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.

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. Great Northern Lake reaches 16 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 196 acres, Great Northern Lake fits the Minnesota median for monitored lakes, with 6.0 miles of shoreline. Within the 55 graded lakes of Stearns County, Great Northern Lake sits at rank 42, near the bottom of the county list.

Zebra mussels have been documented at Great Northern Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Great Northern Lake's fishery is anchored by muskellunge, with 21 documented species in total — a destination water for muskie anglers. 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.