Bass Lake (T30N R19W S23), Lower Willow River Watershed (SC02)
Bass Lake (T30N R19W S23), Lower Willow River Watershed (SC02)
Bass Lake (T30N R19W S23) (2450500)
369.98 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 Seepage
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.
St. Croix
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 Seepage
Deep seepage lake describes the depth and hydrologic charactertistics of the lake. 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.
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.


The 1,398-acre watershed of Bass Lake is relatively small compared to lake size; the watershed-to-lake ratio is approximately 3:1. This is a contributing factor in maintaining good water quality in Bass Lake (Hess et. al. 1997). The watershed has a mixture of land cover, but cropland is decreasing and developed acreage is increasing. Konkel

Date  2007

Author   Aquatic Biologist


Bass Lake is a hardwater seepage lake managed for walleyes, largemouth bass and panfish. The panfish population includes bluegills, black crappies, perch, pumpkinseeds and yellow bullheads. Carp and white suckers are also present. Naturally fluctuating water levels are a problem for the cottage owner and aquatic life. Public access is had by use of a town road to the lake at its south end. Two boat liveries are available. About 65 per cent of the lakeshore is privately developed by a resort and 52 cottages. There is no public frontage on the lake other than the public access. Muskrats and nesting mallards and blue-winged teal utilize the 8 acres of "Scirpus" wetlands bordering the lake. Boating is restricted by local ordinance in motor size and use hours.

Surface Acres = 293.0 S.D.F. = 2.40 Maximum Depth = 37 feet

Source: 1961, Surface Water Resources of St.Croix Co. Bass Lake - T. 30 N., R. 19 W., Sec. 14, 23, 26

Date  1961

Author   Aquatic Biologist

Historical Description

Bass Lake is recommended as an Outstanding Resource Water to be included in NR 102 by Department staff. This is a high quality mesotrophic lake in western St. Croix county near the village of Sommerset. The residents around the lake have recognized the importance of protecting the good water quality that is present in the lake. The residents formed the Bass Lake Protection and Rehabilitation District in early 1987.

WDNR, the lake district and St. Croix county jointly conducted an EPA Phase I Diagnostic and Feasibility Study which was completed in 1992. This study was conducted to develop a comprehensive lake management plan which would protect this high value aquatic ecosystem. The study identified several current and potential threats which would ultimately degrade water quality if they are not controlled. The study found that full rural residential development can occur in the watershed and water quality can actually be improved if lake protection management activities are implemented throughout the watershed. An array of management recommendations were developed in the study and there full implementation will be critical for the long term protection of the Bass Lake ecosystem.

Date  1992

Author   Aquatic Biologist

Bass Lake (T30N R19W S23), Lower Willow River Watershed (SC02) Fish and Aquatic LifeBass Lake (T30N R19W S23), Lower Willow River Watershed (SC02) RecreationBass Lake (T30N R19W S23), Lower Willow River Watershed (SC02) Fish Consumption

General Condition

Bass Lake (T30N R19W S23) (2450500) was assessed during the 2016 listing cycle; total phosphorus and chlorophyll sample data were clearly below 2016 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use. This water is meeting these designated uses and is not considered impaired.

Date  2015

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.



Lake Management Plan Implementation
Bass Lake Management District is sponsoring a Lake Management Planning Implementation project aimed at reducing phosphorus loads and protecting and improving diverse aquatic life through shoreland restoration projects and BMP installations.
Lake Management Plan Development
St. Croix County proposes to hire a half-time staff for five years who will be located in the County Zoning office and will perform the zoning ordinance enhancement activities for the Bass Lake area.
Restoring buffer strips on the margins of cropland and streambanks, as well as shoreline buffer zones are important steps in protecting water quality and improving shoreline and littoral habitat.
Runoff Grant
The Bass Lake watershed should be considered a high priority for selection as a priority lakes project in the Wisconsin Nonpoint Source Pollution Abatement Program (Type B).

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

Bass Lake is located in the Lower Willow River watershed which is 164.38 miĀ². Land use in the watershed is primarily agricultural (32.10%), forest (25.40%) and a mix of grassland (23.70%) and other uses (18.80%). This watershed has 99.33 stream miles, 2,139.74 lake acres and 2,482.81 wetland acres.

Nonpoint Source Characteristics

This watershed is ranked High for runoff impacts on streams, Not Ranked 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

Bass Lake (T30N R19W S23) is considered a Deep Seepage 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.

Deep seepage lake describes the depth and hydrologic charactertistics of the lake. These variables affect the lakes response to watershed variables.