Simian Lake

Simian Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. Secchi readings are the weakest of the scored parameters, suggesting suspended sediment or algal biomass dominates the optical signal.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. 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 187 graded lakes in St. Louis County, Simian Lake sits at rank 82, above the county median.

No invasive species are currently listed at Simian Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Simian Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The lake lacks a documented public access point, so visitor use is limited. Multiple sampling years from Minnesota PCA volunteers and partner agencies back the grade, so the letter should hold steady absent a major watershed shift.