Desalination plant construction underway in Antioch as drought worsens

ANTIOCH – The city of Antioch sits right next to the largest source of fresh water in Northern California. But it’s facing a water supply crisis because of changes to the Delta, both natural and man-made. 

As a result, the city is taking extraordinary measures to increase supply in a way that has the rest of the state watching.

Founded in the 1800s, Antioch was established on the banks of the Delta. But the city’s public works Director, John Samuelson, said it’s been a while since the Delta has provided much life to the area.

“We were only able to use our river intake for 30 days this year,” Samuelson told KPIX 5. “Last year, we weren’t able to use our intake for a single day because of the salinity levels. Because there’s no water runoff from the Sierras to push the salinity back out into the Delta.”

Over the decades, more and more water has been siphoned out of the Delta to supply Southern California cities and Central Valley farmers.

Now, with even more reduced flows because of the drought, seawater from the Bay is pushing up into the system, making Antioch’s historic water supply too salty to use.

“Until we get enough precipitation, enough rain upstream in the watershed, and start to fill our reservoirs and start to add more fresh water in, you’re going to have issues like that,” said Jacob McQuirk, principal engineer for the California Department of Water Resources.

But while the state may be praying for rain, Antioch doesn’t see the situation improving anytime soon.  So, they’re doing what a lot of other cities have only pondered–they’re building the first surface-water desalination plant in the Bay Area.

The new facility, located at the city’s wastewater treatment plant, will use large reverse-osmosis filters to create 6 million gallons of fresh water per day–about a third of the city’s needs–but with room for expansion.

“We’re actually only building about half of this facility,” said Samuelson, “so this building is large enough for us to be able to double the size of this in the future.”

Because they’re dealing with brackish water, which has a lower salt content than regular Bay water, they can clarify it using less energy and creating less salt-concentrated wastewater.

It’s an advantage many other Bay Area cities don’t have, but they’re still closely watching what Antioch is doing.

“Yeah, we’ve received a lot of interest from other water agencies on this project,” Samuelson said.  “I’ve had several reach out to me.  I do anticipate that you’re going to see more of these facilities coming up here in the Bay Area and across the state.”

All told, the desalination plant will cost about $110 million, with about $82 million of that coming from state grants and loans.

Samuelson said supply chain problems have delayed the project a bit, and he predicts it will be operational sometime at the end of next year or the beginning of 2024.