Bad Medicine Lake vs Flat Lake
Water quality, depth, fish species, and recreation comparison.
Bad Medicine Lake and Flat Lake both received the same overall water quality grade of A (Excellent). Both are in Becker County, Minnesota.
Bad Medicine Lake and Flat 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. These two are within a letter of each other on the rubric — Bad Medicine Lake (A) versus Flat 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.
Bad Medicine Lake
Crystal clear, you can see 25 ft down.
Flat Lake
Good clarity, visible to about 11.2 ft.
Side-by-Side Metrics
| Metric | Bad Medicine Lake | Flat Lake |
|---|---|---|
| Overall Grade | A (Excellent) | A (Excellent) |
| Water Clarity | 25 ft Better | 11.2 ft |
| Phosphorus | 6 µg/L Better | 13 µg/L |
| Chlorophyll-a (Algae) | 1.6 µg/L Better | 3.7 µg/L |
| Maximum Depth | 84 ft | - |
| Surface Area | 803 acres | 1,754 acres |
| Public Access | Yes | No |
| Fish Species | 13 Better | 0 |
| Trophic State | oligotrophic | 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 Bad Medicine Lake or Flat Lake against a different lake.
Verdict
Both lakes earn the same Grade A. The tiebreakers come down to clarity (Bad Medicine Lake: 25 ft, Flat Lake: 11.2 ft) and what you want from the lake. Bad Medicine Lake supports more documented fish species.
Source: EPA National Aquatic Resource Surveys, 2026.