Thorn Run
Thorn Run is an earth dam located in Butler County, Pennsylvania, built in 1903. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Thorn Run
The primary purpose of Thorn Run is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Pa American Water Company (private). It impounds the Thorn Run.
The dam stands 40 feet tall and stretches 660 feet across, creates a reservoir covering 49 acres, has a maximum storage capacity of 960 acre-feet, and collects water from a drainage area of 6 square miles. Completed in 1903, the structure is over a century old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 06/08/2020.
At 40 feet, this dam is taller than 87% of dams nationwide.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Pennsylvania dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Pennsylvania |
| County | Butler |
| River/Stream | Thorn Run |
| Coordinates | 40.89444, -79.86500 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 40 ft |
| Dam Height | 40 ft |
| Dam Length | 660 ft |
| Year Completed | 1903 (123 years old) |
Storage & Hydraulics
| NID Storage | 960 acre-ft |
| Max Storage | 960 acre-ft |
| Normal Storage | 560 acre-ft |
| Surface Area | 49 acres |
| Drainage Area | 6 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | PA AMERICAN WATER COMPANY |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/08/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | PA00271 |
| Federal ID | PA00271 |
| More Info | State Dam Safety Program |