Nine Mile
Key Takeaway
Nine Mile is classified as high hazard in Washington. It was completed in 1908 and is 118 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 | 58 ft (taller than 48.9% in WA) |
| Dam Length | 466 ft |
| Dam Type | Gravity |
| Normal Storage | 4.6K acre-ft |
| Surface Area | 440 acres |
| Drainage Area | 4,998 sq mi |
| Max Discharge | 60,000 cfs |
| Year Completed | 1908 (118 years old) |
| NID ID | WA00068 |
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
Avista Corporation
Private
Nearby Dams
Frequently Asked Questions
What is the hazard classification of Nine Mile?
Nine Mile 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 Nine Mile?
Nine Mile is owned by Avista Corporation (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Nine Mile built?
Nine Mile was completed in 1908, making it 118 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 Nine Mile?
Nine Mile serves the following purposes: Hydroelectric, Fish And Wildlife Pond, Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Nine Mile?
Nine Mile has a dam height of 58 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 Nine Mile last inspected?
Nine Mile was last inspected on August 16, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.