Stony Lake

Stony Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in Minnesota. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.

The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. At 50 ft of maximum depth, Stony Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. The lake's 563 acres and 6.6 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Among the 132 graded lakes in Cass County, Stony Lake ranks 26 — in the top quartile locally.

No invasive species are currently listed at Stony Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Stony Lake, one of 12 fish species on record for the lake. A documented public access point at Stony Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a long ice-out record — 53 observations on file, with a median ice-out around Apr 22. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.