Mary Lake

On the LakeGrade rubric, Mary Lake pulls an A: clarity at 19.5 ft and phosphorus readings still being added put it in the top bracket for Minnesota.

Trophically, Mary Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Mary Lake reaches 48 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 235 acres, Mary Lake fits the Minnesota median for monitored lakes, with 3.3 miles of shoreline. Within Hubbard County's 76 graded waters, Mary Lake sits at rank 9, near the top of the local distribution.

Mary Lake has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. The fishery includes walleye among the lake's 14 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 9 times at Mary Lake, with a median around Apr 24. 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.