Birch Lake vs Little Boy Lake
Water quality, depth, fish species, and recreation comparison.
Birch Lake and Little Boy Lake read the same on nutrients and algae. Both are in Cass County, Minnesota.
Birch Lake and Little Boy 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 sit close on the readings, Birch Lake versus Little Boy Lake. The deciding factors for a recreational visitor are likely physical (depth, access, fish species) rather than water-quality differences.
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.
Birch Lake
Good clarity, visible to about 14 ft.
Little Boy Lake
Good clarity, visible to about 11 ft.
Side-by-Side Metrics
| Metric | Birch Lake | Little Boy Lake |
|---|---|---|
| Water Clarity | 14 ft Better | 11 ft |
| Phosphorus | 12 µg/L Better | 14 µg/L |
| Chlorophyll-a (Algae) | 4 µg/L Better | 5.1 µg/L |
| Maximum Depth | 45 ft | 74 ft Better |
| Surface Area | 1,267 acres | 1,452 acres |
| Public Access | Yes | Yes |
| Fish Species | 14 | 18 Better |
| 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 Birch Lake or Little Boy Lake against a different lake.
Verdict
Both lakes earn the same Grade A. The tiebreakers come down to clarity (Birch Lake: 14 ft, Little Boy Lake: 11 ft) and what you want from the lake. Birch Lake has fewer fish species than Little Boy Lake.
Source: EPA National Aquatic Resource Surveys, 2026.