Overview

Located in east central Wisconsin, the Winnebago Pool Lakes, composed of Lakes Winnebago, Butte des Morts, Winneconne, and Poygan, drain 16,654 square kilomerers and compose 17% of Wisconsin's surface water area. Major watersheds include the Wolf River to the north and the Upper Fox River to the south with the system emptying from Lake Winnegabo via the Lower Fox River to the southwestern end of Green Bay on Lake Michigan The Lakes lie in the vegetation tension zone between the Northern Forest and the Prairie-Forest floristic provinces (Curtis. 197 1 ), and the watershed transects three US ecoregions, the Southeastern Wisconsin Till Plain, the North Central Hardwood Forests, and the Northern Lakes and Forests. Consequently, land use ranges from mixed hardwood forest in the north to partially specialized dairying with some generalized farming southward.

The Lake Winnebago System is within 120 km of over 2 million people, and is central to many, often conflicting, resource uses, including outdoor recreation such as fishing and boating, wastewater assimilation for 59 industries and 24 municipal wastewater treatment plants, and as a principal water supply for over 100,000 people in Oshkosh, Neenah-Menasha and Appleton as well as numerous small communities in the watershed (East Central Wisconsin Regional Planning Commission [ECWRPC], 1989). The Lake Winnebago System provides over one million userdays during the peak month of recreation for boaters and anglers from Wisconsin and other states, most notably nearby Illinois. The dam system and water level control program, representing the largest flood control storage reservoir in Wisconsin, provide flood protection for residents and shoreland development within 17 jurisdictions. Water levels in the Upper Lake Winnebago Pool Lakes have been controlled through dam outflows by the Corps of Engineers since the late 1800's; principally to assist commercial navigation and downstream industrial uses of waste assimilation and power generation (WDNR, 1989). As a result of a revised water level management policy instituted in 1982, lake Ievels in the summer are now approximately 1 m higgr than previously occurring levels in the summer, and 10-30 cm higher in the winter. The Corps is required to maintain levels within a seasonal range of 1.05 111. Under the current water level management strategy, the water level rapidly increases in the spring and summer, resulting in high lake levels during early plant growth. 'This is followed by allowing the water levels to gradually decrease through the fall to achieve a drawdown in the winter to prevent ice damage along the lake shores and to be prepared for moderating spring runoff levels (Krug, 1981 ) .

Date  2011

Author   Aquatic Biologist

Historical Description

A detailed description of Lake Winnebago water quality can be found in the Winnebago Comprehensive Management Plan(1989). Major water quality concerns for the lake are rural and urban nonpoint source pollution being delivered to the lake from the immediate drainage area and from the Upper Fox And Wolf River Basins. Potential point source pollution, particularly form the Fond du Lac and Oshkosh areas, is also a concern. A major concern is the impact on local water quality of dredged side channels on the lake. The Fox Valley Water Quality Planning Agency (agency no longer exists) has done extensive monitoring on Lake Winnebago.

Many man-made lateral channels along the shores of the Winnebago pool lakes were constructed prior to the creation of the regulations which now scrutinize such projects. Water quality concerns raised on the potential negative impacts of these channels and the receiving lakes include: creation of direct nonpoint source pollution conduits to the lakes from upland areas; increased nuisance vegetation and algae; destruction or alteration of adjacent wetlands; increased human disturbance of potential critical habitat areas; development and related destruction of adjacent upland habitat; creation of carp spawning areas; and, local planning and zoning issues.

DNR Lake Michigan District Water Resources staff has monitored the Wolf River at Fremont, the Fox River at Omro, the Fond du Lac River at Fond du Lac, and Lake Winnebago outlet at Neenah-Menasha to determine phosphorus loadings to Lake Winnebago associated with runoff from upstream watersheds. In-stream flows and samples for phosphorus and suspended solids were taken at regular intervals.

Monitoring is was completed on the tributaries and the monitoring effort will continue on Lake Winnebago at sites established in 1989. The effort will complement monitoring from the late 1970's and early 1980's that were started with the Fox Valley Water Quality Planning Agency. The goal is two fold: satisfy recommendations in the Winnebago comprehensive Management Plan and better define the trophic status of Lake Winnebago. The trophic status of a lake is a measure of nutrients and how they impact chlorophyll production and water transparency.

A preliminary report on the monitoring described above was prepared in 1990 and an update will be completed after this open water season (1995). Algae are responsible for the high chlorophyll production. Associated with a certain type of algae (blue-greens) are toxins. These toxins are a special concern for Lake Winnebago because of the four municipalities (Appleton, Menasha, Neenah, and Oshkosh) that draw their water supply from the Lake. About 100,000 people depend on Lake Winnebago for drinking water (McLennan, 1994).

