Hat Rapids Flowage Lake

On the LakeGrade scale Hat Rapids Flowage Lake grades a B, with clarity at 11.5 ft and phosphorus readings still being added placing it above the Wisconsin median. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

The lake sits in the mesotrophic zone — the band where most well-managed Wisconsin lakes fall. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. Hat Rapids Flowage Lake covers 295 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within Oneida County's 140 graded lakes, Hat Rapids Flowage Lake ranks 102 — below the local median, though not at the bottom.

Hat Rapids Flowage Lake has at least one documented invasive species (Chinese Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. The state fisheries records do not list documented species for Hat Rapids Flowage 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.