Grindstone Lake
Sawyer County, Wisconsin3,176 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Grindstone Lake. Here is what has been measured.
- Oligotrophic
- 2 aquatic invasives
- 60 ft max depth
- Public access
Grindstone Lake in Sawyer County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 17.4 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 1.4 µg/L. Maximum depth: 60 ft. Surface area: 3176 acres.
Wisconsin DNR rates Walleye as abundant on Grindstone Lake. DNR survey details →
Grindstone Lake is a 3,176-acre cold, clear oligotrophic lake in Sawyer County, Wisconsin with a maximum depth of 60 feet. Phosphorus level is declining over recent sampling years. The lake supports 6 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available with 3 public boat landings. Compared to the 44 other monitored lakes in Sawyer County, Grindstone Lake ranks #12 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2024-09-04. Methodology: how these readings are compared.
What Grindstone Lake is good for
From access and monitoring records, not editorial picks.
- Clear water17.4 ft of visibility
- Boat launch3 documented ramps
- Fishing6 species recorded
- Deep water60 ft surveyed max depth
- Big water3,176 acres
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Grindstone Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Grindstone Lake
These are the measurements Wisconsin DNR publishes for Grindstone Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 17.4 ft down. Phosphorus 15 µg/L. Chlorophyll-a 1.4 µg/L. TSI 38.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 17.4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 15µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 1.4µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 38 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Grindstone Lake
Answers come straight from the public measurements and survey records on this page.
Wisconsin DNR rates Walleye as abundant on Grindstone Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Grindstone Lake’s water-quality measurements separately, and the water-quality trend over 5 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 5 stations on file (most recent sample 2024).
Fish Species (DNR-rated)
Lake Details
Max depth
60 ft
Surface area
3,176 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
20 sq mi
HydroLAKES / HydroSHEDS
Shoreline
11 mi
HydroLAKES / HydroSHEDS
Elevation
1,273 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Grindstone LakePublic
- Grindstone LakePublic
- LCO DrivePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Grindstone Lake
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Top-rated places to stay near Grindstone Lake
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Follow Grindstone Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Grindstone Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Stable
Based on 5 years of monitoring (2020–2024).
Water clarity
Stable5 years
Phosphorus
Worsening+0.44 µg/L/yr5 years
Chlorophyll-a
Improving-0.1 µg/L/yr5 years
Nearby Lakes in Sawyer County
Frequently asked questions about Grindstone Lake
Where is Grindstone Lake?
- Grindstone Lake is a lake in Sawyer County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Grindstone Lake?
- Grindstone Lake in Sawyer County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 17.4 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 1.4 µg/L. Maximum depth: 60 ft. Surface area: 3176 acres.
Is Grindstone Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Grindstone Lake?
- Grindstone Lake has a maximum depth of 60 feet. The lake covers 3176 acres.
What fish are in Grindstone Lake?
- Fish species found in Grindstone Lake include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye. Grindstone Lake is located in Sawyer County, Wisconsin.
What did the DNR fisheries survey find at Grindstone Lake?
- Wisconsin DNR rates Walleye as abundant on Grindstone Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Grindstone Lake’s water-quality measurements separately, and the water-quality trend over 5 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Grindstone Lake?
- Grindstone Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Grindstone Lake, Grindstone Lake, LCO Drive. Public access is listed as yes.
Can I fish at Grindstone Lake?
- Grindstone Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.
Explore Grindstone Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Wisconsin
Fish species and best lakes in Sawyer County
Species activity outlook by water temperature and season
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Where to stay at Wisconsin's top lakes, each with its readings
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Wisconsin's cleanest lakes, ranked on agency measurements
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Compare Grindstone Lake With Nearby Lakes
Where this data comes from
139 measurements from 2 monitoring stations, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Lac Courte Oreilles (Tribal)
LCOWIS_WQX97 samples · 2020–2024 - Wisconsin Department of Natural Resources
WIDNR_WQX42 samples · 2021
Analytical methods
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 4500 P F ~ Phosphorus in Water by Colorimetry Automated Ascorbic Acid Method
- 2320 B ~ Alkalinity by Gran Titration
- 4500 P E ~ Phosphorus by Ascorbic Acid
- 10200 H ~ Chlorophyll a-b-c Determination
- Phosphorus by Colorimetry
Monitoring station identifiers (2)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory