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. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Mesotrophic conditions dominate at Crab Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. The lake's 57 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. Crab Lake covers 420 acres alongside 10.5 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Crab Lake ranks 65 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. 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.