East Bay water company's efforts lead to Chinook salmon spawning in record numbers

California's severe drought had a disastrous effect on many parts of the environment, but nowhere more serious than on the native Chinook salmon population.

The iconic fish now faces the threat of extinction. But in one small river in the Central Valley, the salmon are spawning in record numbers thanks to the efforts of an East Bay water company.

Most have never heard of the Mokelumne River in San Joaquin County — it's not very big. But for Chinook salmon, the place is very important. As EBMUD's Fisheries and Wildlife Manager, Michelle Workman is accustomed to being out on the Mokelumne. But what she's seeing these days is even hard for her to believe.

"This isn't normal," she said, looking down at the roiling water. "Our long-term average from 1940 to present is about 5,000 fish. We have over 24,000 fish in the river now."

Legend has it that there used to be so many salmon in the Mokelumne that you could walk across the river on their backs. It feels a little like that now. A record number of Chinook have arrived at the Camanche Dam in a mad scramble to lay their eggs. But what's truly remarkable about it is that just about everywhere else, the opposite is happening.

"Unfortunately, the same is not being seen on other rivers," said Workman. "And especially in the Upper Sacramento Basin, they experienced very low runs this year."

So low that, in the spring, only 25 adult fish made it to Deer Creek in Tehama County. So, a crew from the California Department of Fish and Wildlife began capturing young Chinook to raise in captivity at UC Davis in case they should go extinct.

"So, we can have a captive brood population that we can use to start a conservation hatchery and make sure these fish don't blink out," said Matt Johnson, with CDFW.

But if things are that bad, what's going on at the Mokelumne? The river is managed by EBMUD, the water supplier for much of Alameda and Contra Costa counties, and for more than 10 years, Workman and her team have leaned in to conservation in a big way. They added gravel to the riverbed to form natural spawning sites and erected a fish hatchery to collect eggs and raise young salmon for release directly into the Bay.

But most importantly, they've taken a more thoughtful approach to releasing water to benefit the fish.

"We now, since 2010, have been pulsing water in the Fall," she said. "So, putting higher releases of water down the river in the Fall, to attract these fish back home."

The fish smell the Mokelumne water hitting the Delta and it acts like a beacon, showing them which way to go. And the increase in water flows during the drought kept the salmon eggs cooler, so more survived.  

"The work that's being done on the Mokelumne — the returns that we're seeing — is a good picture of what can happen if we actually do things right," said Scott Artis.

As Executive Director of the Golden State Salmon Association, Artis can't help but say "I told you so."  His organization has been begging the state for years to release more water into the rivers.

"The Mokelumne had cold water for salmon, and we see what that does. The Sacramento Valley has not had that cold water and those flows to help get those baby salmon to the ocean. This contrast is highlighting the fact that salmon need cold water. If we don't get it to them we're going to continue to see closed fishing seasons and ecosystem collapse," said Artis.

As for Workman? She's just happy that more than a decade of hard work is finally paying off.

"I like to think that other fisheries in California can learn something from some of the work we've done here," she said. "We're all dedicated to this river. We know it like the back of our hands, and we know what it needs and we advocate for that."

The Spring-run Chinook salmon numbers are so low that there is talk of putting them on the federal Endangered Species List. If that happens, it could force California to change its water policies and place further restrictions on the commercial fishing industry.  

The picture for California salmon is still a dark one. But the Mokelumne River is shining a light on what could, and some say must, be done to keep the fish from disappearing.