Upper Tumbling Run is a historic earth dam located in North Manheim Township, Pennsylvania, completed in 1836. This dam serves as a crucial water supply source, with a storage capacity of 980 acre-feet and a normal storage volume of 760 acre-feet. The dam impounds the Tumbling Run stream, covering a surface area of 36 acres and draining a watershed area of 5.5 square miles.

Despite its significant role in water supply, Upper Tumbling Run is currently classified as having a high hazard potential and poor condition assessment. The dam stands at 55 feet in height and stretches 570 feet in length. It is regulated by the Pennsylvania Department of Environmental Protection, with state permitting, inspection, and enforcement in place. The last inspection of the dam was conducted in December 2020, with a frequency of one inspection per year.

For water resource and climate enthusiasts, Upper Tumbling Run presents an intriguing case study of a historic dam with vital water supply functions facing maintenance challenges. With its high hazard potential and poor condition assessment, there is a pressing need for risk assessment, management measures, and potential rehabilitation to ensure the safety and reliability of this essential water infrastructure in Schuylkill County, Pennsylvania.