Upper Maple Lake

Upper Maple Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Wright County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI value of 40 puts Upper Maple Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's 76 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. Upper Maple Lake covers 633 acres alongside 7.2 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within Wright County's 64 graded waters, Upper Maple Lake sits at rank 2, near the top of the local distribution.

Zebra mussels have been documented at Upper Maple Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at Upper Maple Lake, one of 15 fish species on record for the lake. A documented public access point at Upper 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.