Otter Lake

On the LakeGrade scale Otter Lake grades a B, with clarity at 16.4 ft and 31 µg/L of phosphorus placing it above the Wisconsin median. Phosphorus is the parameter holding the grade back — runoff from the surrounding watershed appears to keep nutrient levels elevated through the summer.

A TSI near 45 places Otter Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. 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 172 of 202 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.