Half Moon Lake

Half Moon Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. 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 31 puts Half Moon Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's 60 ft maximum depth is in the upper tier for Wisconsin — deep enough for cold-water fish to find refuge in summer. Half Moon Lake covers 550 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within Polk County's 77 graded waters, Half Moon Lake sits at rank 17, near the top of the local distribution.

Eurasian watermilfoil is established at Half Moon Lake, which can dampen recreational access and pressure the native plant community. Walleye are documented at Half Moon Lake, one of 4 fish species on record for the lake. A documented public access point at Half Moon 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.