Loon Lake vs Round Lake
Water quality, depth, fish species, and recreation comparison.
Round Lake has a higher water quality grade (D, Poor) than Loon Lake (F, Very Poor). Both are in Jackson County, Minnesota.
Loon Lake and Round Lake are both in Minnesota — 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. These two are within a letter of each other on the rubric — Loon Lake (F) versus Round Lake (D). The deciding factors for a recreational visitor are likely physical (depth, access, fish species) rather than water-quality differences.
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.
Loon Lake
Very murky, less than 0.9 ft of visibility.
Round Lake
Very murky, less than 2 ft of visibility.
Side-by-Side Metrics
| Metric | Loon Lake | Round Lake |
|---|---|---|
| Overall Grade | F (Very Poor) | D (Poor) |
| Water Clarity | 0.9 ft | 2 ft |
| Phosphorus | 274 µg/L | 77 µg/L |
| Chlorophyll-a (Algae) | 110 µg/L | 14.7 µg/L |
| Maximum Depth | 8 ft | 9 ft |
| Surface Area | 708 acres | 930 acres |
| Public Access | Yes | Yes |
| Fish Species | 18 | 17 |
| Trophic State | hypereutrophic | eutrophic |
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 D versus Loon Lake's Grade F. Water clarity: 2 ft vs 0.9 ft. For more fish-species variety, Loon Lake edges ahead with 18 documented species.
Source: EPA National Aquatic Resource Surveys, 2026.