Thermalito Afterbay
Key Takeaway
Thermalito Afterbay is classified as high hazard in California. It was completed in 1967 and is 59 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 | 42,000 ft |
| Dam Type | Earth |
| Normal Storage | 57.0K acre-ft |
| Surface Area | 6,900 acres |
| Drainage Area | 13 sq mi |
| Max Discharge | 17,000 cfs |
| Year Completed | 1967 (59 years old) |
| NID ID | CA00042 |
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
Frequently Asked Questions
What is the hazard classification of Thermalito Afterbay?
Thermalito Afterbay 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 Thermalito Afterbay?
Thermalito Afterbay 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 Thermalito Afterbay built?
Thermalito Afterbay was completed in 1967, making it 59 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 Thermalito Afterbay?
Thermalito Afterbay serves the following purposes: Water Supply, Irrigation, Recreation, Hydroelectric. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Thermalito Afterbay?
Thermalito Afterbay 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 Thermalito Afterbay last inspected?
Thermalito Afterbay was last inspected on August 23, 2023. Inspection dates indicate when a formal review occurred, not the results of that inspection.