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810 MW Hydro operating in Walla Walla, WA — Bonneville Power Administration
810 MW
Nameplate Capacity
6
Generators
units
Conventional Hydroelectric
Technology
1969
Operating Since
Coordinates
46.5635, -118.5397
County
Walla Walla, WA
Owner data does not fully agree across sources.
EIA typically reports the operating utility, while GEM resolves to the financial owner or parent corporation. Both can be correct.
| Field | EIA | GEM | Wikidata |
|---|---|---|---|
| Operator | USACE Northwestern Division | US Army Corps of Engineers - Walla Walla District | United States Army Corps of Engineers |
| Owner(s) | USACE Northwestern Division | US Army Corps of Engineers - Walla Walla District | — |
| Status | Operating | operating | — |
GEM identifies the owner as US Army Corps of Engineers - Walla Walla District
This entity is not yet in the GEM ownership database — chain unavailable.
Lower Monumental Lock and Dam is a hydroelectric, concrete, run-of-the-river dam in the northwest United States. Located on the lower Snake River in southeast Washington, it bridges Franklin and Walla Walla counties; it is six miles (10 km) south of Kahlotus and 43 miles (70 km) north of Walla Walla.
Read more on WikipediaLower Monumental is a hydroelectric power plant located in Walla Walla County, Washington. The plant, which began operating in 1969, has a total capacity of 810 MW distributed across six generators. It is owned and operated by the USACE Northwestern Division. The plant uses water as its primary fuel source and employs conventional hydroelectric technology. Lower Monumental ranks as the 10th largest power plant in Washington state out of 23, and 31st nationally out of 194 plants.
In the most recent year with available data, Lower Monumental generated 1,476,976 MWh of electricity, resulting in a capacity factor of 20.8%. The plant operates within the Bonneville Power Administration balancing authority and the Western Electricity Coordinating Council (WECC) NERC region. Recent news coverage of the plant includes 10 articles, with a focus on regulatory matters.
Generated from EIA, GEM, and public data sources
Grid Region
Pacific Northwest
Market
WEIM Participant
NERC Region
WECC — Western Electricity Coordinating Council
Balancing Authority
195.9K MWh
Latest Month
1.5M MWh
Annual Generation
20.8%
Capacity Factor
2013
$2,294/kW
Est. Construction Cost
Total estimated cost: $1.9B
This plant's balancing authority participates in CAISO's Western Energy Imbalance Market (WEIM). Direct nodal pricing data is not yet available.
Last updated 2026-03-26
View all 5 articlesNo ask pi reports yet for this entity.
ask pi about Lower MonumentalBonneville Power Administration (BPAT)
Grid Voltage
500.0 kV
Regulatory Status
RE — Regulated
Entity Type
Federal
Sector
Electric Utility