Balch Afterbay
Key Takeaway
Balch Afterbay is classified as high hazard in California. It was completed in 1928 and is 98 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 | 165 ft (taller than 91.8% in CA) |
| Dam Length | 238 ft |
| Dam Type | Concrete |
| Max Storage | 325 acre-ft |
| Normal Storage | 317 acre-ft |
| Surface Area | 7 acres |
| Drainage Area | 13 sq mi |
| Max Discharge | 43,000 cfs |
| Year Completed | 1928 (98 years old) |
| NID ID | CA00336 |
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
Pacific Gas and Electric Company
Private
Nearby Dams
Frequently Asked Questions
What is the hazard classification of Balch Afterbay?
Balch 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 Balch Afterbay?
Balch Afterbay is owned by Pacific Gas and Electric Company (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Balch Afterbay built?
Balch Afterbay was completed in 1928, making it 98 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 Balch Afterbay?
Balch Afterbay serves the following purposes: Hydroelectric. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Balch Afterbay?
Balch Afterbay has a dam height of 165 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 Balch Afterbay last inspected?
Balch Afterbay was last inspected on August 16, 2023. Inspection dates indicate when a formal review occurred, not the results of that inspection.