Susan Lake

Susan Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. At only 10 ft deep, Susan Lake is shallow — wind keeps the water column mixed and sediment resuspension drives phosphorus levels harder to manage. At 276 acres, Susan Lake fits the Minnesota median for monitored lakes, with 5.1 miles of shoreline. Within St. Louis County's 187 graded lakes, Susan Lake ranks 139 — below the local median, though not at the bottom.

No invasive species are currently listed at Susan Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Susan Lake, one of 7 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.