Grass Island Lake

Grass Island Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in Minnesota.

The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Among the 92 graded lakes in Beltrami County, Grass Island Lake ranks 19 — in the top quartile locally.

No invasive species are currently listed at Grass Island Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Grass Island Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. 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.