Lower Monumental
Hydro power plant in Walla Walla County, Washington. 675 MW of nameplate capacity across 5 generators, operated by USACE Northwestern Division.
Also known as Lower Monumental Powerhouse · EIA plant 3927
Analyst: free account, 1 question a day.
Key facts
- Capacity
- 675 MWNameplate
- Generators
- 5 operatingEIA-860M, August 2026
- Operating since
- June 1969First generator online
- Operator
- USACE Northwestern DivisionEIA operator ID 19400
- Grid
- BPATBalancing authority BPAT
- Price nodes
- None linkedNo verified ISO node
- Location
- Walla Walla County, WA46.5635, −118.5397
- EIA plant ID
- 3927EIA plant page
Data as of EIA-860M August 2026 (published 2026-09-24). Capacity is nameplate, not live output.
How much power Lower Monumental produces
Free · EIA-923Net generation, 2025
1.48 TWh
1,476,976 MWh, final
Capacity factor, 2025
20.8%
2024: 18.0%
January to July 2026
969 GWh
Provisional
Range, 2015 to 2025
1.3–2.8
TWh a year. Low 2024, high 2017
| Year | Net generation, MWh | Capacity factor | Months reported |
|---|---|---|---|
| 2000 | 2,344,481 | Not reported | 12 of 12 |
| 2001 | 1,922,664 | Not reported | 12 of 12 |
| 2002 | 2,509,465 | Not reported | 12 of 12 |
| 2003 | 2,104,335 | Not reported | 12 of 12 |
| 2004 | 2,267,584 | Not reported | 12 of 12 |
| 2005 | 1,850,110 | Not reported | 12 of 12 |
| 2006 | 2,755,839 | Not reported | 12 of 12 |
| 2007 | 1,682,562 | Not reported | 12 of 12 |
| 2008 | 2,200,501 | Not reported | 12 of 12 |
| 2009 | 2,416,856 | Not reported | 12 of 12 |
| 2010 | 1,858,858 | 26.2% | 12 of 12 |
| 2011 | 3,295,329 | 46.4% | 12 of 12 |
| 2012 | 2,520,051 | 35.4% | 12 of 12 |
| 2013 | 1,697,014 | 23.9% | 12 of 12 |
| 2014 | 2,290,236 | Not reported | 12 of 12 |
| 2015 | 1,640,095 | 23.1% | 12 of 12 |
| 2016 | 1,987,131 | 27.9% | 12 of 12 |
| 2017 | 2,767,576 | Not reported | 12 of 12 |
| 2018 | 2,383,418 | 33.6% | 12 of 12 |
| 2019 | 2,240,943 | Not reported | 12 of 12 |
| 2020 | 1,637,311 | 23.0% | 12 of 12 |
| 2021 | 1,338,468 | Not reported | 12 of 12 |
| 2022 | 1,682,647 | 23.7% | 12 of 12 |
| 2023 | 1,553,008 | Not reported | 12 of 12 |
| 2024 | 1,281,014 | 18.0% | 12 of 12 |
| 2025 | 1,476,976 | 20.8% | 12 of 12 |
| 2026 (provisional, partial year) | 968,673 | 23.5% | 7 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 | 135.0 | June 1969 |
| 3 | Conventional Hydroelectric | 135.0 | February 1970 |
| 4 | Conventional Hydroelectric | 135.0 | March 1979 |
| 5 | Conventional Hydroelectric | 135.0 | April 1979 |
| 6 | Conventional Hydroelectric | 135.0 | July 1979 |
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 USACE Northwestern Division as the operator, which is not always the owner.
Modeled data
ProPro adds modeled values for this plant. Everything above stays free.
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Power plants near Lower Monumental
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Questions about Lower Monumental
How much power does Lower Monumental produce?
Lower Monumental reported 1,476,976 MWh (1.48 TWh) of net generation in 2025, a 20.8% capacity factor on 675 MW of nameplate capacity. From January to July 2026 it reported 969 GWh, which is provisional.
Where is Lower Monumental?
Lower Monumental is in Walla Walla County, Washington, at 46.5635, −118.5397. It is in the Bonneville Power Administration balancing area (BPAT).
Who operates Lower Monumental?
EIA-860M for August 2026 lists USACE Northwestern Division as the operator (EIA operator ID 19400). The operator is not always the owner.
When did Lower Monumental start operating?
Its first generator began operating in June 1969, 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