Marshan Lake

On the LakeGrade rubric Marshan Lake fails the cutoffs — a TSI of 74 and persistent algal pressure put it in the bottom tier. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

The hypereutrophic status — TSI 74 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. 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 24 graded lakes of Anoka County, Marshan Lake sits at rank 24, near the bottom of the county list.

Eurasian watermilfoil has been documented at Marshan Lake, requiring shoreline management to keep dense mats from crowding native vegetation. The state fisheries records do not list documented species for Marshan 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. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.