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Birch Lake reads lower on nutrients and algae than Little Wolf Lake. Both are in Cass County, Minnesota.

Reviewed by LakeQuality Editorial Team · Updated

Birch Lake and Little Wolf 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. The readings are meaningfully apart: Birch Lake carries clearly lower phosphorus and chlorophyll-a readings than Little Wolf Lake. A spread that wide reflects real underlying differences, in watershed inputs, depth profiles, or monitoring rigor.

For a recreational visitor, the wider gap in the readings is decisive: Birch Lake has the lower nutrient and algae numbers. For a researcher, the gap is the interesting part: what is different about the two watersheds, and which of those differences is mutable?

Birch Lake

Cass County, Minnesota

Good clarity, visible to about 14 ft.

Little Wolf Lake

Cass County, Minnesota

Moderate clarity, visible to about 7 ft.

Side-by-Side Metrics

MetricBirch LakeLittle Wolf Lake
Water Clarity14 ft Better7 ft
Phosphorus12 µg/L Better26.5 µg/L
Chlorophyll-a (Algae)4 µg/L Better12.7 µg/L
Maximum Depth45 ft Better24 ft
Surface Area1,267 acres525 acres
Public AccessYesYes
Fish Species14 Better13
Trophic Statemesotrophiceutrophic

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.

Verdict

Birch Lake reads lower on nutrients and algae than Little Wolf Lake. Water clarity: 14 ft vs 7 ft. For fishing diversity, Birch Lake also leads with 14 species.

Source: EPA National Aquatic Resource Surveys, 2026.