Grindstone Lake vs Lac Courte Oreilles Lake
Water quality, depth, fish species, and recreation comparison.
Grindstone Lake and Lac Courte Oreilles Lake both received the same overall water quality grade of A (Excellent). Both are in Sawyer County, Wisconsin.
Grindstone Lake and Lac Courte Oreilles Lake are both in Wisconsin — a same-state head-to-head where the comparison comes down to lake-specific differences in depth, watershed, and monitoring history rather than the broader state-level water-quality regime. The grades are close: Grindstone Lake (A) and Lac Courte Oreilles Lake (A) are within one letter of each other on the LakeGrade rubric. The per-parameter sub-grades below will show where the small differences actually live.
With grades this close, the choice between the two lakes turns on non-water-quality factors: depth, fish species, public access, distance from home. The per-lake pages below cover all of those.
Grindstone Lake
Crystal clear, you can see 17.4 ft down.
Lac Courte Oreilles Lake
Good clarity, visible to about 12.2 ft.
Side-by-Side Metrics
| Metric | Grindstone Lake | Lac Courte Oreilles Lake |
|---|---|---|
| Overall Grade | A (Excellent) | A (Excellent) |
| Water Clarity | 17.4 ft | 12.2 ft |
| Phosphorus | 15 µg/L | 15 µg/L |
| Chlorophyll-a (Algae) | 1.4 µg/L | 1.7 µg/L |
| Maximum Depth | 60 ft | 90 ft |
| Surface Area | 3,176 acres | 5,139 acres |
| Public Access | Yes | Yes |
| Fish Species | 6 | 6 |
| Trophic State | oligotrophic | mesotrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Both lakes earn the same Grade A. The tiebreakers come down to clarity (Grindstone Lake: 17.4 ft, Lac Courte Oreilles Lake: 12.2 ft) and what you want from the lake. Grindstone Lake matches its peer on species count.
Source: EPA National Aquatic Resource Surveys, 2026.