Arrowrock
Key Takeaway
Arrowrock is classified as high hazard in Idaho. It was completed in 1915 and is 111 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 | 350 ft (taller than 99% in ID) |
| Dam Length | 1,150 ft |
| Dam Type | Concrete |
| Max Storage | 283.7K acre-ft |
| Normal Storage | 272.2K acre-ft |
| Surface Area | 3,256 acres |
| Drainage Area | 2,230 sq mi |
| Max Discharge | 16,080 cfs |
| Year Completed | 1915 (111 years old) |
| Year Modified | 2010 |
| NID ID | ID00280 |
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 Arrowrock?
Arrowrock 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 Arrowrock?
Arrowrock is owned by RECLAMATION (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Arrowrock built?
Arrowrock was completed in 1915, making it 111 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 Arrowrock?
Arrowrock serves the following purposes: Flood Risk Reduction, Irrigation, Fish And Wildlife Pond, Recreation, Water Supply. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Arrowrock?
Arrowrock has a dam height of 350 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 Arrowrock last inspected?
Arrowrock was last inspected on February 18, 2020. Inspection dates indicate when a formal review occurred, not the results of that inspection.