Great Northern Lake

On the scoring rubric Great Northern Lake grades a D: clarity at 4.0 ft and phosphorus readings still being added keep it in the lower bracket for Stearns 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 57, Great Northern Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 16 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. The lake's 196 acres and 6.0 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Within the 55 graded lakes of Stearns County, Great Northern Lake sits at rank 43, near the bottom of the county list.

Great Northern Lake is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. Muskie are on the species list at Great Northern Lake, alongside the lake's 21 other documented fish. No formal public access is documented at Great Northern Lake — most use is by shoreline residents and their guests. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.