Gunflint Lake

On the LakeGrade rubric, Gunflint Lake pulls an A: clarity at 20.0 ft and phosphorus readings still being added put it in the top bracket for Minnesota. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Trophically, Gunflint Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. The lake's 200 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. Gunflint Lake covers 4,009 acres alongside 39.2 miles of shoreline, large enough that conditions can vary meaningfully between bays. Within Cook County's 128 graded waters, Gunflint Lake sits at rank 14, near the top of the local distribution.

Gunflint Lake has at least one documented invasive species (spiny waterflea), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. The fishery includes walleye alongside the lake's other 12 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a long ice-out record — 81 observations on file, with a median ice-out around May 6. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.