Point Marion Lock and Dam is a gravity dam located in Greene County, Pennsylvania, built in 1959. It carries a Significant hazard potential classification.
Dam profile
NID height · 52 ft52 ft tall and 638 ft long, taller than 93% of U.S. dams with a recorded height. Height is drawn to scale against a ten-story building, about 100 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Point Marion Lock and Dam
The primary purpose of Point Marion Lock and Dam is navigation. The dam maintains water levels sufficient for boat and barge traffic, supporting commercial or recreational navigation on the waterway. The dam is owned by USACE - Pittsburgh District (federal). It impounds the Monongahela River near Point Marion.
The dam stands 52 feet tall and stretches 638 feet across, creates a reservoir covering 710 acres, has a maximum storage capacity of 11,500 acre-feet, and collects water from a drainage area of 2,715 square miles. Completed in 1959, the structure is well into its service life at over 50 years old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. An emergency action plan is in place for this dam. The most recent inspection on record was 06/10/2024.
At 52 feet, this dam is taller than 93% of dams nationwide.
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Location
| State | Pennsylvania |
| County | Greene |
| Nearest City | Point Marion |
| River/Stream | Monongahela River |
| Coordinates | 39.72755, -79.91180 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 52 ft |
| Dam Length | 638 ft |
| Year Completed | 1959 (67 years old) |
Storage & Hydraulics
| NID Storage | 11,500 acre-ft |
| Max Storage | 11,500 acre-ft |
| Normal Storage | 11,500 acre-ft |
| Surface Area | 710 acres |
| Drainage Area | 2,715 sq mi |
| Max Discharge | 55,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Navigation |
| Owner | USACE - Pittsburgh District |
| Owner Type | Federal |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 06/10/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | PA00125 |
| Federal ID | PA00125 |
| More Info | State Dam Safety Program |