FRESNO -- Skeptical farmers often ask a big key question about the $2 billion revival of the San Joaquin River and salmon runs: How can cold-water salmon possibly survive here as the climate heats up the river?
Prominent fishery biologist Peter Moyle replies that the San Joaquin will be an ideal place for salmon in the future. It will be a pipeline of chilly snowmelt from the high Sierra.
But for years, nobody has been able to settle that debate with science. Now, using a $1.5 million National Science Foundation grant, UC Merced is working on at least part of the answer -- a profile of the future San Joaquin River.
The study will guide authorities who manage reservoirs, recreation areas and hydroelectric lakes as the climate warms. It also will give farm water leaders and districts new insights on the timing of snowmelt decades from now.
But for 15,000 Valley farmers who irrigate with river water in Fresno, Madera, Merced, Tulare and Kern counties, this is all about salmon.
Their doubts about the salmon have haunted the restoration since 2006. That year, farmers, environmentalists and federal agencies agreed to end a lawsuit and revive dried sections of California's second-longest river.
Farmers agreed to give up some irrigation water and restore salmon because they were losing the lawsuit. But many say the restored salmon runs will be doomed in the next 50 years, anyway.
Farmers instead prefer warm-water fish, such as bass, in the restoration area.
"I'm not sure the salmon runs are the best investment for society as a whole," said farmer Kole Upton, who helped negotiate the river restoration settlement.
But since the lawsuit settlement requires the salmon restoration, there is little choice.
In the opinion of biologist Moyle, salmon restoration is a very good idea. He is considered a foremost authority on California fish, spending more than four decades studying them.
"The San Joaquin historically had one of the biggest runs of chinook salmon in the world," he said. "It's because the highest of the high Sierra is on the southern end of the mountain range. You get more snowmelt."
Cold water pools
The peaks, some ranging higher than 14,000 feet, still will be getting snow as the climate warms, he said. Some of the cold water will remain in deep pools just below Friant Dam, allowing spring-run salmon to safely live for the summer and migrate later in the year, Moyle said.
In Northern California, UC Davis research at Butte Creek has suggested salmon might perish there by the end of the century. Scientists continue to look at ways the dams and river systems can be managed to keep cold water around for the fish survive.
But the mountains around Butte Creek, a tributary of the Sacramento River, are lower in elevation than the Sierra around the San Joaquin, Moyle said. The Butte Creek watershed will not have much snow in the future.
The UC Merced study of the San Joaquin will look at many aspects of climate-change impacts on the river, including water temperature, says environmental engineering professor Thomas Harmon, who leads the investigation.
"Climate change could very well affect the flow of water for salmon," he said. "We expect to see some results after the first year of the study. It should be complete in the next three or four years."
Harmon said that there are records on snow, rain, temperature and other factors at hydroelectric lakes in the San Joaquin River watershed above Millerton Lake.
The data will give researchers a picture of conditions at various elevations for lakes such as Edison, Huntington, Redinger and Mammoth Pool, he said.
The Sierra Nevada Research Institute, run by fellow UC Merced researcher Roger Bales, also will provide data from its investigations of the Sierra over the past several years.
With established climate prediction models, researchers can use their analysis of the watershed to project a range of possibilities for the future San Joaquin.
The research is welcomed by the U.S. Bureau of Reclamation, which is running the restoration project. The bureau, along with state and federal wildlife agencies, will release young salmon in the San Joaquin this fall to study how they move through the river. The climate change study will add to the background the bureau needs on this project.
Said bureau spokesman Pete Lucero: "All research conducted to better inform decisionmakers about the availability, quantity and quality of water is important."