Blass Lake, Dell Creek Watershed (LW26)
Blass Lake, Dell Creek Watershed (LW26)
Blass Lake (1295800)
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.
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.
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.


Blass Lake was created in 1929 by impounding Springbrook Creek just outside of Lake Delton. It is a 34-acre hyper-eutrophic lake with poor water quality and excessive algae and aquatic plant growth. The lake has a good panfish, largemouth bass and northern pike fishery.

Date  2002

Author   Aquatic Biologist

Historical Description

Blass Lake is an impoundment of Spring Brook above Lake Delton. It is a hypereutrophic
lake with poor water quality (WDNR, 1991).

Date  1994

Author   Surface Water Inventory Of Wisconsin

Historical Description

Source: 1971, Surface Water Resources of Sauk County Blass Lake, T13N R6E, Sec. 17, 20

A drainage lake created by a dam with a 16-foot head on Spring Brook one mile west of the City of Lake Delton. The dam was constructed in 1929 across the deep gorge through which Spring Brook flows. The watershed area of the lake totals 6.14 square miles and Spring Brook is an intermittent stream during the dry summer months. Largemouth bass, northern pike and panfish comprise the major sport fishery. Aquatic vegetation is a major use problem and a fish kill caused by chemical spraying to control the problem occurred in 1958. Game assets found on the lake and surrounding shores include whitetailed deer, squirrels, ruffed grouse and puddle ducks. Many private cottages, a Jewish Community Center, and a Senior Citizens Resort are located along the shores. A controversy arose in 1962 as to whether the lake was public or private due to the fact that all surrounding land was in private ownership. It was officially determined to be a public lake and a walk-in gravel path and boat landing pier was proposed on the northwestern shore in 1970 by the Town of Delton. Interstate 90-94 also provides access to the lake by a widening of the Spring Brook inlet.

Surface area 34.4 acres, S.D.F. = 2.15, maximum depth 17 feet.

Date  1971

Author   Surface Water Inventory Of Wisconsin

Blass Lake, Dell Creek Watershed (LW26) Fish and Aquatic LifeBlass Lake, Dell Creek Watershed (LW26) RecreationBlass Lake, Dell Creek Watershed (LW26) Fish Consumption


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.



Aquatic Plant Management Plan
Informational Meetings
Aquatic Plant Monitoring or Survey
summer plant survey will be conducted, voucher specimens of plant species present will be preserved

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

Blass Lake is located in the Dell Creek watershed which is 133.73 miĀ². Land use in the watershed is primarily forest (48.30%), agricultural (22.50%) and a mix of grassland (11.20%) and other uses (18.00%). This watershed has 231.97 stream miles, 193.10 lake acres and 4,715.88 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

Blass Lake is considered a Reservoir 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.

Fish Stocking
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