Thorn Run, located in Oakland Township, Butler, Pennsylvania, is a privately owned Earth dam completed in 1903 for water supply purposes. The dam stands at a height of 39.7 feet and has a length of 660 feet, with a storage capacity of 960 acre-feet. It serves a drainage area of 6.3 square miles and has a surface area of 49 acres, making it a crucial water resource in the region.

Managed by the Pennsylvania Department of Environmental Protection, Thorn Run is regulated, permitted, inspected, and enforced to ensure its structural integrity and operational efficiency. The dam has a high hazard potential but is currently in satisfactory condition, as per the last inspection in June 2020. It has undergone modifications in 2012 for hydraulic improvements, further enhancing its ability to manage water flow and storage.

With its vital role in water supply and its historical significance dating back over a century, Thorn Run represents a significant piece of infrastructure in the region. Climate and water resource enthusiasts can appreciate its design, purpose, and the effort put into its maintenance to ensure the safety and reliability of the dam for the community it serves.