Billy Boy, also known as Bolger, is a gravity dam located in Sawyer, Wisconsin, specifically in the city of Couderay. Completed in 1936, this dam serves primarily for recreation purposes and stands at a height of 13 feet with a hydraulic height of 8 feet. With a storage capacity of 53,600 acre-feet and a normal storage of 28,300 acre-feet, Billy Boy covers a surface area of 8,464 acres and has a drainage area of 110 square miles.

Managed by the local government and regulated by the Wisconsin Department of Natural Resources, Billy Boy has a significant hazard potential with a fair condition assessment as of May 2020. Despite its age, the dam has been inspected regularly, with the last inspection conducted in October 2018. The risk assessment for Billy Boy is categorized as very high, highlighting the importance of ongoing risk management measures to ensure the safety and integrity of the structure.

Situated on the Couderay River, Billy Boy offers a controlled spillway type and a maximum discharge capacity of 910 cubic feet per second. While the dam has not been modified in recent years, its historical significance and role in providing recreational opportunities underscore the importance of continued monitoring and maintenance to safeguard both the environment and surrounding communities.