Crab Lake

On the LakeGrade scale Crab Lake grades a B, with clarity at 13.0 ft and phosphorus readings still being added placing it above the Minnesota median.

A TSI near 40 places Crab Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. At 57 ft of maximum depth, Crab Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. The lake's 420 acres and 10.5 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Crab Lake ranks 61 of 187 in St. Louis County — solidly in the upper half of the local distribution.

Crab 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 Crab Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Crab 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.