Merwin Dam
| Company type | Hydroelectric facility |
|---|---|
| Industry | Energy |
| Founded | 1929 |
| Headquarters | Washington , United States |
| Products | Hydroelectric power |
| Owner | PacifiCorp |
Merwin Dam, also referred to as Ariel Dam, is a concrete arch-gravity hydroelectric facility situated on the Lewis River, straddling the boundary between Cowlitz and Clark counties in Washington State, USA. The dam impounds Lake Merwin.
Built during the period from 1929 to 1931, this structure is managed by PacifiCorp. It extends 1,250 feet in length and rises to a height of 313 feet. The reservoir created by the dam holds up to 422,000 acre-feet of water and drains a watershed spanning 731 square miles.
The power generation station at Merwin Dam is equipped with three Francis turbines rated at 45 MW each, along with an additional 1 MW unit, delivering a combined installed capacity of 136 MW. Its annual electricity output is roughly 511,534 MWh. The plant was brought online in stages across the years 1931, 1949, and 1958.
As a vital contributor to clean energy in the region, Merwin Dam constitutes an important component of PacifiCorp’s hydroelectric assets.