Merwin
Merwin is a 136 MW hydroelectric power plant in Cowlitz County, Washington, operated by PacifiCorp. EIA-860M lists 4 generating units here. Its units entered service between 1931 and 1958.
As of 2026-07 (inventory dated 2026-07-31) · EIA-860M Preliminary Monthly Electric Generator Inventory · eia.gov/…/july_generator2026.xlsx · eia.gov/…/eia860m
- Nameplate capacity
- 136 MW
- 151 MW net summer
- Generating units
- 4
- In service
- 1931–1958
- EIA plant ID
- 3847
Where it is
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- County
- Cowlitz County, Washington
- Coordinates
- 45.9567, -122.5544
- Balancing authority
- PACW
- Sector
- Electric Utility
Units, technology and status
- Operator of record
- PacifiCorp
- Primary energy source
- Hydro
- Technologies
- Conventional Hydroelectric
- Status
- Operating
Merwin: FAQ
- Where is Merwin?
- In Cowlitz County, Washington (WA). The map on this page is placed at the coordinates EIA files for the plant, which locate the site rather than any individual unit.
- How big is Merwin?
- 136 MW of nameplate capacity across 4 units, as of the EIA-860M release for 2026-07.
- Who owns Merwin?
- EIA-860M names PacifiCorp as the reporting entity. That is the operator of record on the survey, which is not always the ultimate owner.
- Is this the same as Merwin LLC?
- Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — PacifiCorp here — not the project company that holds the asset. Project companies are commonly registered as an LLC carrying the plant's name, so a search for "Merwin LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.
- Is Merwin still running?
- EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.