Rock Dam Lake, South Fork Eau Claire River Watershed (LC16)
Rock Dam Lake, South Fork Eau Claire River Watershed (LC16)
Rock Dam Lake (2139000)
95.87 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 impoundment is impaired
Impairment Unknown
Total Phosphorus, Mercury
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.


Rock Dam Lake is an impoundment of Hay Creek in Clark County. Flooding in 1993 damaged the dam and drained most of the lake. While the lake was drained, some landowners dredged small areas around their docks. After Clark County repaired the dam, bass and northern pike were stocked by WDNR fisheries staff. Due to the scarcity of lakes in thls region, this impoundment is an important recreational resource to the area. A lake management organization for Rock Dam Lake could be instrumental in obtaining a lake planning grant. WDNR has no data on current water quality; a self-help volunteer could be instrumental in obtaining data.

Date  1996

Author   Aquatic Biologist

Historical Description

Source: 1965, Surface Water Resources of Clark County Hay Creek Lake (Rock Dam Lake) T26N, R4W, S15

This is a soft water, drainage impoundment located on Hay Creek. The dam has a 12-foot head and it is owned by Clark County. It was constructed in 1938 by the W.P.A. for the purpose of creating a recreational area. The light brown colored water is slightly acid and has a low transparency. Largemouth bass, bluegill, black crappie, rock bass, perch, bullhead, and white sucker comprise the fishery. There are two county-owned park areas, including a swimming beach and a boat launching site. Around the flowage, there are 76 dwellings. Aquatic vegetation poses a problem to anglers and boaters during the summer months. During the migratory seasons, ducks may be found.

Surface Acres = 105, S.D.F. = 2.76, Known Maximum Depth = 16 feet

Date  1965

Author   Surface Water Inventory Of Wisconsin

Rock Dam Lake, South Fork Eau Claire River Watershed (LC16) Fish and Aquatic LifeRock Dam Lake, South Fork Eau Claire River Watershed (LC16) RecreationRock Dam Lake, South Fork Eau Claire River Watershed (LC16) Fish Consumption

Impaired Waters

Rock Dam Lake (WBIC 2139000) was placed on the impaired waters list for Mercury in 1998 and for total phosphorus in 2014. The 2018 assessments showed continued impairment by phosphorus; new total phosphorus sample data exceeded the 2018 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use. Chlorophyll-a sample data did not exceed the REC or FAL thresholds. Based on the most updated information, no change in the existing impaired waters listing was needed.

Date  2017

Author  Ashley Beranek

Impaired Waters

Rock Dam Lake (2139000) was placed on the impaired waters list for Mercury in 1998 and for total phosphorus in 2014. The 2016 assessments showed continued impairment by phosphorus; total phosphorus sample data exceeded 2016 WisCALM listing thresholds for the Recreation, however, chlorophyll data do not exceed REC thresholds. Total phosphorus and chlorophyll data clearly met thresholds for Fish and Aquatic Life use. Based on the most updated information, no change in existing impaired waters listing is needed.

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.



Monitor Fish Tissue

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

Rock Dam Lake is located in the South Fork Eau Claire River watershed which is 229.49 miĀ². Land use in the watershed is primarily forest (56%), agricultural (22.80%) and a mix of wetland (12%) and other uses (9.20%). This watershed has 421.59 stream miles, 307.67 lake acres and 23,719.61 wetland acres.

Nonpoint Source Characteristics

This watershed is ranked Low for runoff impacts on streams, High for runoff impacts on lakes and Medium for runoff impacts on groundwater and therefore has an overall rank of Medium. 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

Rock Dam 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.