Billy Boy Flowage Lake

Billy Boy Flowage Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin.

Mesotrophic conditions dominate at Billy Boy Flowage Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. A maximum depth of 46 ft puts Billy Boy Flowage Lake in the middle of Wisconsin's depth distribution. The lake's 221 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 Sawyer County's 50 graded waters, Billy Boy Flowage Lake sits at rank 7, near the top of the local distribution.

Billy Boy Flowage Lake carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. The fishery includes walleye among the lake's 6 documented species — a notable draw for Wisconsin anglers. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.