Mule Lake

Mule Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in 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.

Trophically, Mule Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. A maximum depth of 47 ft puts Mule Lake in the middle of Minnesota's depth distribution. The lake's 525 acres and 7.3 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 133 graded lakes in Cass County, Mule Lake ranks 29 — in the top quartile locally.

No invasive species are currently listed at Mule Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye alongside the lake's other 11 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. Ice-out has been recorded 10 times at Mule Lake, with a median around Apr 19. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.