Doctor Fun Chu, a professor from the University of Wisconsin Madison's Food Science Program has measured these toxins at the four municipal water treatment plants. His results have shown that there are very small levels, at the part per trillion level, getting into the finished water supply at the four municipalities. An information newsletter was sent out to the press in December 1993 informing the public. "It is unlikely that the trace amount of the toxin in the finished water (almost non-detectable) has any acute toxic effect on human and animal health", Chu concluded.

Date  1995

Author   Surface Water Inventory Of Wisconsin

General Condition

Lake Winnebago Menominee Park Beach was assessed for the 2018 listing cycle; E. coli data sample data were clearly below the 2018 WisCALM listing thresholds for the Recreation use. This beach was meeting this designated use and was not considered impaired.

Date  2017

Author  Ashley Beranek

General Condition

Lake Winnebago Fresh Air Park Beach was assessed for the 2018 listing cycle; E. coli data sample data were clearly below the 2018 WisCALM listing thresholds for the Recreation use. This beach was meeting this designated use and was not considered impaired.

Date  2017

Author  Ashley Beranek

Impaired Waters

High Cliff SP - Lake Winnebago Beach was evaluated for bacteria in the 2022 cycle; E. coli levels were above listing thresholds as outlined in 2022 WisCALM. This beach was added to the 2022 Impaired Waters List.

Date  2022

Author  Ashley Beranek

Impaired Waters

Lake Winnebago (131100) was placed on the impaired waters list in 1998 for total phosphorus, sediment/total suspended solids, and PCBs. The 2016 assessments showed continued impairment by phosphorus; total phosphorus sample data overwhelmingly exceed 2016 WisCALM listing thresholds for the Recreation use and exceeded Fish and Aquatic Life use, however, chlorophyll data only exceeds REC thresholds. Based on the most updated information, no change in existing impaired waters listing is needed.

Date  2015

Author  Aaron Larson

Condition

Wisconsin has over 84,000 miles of streams, 15,000 lakes and milllions of acres of wetlands. Assessing the condition of this vast amount of water is challenging. The state's water monitoring program uses a media-based, cross-program approach to analyze water condition. An updated monitoring strategy (2015-2020) is now available. Compliance with Clean Water Act fishable, swimmable standards are located in the Executive Summary of Water Condition in 2018. See also the 'monitoring and projects' tab.

Reports

Recommendations

Management Goals

Wisconsin's Water Quality Standards provide qualitative and quantitative goals for waters that are protective of Fishable, Swimmable conditions [Learn more]. Waters that do not meet water quality standards are considered impaired and restoration actions are planned and carried out until the water is once again fishable and swimmable

Management goals can include creation or implementation of a Total Maximum Daily Load analysis, a Nine Key Element Plan, or other restoration work, education and outreach and more. If specific recommendations exist for this water, they will be displayed below online.

Monitoring

Monitoring the condition of a river, stream, or lake includes gathering physical, chemical, biological, and habitat data. Comprehensive studies often gather all these parameters in great detail, while lighter assessment events will involve sampling physical, chemical and biological data such as macroinvertebrates. Aquatic macroinvertebrates and fish communities integrate watershed or catchment condition, providing great insight into overall ecosystem health. Chemical and habitat parameters tell researchers more about human induced problems including contaminated runoff, point source dischargers, or habitat issues that foster or limit the potential of aquatic communities to thrive in a given area. Wisconsin's Water Monitoring Strategy was recenty updated.

Grants and Management Projects

Monitoring Projects

Watershed Characteristics

Lake Winnebago is located in the Lake Winnebago - East watershed which is 99.40 mi². Land use in the watershed is primarily agricultural (51.20%), grassland (19.40%) and a mix of suburban (11.60%) and other uses (17.80%). This watershed has 177.39 stream miles, 252.07 lake acres and 1,539.57 wetland acres.

Nonpoint Source Characteristics

This watershed is ranked High for runoff impacts on streams, Not Available for runoff impacts on lakes and High for runoff impacts on groundwater and therefore has an overall rank of High. This value can be used in ranking the watershed or individual waterbodies for grant funding under state and county programs.However, all waters are affected by diffuse pollutant sources regardless of initial water quality. Applications for specific runoff projects under state or county grant programs may be pursued. For more information, go to surface water program grants.