Site Information
- Ecological Landscape: Southeast Glacial Plains
- Location: Winnebago County
- Priority Habitats: Emergent Marsh, Southern Sedge Meadow and Marsh, Wet Prairie, Idle Cool Season Grasses and Forbs, Oak Opening
Introduction
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
- Manage water levels including drawdowns as needed to encourage re-establishment of bulrush and other emergent vegetation and facilitate winter kill of carp.
- Continue control of carp, cat-tail, purple loosestrife, and other invasive species through biological, chemical, and mechanical means.
- Restore native grasslands adjacent to the lake for nesting wetland and grassland birds.
- Restore drained wetlands within the Rush Lake watershed to increase wildlife habitat and improve water quality.
- Collaborate with partners in the Rush Lake/Eightmile Creek watershed to reduce transport of sediments and nonpoint pollutants into the lake.
- Work with the towns of Ripon and Nepeuskun to maintain agriculture and limit development on critical upland habitat adjacent to the lake.
- Continue to use Stewardship funds to acquire uplands adjacent to the lake as part of the GHRA program.
- Implement a marshbird monitoring program to adequately measure abundance, distribution, population status, and habitat use at Rush Lake.
Partners
- Ducks Unlimited: http://www.ducks.org
- Pheasants Forever: http://www.foxvalleypheasants.com/
- Rush Lake Watershed Restoration, Inc.
- U.S. Fish and Wildlife Service: http://www.fws.gov/
- Winnebago County Land and Water Conservation Department: http://wclwcd.org/index.htm
- Wisconsin Department of Natural Resources: http://www.dnr.state.wi.us/
Information Sources
- Rush Lake Resource Inventory and Strategic Planning Project Report: http://www.northernenvironmental.com/projects/Rush%20Lake/Rush%20Lake%20Report/Rush%20Lake%20Report.html
- Wisconsin Department of Natural Resources Rush Lake page: http://www.dnr.state.wi.us/org/land/wildlife/rushlake/index.htm
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
- Compiler: Yoyi Steele, Yoyi.Steele@Wisconsin.gov
- Editor: Kim Kreitinger, K.Kreitinger@gmail.com