Loon Lake

Loon Lake earns an F: 122 µg/L of phosphorus and clarity at 2.0 ft signal heavy nutrient loading from the surrounding watershed. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

The hypereutrophic status — TSI 70 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. A maximum depth of just 9 ft means sediment-bound phosphorus releases back into the water column whenever wind stirs the bottom — a classic shallow-lake dynamic. Loon Lake covers 125 acres alongside 2.2 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Loon Lake sits at rank 4 of 6 in Waseca County, in the lower half of the local distribution.

No invasive species are currently listed at Loon Lake — the lake remains off the Minnesota infested-waters roster. Bass fishing is part of the appeal: the species list runs to 7, anchored by largemouth and/or smallmouth bass. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a long ice-out record — 35 observations on file, with a median ice-out around Mar 27. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.