Sealion Lake

On the LakeGrade rubric, Sealion Lake pulls an A: clarity at 84.0 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. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Within Florence County's 39 graded lakes, Sealion Lake ranks 29 — below the local median, though not at the bottom.

No invasive species are currently listed at Sealion Lake — the lake remains off the Wisconsin infested-waters roster. The state fisheries records do not list documented species for Sealion Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. 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.