Crystal Lake, Mullet River Watershed (SH05)
Crystal Lake, Mullet River Watershed (SH05)
Crystal Lake (45200)
128.98 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.
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.
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.


Crystal Lake is a large, moderately fertile, natural lake; heavily used lake for
fishing and boating. The presence of a resort and 181 cottages confirms
its value as a desirable recreational lake. Two small islands enhance
its character. The management of the lake's fishery has been a
controversial issue for many years--walleyes or trout? Changing
ecological factors have denied walleyes natural reproduction and
survival. In the best interest of the public andthe lake's capacity,
rainbow and brown trout are stocked annually, diversifying the fishery to
bass, panfish and trout. A property owners association maintains an
annual program of aquatic plant and algae control, reflecting a major use
problem. In the fall of 1966, a sanitary district was organized with
potential for a future cooperative sewage system, rather than individual
septic tanks. A public boat launching access with parking is available
in the SW bay, but parking is inadequate during peak use times.

Crystal Lake T16N, R21E, Section 31, 32
Surface Acres = 113.7, S.D.F. = 1.87, Maximum Depth = 61 feet

Source: 1968, Surface Water Resources of Sheboygan County

Date  1968

Author   Aquatic Biologist

Historical Description

At 113.7 acres, Crystal Lake is a moderately fertile, natural lake, heavily used for fishing and boating. The lake's shoreline is intensively developed with residential dwellings. Many property owners have reinforced the shoreline with seawalls that have detracted from the aesthetic quality as well as the fisheries value. In the autumn of 1966, a sanitary district was organized and sewers were installed in the late 1970s.

The lake's fishery has undergone several major changes over the past 35 years due to shifts in management philosophy. Over time it has been managed for walleye and northern pike, then trout and panfish, then largemouth bass and panfish. It is currently being managed for the native fish community: largemouth bass, panfish and with limited walleye due to stocking by private organizations. The existing bass and panfish community is improving due in part to the new bass size limit restrictions.

Historically, the lake was chemically treated to control aquatic plants and algae. In 1989, the DNR conducted a Sensitive Area Survey of the lake and as a result prohibited the use of aquatic herbicides and algicides in an attempt to protect the fish habitat and the water quality.

Since 1986, the water quality, aquatic plant community, and phyto- and zooplankton have been surveyed to obtain baseline water quality data and to assess trends. The results from this survey indicate that the water quality is excellent. The lake boasts some of the clearest water found in southeastern Wisconsin. A significant amount of Eurasian water milfoil is present in Crystal Lake. The DNR, in cooperation with the Crystal Lake Property Owners Association, attempted to displace the Eurasian water milfoil with a native species, Large Leaf Pondweed during the summer of 1994. The control program was effective for only a few years. By 1997 Eurasian water milfoil had again moved into the area displacing the newly planted native species (Wakeman 1998).

A public boat launch with adequate parking is available in the southwest bay. A unique boating ordinance on the lake prohibits the use of motors on Sundays. This is strongly supported by residents on the lake.

T16N R21E Sec. 31; Surface Acres = 113.7; S.D.F. = 1.87; Maximum Depth = 61 feet

Date  2001

Author   Aquatic Biologist

Crystal Lake, Mullet River Watershed (SH05) Fish and Aquatic LifeCrystal Lake, Mullet River Watershed (SH05) RecreationCrystal Lake, Mullet River Watershed (SH05) Fish Consumption

Impaired Waters

Crystal Lake (45200) was placed on the impaired waters list for Mercury in fish tissue in 1998. This water 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 lake is considered impaired for Fish Consumption use and meeting REC and FAL uses.

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
Crystal Lake confirm fish advice - previously listed water from before 2000.
Protect Riparian or Shorelands
Promote shoreland restoration practices among Crystal Lake shoreland owners to improve water quality and fish habitat.
Monitor Targeted Area
Continue to support the Crystal Lake water level studies.

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

Crystal Lake is located in the Mullet River watershed which is 88.19 miĀ². Land use in the watershed is primarily agricultural (38.90%), forest (21.40%) and a mix of grassland (17.90%) and other uses (21.80%). This watershed has 97.54 stream miles, 789.87 lake acres and 6,609.38 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

Crystal Lake is considered a Two-Story 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.

Shallow headwater lake describes the depth and location of the lake in a watershed. These variables affect the lakes response to watershed variables.