Island Lake

Island Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in 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 28 puts Island Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake bottoms out at 35 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Island Lake covers 865 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within Vilas County's 202 graded waters, Island Lake sits at rank 22, near the top of the local distribution.

Island Lake has at least one documented invasive species (Banded Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. The fishery includes walleye alongside the lake's other 6 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. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.