| Merwin Dam | |
|---|---|
| Location | Clark / Cowlitz counties, Washington, USA |
| Coordinates | [1] |
| Opening date | 1931[2] |
| Dam and spillways | |
| Height | 313 feet (95 m) |
| Length | 1,250 feet (381 m)[2] |
| Impounds | Lewis River |
| Reservoir | |
| Creates | Lake Merwin |
| Capacity | 422,000 acre feet (0.521 km3)[2] |
| Catchment area | 731 square miles (1,890 km2)[2] |
| Surface area | 3,921 acres (15.9 km2)[2] |
Merwin Dam (also known as Ariel Dam[1]) is a concrete arch gravity-type hydroelectric dam on the Lewis River, in the U.S. state of Washington. It is located on the border between Cowlitz County and Clark County. Its reservoir is called Lake Merwin.