Merwin
Hydro power plant in Cowlitz County, Washington. 136 MW of nameplate capacity across 4 generators, operated by PacifiCorp.
Also known as Merwin Dam · EIA plant 3847
Analyst: free account, 1 question a day.
Key facts
- Capacity
- 136 MWNameplate
- Generators
- 4 operatingEIA-860M, August 2026
- Operating since
- July 1931First generator online
- Operator
- PacifiCorpEIA operator ID 14354
- Grid
- PACWBalancing authority PACW
- Price nodes
- None linkedNo verified ISO node
- Location
- Cowlitz County, WA45.9567, −122.5544
- EIA plant ID
- 3847EIA plant page
Data as of EIA-860M August 2026 (published 2026-09-24). Capacity is nameplate, not live output.
How much power Merwin produces
Free · EIA-923Net generation, 2025
423 GWh
422,567 MWh, final
Capacity factor, 2025
35.5%
2024: 39.1%
January to July 2026
Not reported
Provisional. 0 of 7 months reported
Range, 2015 to 2025
337.0–629.6
GWh a year. Low 2019, high 2017
| Year | Net generation, MWh | Capacity factor | Months reported |
|---|---|---|---|
| 2000 | 478,439 | Not reported | 12 of 12 |
| 2001 | 353,415 | Not reported | 12 of 12 |
| 2002 | 486,481 | Not reported | 12 of 12 |
| 2003 | 501,921 | Not reported | 12 of 12 |
| 2004 | 457,331 | Not reported | 12 of 12 |
| 2005 | 406,308 | Not reported | 12 of 12 |
| 2006 | 547,025 | Not reported | 12 of 12 |
| 2007 | 473,458 | Not reported | 12 of 12 |
| 2008 | 481,775 | Not reported | 12 of 12 |
| 2009 | 452,443 | Not reported | 12 of 12 |
| 2010 | 559,382 | 47.0% | 12 of 12 |
| 2011 | 576,030 | 48.4% | 12 of 12 |
| 2012 | 657,559 | 55.0% | 12 of 12 |
| 2013 | 460,852 | 38.7% | 12 of 12 |
| 2014 | 579,582 | 48.6% | 12 of 12 |
| 2015 | 398,837 | 33.5% | 12 of 12 |
| 2016 | 560,116 | 46.9% | 12 of 12 |
| 2017 | 629,623 | 52.8% | 12 of 12 |
| 2018 | 450,459 | 37.8% | 12 of 12 |
| 2019 | 337,034 | 28.3% | 12 of 12 |
| 2020 | 471,718 | 39.5% | 12 of 12 |
| 2021 | 465,720 | 39.1% | 12 of 12 |
| 2022 | 487,064 | 40.9% | 12 of 12 |
| 2023 | 471,579 | 39.6% | 12 of 12 |
| 2024 | 467,317 | 39.1% | 12 of 12 |
| 2025 | 422,567 | 35.5% | 12 of 12 |
| 2026 (provisional, partial year) | Not reported | Not reported | 0 of 7 |
* 2026 covers January to July and is provisional. Capacity factor is net generation divided by nameplate capacity times the hours of each reported month.
Power prices and basis
Free accountNo verified ISO price node is linked to this plant, or its price history could not load.
Emissions
Free · EPA CAMPDNo EPA emissions units are linked to this plant.
Water use
Free · EIA-923 cooling, USGSNo EIA cooling-water record for this plant in 2024. Plants without steam cooling, such as wind, solar and batteries, do not report cooling water.
Generators
Free · EIA-860M| Generator | Technology | Nameplate MW | Online since |
|---|---|---|---|
| 1 | Conventional Hydroelectric | 45.0 | January 1932 |
| 2 | Conventional Hydroelectric | 45.0 | December 1949 |
| 3 | Conventional Hydroelectric | 45.0 | September 1958 |
| House | Conventional Hydroelectric | 1.0 | July 1931 |
Ownership and offtake
ProOwnership and offtake are part of Pro
Owners and their shares, parent companies, and power purchase agreements with their buyers. EIA-860M lists PacifiCorp as the operator, which is not always the owner.
Modeled data
ProPro adds modeled values for this plant. Everything above stays free.
300 analyst questions a month, plus MCP
Query Merwin and 14,224 other projects from Claude or your own tools. Free accounts get 1 question a day.
Power plants near Merwin
More plants operated by PacifiCorp
Questions about Merwin
How much power does Merwin produce?
Merwin reported 422,567 MWh (423 GWh) of net generation in 2025, a 35.5% capacity factor on 136 MW of nameplate capacity.
Where is Merwin?
Merwin is in Cowlitz County, Washington, at 45.9567, −122.5544. It is in the PacifiCorp - West balancing area (PACW).
Who operates Merwin?
EIA-860M for August 2026 lists PacifiCorp as the operator (EIA operator ID 14354). The operator is not always the owner.
When did Merwin start operating?
Its first generator began operating in July 1931, according to EIA-860M.
Sources
- EIA-860 2025 (final) and EIA-860M August 2026: plant, generators, capacity, operator and location
- EIA-923 monthly net generation, 2000 to July 2026 (2026 provisional)
- Plant names from OpenStreetMap, © OpenStreetMap contributors (ODbL)
Page updated 2026-10-04 from the InfraMap data build. Methodology · Data sources · EIA plant page