Nelson Lake vs Round Lake
Water quality, depth, fish species, and recreation comparison.
Round Lake has a higher water quality grade (A, Excellent) than Nelson Lake (B, Good). Both are in Sawyer County, Wisconsin.
Nelson Lake and Round 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: Nelson Lake (B) and Round 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.
Nelson Lake
Murky, only visible to about 5 ft.
Round Lake
Crystal clear, you can see 21.1 ft down.
Side-by-Side Metrics
| Metric | Nelson Lake | Round Lake |
|---|---|---|
| Overall Grade | B (Good) | A (Excellent) |
| Water Clarity | 5 ft | 21.1 ft |
| Phosphorus | 22.8 µg/L | 14 µg/L |
| Chlorophyll-a (Algae) | No data | 0.9 µg/L |
| Maximum Depth | - | 74 ft |
| Surface Area | 2,503 acres | 3,294 acres |
| Public Access | Yes | Yes |
| Fish Species | 0 | 6 |
| Trophic State | eutrophic | oligotrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Round Lake wins on overall water quality with a Grade A versus Nelson Lake's Grade B. Water clarity: 21.1 ft vs 5 ft. For fishing diversity, Round Lake also leads with 6 species.
Source: EPA National Aquatic Resource Surveys, 2026.