Youngstown Upground Reservoir
Youngstown Upground Reservoir is a concrete dam located in Mahoning County, Ohio, built in 1929. It carries a High hazard potential classification and has a fair condition assessment.
About Youngstown Upground Reservoir
The primary purpose of Youngstown Upground Reservoir 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 Mahoning Valley Sanitary District (local government). It impounds the Offstream near Youngstown.
The dam stands 29 feet tall and stretches 1,584 feet across, creates a reservoir covering 3 acres, and has a maximum storage capacity of 101 acre-feet. Completed in 1929, the structure is well-established, with more than 75 years of service.
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 fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 11/10/2021.
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 Ohio 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 | Ohio |
| County | Mahoning |
| Nearest City | Youngstown |
| River/Stream | Offstream |
| Coordinates | 41.10556, -80.70833 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 29 ft |
| Dam Height | 29 ft |
| Dam Length | 1,584 ft |
| Year Completed | 1929 (97 years old) |
Storage & Hydraulics
| NID Storage | 101 acre-ft |
| Max Storage | 101 acre-ft |
| Normal Storage | 96 acre-ft |
| Surface Area | 3 acres |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Mahoning Valley Sanitary District |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 11/10/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | OH03105 |
| Federal ID | OH03105 |
| More Info | State Dam Safety Program |