Grignon Lake

On the LakeGrade rubric, Grignon Lake pulls an A: clarity at 19.7 ft and 23 µg/L of phosphorus put it in the top bracket for Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

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. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Grignon Lake ranks 54 of 66 in Oconto County — at the lower end of the locally monitored distribution.

Grignon Lake has no invasive species recorded in Wisconsin state databases as of 2021, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Grignon Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.