| NPDP ID | WA00149 |
| Dam Name | Merwin |
| Other Dam Name | |
| Year of Completion | 1931 |
| State ID | 00935-01-01 |
| Is in NID | Yes |
| Is in Operation | Yes |
| Longitude | -122.48 |
| Latitude | 45.99 |
| State | WA |
| County | Clark |
| Town Section | T6N,R2E,S33 & 34,WM |
| River | Lewis R |
| Owner Name | Pacificorp |
| Owner Type | Private |
| Dam Types | Arch Gravity Concrete |
| NID Core | Homogenous dam; Concrete; Known; |
| Crest Length | 1250 |
| Dam NID Height | 313 |
| Structral Height | |
| Hydraulic Height | |
| Dam Volume | |
| NID Type | Rock |
| Max Storage Capacity | 422000 |
| Normal Storage Capacity | 422000 |
| NID Storage Capacity | 422000 |
| Surface Area | 3921 |
| Drainage Area | 731 |
| Primary Purpose | Hydroelectric |
| Secondary Purpose | Recreation |
| Hazard Classification | High |
| EAP | Yes |
| Is State Regulated | No |
| State Regulatory Agency | |
| Federal Regulatory Agency | DOE FERC |