Long Valley
Key Takeaway
Long Valley is classified as high hazard in California. It was completed in 1941 and is 85 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 | 126 ft (taller than 86.9% in CA) |
| Dam Length | 595 ft |
| Dam Type | Earth |
| Max Storage | 183.5K acre-ft |
| Surface Area | 5,280 acres |
| Drainage Area | 437 sq mi |
| Year Completed | 1941 (85 years old) |
| NID ID | CA00090 |
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
City of Los Angeles Department of Water And Power
Local Government
Nearby Dams
Frequently Asked Questions
What is the hazard classification of Long Valley?
Long Valley 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 Long Valley?
Long Valley is owned by City of Los Angeles Department of Water And Power (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Long Valley built?
Long Valley was completed in 1941, making it 85 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 Long Valley?
Long Valley serves the following purposes: Water Supply, Recreation, Hydroelectric. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Long Valley?
Long Valley has a dam height of 126 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 Long Valley last inspected?
Long Valley was last inspected on November 18, 2021. Inspection dates indicate when a formal review occurred, not the results of that inspection.