Upper Buffalo #33a Dam
Upper Buffalo #33a Dam is an earth dam located in Marion County, West Virginia, built in 1992. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Upper Buffalo #33a Dam
The primary purpose of Upper Buffalo #33a Dam 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 Monongahela Cd (local government). It impounds the Flat Run near Mannington.
The dam stands 51 feet tall and stretches 393 feet across, creates a reservoir covering 6 acres, has a maximum storage capacity of 503 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1992, the structure is 34 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 06/30/2025.
At 51 feet, this dam is taller than 93% 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 West Virginia 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 | West Virginia |
| County | Marion |
| Nearest City | Mannington |
| River/Stream | Flat Run |
| Coordinates | 39.59444, -80.33306 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 51 ft |
| Dam Height | 51 ft |
| Dam Length | 393 ft |
| Year Completed | 1992 (34 years old) |
Storage & Hydraulics
| NID Storage | 503 acre-ft |
| Max Storage | 503 acre-ft |
| Normal Storage | 51 acre-ft |
| Surface Area | 6 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 9,249 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Monongahela CD |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/30/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WV04934 |
| Federal ID | WV04934 |
| More Info | State Dam Safety Program |