Merwin
Lewis River·
Cowlitz, Washington·
Built 1931·
Arch·
313 ft tall
Physical Details
| Dam Height | 313 ft (taller than 91.3% in WA) |
| Dam Length | 1,250 ft |
| Dam Type | Arch |
| Max Storage | 422.0K acre-ft |
| Normal Storage | 422.0K acre-ft |
| Surface Area | 3,921 acres |
| Drainage Area | 726 sq mi |
| Max Discharge | 120,000 cfs |
| Year Completed | 1931 (95 years old) |
| NID ID | WA00149 |
Safety Information
High Hazard
Loss of human life is likely if the dam fails
Emergency Action Plan: Yes
Last Inspection: April 19, 2022
State Regulated: No
Ownership
PacifiCorp
Private
Nearby Dams
Frequently Asked Questions
What is the hazard classification of Merwin?
Merwin is classified as High Hazard. Loss of human life is likely if the dam fails.
Who owns Merwin?
Merwin is owned by PacifiCorp (Private).
When was Merwin last inspected?
Merwin was last inspected on April 19, 2022.
When was Merwin built?
Merwin was completed in 1931, making it 95 years old.
Data from the National Inventory of Dams (NID) maintained by the US Army Corps of Engineers. Dam conditions may have changed since the last update. This site is not affiliated with USACE. Do not use for emergency planning — contact your local dam safety program.