Allison Reservoir
Key Takeaway
Allison Reservoir is classified as high hazard in Pennsylvania. It was completed in 1917 and is 109 years old. Its primary use is recreation. High hazard means loss of life is likely if the dam fails — it does not indicate the dam's current condition. Learn more.
Physical Details
| Dam Height | 45 ft (taller than 81.2% in PA) |
| Dam Length | 348 ft |
| Dam Type | Earth |
| Max Storage | 180 acre-ft |
| Normal Storage | 140 acre-ft |
| Surface Area | 14 acres |
| Drainage Area | 1 sq mi |
| Year Completed | 1917 (109 years old) |
| NID ID | PA01076 |
Safety Information
Loss of human life is likely if the dam fails.
Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?
Ownership
O-RYAN DEVELOPMENT, INC.
Private
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Low Hazard 29 ftFrequently Asked Questions
What is the hazard classification of Allison Reservoir?
Allison Reservoir is classified as High Hazard. Loss of human life is likely if the dam fails. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.
Who owns and operates Allison Reservoir?
Allison Reservoir is owned by O-RYAN DEVELOPMENT, INC. (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Allison Reservoir built?
Allison Reservoir was completed in 1917, making it 109 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.
What is the primary purpose of Allison Reservoir?
Allison Reservoir serves the following purposes: Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Allison Reservoir?
Allison Reservoir has a dam height of 45 ft. Dam height is measured from the natural streambed at the downstream toe to the top of the dam, and may differ from the visible height.
When was Allison Reservoir last inspected?
Allison Reservoir was last inspected on March 30, 2021. Inspection dates indicate when a formal review occurred, not the results of that inspection.