Heart Lake

Heart Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in 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 Heart Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's 55 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. At 224 acres, Heart Lake fits the Minnesota median for monitored lakes, with 3.5 miles of shoreline. Within Clearwater County's 40 graded waters, Heart Lake sits at rank 3, near the top of the local distribution.

Heart Lake has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. The fishery is bass-led, with 5 documented species across the lake's records. 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.