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Drought is taking a toll on one of California's most precious native fish. The winter-run Chinook salmon. The past two years have seen a decline in the numbers of juvenile salmon migrating downstream from Northern California, where they have spawning grounds. Experts warn that the species, which is already endangered, is now moving to the brink of extinction. NPR's Richard Gonzales reports.
RICHARD GONZALES, BYLINE: It's early morning, and we're on a small boat carrying us to the Red Bluff diversion dam on the upper Sacramento River, about three hours north of San Francisco.
JIM SMITH: And we're going to be seeing what we call rotary screw traps.
GONZALES: That's Jim Smith, the project leader of the Red Bluff Fish and Wildlife Service. The traps look like miniature cement mixers, about the size of a Mini Cooper attached to a floating platform. They'll capture small salmon and large clumps of green water weeds. Smith's staff has to sift through these weeds by hand, looking for small, silvery salmon, some not much bigger than your fingernail. Others are the size of your index finger.
SAMANTHA ADAMS: Sixty-five, 63, 80, 63.
GONZALES: One crew member, Samantha Adams, is measuring the salmon by millimeters. Their size indicates whether they are winter-run or larger fall-run salmon. Either way, there just aren't very many fish, says Jim Smith.
SMITH: This time of year in more normal years, you know, we'd be seeing hundreds of fish in here - in each trap. But right now - we'll be lucky to see in the tens, right now. So the numbers this year are very low. They're some of the lowest we have seen. And that has us all concerned.
GONZALES: Concerned because there are far fewer salmon counted this year than in 2014. And last year was considered a disaster for the fish. They have a three-year life cycle. So what's at stake is a whole generation of salmon. And they're an important food source, not only for wildlife but also for humans. If there's another year of low salmon counts, the commercial fishing industry could take a big hit too.
JON ROSENFIELD: This catastrophe this year, where we've lost more than 95 percent of our winter-run Chinook salmon, was entirely avoidable and entirely foreseeable.
GONZALES: Jon Rosenfield is a fish biologist with The Bay Institute. It's one of several environmental groups that has sued federal and state water managers. Rosenfield says the salmon require reliably cold water to survive. But that resource was depleted when too much water was allocated to farmers with senior water rights and reservoir levels dropped.
ROSENFIELD: And when the reservoir levels get low, the sun reaches more and more of the water and heats it up more and more. And there's less of that cold water resource at the bottom of the reservoir that can be provided for fish.
GONZALES: Maria Rey manages the West Coast Fisheries office for the National Oceanic and Atmospheric Administration. She says officials relied on measurements of cold water that were just wrong.
MARIA REY: Had we known that there was limited cold water, I think other types of operations would have been considered, including further limiting releases in April and May.
GONZALES: In other words, limiting the amount of water released to farmers. Of course, that wouldn't be very popular with farmers, many of whom are growing rice in the region, which requires lots of water. Thad Bettner is a general manager of the Glen Colusa water district. He says farmers received only 60 to 65 percent of the water they were entitled to. He admits the salmon numbers are bad. But he says the fish are a tough species.
THAD BETTNER: They are built for droughts. They're built for low-flow conditions. You know, that's built into their genetics. So I think we need to wait.
GONZALES: For now, the federal and state agencies balancing the needs of farmers and the fish are hoping Mother Nature will provide the answer for next year - a wet winter. Richard Gonzales, NPR News. Transcript provided by NPR, Copyright NPR.