Mole Lake

Mole 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.

A TSI value of 36 puts Mole Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. A maximum depth of 17 ft puts Mole Lake in the middle of Wisconsin's depth distribution. Mole Lake is small — 77 acres alongside partial shoreline records — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Mole Lake sits at rank 19 of 35 in Forest County, in the lower half of the local distribution.

Eurasian watermilfoil has been documented at Mole Lake, requiring shoreline management to keep dense mats from crowding native vegetation. Walleye are documented at Mole Lake, one of 4 fish species on record for the lake. Public access is available — the lake is on the Wisconsin DNR public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.