Alpine Main
Key Takeaway
Alpine Main is classified as high hazard in California. It was completed in 1891 and is 135 years old. Its primary use is hydroelectric. 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 | 49 ft (taller than 57.9% in CA) |
| Dam Length | 401 ft |
| Dam Type | Rockfill |
| Max Storage | 4.3K acre-ft |
| Normal Storage | 4.1K acre-ft |
| Surface Area | 172 acres |
| Drainage Area | 5 sq mi |
| Max Discharge | 6,700 cfs |
| Year Completed | 1891 (135 years old) |
| NID ID | CA00422 |
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
Northern California Power Agency
Private
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High Hazard 317 ftFrequently Asked Questions
What is the hazard classification of Alpine Main?
Alpine Main 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 Alpine Main?
Alpine Main is owned by Northern California Power Agency (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Alpine Main built?
Alpine Main was completed in 1891, making it 135 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 Alpine Main?
Alpine Main serves the following purposes: Hydroelectric, Recreation, Water Supply. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Alpine Main?
Alpine Main has a dam height of 49 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 Alpine Main last inspected?
Alpine Main was last inspected on August 10, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.