Birch Lake

On the LakeGrade rubric, Birch Lake pulls an A: clarity at 18.0 ft and 28 µg/L of phosphorus put it in the top bracket for Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

The lake sits in the mesotrophic zone — the band where most well-managed Wisconsin lakes fall. At 73 ft of maximum depth, Birch Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. The lake's 364 acres and partial shoreline records put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Within the 48 graded lakes of Washburn County, Birch Lake sits at rank 39, near the bottom of the county list.

Birch Lake has at least one documented invasive species (Banded Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. The fishery includes walleye alongside the lake's other 5 documented species — a notable draw for Wisconsin anglers. Public access is available — the lake is on the Wisconsin DNR public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.