Delton Lake, Dell Creek Watershed (LW26)
Delton Lake, Dell Creek Watershed (LW26)
Delton Lake (1295400)
249.24 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.
This lake is impaired
Eutrophication, Excess Algal Growth
Total Phosphorus
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 Lowland
Shallow 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.


Lake Delton is a 267-acre impoundment of Dell Creek. Much of its shoreline has been developed with summer homes, year-round homes and condominiums. The fishery of the lake is northern pike, walleye, largemouth bass, channel catfish and panfish.

The lake is eutrophic and has poor water quality, which is common to impoundments in southwest Wisconsin. Some of the water quality problems may be due to construction site erosion as well as rural nonpoint source pollution. The lake is experiencing increasing development pressure and may also experience problems as a result of urban stormwater runoff.

As a result of the development and the popularity of the lake for recreational and tourism purposes, the lake may also experience usage conflicts, particularly during the summer. Sewage pollution used to be a threat to the lake, but municipal sewer now serves residences
around the lake. The lake has nuisance aquatic weed growth that has required chemical treatment. Eurasian water milfoil has been found in the lake.

The Lake Delton Lake Association and the Village of Lake Delton contracted for a lake study and management plan to be developed for Lake Delton. The information collected and its analysis points to nonpoint sources of pollution in the Dell Creek watershed as being the primary sources of phosphorus loading to the lake.

Date  2002

Author   Aquatic Biologist

Historical Description

Lake Delton is an impoundment of Dell Creek. Much of its shoreline has been developed with summer homes, year-round homes, and condominiums. The lake is eutrophic and has poor water quality (WDNR, 1991) which is common to impoundments in southwest Wisconsin. Some of the water quality problems may be due to construction site erosion as well as rural nonpoint source pollution (Bachhuber, 1992). The lake also has nuisance aquatic weed growth that has required chemical treatment (WDNR, 1991). Because of the development around the lake, usage conflicts may occur, particularly durring the summer. Residences around the lake are served by municipal sewer.

Date  1994

Author   Surface Water Inventory Of Wisconsin

Historical Description

Source: 1971, Surface Water Resources of Sauk County Lake Delton, T13N, R6E, Sec. 15, 16, 21

A highly developed drainage lake created by a dam with a 20-foot head on Dell Creek in the northeastern corner of Sauk County. The watershed area of the lake totals 79.6 square miles and Dell Creek ranks number one as a trout stream in Sauk County. Largemouth bass, walleyes and panfish provide the major sport fishery. Northern pike, smallmouth bass, carp, and white suckers are also present. Lake Delton and the Dells area are an important tourist attraction for Wisconsin. Lake Delton is used extensively for fishing, pleasure boating, water skiing, and swimming during the summer months. Ice fishing and snowmobiling are popular activities on the lake in the winter. Game assets are limited due to the population density of the area, but puddle ducks are frequently seen during the spring and fall migratory periods. Sewage pollution from the many cottages and resorts has been a major problem in the past and is still a potential source today. Extension of sewerage in this area is in progress. Public access is available from two boat launching sites, one town park and one bridge crossing. Four boat rentals and two private campgrounds are located nearby.

Surface area = 266.88 acres, S.D.F. = 2.92, Maximum depth = 16 feet.

Date  1971

Author   Surface Water Inventory Of Wisconsin

Delton Lake, Dell Creek Watershed (LW26) Fish and Aquatic LifeDelton Lake, Dell Creek Watershed (LW26) RecreationDelton Lake, Dell Creek Watershed (LW26) Fish Consumption

Impaired Waters

Delton Lake (WBIC 1295400) was placed on the impaired waters list for total phosphorus in 2016. The 2018 assessments showed continued impairment by phosphorus; total phosphorus sample data was overwhelmingly exceeded the 2018 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use. Chlorophyll-a sample data exceeded the REC and FAL use thresholds. Based on the most updated information the impairments of Excess Algal Growth and Eutrophication were added to the Total Phosphorus listing.

Date  2017

Author  Ashley Beranek

Impaired Waters

Delton Lake (1295400) was assessed during the 2016 listing cycle; total phosphorus sample data overwhelmingly exceeded 2016 WisCALM listing thresholds for the Recreation use; however chlorophyll data did not exceed REC thresholds. Total phosphorus and chlorophyll data did not exceed Fish and Aquatic Life thresholds.

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.



Aquatic Plant Management Plan
Project Deliverable
. Final recommendations will be presented in the plan, and the plan will be made available at the local library and presented at an organized public lake meeting.
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

Delton 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

Delton 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.