Loon Lake

Loon Lake comes in at a B on the grading rubric — a respectable showing for a Minnesota lake of its size and depth. The lake's weakest score is on Secchi depth — the water looks more turbid than its phosphorus number alone would predict.

Mesotrophic conditions dominate at Loon 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. Among the 187 graded lakes in St. Louis County, Loon Lake sits at rank 55, above the county median.

Loon Lake has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Loon 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.