Bone Lake

On the LakeGrade rubric, Bone Lake pulls an A: clarity at 24.6 ft and 20 µg/L of phosphorus put it in the top bracket for 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 39 puts Bone Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake bottoms out at 43 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. With 1,667 acres of surface and partial shoreline records, Bone Lake is a large water by Wisconsin standards — recreational pressure is spread across a long shoreline. Bone Lake ranks 31 of 77 in Polk County — solidly in the upper half of the local distribution.

Zebra mussels have been documented at Bone Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Bass fishing is part of the appeal: the species list runs to 4, anchored by largemouth and/or smallmouth bass. 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.