Pit No. 4 Diversion
Key Takeaway
Pit No. 4 Diversion is classified as high hazard in California. It was completed in 1927 and is 99 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 | 110 ft (taller than 83.9% in CA) |
| Dam Length | 415 ft |
| Dam Type | Concrete |
| Max Storage | 2.0K acre-ft |
| Normal Storage | 2.0K acre-ft |
| Surface Area | 105 acres |
| Drainage Area | 4,643 sq mi |
| Max Discharge | 77,000 cfs |
| Year Completed | 1927 (99 years old) |
| NID ID | CA00397 |
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 Pit No. 4 Diversion?
Pit No. 4 Diversion 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 Pit No. 4 Diversion?
Pit No. 4 Diversion is owned by Pacific Gas and Electric Company (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Pit No. 4 Diversion built?
Pit No. 4 Diversion was completed in 1927, making it 99 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 Pit No. 4 Diversion?
Pit No. 4 Diversion 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 Pit No. 4 Diversion?
Pit No. 4 Diversion has a dam height of 110 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 Pit No. 4 Diversion last inspected?
Pit No. 4 Diversion was last inspected on July 26, 2023. Inspection dates indicate when a formal review occurred, not the results of that inspection.