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

Reviewed by LakeQuality Editorial Team · Updated

Both Birch Lake and Ten Mile 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: Birch Lake and Ten Mile 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.

Birch Lake

Cass County, Minnesota

Good clarity, visible to about 14 ft.

Ten Mile Lake

Cass County, Minnesota

Crystal clear, you can see 20.5 ft down.

Side-by-Side Metrics

MetricBirch LakeTen Mile Lake
Water Clarity14 ft20.5 ft Better
Phosphorus12 µg/L8.5 µg/L Better
Chlorophyll-a (Algae)4 µg/L1.9 µg/L Better
Maximum Depth45 ft208 ft Better
Surface Area1,267 acres5,080 acres
Public AccessYesYes
Fish Species1417 Better
Trophic Statemesotrophicoligotrophic

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, Ten Mile Lake: 20.5 ft) and what you want from the lake. Birch Lake has fewer fish species than Ten Mile Lake.

Source: EPA National Aquatic Resource Surveys, 2026.