Namakan Lake

The LakeGrade rubric puts Namakan Lake at a C: clarity at 8.2 ft, phosphorus readings still being added, and a TSI of 47 signal an intermediate trophic state. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Mesotrophic conditions dominate at Namakan Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. At 150 ft of maximum depth, Namakan Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. Namakan Lake covers 24,066 acres alongside 319.9 miles of shoreline, large enough that conditions can vary meaningfully between bays. Among the 187 graded lakes in St. Louis County, Namakan Lake sits at rank 84, above the county median.

An invasive species record — spiny waterflea — has been logged at Namakan Lake; Minnesota PCA maintains the official infested-waters list. The fishery includes walleye alongside the lake's other 18 documented species — a notable draw for Minnesota anglers. 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.