Alton Power Dam
Key Takeaway
Alton Power Dam is classified as high hazard in New Hampshire. It was completed in 1923 and is 103 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 | 16 ft (taller than 54.9% in NH) |
| Dam Length | 190 ft |
| Dam Type | Concrete |
| Max Storage | 3.4K acre-ft |
| Normal Storage | 1.2K acre-ft |
| Surface Area | 719 acres |
| Drainage Area | 35 sq mi |
| Max Discharge | 3,900 cfs |
| Year Completed | 1923 (103 years old) |
| Year Modified | 1986 |
| NID ID | NH00011 |
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
NH FISH AND GAME DEPARTMENT
State Government
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Low Hazard 14 ftLocke Lake Dam
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Low Hazard 12 ftFrequently Asked Questions
What is the hazard classification of Alton Power Dam?
Alton Power Dam 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 Alton Power Dam?
Alton Power Dam is owned by NH FISH AND GAME DEPARTMENT (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Alton Power Dam built?
Alton Power Dam was completed in 1923, making it 103 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 Alton Power Dam?
Alton Power Dam 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 Alton Power Dam?
Alton Power Dam has a dam height of 16 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 Alton Power Dam last inspected?
Alton Power Dam was last inspected on April 26, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.