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 43 ft puts Spider Lake in the middle of Wisconsin's depth distribution. Spider Lake covers 278 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Spider Lake ranks 9 of 202 in Vilas County, putting it in the upper tier of locally monitored lakes.

Eurasian watermilfoil is established at Spider Lake, which can dampen recreational access and pressure the native plant community. The fishery includes walleye alongside the lake's other 6 documented species — a notable draw for Wisconsin anglers. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.