Lower Monumental Lock and Dam
Key Takeaway
Lower Monumental Lock and Dam is classified as high hazard in Washington. It was completed in 1969 and is 57 years old. Its primary use is navigation. 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 Length | 3,800 ft |
| Dam Type | Concrete |
| Max Storage | 432.0K acre-ft |
| Normal Storage | 377.0K acre-ft |
| Surface Area | 6,590 acres |
| Drainage Area | 108,500 sq mi |
| Max Discharge | 850,000 cfs |
| Year Completed | 1969 (57 years old) |
| NID ID | WA00270 |
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
USACE - Walla Walla District
Federal Government
Frequently Asked Questions
What is the hazard classification of Lower Monumental Lock and Dam?
Lower Monumental Lock and Dam 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 Lower Monumental Lock and Dam?
Lower Monumental Lock and Dam is owned by USACE - Walla Walla District (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Lower Monumental Lock and Dam built?
Lower Monumental Lock and Dam was completed in 1969, making it 57 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 Lower Monumental Lock and Dam?
Lower Monumental Lock and Dam serves the following purposes: Navigation, Fish And Wildlife Pond, Recreation, Hydroelectric. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
When was Lower Monumental Lock and Dam last inspected?
Lower Monumental Lock and Dam was last inspected on June 15, 2021. Inspection dates indicate when a formal review occurred, not the results of that inspection.