Loon Lake

On the LakeGrade rubric Loon Lake fails the cutoffs — a TSI of 82 and persistent algal pressure put it in the bottom tier. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.

The hypereutrophic status — TSI 82 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. Loon Lake is a shallow lake at 8 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. At 708 acres, Loon Lake fits the Minnesota median for monitored lakes, with 6.3 miles of shoreline. Loon Lake ranks 6 of 7 in Jackson County — at the lower end of the locally monitored distribution.

Loon Lake has at least one documented invasive species (bighead carp), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. Walleye are documented at Loon Lake, one of 18 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.