster?s and Black terns, Redhead, Ruddy Duck, King, Virginia, and Sora rails, Black-crowned Night-Heron, Marsh Wren, and Swamp Sparrow. The site hosts a robust community of grassland birds, among them Northern Harrier, Sedge Wren, Vesper Sparrow, Savannah Sparrow, Bobolink, and Eastern Meadowlark. American White Pelicans and Double-crested Cormorants use the lake as a foraging area, as do many herons and egrets. Waterfowl concentrate here in migration, and Short-eared Owls use the grassland areas in winter. Rush Lake has been identified as a wetland of high conservation significance and as a priority site for grassland birds (Pohlman et al. 2006, Sample and Mossman 1997).

Conservation Issues

Three major problems have contributed to habitat degradation and declining wildlife populations at Rush Lake: 1) artificially stable high water levels resulting from the Waukau Creek dam and its silted outlet channel have drowned out emergent vegetation, particularly the hardstem bulrush for which the lake is named, 2) sediment and nutrient runoff have degraded water quality, and 3) invasion by non-native carp has negatively impacted aquatic vegetation. In addition, lake sediments have been contaminated by lead shot from decades of intense waterfowl hunting. A steering committee made up of government representatives, citizens, and user groups was formed in 1999 and worked for several years to develop a restoration plan, which is now being implemented with the participation of many partners. The steering committee has been restructured to form Rush Lake Watershed Restoration, Inc., a nonprofit organization that will manage funds and guide restoration efforts. Restoration goals include restoring bulrush beds and submergent vegetation, reestablishing grassland habitat around the lake, eradicating carp, and monitoring sediment and nutrient levels. A two-year drawdown of water levels was begun in March, 2006 to start allowing native wetland plants to regenerate, consolidate bottom sediments, and facilitate winterkill of carp (WDNR 2007).

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