Lower Granite

Hydro power plant in Washington, United States of America. Approximate location 46.6595, -117.4294.

HydroWashingtonUnited States of America

Lower Granite is a 810 MW hydro power station in Washington, United States of America. It is operated by USACE Northwestern Division. Based on reported annual generation of 2,193 GWh, it can supply roughly 626,514 homes. It ranks #419 of 9,833 United States of America power plants by installed capacity. Commissioned in 1976, it is around 50 years old — long-established. As a non-combustion source, it has no direct CO₂ emissions from generation. In context, hydro supplies about 5.3% of United States of America's electricity; the national grid averages 384 gCO₂/kWh (43.0% low-carbon) (2025).

810MW installed capacity
2,193GWh reported / yr
626,514homes powered
1976commissioned (~50 yrs)

Plant data: WRI Global Power Plant Database (CC BY 4.0), id USA0006175.

Reported generation trend

2013: 1,680 GWh20132014: 2,285 GWh20142015: 1,698 GWh20152016: 2,104 GWh20162017: 2,666 GWh20172018: 2,467 GWh20182019: 2,193 GWh20193k GWh

Annual generation (GWh), WRI Global Power Plant Database (CC BY 4.0).

Owner

Operated by USACE Northwestern Division. All plants by this company →

Local climate & thermal context

This hydro plant converts the energy of falling or flowing water through hydro turbines. It sits in a warm-summer Mediterranean climate (Köppen Csb) — Northern Hemisphere, latitude 46.7°N — which shapes how much energy it can produce and how its output varies through the year.

9.7°Cannual mean temp
3,159heating degree-days (base 18°C)
162cooling degree-days (base 18°C)
636 melevation

Monthly mean temperature

J: 0 °CJF: 3 °CFM: 6 °CMA: 9 °CAM: 13 °CMJ: 17 °CJJ: 21 °CJA: 21 °CAS: 16 °CSO: 10 °CON: 4 °CND: 0 °CD21 °C

Heating degree-days here run 29% above the median power plant in this dataset — a proxy for how much extra energy heated equipment must replace through its surfaces in winter.

Climate heat-demand index: 67/100 — this site sits in the top third of the power plants we cover by heating degree-days.

In colder climates, uninsulated hot equipment (boilers, turbines, valves, steam lines) loses proportionally more heat to ambient air — exactly the loss Inzonex modular insulation is designed to cut.

Climate normals: WorldClim 2.1 (1970–2000 monthly normals, 10 arc-min, CC BY 4.0); zone: Köppen-Geiger world climate classification (Kottek et al. 2006, 0.5° grid). Degree-days & heat-demand index computed by PowerAtlas — a modelled heat-demand proxy, not a measured site figure.

How it compares & nearby plants

The #27 largest hydro power plant of 1449 in United States of America by capacity.

United States of America has 1449 hydro power plants in this dataset, together about 101,657 MW of capacity.

Nearby power plants

Location

Coordinates 46.6595, -117.4294 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.

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