Flash Lake

Flash Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI near 45 places Flash Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. Flash Lake reaches 24 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Flash Lake is small — 83 acres alongside 3.0 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Within Lake County's 142 graded lakes, Flash Lake ranks 101 — below the local median, though not at the bottom.

No invasive species are currently listed at Flash Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Flash Lake, one of 5 fish species on record for the lake. The lake lacks a documented public access point, so visitor use is limited. 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.