Twin Bear Lake

On the LakeGrade rubric, Twin Bear Lake pulls an A: clarity at 64.0 ft and phosphorus readings still being added put it in the top bracket for Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. At 59 ft of maximum depth, Twin Bear Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. The lake's 157 acres and partial shoreline records put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Within Bayfield County's 55 graded lakes, Twin Bear Lake ranks 37 — below the local median, though not at the bottom.

Eurasian watermilfoil has been documented at Twin Bear Lake, requiring shoreline management to keep dense mats from crowding native vegetation. Walleye are documented at Twin Bear Lake, one of 6 fish species on record for the lake. Public access is available — the lake is on the Wisconsin DNR public-access list. 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.