Patterson
Key Takeaway
Patterson is classified as high hazard in California. It was completed in 1962 and is 64 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 | 39 ft (taller than 44.4% in CA) |
| Dam Length | 1,275 ft |
| Dam Type | Earth |
| Max Storage | 104 acre-ft |
| Surface Area | 4 acres |
| Drainage Area | 0 sq mi |
| Year Completed | 1962 (64 years old) |
| NID ID | CA00048 |
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
California Department of Water Resources
State Government
Nearby Dams
Dyer
Alameda, CA
High Hazard 30 ftDel Valle
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High Hazard 222 ftBethany Forebay
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High Hazard 95 ftLos Vaqueros
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High Hazard 231 ftMaria
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High Hazard 48 ftClifton Court Forebay
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Low Hazard 34 ftJames H. Turner
Alameda, CA
High Hazard 193 ftFrequently Asked Questions
What is the hazard classification of Patterson?
Patterson 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 Patterson?
Patterson is owned by California Department of Water Resources (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Patterson built?
Patterson was completed in 1962, making it 64 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 Patterson?
Patterson 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 Patterson?
Patterson has a dam height of 39 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 Patterson last inspected?
Patterson was last inspected on November 17, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.