Mons Lake

Mons Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in Minnesota. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

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. Mons Lake is unusually deep for Minnesota at 80 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. Mons Lake is small — 95 acres alongside 1.8 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Within Todd County's 17 graded waters, Mons Lake sits at rank 1, near the top of the local distribution.

Mons Lake has no invasive species recorded in Minnesota state databases as of 2022, though prevention practices still apply at all access points. Mons Lake's fishery is anchored by muskellunge, with 15 documented species in total — a destination water for muskie anglers. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.