Ash Lake vs Blackduck Lake
Water quality, depth, fish species, and recreation comparison.
Blackduck Lake has a higher water quality grade (C, Fair) than Ash Lake (D, Poor). Both are in St. Louis County, Minnesota.
Both Ash Lake and Blackduck Lake sit in Minnesota. 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: Ash Lake (D) and Blackduck Lake (C) 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.
Ash Lake
Murky, only visible to about 5.5 ft.
Blackduck Lake
Moderate clarity, visible to about 6.8 ft.
Side-by-Side Metrics
| Metric | Ash Lake | Blackduck Lake |
|---|---|---|
| Overall Grade | D (Poor) | C (Fair) |
| Water Clarity | 5.5 ft | 6.8 ft |
| Phosphorus | No data | 58.5 µg/L |
| Chlorophyll-a (Algae) | No data | No data |
| Maximum Depth | 25 ft | 30 ft |
| Surface Area | 689.62 acres | 1.2K acres |
| Public Access | Yes | Yes |
| Fish Species | 9 | 8 |
| Trophic State | eutrophic | eutrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Blackduck Lake wins on overall water quality with a Grade C versus Ash Lake's Grade D. Water clarity: 6.8 ft vs 5.5 ft. For more fish-species variety, Ash Lake edges ahead with 9 documented species.