Rock Island
Key Takeaway
Rock Island is classified as high hazard in Washington. It was completed in 1932 and is 94 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 | 71 ft (taller than 54.3% in WA) |
| Dam Length | 3,108 ft |
| Dam Type | Gravity |
| Max Storage | 131.0K acre-ft |
| Normal Storage | 113.7K acre-ft |
| Surface Area | 3,120 acres |
| Drainage Area | 89,400 sq mi |
| Max Discharge | 920,000 cfs |
| Year Completed | 1932 (94 years old) |
| NID ID | WA00084 |
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
PUD #1 of Chelan County, WA
Public Utility
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High HazardFrequently Asked Questions
What is the hazard classification of Rock Island?
Rock Island 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 Rock Island?
Rock Island is owned by PUD #1 of Chelan County, WA (Public Utility). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Rock Island built?
Rock Island was completed in 1932, making it 94 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 Rock Island?
Rock Island serves the following purposes: Hydroelectric, Flood Risk Reduction. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Rock Island?
Rock Island has a dam height of 71 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 Rock Island last inspected?
Rock Island was last inspected on June 15, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.