Mountain Island
Key Takeaway
Mountain Island is classified as high hazard in North Carolina. It was completed in 1923 and is 103 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 | 140 ft (taller than 84.5% in NC) |
| Dam Length | 2,375 ft |
| Dam Type | Gravity |
| Max Storage | 46.0K acre-ft |
| Normal Storage | 46.0K acre-ft |
| Surface Area | 3,235 acres |
| Drainage Area | 1,860 sq mi |
| Max Discharge | 383,685 cfs |
| Year Completed | 1923 (103 years old) |
| NID ID | NC00787 |
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
Duke Energy
Public Utility
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Significant HazardFrequently Asked Questions
What is the hazard classification of Mountain Island?
Mountain 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 Mountain Island?
Mountain Island is owned by Duke Energy (Public Utility). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Mountain Island built?
Mountain Island was completed in 1923, making it 103 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 Mountain Island?
Mountain Island serves the following purposes: Hydroelectric, Water Supply. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Mountain Island?
Mountain Island has a dam height of 140 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 Mountain Island last inspected?
Mountain Island was last inspected on June 7, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.