Diamond Lake

The LakeGrade rubric puts Diamond Lake at a C: clarity at 8.2 ft, phosphorus readings still being added, and a TSI of 47 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.

Mesotrophic conditions dominate at Diamond Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. 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. Diamond Lake sits at rank 41 of 74 in Polk County, in the lower half of the local distribution.

Diamond Lake 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 Diamond 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.