Pa-479
Pa-479 is an earth dam located in Washington County, Pennsylvania, built in 1969. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Pa-479
The primary purpose of Pa-479 is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Washington County (local government). It impounds the Tr Harmon Creek.
The dam stands 63 feet tall and stretches 650 feet across, creates a reservoir covering 4 acres, has a maximum storage capacity of 343 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1969, the structure is well into its service life at over 50 years 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 11/04/2020.
At 63 feet, this dam is taller than 96% of all dams in the United States.
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 | Washington |
| River/Stream | Tr Harmon Creek |
| Coordinates | 40.36750, -80.48444 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 63 ft |
| Dam Height | 63 ft |
| Dam Length | 650 ft |
| Year Completed | 1969 (57 years old) |
Storage & Hydraulics
| NID Storage | 343 acre-ft |
| Max Storage | 343 acre-ft |
| Normal Storage | 26 acre-ft |
| Surface Area | 4 acres |
| Drainage Area | 1 sq mi |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | WASHINGTON COUNTY |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 11/04/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | PA00509 |
| Federal ID | PA00509 |
| More Info | State Dam Safety Program |