Blair Gap
Blair Gap is a gravity dam located in Blair County, Pennsylvania, built in 1907. It carries a High hazard potential classification and has a fair condition assessment.
About Blair Gap
The primary purpose of Blair Gap 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 Altoona Water Authority (local government). It impounds the Blair Gap Run.
The dam stands 47 feet tall and stretches 316 feet across, creates a reservoir covering 4 acres, has a maximum storage capacity of 100 acre-feet, and collects water from a drainage area of 3 square miles. Completed in 1907, 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 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 05/13/2020.
At 47 feet, this dam is taller than 92% 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 | Blair |
| River/Stream | Blair Gap Run |
| Coordinates | 40.44778, -78.52833 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 47 ft |
| Dam Height | 47 ft |
| Dam Length | 316 ft |
| Year Completed | 1907 (119 years old) |
Storage & Hydraulics
| NID Storage | 100 acre-ft |
| Max Storage | 100 acre-ft |
| Normal Storage | 92 acre-ft |
| Surface Area | 4 acres |
| Drainage Area | 3 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | ALTOONA WATER AUTHORITY |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 05/13/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | PA00521 |
| Federal ID | PA00521 |
| More Info | State Dam Safety Program |