Big Muskego Lake, Middle Fox River - Illinois Watershed (FX04)
Big Muskego Lake, Middle Fox River - Illinois Watershed (FX04)
Big Muskego Lake (762400)
2194.34 Acres
Natural Community
Natural communities (stream and lake natural communities) represent model results that use predicted flow and temperature based on landscape features and related assumptions. Ranges of flow and temperature associated with specific aquatic life communities (fish, macroinvertebrates) help biologists identify appropriate resource management goals. Wisconsin Natural Communities.
Shallow Lowland
Year Last Monitored
This is the most recent date of monitoring data stored in SWIMS. Additional surveys for fish and habitat may be available subsequent to this date.
Trout Water 
Trout Waters are represented by Class I, Class II or Class III waters. These classes have specific ecological characteristics and management actions associated with them. For more information regarding Trout Classifications, see the Fisheries Trout Class Webpages.
Outstanding or Exceptional 
Wisconsin has designated many of the state's highest quality waters as Outstanding Resource Waters (ORWs) or Exceptional Resource Waters (ERWs). Waters designated as ORW or ERW are surface waters which provide outstanding recreational opportunities, support valuable fisheries and wildlife habitat, have good water quality, and are not significantly impacted by human activities. ORW and ERW status identifies waters that the State of Wisconsin has determined warrant additional protection from the effects of pollution. These designations are intended to meet federal Clean Water Act obligations requiring Wisconsin to adopt an 'antidegradation' policy that is designed to prevent any lowering of water quality - especially in those waters having significant ecological or cultural value.
Impaired Water 
A water is polluted or 'impaired' if it does not support full use by humans, wildlife, fish and other aquatic life and it is shown that one or more of the pollutant criteria are not met.

Fish and Aquatic Life

Current Use
The use the water currently supports. This is not a designation or classification; it is based on the current condition of the water. Information in this column is not designed for, and should not be used for, regulatory purposes.
Shallow Lowland
Shallow lowland lake describes the depth and location of the lake in a watershed. These variables affect the lakes response to watershed variables.
Attainable Use
The use that the investigator believes the water could achieve through managing "controllable" sources. Beaver dams, hydroelectric dams, low gradient streams, and naturally occurring low flows are generally not considered controllable. The attainable use may be the same as the current use or it may be higher.
Fish and Aquatic Life - waters that do not have a specific use designation subcategory assigned but which are considered fishable, swimmable waters.
Designated Use
This is the water classification legally recognized by NR102 and NR104, Wis. Adm. Code. The classification determines water quality criteria and effluent limits. Waters obtain designated uses through classification procedures.
Default FAL
Fish and Aquatic Life - Default Waters do not have a specific use designation subcategory but are considered fishable, swimmable waters.


Big Muskego Lake is a large shallow remnant basin occupying part of an old glacial lake bed. A conspicuous band of beach sand and gravel occupies the original east shore some distance from the present open water. Nearly 1,000 acres of the basin are presently classed as deep marsh in wetlands inventories. Originally the lake drained to the Root River, thence to Lake Michigan; construction of a canal to Wind Lake, Racine County, altered the drainage. The lake presently drains to the Fox (Illinois) River and the Mississippi River system. A head of about three feet is maintained by a dam on the outlet canal. The fishery is composed of pan fish, northern pike, walleye, and largemouth bass. Winterkill, weeds, and carp have all at times been cited as use problems. Rough fish removal operations were undertaken here as recently as 1958. Public access at present is questionable. This was formerly considered one of the best duck hunting lakes in southeastern Wisconsin In 1942, the Game Management Division suggested additional head on the dam, weed treatment, continued carp removal, and closed season on muskrats as methods of creating better waterfowl habitat.

Source: 1963, Surface Water Resources of Waukesha County Big Muskego Lake T5N, R20E, Sections 13, 14, 22, 23, 26, and 27 Surface Acres = 2,260, S.D.F. = 2.66, Maximum Depth = 26 feet (in Bass Bay).

Date  1963

Author   Aquatic Biologist


Diagnostic/Feasibility Assessment
The Big Muskego/Bass Bay Protection and Rehabilitation District conduced an extensive water quality and aquatic plant diagnostic feasibility examination of the drawdown and fish eradication at Big Muskego Lake. Project activities include determining rates of nitrogen and phosphorous release from sediments, analyzing sediment cores to determine moisture content, density, organic matter, total sediment nitrogen and phosphorous, porewater nitrogen and phosphorous, extractable phosphorous, and exchangeable sediment nitrogen, and evaluating changes in the distribution, abundance, and species composistion of aquatic macrophytes from aerial photography and field survey work before and after drawdown.
Nine Key Element Plan
Muskego-Wind Lakes PWS Plan - Nine Key Element Plan - The Muskego-Wind Lakes Priority Watershed Project plan assesses the nonpoint sources of pollution in the Muskego-Wind Lakes Watershed and guides the implementation of nonpoint source control measures. These control measures are needed to meet specific water resource objectives for the Muskego-Wind Lakes Priority Watershed Project area. The purpose of this project is to reduce the amount of pollutants originating from nonpoint sources that reach surface water and groundwater within the Muskego-Wind Lakes Priority Watershed Project area.
Monitor Aquatic Biology
This lake is undergoing intensive management following the principles of biomanipulation to improve water quality not only within the lake, but further downstream to Wind Lake and the Fox River..

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 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

Big Muskego Lake is located in the Middle Fox River - Illinois watershed which is 247.72 miĀ². Land use in the watershed is primarily agricultural (35.50%), suburban (19.20%) and a mix of wetland (16.20%) and other uses (29.10%). This watershed has 316.41 stream miles, 6,810.35 lake acres and 22,750.85 wetland acres.

Nonpoint Source Characteristics

This watershed is ranked High for runoff impacts on streams, Medium 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.

Natural Community

Big Muskego Lake is considered a Shallow Lowland under the state's Natural Community Determinations.

Natural communities (stream and lake natural communities) represent model resultsand DNR staff valiation processes that confirm or update predicted conditions based on flow and temperature modeling from historic and current landscape features and related variables. Predicated flow and temperatures for waters are associated predicated fish assemblages (communities). Biologists evaluate the model results against current survey data to determine if the modeled results are corect and whether biological indicators show water quaity degradation. This analysis is a core component of the state's resource management framework. Wisconsin's Riverine Natural Communities.

Shallow lowland lake describes the depth and location of the lake in a watershed. These variables affect the lakes response to watershed variables.