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Birch Lake and Washburn Lake read the same on nutrients and algae. Both are in Cass County, Minnesota.

Reviewed by LakeQuality Editorial Team · Updated

Birch Lake and Washburn 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 Washburn 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

Cass County, Minnesota

Good clarity, visible to about 14 ft.

Washburn Lake

Cass County, Minnesota

Good clarity, visible to about 14.1 ft.

Side-by-Side Metrics

MetricBirch LakeWashburn Lake
Water Clarity14 ft14.1 ft Better
Phosphorus12 µg/L11 µg/L Better
Chlorophyll-a (Algae)4 µg/L3.7 µg/L Better
Maximum Depth45 ft111 ft Better
Surface Area1,267 acres1,590 acres
Public AccessYesYes
Fish Species1421 Better
Trophic Statemesotrophicmesotrophic

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

Both lakes earn the same Grade A. The tiebreakers come down to clarity (Birch Lake: 14 ft, Washburn Lake: 14.1 ft) and what you want from the lake. Birch Lake has fewer fish species than Washburn Lake.

Source: EPA National Aquatic Resource Surveys, 2026.