Brule Lake

Brule Lake comes in at a B on the grading rubric — a respectable showing for a Minnesota lake of its size and depth. 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.

A TSI near 44 places Brule Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. The lake's 78 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. With 4,327 acres of surface and 63.1 miles of shoreline, Brule Lake is a large water by Minnesota standards — recreational pressure is spread across a long shoreline. Among the 128 graded lakes in Cook County, Brule Lake sits at rank 51, above the county median.

No invasive species are currently listed at Brule Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye alongside the lake's other 6 documented species — a notable draw for Minnesota anglers. A documented public access point at Brule Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a partial ice record — 8 observed ice-outs, centered near May 5. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.