Grand Coulee
Key Takeaway
Grand Coulee is classified as high hazard in Washington. It was completed in 1941 and is 85 years old. Its primary use is flood risk reduction. 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 | 550 ft (taller than 98.9% in WA) |
| Dam Length | 5,673 ft |
| Dam Type | Concrete |
| Max Storage | 9.6M acre-ft |
| Normal Storage | 9.6M acre-ft |
| Surface Area | 82,300 acres |
| Drainage Area | 74,100 sq mi |
| Max Discharge | 265,000 cfs |
| Year Completed | 1941 (85 years old) |
| Year Modified | 1974 |
| NID ID | WA00262 |
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
RECLAMATION
Federal Government
Nearby Dams
Frequently Asked Questions
What is the hazard classification of Grand Coulee?
Grand Coulee 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 Grand Coulee?
Grand Coulee is owned by RECLAMATION (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Grand Coulee built?
Grand Coulee was completed in 1941, making it 85 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 Grand Coulee?
Grand Coulee serves the following purposes: Flood Risk Reduction, Irrigation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Grand Coulee?
Grand Coulee has a dam height of 550 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 Grand Coulee last inspected?
Grand Coulee was last inspected on September 15, 2020. Inspection dates indicate when a formal review occurred, not the results of that inspection.