Spider Lake

Spider Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in 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. A maximum depth of 15 ft puts Spider Lake in the middle of Wisconsin's depth distribution. At 66 acres, Spider Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Within Bayfield County's 55 graded waters, Spider Lake sits at rank 3, near the top of the local distribution.

No invasive species are currently listed at Spider Lake — the lake remains off the Wisconsin infested-waters roster. The fishery includes walleye alongside the lake's other 4 documented species — a notable draw for Wisconsin anglers. 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.