Grindstone Lake, Couderay River Watershed (UC20)
Grindstone Lake, Couderay River Watershed (UC20)
Grindstone Lake (2391200)
3176.40 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.


Grindstone Lake, in the Couderay River Watershed, is a 3,176.33 acre lake that falls in Sawyer County. This lake is an outstanding/exceptional resource water under NR102 under the Fisheries Program. This lake is managed for fishing and swimming and is currently not considered impaired.

Date  2011

Author   Aquatic Biologist

Historical Description

Source: 1969, Surface Water Resources of Sawyer County Grindstone Lake, T40N, R8, 9W, Section = several

A hard water drainage lake with a relatively small outlet flow of an estimated 6.0 cfs. normal flow to nearby Lac Court Oreilles. Common game fish include muskellunge, walleyes, northern pike, smallmouth bass, and largemouth bass. Cisco are also present. The most common panfish are the perch, bluegill, and rock bass, while black crappie, pumpkinseed, and bullheads inhabit the lake also. Other fish species include longnose gar, white suckers, common shiners, creek chubs, hognose sucker, mudminnows, and fathead minnows. The only stream to the lake, Grindstone Creek, is a brook trout stream. A number of nesting ducks are found here and includes mallards, black ducks, blue-winged teal, hooded mergansers, and coot. Additional numbers of migratory waterfowl that includes Canada Geese are found here seasonally. Most of the shore vegetation is upland hardwood and pine, except for a spruce bog at the lake outlet and small areas of tamarack-spruce bog on the west end of the lake. With an exception of about two percent of the shore, the bottom type is a mixture of sand, gravel, and boulder. The aesthetic and recreational qualities are so appealing that extensive development of the shore has occurred. There are 16 resorts, three boat rentals, and 113 cottages and dwellings, along with a private camp and a commercial cranberry marsh. A public access is located one-quarter mile west of the outlet. Of the 10.5 miles of shoreline, 0.66 miles are in public ownership. This latter figure includes the shoreline of two Department of Natural Resources owned islands and the 14 platted access sites.

Surface Acres = 3,110.9, Maximum Depth = 59 feet, M.P.A. = 52 ppm, Secchi Disk = 12 feet

Date  1969

Author   Surface Water Inventory Of Wisconsin

Grindstone Lake, Couderay River Watershed (UC20) Fish and Aquatic LifeGrindstone Lake, Couderay River Watershed (UC20) RecreationGrindstone Lake, Couderay River Watershed (UC20) Fish Consumption

General Condition

Grindstone Lake (2391200) 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 water is meeting these designated uses and is not considered impaired.

Date  2015

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

Grindstone Lake is located in the Couderay River watershed which is 212.25 miĀ². Land use in the watershed is primarily forest (64.90%), wetland (13.50%) and a mix of open (12.90%) and other uses (8.70%). This watershed has 211.96 stream miles, 18,300.76 lake acres and 14,697.69 wetland acres.

Nonpoint Source Characteristics

This watershed is ranked Low for runoff impacts on streams, High for runoff impacts on lakes and Low for runoff impacts on groundwater and therefore has an overall rank of Low. This value can be used in ranking the watershed or individual waterbodies for grant funding under state and county programs.This water is ranked High Lake for individual Lakes based on runoff problems and the likelihood of success from project implementation.

Natural Community

Grindstone 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.

Fish Stocking
Maps of Watershed