Little Armstrong Lake

Little Armstrong Lake earns an A — every scored parameter (clarity) rates among the best monitored waters in St. Louis County.

A TSI value of 38 puts Little Armstrong Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Little Armstrong Lake reaches 26 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Little Armstrong Lake is small — 70 acres alongside 2.2 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Within St. Louis County's 187 graded waters, Little Armstrong Lake sits at rank 9, near the top of the local distribution.

No invasive species are currently listed at Little Armstrong Lake — the lake remains off the Minnesota infested-waters roster. The fishery is bass-led, with 2 documented species across the lake's records. The lake lacks a documented public access point, so visitor use is limited. 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.