Mathay (Pa-459) is a flood risk reduction dam located in Hempfield Township, Mercer County, Pennsylvania. Built in 1962 by the USDA NRCS, this earth dam stands at a height of 22 feet and spans 3260 feet in length. Its primary purpose is to mitigate flooding along Mathay Run, providing protection to the surrounding community and infrastructure.

Managed by the Pennsylvania Department of Environmental Protection, Mathay (Pa-459) is regulated, permitted, inspected, and enforced to ensure its structural integrity and functionality. With a storage capacity of 755 acre-feet and a drainage area of 1.4 square miles, this dam plays a crucial role in water resource management in the region. Despite being classified as having a high hazard potential, its current condition is assessed as fair, highlighting the importance of regular inspections and maintenance.

Mathay (Pa-459) serves as a vital infrastructure for flood control in the area, working to safeguard lives and properties from potential disasters. As a key component of the local government's water resource management strategy, this dam exemplifies the collaborative efforts between state and federal agencies to ensure the safety and resilience of communities in the face of changing climate conditions.