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. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Trophically, Mary Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. The lake bottoms out at 48 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 235 acres, Mary Lake fits the Minnesota median for monitored lakes, with 3.3 miles of shoreline. Among the 77 graded lakes in Hubbard County, Mary Lake ranks 9 — in the top quartile locally.

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 alongside the lake's other 14 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a partial ice record — 9 observed ice-outs, centered near 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.