Mi40 Lake

Mi40 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.

Trophically, Mi40 Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. 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. Among the 11 graded lakes in Door County, Mi40 Lake sits at rank 3, above the county median.

Mi40 Lake has no invasive species recorded in Wisconsin state databases as of 2023, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Mi40 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.