Big Cormorant Lake

On the LakeGrade rubric, Big Cormorant Lake pulls an A: clarity at 24.3 ft and 16 µg/L of phosphorus put it in the top bracket for Minnesota. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.

Trophically, Big Cormorant Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. At 75 ft of maximum depth, Big Cormorant Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. At 3,657 acres, Big Cormorant Lake is one of the larger lakes in Becker County, with 18.7 miles of shoreline supporting multiple distinct use patterns. Among the 93 graded lakes in Becker County, Big Cormorant Lake ranks 9 — in the top quartile locally.

Big Cormorant 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. Walleye are documented at Big Cormorant Lake, one of 16 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a long ice-out record — 51 observations on file, with a median ice-out around Apr 19. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.