Mary Lake

Mary Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Lincoln County. 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.

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. The lake bottoms out at 42 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. The lake is compact at 25 acres, with partial shoreline records and little volume to buffer nutrient inputs. Among the 21 graded lakes in Lincoln County, Mary Lake sits at rank 6, above the county median.

Mary Lake has no invasive species recorded in Wisconsin state databases as of 2023, though prevention practices still apply at all access points. Bass fishing is part of the appeal: the species list runs to 1, anchored by largemouth and/or smallmouth bass. 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.