Alden Lake

On the scoring rubric Alden Lake grades a D: clarity at 4.9 ft and phosphorus readings still being added keep it in the lower bracket for St. Louis County. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

At a TSI of 54, Alden Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 29 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 190 acres, Alden Lake fits the Minnesota median for monitored lakes, with 4.1 miles of shoreline. Within the 187 graded lakes of St. Louis County, Alden Lake sits at rank 170, near the bottom of the county list.

No invasive species are currently listed at Alden Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Alden Lake, one of 11 fish species on record for the 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.