REDWOOD CITY (KCBS)— A first-of-its kind tunnel dug underneath San Francisco Bay began delivering water from the Hetch Hetchy Reservoir in Yosemite National Park on Wednesday.

Water officials at Crystal Springs Reservoir in the Santa Cruz Mountains in San Mateo County called it a major seismic improvement to the Bay Area’s water delivery system. Water flowed into Crystal Springs through the $288 million, five-mile-long tunnel just before a ceremony was held.

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San Francisco Public Utilities Commission President Vince Courtney said the tunnel goes from Newark to Redwood City; ending at the exact location where 80 years ago, Hetch Hetchy water was first delivered to Bay Area customers.

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San Francisco Public Utilities Commission Assistant General Manager of the Water Enterprise Steve Ritchie said the tunnel replaces two pipelines built in the 1920s that were leaky and unsafe and “well beyond their life expectancy.”

“Also, coincidentally, 25 years ago we had one of the biggest earthquakes in modern times and that’s simply a reminder of how important this infrastructure is and how important it is to invest in this,” said Courtney.

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Bay Area voters approved a bond measure to upgrade the water system in 2002. Construction on the tunnel started in 2010. It’s among 83 projects and a $4.6 billion investment to keep water flowing after a major earthquake.