Middle Twin Lake at

The LakeGrade rubric puts Middle Twin Lake at at a C: clarity at 7.5 ft, phosphorus readings still being added, and a TSI of 48 signal an intermediate trophic state. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI near 48 places Middle Twin Lake at in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. 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 the 47 graded lakes of Washburn County, Middle Twin Lake at sits at rank 39, near the bottom of the county list.

Middle Twin Lake at has no invasive species recorded in Wisconsin state databases as of 2020, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Middle Twin Lake at, 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.