Loon Lake

On the LakeGrade scale Loon Lake grades a B, with clarity at 8.5 ft and 19 µg/L of phosphorus placing it above the Wisconsin median. 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. A maximum depth of 26 ft puts Loon Lake in the middle of Wisconsin's depth distribution. The lake is compact at 91 acres, with partial shoreline records and little volume to buffer nutrient inputs. Within Barron County's 37 graded waters, Loon Lake sits at rank 8, near the top of the local distribution.

Loon Lake has at least one documented invasive species (Chinese Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. Walleye are documented at Loon Lake, one of 4 fish species on record for the lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.