Lake Du Bay, Lower Big Eau Pleine River,Mosinee Flowage,Little Eau Pleine River,Johnson and Peplin Creeks,Little Eau Claire River,Mill Creek Watershed (CW11)
Lake Du Bay, Lower Big Eau Pleine River,Mosinee Flowage,Little Eau Pleine River,Johnson and Peplin Creeks,Little Eau Claire River,Mill Creek Watershed (CW11)
Lake Du Bay (1412200)
5154.75 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.
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.
Marathon, Portage
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.
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.
Supported Aquatic Life
Waters that support fish and aquatic life communities (healthy biological communities).
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.


Lake DuBay, in the Johnson and Peplin Creeks, Little Eau Claire River, Little Eau Pleine River, Mill Creek and Mosinee Flowage Watersheds, is a 4,649.20 acre impoundment that falls in Marathon and Portage Counties. This impoundment is managed for fishing and swimming and is currently considered impaired.

Date  2015

Author   Aquatic Biologist

Historical Description

Source: 1977, Surface Water Resources of Marathon County

Lake DuBay, T26N, R7E, Section 33
Surface Acres = 6,653, Maximum Depth = 30 feet, Secchi Disk = Not
A soft water drainage lake (impoundment) having slightly acid,
medium brown water of low transparency. The immediate shoreline
is predominantly upland (95 percent) with the remainder being
wetland. Sand is the dominant littoral material, with lesser
amounts of rubble, gravel and muck. Fish inhabiting the flowage
include walleye, northern pike, yellow perch, black crappie,
pumpkinseed, black bullhead, brown bullhead, white sucker and carp.
Migratory waterfowl make considerable use of this flowage.
Emergent and submergent vegetation are common in the littoral area.
Public access is possible from one county and two state access
points. Of the flowage's 42.3 miles of shoreline, 0.9 mile is
public. Developments on the shoreline include 122 dwellings, a
wayside park, Ashley County Park and DuBay County Park. The water
control structure, owned by the Consolidated Water Power Company,
is used to generate electric power. The dam has a head of 25 feet.
Streams entering the flowage include the Wisconsin River, the Big
Eau Pleine River, the Little Eau Pleine River, the Little Eau
Claire River, Peplin Creek, Johnson Creek, Hog Creek and five
unnamed streams. Although Lake DuBay extends into Portage County,
the acreage and shoreline figures for Marathon County represent the
entire flowage. In 1977 the flowage experienced a winterkill, the
first of any significance known to have occurred. This
circumstance was likely precipitated by a significantly reduced
stream flow in the Wisconsin River due to drought conditions.

Date  1977

Author   Surface Water Inventory Of Wisconsin

Lake Du Bay, Lower Big Eau Pleine River,Mosinee Flowage,Little Eau Pleine River,Johnson and Peplin Creeks,Little Eau Claire River,Mill Creek Watershed (CW11) Fish and Aquatic LifeLake Du Bay, Lower Big Eau Pleine River,Mosinee Flowage,Little Eau Pleine River,Johnson and Peplin Creeks,Little Eau Claire River,Mill Creek Watershed (CW11) RecreationLake Du Bay, Lower Big Eau Pleine River,Mosinee Flowage,Little Eau Pleine River,Johnson and Peplin Creeks,Little Eau Claire River,Mill Creek Watershed (CW11) Fish Consumption

Impaired Waters

Lake DuBay (1412200) was placed on the impaired waters list due to excess algal growth caused by an unknown pollutant. The 2016 assessments showed continued excess algal growth but also showed impairment by phosphorus; total phosphorus sample data overwhelmingly exceed 2016 WisCALM listing thresholds for the Recreation use, and chlorophyll data exceed REC thresholds. Total phosphorus and chlorophyll data do not exceed Fish and Aquatic Life thresholds. Based on the most updated information, the unknown pollutant listing was replaced by total phosphorus.

Date  2015

Author  Aaron Larson


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.


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

Lake Du Bay is located in the Mill Creek watershed which is 166.85 miĀ². Land use in the watershed is primarily agricultural (32.70%), forest (28.50%) and a mix of grassland (19%) and other uses (19.70%). This watershed has stream miles, lake acres and 22,403.58 wetland acres.

Nonpoint Source Characteristics

This watershed is ranked High for runoff impacts on streams, Low 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

Lake Du Bay is considered a Reservoir under the state's Natural Community Determinations.

Natural communities (stream and lake natural communities) represent model results and 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.