Little Muskego Lake, Middle Fox River - Illinois Watershed (FX04)
Little Muskego Lake, Middle Fox River - Illinois Watershed (FX04)
Little Muskego Lake (762700)
469.76 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.
Deep 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.
Deep Lowland
Deep 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.


Little Muskego Lake is a medium-sized natural drainage lake bordering the terminal moraine, drained by Muskego Creek. An impounding structure maintains the lake level. Several small islands break up the open expanse of water. The fishery consists of pan fish, largemouth bass and northern pike. Access is afforded by a city road, community parks, and bathing beaches. Weed and algae control has been necessitated in the past in shallow bays.

Source: 1963, Surface Water Resources of Waukesha County Little Muskego Lake T5N, R20E, Section 9 Surface Acres = 460, S.D.F. = 1.90, Maximum Depth = 65 feet.

Date  1963

Author   Aquatic Biologist

Little Muskego Lake, Middle Fox River - Illinois Watershed (FX04) Fish and Aquatic LifeLittle Muskego Lake, Middle Fox River - Illinois Watershed (FX04) RecreationLittle Muskego Lake, Middle Fox River - Illinois Watershed (FX04) Fish Consumption

General Condition

Little Muskego Lake (WBIC 762700) was placed on the impaired waters list for total phosphorus and low dissolved oxygen in 1998. This water was assessed during the 2018 listing cycle; new total phosphorus, chlorophyll-a, and dissolved oxygen sample data were clearly below the 2018 WisCALM listing thresholds for the Recreation use and the Fish and Aquatic Life use. This water was meeting these designated uses and was not considered impaired.

Date  2017

Author  Ashley Beranek


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.



Best Management Practices, Implement
The City of Muskego will install a number of shoreline restoration best management practices on Holz Island, located on Little Muskego Lake. These include vegetated rip rap, coconut logs, tree drops, emergent shoreline plantings and prairie plantings. Existing invasive plant species on the island will be cleared and eradicated to the extent possible.
Land Acquisition
The Little Muskego Lake Protection and Rehabilitation District will acquire 20.57 acres in Waukesha County.The property contains an intermittent stream and wetlands including an emergent wet meadow with thick stand of cattails. Educational benefits of this property will include a formal trail system and educational study station.
Land Acquisition
The Little Muskego Lake P & R District will acquire 8.8 acres located in the SW 1/4 of Section 33 in the City of New Berlin, as part of the Little Muskego Lake Community's plan to purchase, reclaim, restore and preserve approximately 12 miles of stream corridor tributary to Little Muskego Lake. The property includes a segment of Calhoun Creek, wooded floodplain, wetlands, and uplands.

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

Little 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.This water is ranked High Lake for individual Lakes based on runoff problems and the likelihood of success from project implementation.

Natural Community

Little Muskego Lake is considered a Deep 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.

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