Loon Lake vs Madison Lake
Water quality, depth, fish species, and recreation comparison.
Madison Lake has a higher water quality grade (D, Poor) than Loon Lake (F, Very Poor). Both are in Blue Earth County, Minnesota.
Loon Lake and Madison 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. The grades are close: Loon Lake (F) and Madison Lake (D) 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.
Loon Lake
Very murky, less than 2 ft of visibility.
Madison Lake
Murky, only visible to about 3.6 ft.
Side-by-Side Metrics
| Metric | Loon Lake | Madison Lake |
|---|---|---|
| Overall Grade | F (Very Poor) | D (Poor) |
| Water Clarity | 2 ft | 3.6 ft |
| Phosphorus | No data | 81 µg/L |
| Chlorophyll-a (Algae) | No data | No data |
| Maximum Depth | 7 ft | 59 ft |
| Surface Area | 808.62 acres | 1.4K acres |
| Public Access | Yes | Yes |
| Fish Species | 1 | 1 |
| Trophic State | eutrophic | eutrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Madison Lake wins on overall water quality with a Grade D versus Loon Lake's Grade F. Water clarity: 3.6 ft vs 2 ft. For fishing diversity, Madison Lake also leads with 1 species.