The best hope for cold-water chinook salmon to survive global warming may be near sweltering Fresno -- in the San Joaquin River, where salmon have been extinct for 60 years.
That's the latest twist in the long-running debate over restoring the San Joaquin, a project that will begin in less than 18 months.
Farmers, forced by legal settlement to give up irrigation water for the project, are skeptical about the claim. They see global warming as a reason to reconsider the half-billion-dollar restoration. Warmer conditions will kill the restored fish runs, they say.
But fishery experts say San Joaquin salmon would tolerate climate warming better than salmon in cooler places, such as Northern California.
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The reason: The highest of the High Sierra would continue to provide the cold water that salmon must have to survive in the San Joaquin. Northern California has the lower end of the Sierra and, scientists predict, eventually won't have much of a snowpack, eliminating a lot of cold water.
"The restored San Joaquin may be an important place for the survival of salmon in the next century," said fishery biologist Peter Moyle of the University of California at Davis.
The back-and-forth over restoring the river has been unfolding for decades, with debate focused mostly on a troubled, 149-mile section of the San Joaquin between Fresno and its confluence with the Merced River.
Global warming came into the picture last year when a report from a worldwide panel of experts said about 40% of the salmon habitat in the Pacific Northwest could be lost during climate change.
If the San Joaquin is revived, as is planned over the next decade, it would have the southernmost salmon fishery in North America.
And the San Joaquin Valley is expected to warm up faster than the Pacific Northwest or Northern California.
This prompts some farmers to question the wisdom of trying to return salmon to the San Joaquin.
"Does it really make sense to spend this money and restore salmon down here?" asked Chowchilla-area farmer Kole Upton.
But Moyle, an authority on California's native fish, said it is a very good idea for spring-run salmon. The fish will move up the river from the ocean in spring and spend summer in deep, cool ponds near Friant Dam before spawning during fall.
The release of cold snowmelt from Millerton Lake in summer should keep the ponds cool enough for salmon even as the climate warms up, Moyle said.
The undercurrent of this discussion is political, as it has been all along.
Farmers agreed in 2006 to cooperate in the restoration only because they were losing a marathon lawsuit over the issue. They remain worried about the $2.5 billion agriculture economy that the river helped to create on the Valley's east side.
Now, they're committed to give up an average of 19% of their river water each year to reconnect the San Joaquin with the Sacramento-San Joaquin River Delta.
Some of the water losses will begin next year. The first salmon are supposed to be in the river by the end of 2012.
Congress continues to work on a bill to fund about $500 million of the restoration. Much of the money is needed to rebuild the river channel for better flows that will help fish.
Farm officials have long doubted whether salmon could be restored on the San Joaquin. General manager Doug Welch of the Chowchilla Water District was involved in river studies several years ago. He said the restored salmon runs may not live long enough to experience global warming later in the century.
"The temperature will not be suitable for salmon," he said. "It will just get too warm when you get downstream."
Knowing there is a gloomy forecast for cold-water fish, such as salmon and steelhead, the restoration now looks like an even worse investment to many farmers.
But they don't speak publicly about it, saying privately that they fear they will trigger a movement to dissolve the 2006 settlement.
They do not want to see a federal judge decide how much water they must give up.
Upton, a Chowchilla district board member and a former negotiator in the settlement, has lost faith in the agreement. He does not fear the prospect of going back to court. Global warming plays a part in his thinking.
"I'm very concerned about investing in bringing back these fish if we're just going to lose them later on," Upton said. "As a society, we need to consider the best way to invest this money. That's something we need to talk about."
He said it would make more sense to forget about the salmon and restore about 85 miles of the river to Sack Dam, north of Firebaugh. That would at least help other fish species, such as trout, that are already in the river, he said.
He suggested spending more money on existing salmon restoration programs to the north, on the Merced, Stanislaus and Tuolumne rivers.
The most-quoted study in the argument was published last year by the Intergovernmental Panel on Climate Change, a U.N. network of 2,000 scientists and more than 100 governments.
The panel said salmon and trout in North America are likely to suffer the most harm. Effects could be seen in the Pacific Northwest over the next four decades, the panel said.
North of Fresno, the same possible problems await salmon on such Sacramento River tributaries as Butte Creek, California fishery experts said. The northern Sierra's elevation appears to be too low to support much of a snowpack decades from now, they said.
But the San Joaquin is different, said John Cain, a scientist specializing in river restoration with the nonprofit Natural Heritage Institute, based in San Francisco.
He said the Sierra above the San Joaquin rises well beyond 9,000 feet, with peaks ranging as high as 13,000 and 14,000 feet. The alpine wilderness is easily high enough to keep a snowpack, he said.
UC biologist Moyle said salmon historically developed a higher tolerance to warm water in the San Joaquin. And if temperatures are a little higher, the young fish will grow faster.
"The name of the game for juvenile salmon is to be as big as possible," Moyle said. "The bigger they get, the better their chance for survival in the ocean."
He said a chinook salmon in the San Joaquin can live in water 65 to 68 degrees, and it can survive in water six degrees higher for a short time.
"They move around to find the cooler places during the day, and the water cools down at night," he said. "Remember, they'll only be passing through areas downstream on their way out to the ocean."
But what happens during a prolonged drought? What happens if the water becomes too warm for young salmon to swim down the river to the Pacific Ocean?
Moyle said juvenile salmon could be captured and transported in trucks to the ocean during the worst years. But he said that scenario could develop at any time, even without climate change.
He added that now is not the time for Valley residents to shy away from restoring the San Joaquin.
The healthy river will mean far more than restored salmon runs, he said.
"The river will change from being an eyesore to an asset for the community," he said. "The salmon is the poster child. But you will get more native fishes back -- tule perch, pike minnow, hardhead, hitch and California roach. If you have those fish, you have a thriving ecosystem."