RIO VISTA (KCBS) — State and federal fishing officials began relocating Chinook salmon by the millions on Tuesday from five Northern California hatcheries to aid in their journey to the ocean as drought conditions are expected to deteriorate.

U.S. Fish and Wildlife Service, California Department of Fish and Wildlife and National Marine Fisheries Service have joined together in a 2-and-a-half month operation to transport the salmon by the truckload, downstream of the delta.

The shallow, warm waters of region’s rivers leave the juvenile fish vulnerable to predators so officials are helping them migrate to ensure the species continues to flourish.

It’s being called the largest salmon trucking operation in California.

One of the hatcheries is in Rio Vista where an unprecedented amount of baby salmon and smolts were taken to be re-released. By the end of the release period, more than 30 million fish will have been released.

“If we didn’t truck these fish under these drought conditions, we believe we’d likely lose them all. It means fish in the ocean for us to catch in the year 2016,” said John McManus with the Golden Gate Salmon Association.

He recalled salmon season was shut down in the ocean in 2008 and 2009. Fish and wildlife officials had employed the truck migration technique in the drought of 1991 and 1992.