Mary Lake vs Rachel Lake
Water quality, depth, fish species, and recreation comparison.
Mary Lake and Rachel Lake both received the same overall water quality grade of A (Excellent). Both are in Douglas County, Minnesota.
Both Mary Lake and Rachel 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 (A) versus Rachel Lake (A). 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
Good clarity, visible to about 10.5 ft.
Rachel Lake
Moderate clarity, visible to about 7.9 ft.
Side-by-Side Metrics
| Metric | Mary Lake | Rachel Lake |
|---|---|---|
| Overall Grade | A (Excellent) | A (Excellent) |
| Water Clarity | 10.5 ft Better | 7.9 ft |
| Phosphorus | 20 µg/L Better | 22.5 µg/L |
| Chlorophyll-a (Algae) | 5.5 µg/L | 3.9 µg/L Better |
| Maximum Depth | 40 ft | 65 ft Better |
| Surface Area | 2,450 acres | 448 acres |
| Public Access | Yes | Yes |
| Fish Species | 17 Better | 14 |
| Trophic State | mesotrophic | mesotrophic |
A green ✓ marks the better value for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better). Surface area and trophic state carry no tick — a bigger lake is not a better lake.
Swap a lake
Compare Mary Lake or Rachel Lake against a different lake.
Verdict
Both lakes earn the same Grade A. The tiebreakers come down to clarity (Mary Lake: 10.5 ft, Rachel Lake: 7.9 ft) and what you want from the lake. Mary Lake supports more documented fish species.
Source: EPA National Aquatic Resource Surveys, 2026.