Grindstone Lake
Grindstone Lake in Sawyer County, Wisconsin has a water quality grade of A (Excellent). 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.
- Clarity
- 17.4 ft
- Max depth
- 60 ft
- Area
- 3,176 acres
- Type
- Oligotrophic
- Trend
- → Stable
- Public access
- Yes
Next lake in Sawyer County
Grindstone Lake is a 3,176-acre cold, clear oligotrophic lake in Sawyer County, Wisconsin with a maximum depth of 60 feet. Water quality is graded A based on 2 sampling years through 2024. 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 2 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. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Crystal clear, you can see 17.4 ft down. Phosphorus level: 15 µg/L. Chlorophyll-a: 1.4 µg/L. Trophic State Index: 38.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 17.4 ft | Not graded |
| Phosphorus | 15 µg/L | Good |
| Chlorophyll-a (Algae) | 1.4 µg/L | Good |
| Trophic State Index (TSI) | 38 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Grindstone Lake
Compare lakeside cabins, hotels, and vacation rentals near Grindstone Lake in Sawyer County, Wisconsin — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 60 ft |
| Surface Area | 3,176 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Grindstone LakePublic
- LCO DrivePublic
Fish Species
Click a species to see every graded 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.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 5 stations on file (most recent sample 2024).
Fish Species (DNR-rated)
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.315 m/yr | 5 |
| Phosphorus | ↓ Declining | +0.44 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.1 µg/L/yr | 5 |
County Ranking
Ranked #12 of 45 lakes in Sawyer County
Nearby Lakes in Sawyer County
Frequently asked questions about Grindstone Lake
What is the water quality grade for Grindstone Lake?
- Grindstone Lake in Sawyer County, Wisconsin has a water quality grade of A (Excellent). 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?
- Excellent for swimming, crystal clear water with minimal algae. Grindstone Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 1.4 µg/L. Always check local health department advisories before swimming.
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.
Are there boat ramps on Grindstone Lake?
- Grindstone Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Grindstone Lake, LCO Drive. Public access is listed as yes.
Explore Grindstone Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded 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 grade
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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)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated 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