Blackwater Lake vs Mule Lake
Water quality, depth, fish species, and recreation comparison.
Blackwater Lake and Mule Lake read the same on nutrients and algae. Both are in Cass County, Minnesota.
Both Blackwater Lake and Mule Lake sit in Minnesota. A same-state comparison strips out the state-level water-quality regime as a variable: any differences in the readings here are about the lakes themselves, not the agencies sampling them. The readings are close: Blackwater Lake and Mule Lake sit within a narrow band of each other on phosphorus, chlorophyll-a and clarity. The per-parameter table below shows where the small differences actually live.
With readings 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.
Blackwater Lake
Good clarity, visible to about 14.1 ft.
Mule Lake
Crystal clear, you can see 18 ft down.
Side-by-Side Metrics
| Metric | Blackwater Lake | Mule Lake |
|---|---|---|
| Water Clarity | 14.1 ft | 18 ft Better |
| Phosphorus | 12 µg/L | 10 µg/L Better |
| Chlorophyll-a (Algae) | 4 µg/L | 2.4 µg/L Better |
| Maximum Depth | 67 ft Better | 47 ft |
| Surface Area | 771 acres | 525 acres |
| Public Access | Yes | Yes |
| Fish Species | 16 Better | 11 |
| Trophic State | mesotrophic | oligotrophic |
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 Blackwater Lake or Mule Lake against a different lake.
Verdict
Both lakes earn the same Grade A. The tiebreakers come down to clarity (Blackwater Lake: 14.1 ft, Mule Lake: 18 ft) and what you want from the lake. Blackwater Lake supports more documented fish species.
Source: EPA National Aquatic Resource Surveys, 2026.