Shell Lake

On the LakeGrade rubric, Shell Lake pulls an A: clarity at 42.7 ft and 11 µg/L of phosphorus put it in the top bracket for Minnesota. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI value of 31 puts Shell Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. 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 86 graded lakes in Beltrami County, Shell Lake ranks 6 — in the top quartile locally.

No invasive species are currently listed at Shell Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Shell Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.