Mille Lacs Lake

Mille Lacs Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year.

A TSI near 45 places Mille Lacs Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. Mille Lacs Lake reaches 42 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Mille Lacs Lake covers 128,250 acres alongside 105.5 miles of shoreline, large enough that conditions can vary meaningfully between bays. Mille Lacs Lake ranks 10 of 11 in Mille Lacs County — at the lower end of the locally monitored distribution.

Zebra mussel presence at Mille Lacs Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. Muskie are on the species list at Mille Lacs Lake, among the lake's 21 documented fish. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a long ice-out record — 105 observations on file, with a median ice-out around Apr 25. 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.