Third Lake

On the scoring rubric Third Lake grades a D: clarity at 5.5 ft and phosphorus readings still being added keep it in the lower bracket for Chisago County. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

At a TSI of 53, Third Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. 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 the 31 graded lakes of Chisago County, Third Lake sits at rank 24, near the bottom of the county list.

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. 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.