Merwin
Cowlitz County, Washington · EIA plant ID 3847 · Operator: PacifiCorp
Nameplate136MWSummer 151 MW
Generators4in service
Net generation423GWh12 mo to Dec 2025
Capacity factor32%hydro units, summer MW
Heat rate—thermal plants only
First online1931
Monthly net generation
EIA-923, all units at the plant. Net of station use; storage can go negative.
FinalPreliminary
Capacity factor by year
Net MWh ÷ (summer MW × hours), hydro units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2001 | 353.4 | 28.0% | — |
| 2002 | 486.5 | 38.6% | — |
| 2003 | 501.9 | 39.8% | — |
| 2004 | 457.3 | 35.9% | — |
| 2005 | 406.3 | 32.0% | — |
| 2006 | 547 | 43.1% | — |
| 2007 | 473.5 | 35.8% | — |
| 2008 | 481.8 | 36.3% | — |
| 2009 | 452.4 | 34.2% | — |
| 2010 | 559.4 | 42.3% | — |
| 2011 | 576 | 43.5% | — |
| 2012 | 657.6 | 49.6% | — |
| 2013 | 460.9 | 34.8% | — |
| 2014 | 579.6 | 43.8% | — |
| 2015 | 398.8 | 30.1% | — |
| 2016 | 560.1 | 42.2% | — |
| 2017 | 629.6 | 47.6% | — |
| 2018 | 450.5 | 34.1% | — |
| 2019 | 337 | 25.5% | — |
| 2020 | 471.7 | 35.6% | — |
| 2021 | 465.7 | 35.2% | — |
| 2022 | 487.1 | 36.8% | — |
| 2023 | 471.6 | 35.6% | — |
| 2024 | 467.3 | 35.2% | — |
| 2025 | 422.6 | 31.9% | — |
Generators
EIA-860 (annual) with EIA-860M updates through Sep 2026. EIA-923 reports generation by plant, prime mover and fuel, not by unit, so unit-level output isn't shown.
| Gen ID | Technology | Prime mover | Nameplate MW | Summer MW | Online | Status | Planned retirement | OEM / model |
|---|---|---|---|---|---|---|---|---|
| 1 | Conventional Hydroelectric | HY | 45 | 50 | Jan 1932 | Operating | — | coming soon |
| 2 | Conventional Hydroelectric | HY | 45 | 50 | Dec 1949 | Operating | — | coming soon |
| 3 | Conventional Hydroelectric | HY | 45 | 50 | Sep 1958 | Operating | — | coming soon |
| House | Conventional Hydroelectric | HY | 1 | 1 | Jul 1931 | Operating | — | coming soon |
Owner / operator
Operator: PacifiCorp. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| PacifiCorp | 100.0% | 136 MW |
Nearby plants
Within 80 km.
| Yale | 134 MW | 16.9 km |
| Swift 2 | 72 MW | 25.5 km |
| Swift 1 | 240 MW | 29.6 km |
| Longview Fibre | 45 MW | 32.5 km |
| River Road Gen Plant | 248 MW | 36.6 km |
| Nippon Dynawave Packaging Longview WA | 62 MW | 37.2 km |