Kidney Lake

Kidney Lake comes in at a B on the grading rubric — a respectable showing for a Minnesota lake of its size and depth. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI near 42 places Kidney Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. Kidney Lake is unusually deep for Minnesota at 55 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. Kidney Lake is small — 56 acres alongside 1.6 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Within Cass County's 133 graded lakes, Kidney Lake ranks 92 — below the local median, though not at the bottom.

Kidney Lake has no invasive species recorded in Minnesota state databases as of 2021, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Kidney Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Kidney Lake — most use is by shoreline residents and their guests. 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.