Forest Lake

Forest Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. 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 32 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 51 acres, Forest Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Forest Lake ranks 4 of 10 in Fond du Lac County — solidly in the upper half of the local distribution.

Forest Lake carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. Walleye are documented at Forest Lake, one of 4 fish species on record for the lake. A documented public access point at Forest Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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.