Loon Lake

Loon Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI value of 39 puts Loon Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. A maximum depth of 21 ft puts Loon Lake in the middle of Wisconsin's depth distribution. At 36 acres, Loon Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Loon Lake ranks 58 of 191 in Vilas County — solidly in the upper half of the local distribution.

Loon Lake has at least one documented invasive species (Chinese Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. The fishery is bass-led, with 3 documented species across the lake's records. 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.