Otter Lake

The LakeGrade rubric puts Otter Lake at a C: clarity at 5.0 ft, 31 µg/L of phosphorus, and a TSI of 54 signal an intermediate trophic state. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

At a TSI of 54, Otter Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 30 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Otter Lake covers 174 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Otter Lake ranks 166 of 191 in Vilas County — at the lower end of the locally monitored distribution.

Eurasian watermilfoil has been documented at Otter Lake, requiring shoreline management to keep dense mats from crowding native vegetation. Walleye are documented at Otter Lake, one of 6 fish species on record for the lake. 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.