Half Moon Lake

On the scoring rubric Half Moon Lake grades a D: clarity at 3.9 ft and 116 µg/L of phosphorus keep it in the lower bracket for Hennepin 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. Half Moon Lake reaches 25 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Half Moon Lake is small — 33 acres alongside 1.2 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Half Moon Lake sits at rank 57 of 95 in Hennepin County, in the lower half of the local distribution.

Half Moon Lake has no invasive species recorded in Minnesota state databases as of 2023, though prevention practices still apply at all access points. Walleye are documented at Half Moon Lake, one of 12 fish species on record for the lake. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.