Mount St. Helens Sediment Retention Structure
Key Takeaway
Mount St. Helens Sediment Retention Structure is classified as high hazard in Washington. It was completed in 1988 and is 38 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 | 186 ft (taller than 75% in WA) |
| Dam Length | 1,800 ft |
| Dam Type | Earth |
| Max Storage | 0 acre-ft |
| Normal Storage | 0 acre-ft |
| Surface Area | 0 acres |
| Drainage Area | 143 sq mi |
| Max Discharge | 228,000 cfs |
| Year Completed | 1988 (38 years old) |
| NID ID | WA00558 |
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
USACE - Portland District
Federal Government
Nearby Dams
Frequently Asked Questions
What is the hazard classification of Mount St. Helens Sediment Retention Structure?
Mount St. Helens Sediment Retention Structure 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 Mount St. Helens Sediment Retention Structure?
Mount St. Helens Sediment Retention Structure is owned by USACE - Portland District (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Mount St. Helens Sediment Retention Structure built?
Mount St. Helens Sediment Retention Structure was completed in 1988, making it 38 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 Mount St. Helens Sediment Retention Structure?
Mount St. Helens Sediment Retention Structure serves the following purposes: Flood Risk Reduction, Debris Control. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Mount St. Helens Sediment Retention Structure?
Mount St. Helens Sediment Retention Structure has a dam height of 186 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 Mount St. Helens Sediment Retention Structure last inspected?
Mount St. Helens Sediment Retention Structure was last inspected on March 10, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.