Plane Nine
Key Takeaway
Plane Nine is classified as high hazard in Pennsylvania. It was completed in 1907 and is 119 years old. Its primary use is water supply. 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 | 51 ft (taller than 84.8% in PA) |
| Dam Length | 735 ft |
| Dam Type | Earth |
| Max Storage | 561 acre-ft |
| Normal Storage | 337 acre-ft |
| Surface Area | 23 acres |
| Drainage Area | 13 sq mi |
| Year Completed | 1907 (119 years old) |
| NID ID | PA00520 |
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
ALTOONA WATER AUTHORITY
Local Government
Nearby Dams
Hollidaysburg Muleshoe Reservoir
Blair, PA
High Hazard 66 ftBlair Gap
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High Hazard 47 ftUpper Kittanning
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High Hazard 45 ftWilliam L. Cochran Impounding
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High Hazard 60 ftLake Altoona
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High Hazard 65 ftScotch Run
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Low Hazard 40 ftReservoir No 4
Cambria, PA
Significant Hazard 18 ftReservoir No 5
Cambria, PA
Significant Hazard 20 ftFrequently Asked Questions
What is the hazard classification of Plane Nine?
Plane Nine 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 Plane Nine?
Plane Nine is owned by ALTOONA WATER AUTHORITY (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Plane Nine built?
Plane Nine was completed in 1907, making it 119 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 Plane Nine?
Plane Nine serves the following purposes: Water Supply. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Plane Nine?
Plane Nine has a dam height of 51 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 Plane Nine last inspected?
Plane Nine was last inspected on May 13, 2020. Inspection dates indicate when a formal review occurred, not the results of that inspection.