Ten Mile Lake

On the LakeGrade rubric, Ten Mile Lake pulls an A: clarity at 20.0 ft and 8 µg/L of phosphorus put it in the top bracket for Minnesota. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

A TSI value of 34 puts Ten Mile Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. At 208 ft of maximum depth, Ten Mile Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. With 5,080 acres of surface and 24.8 miles of shoreline, Ten Mile Lake is a large water by Minnesota standards — recreational pressure is spread across a long shoreline. Among the 133 graded lakes in Cass County, Ten Mile Lake ranks 21 — in the top quartile locally.

Ten Mile Lake is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. Walleye are documented at Ten Mile Lake, one of 17 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. Ice-out has been logged at Ten Mile Lake more than two dozen times, putting the median around Apr 25 — a useful baseline for tracking climate trends. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.