Rush Lake

Site Information


Prior to European settlement, Rush Lake was a large, shallow prairie-pothole lake embedded within a rich mosaic of forest, savanna, prairie, and wetland habitats. Its shallow depth, marshy shoreline, and extensive stands of hard-stem bulrush and other native aquatic vegetation provided ideal waterfowl and waterbird habitat. Settlement of the region began in the early 1800s and resulted in native habitats being converted to agricultural fields and pastures. Waterways were ditched, drained, or otherwise altered for human use causing sediment and nutrient runoff and an overall reduction in water quality within the Rush Lake watershed. Decades of market and sport waterfowl hunting introduced large amounts of lead shot and further contaminated the aquatic ecosystem. Dams along Waukau Creek maintained artificially high water levels that limited aquatic plant growth and impacted the ecological community. In recent years, a group of local residents, state and federal officials, and others formed the Rush Lake Steering Committee to address these issues and revitalize the lake and surrounding wetlands.

Existing topography/vegetation

Rush Lake covers 1,240 hectares and is the largest prairie-pothole lake east of the Mississippi River. Shallow water depth (< 0.7 meter) and mucky bottom sediments support emergent and submergent plant communities of cat-tail, hard-stem bulrush, sedges, water-willow, coon’s-tail, common water-milfoil, and pondweeds. Wet prairie, shrub-carr, and other natural communities buffer portions of the lakeshore from surrounding agricultural lands. Although row crops dominate the landscape, idle warm season grassland, pasture, restored prairie, and oak savanna habitats persist in some upland areas.

Current management/land use

Rush Lake is located within a regional network of habitat restoration projects known as the Glacial Habitat Restoration Area (GHRA). The GHRA is managed by the Wisconsin Department of Natural Resources and aims to restore and conserve 15,600 hectares of permanent grassland nesting cover and 4,500 hectares of wetlands in Columbia, Dodge, Fond du Lac, and Winnebago counties. Although most lands surrounding Rush Lake are in private ownership, Rush Lake State Natural Area is a 178-hectare wetland parcel located directly adjacent to the lake that is owned and managed by The Nature Conservancy.

Current management of Rush Lake focuses on improving water quality and wildlife habitat. In 2005, the dam at the outlet of Rush Lake was replaced with a new structure to facilitate water level management for the benefit of wildlife and habitat. From the spring of 2006 through the fall of 2007, the lake was drawn down to encourage regeneration of native emergent vegetation (especially bulrush beds), consolidate bottom sediments, improve water clarity, and facilitate winter kill of non-native carp. During this time, over 50% of the lake bottom was exposed and the remainder had shallow water depths less than 30 cm. Furthermore, a chemical treatment was conducted in late summer of 2007 to reduce the number of carp within the lake.

Importance to Birds

Although human activities have altered the ecological conditions of Rush Lake, it continues to support a diverse avifauna. It hosts the largest breeding population of Red-necked Grebes in Wisconsin and also supports breeding Redhead, Ruddy Duck, Forster’s Tern, Black Tern, Least Bittern, American Bittern, King Rail, Marsh Wren, and Swamp Sparrow. It provides an important foraging area for American White Pelican, Double-crested Cormorant, and several species of herons and egrets. The surrounding upland areas provide nesting habitat for grassland birds including Sedge Wren, Vesper Sparrow, Savannah Sparrow, Bobolink, and Eastern Meadowlark. Rush Lake was identified as a Wisconsin Important Bird Area in 2006.

Priority Birds

Species Opportunity Special Habitat Feature
Canada Goose Low  
Tundra Swan Moderate  
Mallard High  
Blue-winged Teal High  
Northern Pintail Moderate  
Canvasback Low  
Redhead Moderate  
Lesser Scaup Low  
Red-necked Grebe High  
American Bittern Moderate  
Great Egret Low  
Northern Harrier Moderate  
King Rail Low  
American Golden Plover Moderate  
Greater Yellowlegs Moderate  
Solitary Sandpiper Moderate  
Whimbrel Moderate  
Hudsonian Godwit Moderate  
Marbled Godwit Moderate  
Buff-breasted Sandpiper Moderate  
Short-billed Dowitcher Moderate  
Forster’s Tern High  
Black Tern High  
Short-eared Owl Moderate Wintering and migratory stopover area.
Willow Flycatcher Low  
Marsh Wren High  
Sedge Wren High  
Dickcissel Low  
Field Sparrow Low  
Vesper Sparrow Moderate  
Swamp Sparrow Moderate  
Henslow’s Sparrow Moderate  
Bobolink Moderate  
Eastern Meadowlark Moderate  
Yellow-headed Blackbird High  

Conservation Issues

More than a century of artificially high water levels eliminated and precluded re-establishment of most emergent vegetation stands at Rush Lake. The significant decline of hard-stem bulrush cover in particular altered the suitability of Rush Lake for many breeding species of high conservation priority. Sediments and nutrients enter the watershed from surrounding agricultural land and reduce water quality. Non-native carp further degrade habitat and water quality by re-suspending sediments during bottom feeding, uprooting vegetation, and consuming desirable plants. Rush Lake’s deep, mucky bottom sediments are contaminated with an estimated 300 tons of lead shot from decades of intensive waterfowl hunting. Birds that ingest lead shot during feeding can die from lead poisoning. A large mortality event attributed to lead poisoning occurred in 1989 and killed more than 1,270 waterfowl. Few invasive plants occur at Rush Lake but purple loosestrife and hybrid cat-tail are present within the watershed and should be monitored and controlled.

Management Recommendations


Information Sources

Information for this account was taken from:

Northern Environmental. 2002. Rush Lake/Upper Waukau Creek Resource Inventory and Strategic Planning Project Report. Northern Environmental Technologies, Inc., Waupun, WI.

Steele, Y. (ed.). 2007. Important Bird Areas of Wisconsin: critical sites for the conservation and management of Wisconsin birds. Wisconsin Department of Natural Resources PUB-WM-475-2007. Madison, WI.

Contact Information


Kreitinger, K., Y. Steele and A. Paulios, editors. 2013.
The Wisconsin All-bird Conservation Plan, Version 2.0. Wisconsin Bird Conservation Initiative.
Wisconsin Department of Natural Resources. Madison, WI.

Website by J Davis Web Design