Birch Lake

On the scoring rubric Birch Lake grades a D: clarity readings still being added and 60 µg/L of phosphorus keep it in the lower bracket for Sawyer County. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

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. At 73 ft of maximum depth, Birch Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. At 364 acres, Birch Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Within the 52 graded lakes of Sawyer County, Birch Lake sits at rank 50, near the bottom of the county list.

An invasive species record — Banded Mystery Snail — has been logged at Birch Lake; Wisconsin DNR maintains the official infested-waters list. Walleye are documented at Birch Lake, one of 5 fish species on record for the lake. A documented public access point at Birch Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.