Blackduck Lake

Blackduck Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. 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.

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. A maximum depth of 30 ft puts Blackduck Lake in the middle of Minnesota's depth distribution. With 1,250 acres of surface and 12.1 miles of shoreline, Blackduck Lake is a large water by Minnesota standards — recreational pressure is spread across a long shoreline. Within St. Louis County's 187 graded lakes, Blackduck Lake ranks 107 — below the local median, though not at the bottom.

No invasive species are currently listed at Blackduck Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Blackduck Lake, one of 8 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. Ice-out has been recorded 12 times at Blackduck Lake, with a median around Apr 18. 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.