Maple Lake

The LakeGrade rubric puts Maple Lake at a C: clarity at 3.4 ft, 38 µg/L of phosphorus, and a TSI of 58 signal an intermediate trophic state. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than 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 14 ft deep, Maple Lake is shallow — wind keeps the water column mixed and sediment resuspension drives phosphorus levels harder to manage. Maple Lake covers 1,641 acres alongside 19.8 miles of shoreline, large enough that conditions can vary meaningfully between bays. Among the 20 graded lakes in Polk County, Maple Lake sits at rank 10, above the county median.

No invasive species are currently listed at Maple Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Maple Lake, one of 12 fish species on record for the lake. A documented public access point at Maple 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.