Third Lake

On the LakeGrade scale Third Lake grades a B, with clarity at 8.5 ft and 14 µg/L of phosphorus placing it above the Minnesota median. Secchi readings are the weakest of the scored parameters, suggesting suspended sediment or algal biomass dominates the optical signal.

A TSI near 42 places Third Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. 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. Within Carlton County's 33 graded waters, Third Lake sits at rank 2, near the top of the local distribution.

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