Pine Mountain Lake

Pine Mountain Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in Minnesota. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. At 80 ft of maximum depth, Pine Mountain Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. At 1,617 acres, Pine Mountain Lake is one of the larger lakes in Cass County, with 9.4 miles of shoreline supporting multiple distinct use patterns. Within Cass County's 133 graded lakes, Pine Mountain Lake ranks 75 — below the local median, though not at the bottom.

Zebra mussels have been documented at Pine Mountain Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The fishery includes walleye alongside the lake's other 16 documented species — a notable draw for Minnesota anglers. A documented public access point at Pine Mountain Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a partial ice record — 14 observed ice-outs, centered near Apr 16. 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.