Birch Lake

On the LakeGrade rubric, Birch Lake pulls an A: clarity at 21.3 ft and 17 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.

A TSI value of 39 puts Birch Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. A maximum depth of 45 ft puts Birch Lake in the middle of Wisconsin's depth distribution. The lake's 506 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 Vilas County's 202 graded waters, Birch Lake sits at rank 13, near the top of the local distribution.

Birch Lake has at least one documented invasive species (Chinese 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 6 documented species — a notable draw for Wisconsin anglers. Public access is available — the lake is on the Wisconsin DNR public-access list. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.