Posted on October 17, 2011

By the Numbers: Helms Pumped Storage Facility


Helms Powerhouse

Helms Pumped Storage operates between two reservoirs in the Sierra. (Photo by James Green.)


  • 8,000 (feet): Approximate elevation
  • 1,212 (MW): Generation capability from three 400-MW reversible generators
  • 900,000 (homes): Powered by 1,212 MW of power
  • 1,000 (feet): Depth of power house
  • 9,000 (cubic feet per second): How fast water flows downhill from Courtright Reservoir to Lake Wishon
  • 1,744 (feet): Vertical drop from Courtright to Wishon
  • 8 (minutes): How long it takes Helms to go from dead stop to full generation
  • 1984: When Helms opened
  • 50 (miles): East of Fresno, in the Sierra Nevada
  • 24: Full-time employees
  • 320 (feet): Length of powerhouse chamber, or about the length of a football field
  • 126 (feet): Height of the powerhouse chamber, or about as high as a 10-story building
  • 21,000 (linear feet): Of 38-foot diameter tunnels inside the facility
  • 1.1 million (cubic yards): Of underground excavation during construction
  • 2 million (pounds): Of reinforcing/structural steel used to build Helms
  • 21.5 (GW): Amount of pumped storage generating capacity in the U.S., according to Wikipedia.

For a video look at PG&E’s Helms Pumped Storage facility, click here.

Sources: PG&E; Granite Construction; Wikipedia

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