Superior Lake

Superior Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in St. Louis County. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. 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 St. Louis County's 187 graded waters, Superior Lake sits at rank 28, near the top of the local distribution.

Zebra mussel presence at Superior Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. The state fisheries records do not list documented species for Superior Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. A documented public access point at Superior Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.