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.

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 132 graded lakes, Kidney Lake ranks 90 — 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. 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.