Shell Lake

Shell Lake grades an F: water clarity, phosphorus, and chlorophyll-a all rate poorly, placing it among the most stressed lakes monitored in Minnesota. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

At a TSI of 61, Shell Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 15 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 493 acres, Shell Lake fits the Minnesota median for monitored lakes, with 8.3 miles of shoreline. Within the 187 graded lakes of St. Louis County, Shell Lake sits at rank 179, near the bottom of the county list.

No invasive species are currently listed at Shell Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Shell Lake, one of 8 fish species on record for the lake. No formal public access is documented at Shell Lake — most use is by shoreline residents and their guests. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.