Twenty-One Lake

On the LakeGrade rubric, Twenty-One Lake pulls an A: clarity at 17.0 ft and 10 µg/L of phosphorus put it in the top bracket for Minnesota. 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 value of 37 puts Twenty-One Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's 52 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. At 36 acres, Twenty-One Lake sits below the Minnesota median: a small water where shoreline activity has an outsized effect on water quality. Among the 77 graded lakes in Hubbard County, Twenty-One Lake sits at rank 26, above the county median.

No invasive species are currently listed at Twenty-One Lake — the lake remains off the Minnesota infested-waters roster. The fishery is bass-led, with 6 documented species across the lake's records. A documented public access point at Twenty-One 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.