Lac Courte Oreilles Lake vs Nelson Lake
Water quality, depth, fish species, and recreation comparison.
Lac Courte Oreilles Lake has a higher water quality grade (A, Excellent) than Nelson Lake (B, Good). Both are in Sawyer County, Wisconsin.
Both Lac Courte Oreilles Lake and Nelson Lake sit in Wisconsin. A same-state comparison strips out the state-level water-quality regime as a variable: any grade differences here are about the lakes themselves, not the agencies grading them. The grades are close: Lac Courte Oreilles Lake (A) and Nelson Lake (B) 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.
Lac Courte Oreilles Lake
Good clarity, visible to about 12.2 ft.
Nelson Lake
Murky, only visible to about 5 ft.
Side-by-Side Metrics
| Metric | Lac Courte Oreilles Lake | Nelson Lake |
|---|---|---|
| Overall Grade | A (Excellent) | B (Good) |
| Water Clarity | 12.2 ft | 5 ft |
| Phosphorus | 15 µg/L | 22.8 µg/L |
| Chlorophyll-a (Algae) | 1.7 µg/L | No data |
| Maximum Depth | 90 ft | - |
| Surface Area | 5,139 acres | 2,503 acres |
| Public Access | Yes | Yes |
| Fish Species | 6 | 0 |
| Trophic State | mesotrophic | eutrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Lac Courte Oreilles Lake wins on overall water quality with a Grade A versus Nelson Lake's Grade B. Water clarity: 12.2 ft vs 5 ft. For fishing diversity, Lac Courte Oreilles Lake also leads with 6 species.
Source: EPA National Aquatic Resource Surveys, 2026.