Saint John
Key Takeaway
Saint John is classified as high hazard in Idaho. It was completed in 1918 and is 108 years old. Its primary use is irrigation. 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 | 43 ft (taller than 74.3% in ID) |
| Dam Length | 680 ft |
| Normal Storage | 630 acre-ft |
| Surface Area | 41 acres |
| Drainage Area | 11 sq mi |
| Max Discharge | 76 cfs |
| Year Completed | 1918 (108 years old) |
| NID ID | ID00001 |
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
Private
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High Hazard 42 ftFrequently Asked Questions
What is the hazard classification of Saint John?
Saint John 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 Saint John?
Saint John is owned by information not available (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Saint John built?
Saint John was completed in 1918, making it 108 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 Saint John?
Saint John serves the following purposes: Irrigation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Saint John?
Saint John has a dam height of 43 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 Saint John last inspected?
Saint John was last inspected on April 23, 2019. Inspection dates indicate when a formal review occurred, not the results of that inspection.