"It truly is a renewable source of energy, and it plays a critical role on our grid," said PG&E Vice President of Power Generation Dave Gabbard.
Gabbard says it was an engineering marvel not only in 1984 but today.
The company is now celebrating 40 years since the Helms operation came online.
The facility pumps water between the Courtright Reservoir above and Wishon Lake below.
Officials say that a tunnel cap is holding the entirety of Courtright Reservoir back.
The Helms powerhouse can pump the water in both directions, using the same water to generate electricity over and over again.
We were there as a massive hydraulic pump sent water from Wishon Lake back to the Courtright reservoir.
The generator weighs more than a million pounds and spins at about 360 RPM.
The behind the scenes look comes as PG&E faces criticism from Central Valley customers.
Electricity bills costing hundreds of dollars for many customers this summer.
PG&E Chief Operating Officer Sumeet Singh tells Action News executives hear customers' concerns.
"The customers want to know that the executives at the company are hearing their concerns. Is that true?" Action News reporter Gabe Ferris asked Singh.
"That is absolutely true," Singh responded. "One of the things we actually talk about is keeping the customers at the heart. So, what does that mean? Keeping the customers at the heart of all the decisions and actions that we take. That's where it stops and starts for us."
Singh says the electricity company is committed to its Fresno County workers and customers.
PG&E is preparing Helms for a six-month repair project.
"That's going to be a sustained, clean, reliable, affordable asset for our Fresno residents and the grid for a long time to come," Singh said.
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