Cottonwood Lake

On the scoring rubric Cottonwood Lake grades a D: clarity at 3.9 ft and 86 µg/L of phosphorus keep it in the lower bracket for Cottonwood County. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. At only 10 ft deep, Cottonwood Lake is shallow — wind keeps the water column mixed and sediment resuspension drives phosphorus levels harder to manage. The lake's 155 acres and 3.5 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Cottonwood Lake ranks 2 of 6 in Cottonwood County — solidly in the upper half of the local distribution.

Cottonwood Lake has no invasive species recorded in Minnesota state databases as of 2022, though prevention practices still apply at all access points. Walleye are documented at Cottonwood Lake, one of 15 fish species on record for the lake. A documented public access point at Cottonwood Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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.