Flynn Lake vs Upper Eau Claire Lake
Water quality, depth, fish species, and recreation comparison.
Upper Eau Claire Lake has a higher water quality grade (A, Excellent) than Flynn Lake (C, Fair). Both are in Bayfield County, Wisconsin.
Flynn Lake and Upper Eau Claire 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 meaningfully apart: Upper Eau Claire Lake grades a A while Flynn Lake grades a C. That two-letter spread reflects real underlying differences — different watershed inputs, different depth profiles, or different monitoring rigor.
For a recreational visitor, the wider grade gap is decisive — Upper Eau Claire Lake is the better water-quality choice. For a researcher, the gap is the interesting part: what is different about the two watersheds, and which of those differences is mutable?
Flynn Lake
Moderate clarity, visible to about 9 ft.
Upper Eau Claire Lake
Crystal clear, you can see 18.7 ft down.
Side-by-Side Metrics
| Metric | Flynn Lake | Upper Eau Claire Lake |
|---|---|---|
| Overall Grade | C (Fair) | A (Excellent) |
| Water Clarity | 9 ft | 18.7 ft |
| Phosphorus | No data | 11.5 µg/L |
| Chlorophyll-a (Algae) | No data | No data |
| Maximum Depth | - | - |
| Surface Area | 650 acres | 1.0K acres |
| Public Access | Unknown | Unknown |
| Fish Species | 0 | 0 |
| Trophic State | mesotrophic | oligotrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Upper Eau Claire Lake wins on overall water quality with a Grade A versus Flynn Lake's Grade C. Water clarity: 18.7 ft vs 9 ft. For fishing diversity, Upper Eau Claire Lake also leads with 0 species.