Island Lake

On the LakeGrade rubric, Island Lake pulls an A: clarity at 55.8 ft and phosphorus readings still being added put it in the top bracket for Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

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. Island Lake is unusually deep for Wisconsin at 51 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. The lake is compact at 63 acres, with partial shoreline records and little volume to buffer nutrient inputs. Within Bayfield County's 55 graded waters, Island Lake sits at rank 8, near the top of the local distribution.

Island Lake has no invasive species recorded in Wisconsin state databases as of 2025, though prevention practices still apply at all access points. The fishery includes walleye alongside the lake's other 4 documented species — a notable draw for Wisconsin anglers. A documented public access point at Island Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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.