Mary Lake vs Mill Lake
Water quality, depth, fish species, and recreation comparison.
Mary Lake and Mill Lake both received the same overall water quality grade of B (Good). Both are in Douglas County, Minnesota.
Both Mary Lake and Mill 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. These two are within a letter of each other on the rubric — Mary Lake (B) versus Mill Lake (B). 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.
Mary Lake
Moderate clarity, visible to about 9.8 ft.
Mill Lake
Good clarity, visible to about 11 ft.
Side-by-Side Metrics
| Metric | Mary Lake | Mill Lake |
|---|---|---|
| Overall Grade | B (Good) | B (Good) |
| Water Clarity | 9.8 ft | 11 ft |
| Phosphorus | 19 µg/L | 24 µg/L |
| Chlorophyll-a (Algae) | No data | No data |
| Maximum Depth | 40 ft | 40 ft |
| Surface Area | 2.5K acres | 451.12 acres |
| Public Access | Yes | Yes |
| Fish Species | 1 | 1 |
| Trophic State | mesotrophic | mesotrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Both lakes earn the same Grade B. The tiebreakers come down to clarity (Mary Lake: 9.8 ft, Mill Lake: 11 ft) and what you want from the lake. Mary Lake matches its peer on species count.