Where is Lower Monumental?

In Walla Walla 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 Lower Monumental?

810 MW of nameplate capacity across 6 units, as of the EIA-860M release for 2026-07.

Who owns Lower Monumental?

EIA-860M names USACE Northwestern Division 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 Lower Monumental LLC?

Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — USACE Northwestern Division 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 "Lower Monumental LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.

Is Lower Monumental still running?

EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.

Lower Monumental

Lower Monumental is a 810 MW hydroelectric power plant in Walla Walla County, Washington, operated by USACE Northwestern Division. EIA-860M lists 6 generating units here. Its units entered service between 1969 and 1979.

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: 810 MW; 810 MW net summer
Generating units: 6
In service: 1969–1979
EIA plant ID: 3927

Where it is

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County: Walla Walla County, Washington
Coordinates: 46.5635, -118.5397
Balancing authority: BPAT
Sector: Electric Utility

Units, technology and status

Operator of record: USACE Northwestern Division
Primary energy source: Hydro
Technologies: Conventional Hydroelectric
Status: Operating (5) · Out of service but expected to return to service in next calendar year (1)

Every plant USACE Northwestern Division reports to EIA →

Lower Monumental: FAQ

Where is Lower Monumental?: In Walla Walla 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 Lower Monumental?: 810 MW of nameplate capacity across 6 units, as of the EIA-860M release for 2026-07.
Who owns Lower Monumental?: EIA-860M names USACE Northwestern Division 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 Lower Monumental LLC?: Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — USACE Northwestern Division 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 "Lower Monumental LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.
Is Lower Monumental still running?: EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.