Deep Lake

Deep 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 49 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Deep Lake is small — 33 acres alongside partial shoreline records — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Deep Lake ranks 4 of 20 in Adams County, putting it in the upper tier of locally monitored lakes.

Eurasian watermilfoil has been documented at Deep Lake, requiring shoreline management to keep dense mats from crowding native vegetation. Bass fishing is part of the appeal: the species list runs to 4, 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.