Fowler Lake, Oconomowoc River Watershed (UR09)
Fowler Lake, Oconomowoc River Watershed (UR09)
Fowler Lake (849400)
96.56 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.
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 headwater 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.


This small drainage lake on the Oconomowoc River was enlarged to 78 acres by a 8-foot dam in the City of Oconomowoc. The water is clear and only about 15 percent of the basin is deeper than 20 feet. Overgrowth of rooted aquatic plants and algae have frequently necessitated control measures. The fishery is primarily largemouth bass and panfish. Walleyes are stocked and muskellunge have become established from upstream Okauchee Lake. Carp are common in this drainage system. Adequate public access is afforded by the city park boat launch, several city roads, and terraces.

The U.S. Geological Survey, in cooperation with the Fowler Lake Management District, completed a hydrologic and water-quality study of Fowler Lake in 1984. The report, Hydrology, Water Quality, Trophic Status and Aquatic Plants of Fowler Lake, Wisconsin, is available at WDNR Southeast District Headquarters.

In 1990, the Fowler Lake Management District received a Wisconsin Lake Management Planning Grant. The grant was used to hire the U.S. Geological Survey to monitor the water quality for six years (1991-1996). The report concluded that Fowler Lake is moderately fertile with excellent water clarity. The lake thermally stratifies during the summer with oxygen depletion occurring in the deepest part of the lake. The Oconomowoc River contributes 98 percent of the inflow and 88 percent of the phosphorus load to the lake. The annual phosphorus load was estimated to be 28 pounds per square mile. This is considered low and indicates the presence of upstream lakes that are filtering out available nutrients. The aquatic macrophyte community is dominated by Chara sp. (muskgrass), Myriophyllum sp. (native water milfoil), Najas marina and Vallisneria americana (wild celery).

Zebra mussel veligers have been identified in the watershed, upstream of Fowler Lake. No evidence of this exotic species currently exists in this lake.

Date  2002

Author   Aquatic Biologist

Historical Description

Source: 1963, Surface Water Resources of Waukesha County Fowler Lake T8N, R17E, Section 33

A small drainage lake on the Oconomowoc River enlarged in area by an impounding structure of 8 feet in the City of Oconomowoc. The water is clear and only about 15 per cent of the basin is greater than 20 feet deep. Weeds and algae are use problems which have frequently necessitated control measures. The fishery is primarily for largemouth bass and pan fish. Carp are common in this drainage system. . Adequate public access is afforded by a city park, several city roads and terraces.

Surface Acres = 78, S.D.F. = 1.37, Maximum Depth = 50 feet

Date  1963

Author   Surface Water Inventory Of Wisconsin

Fowler Lake, Oconomowoc River Watershed (UR09) Fish and Aquatic LifeFowler Lake, Oconomowoc River Watershed (UR09) RecreationFowler Lake, Oconomowoc River Watershed (UR09) Fish Consumption

General Condition

Fowler Lake (WBIC 849400) was assessed during the 2018 listing cycle; new total phosphorus and chlorophyll-a sample data were clearly below 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.


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

Fowler Lake is located in the Oconomowoc River watershed which is 130.86 miĀ². Land use in the watershed is primarily agricultural (24.90%), forest (19.70%) and a mix of wetland (16.90%) and other uses (38.40%). This watershed has 136.99 stream miles, 2,858.66 lake acres and 11,105.19 wetland acres.

Nonpoint Source Characteristics

This watershed is ranked Not Available 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.

Natural Community

Fowler Lake is considered a Two-Story 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 headwater lake describes the depth and location of the lake in a watershed. These variables affect the lakes response to watershed variables.