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Delta Blues 

Can salmon survive California's 'Peripheral Canal'?

click to enlarge SPAWNED Gov. Brown's proposal to send more water to Southern California threatens the resurgent salmon population.
  • SPAWNED Gov. Brown's proposal to send more water to Southern California threatens the resurgent salmon population.

Chinook salmon are abundant this year in one of the best seasons in local fishing memory, with sport and commercial fishermen reeling in easy boatloads of the most prized food and game fish on the Pacific Coast.

Still, a local conservation group warns that all this could change if state officials in Sacramento, now plotting the near future of California's water-development infrastructure, approve and build a large canal intended to deliver Sacramento River water to Southern California.

The project has been tentatively called the "Peripheral Canal" for decades since state voters rejected a proposal to build such a conveyance structure in 1982. Opponents of the canal say the project would remove so much water from the Sacramento River that it would make the estuary habitat of the Delta, where juvenile salmon spend their first six months of life, incapable of supporting certain native fishes.

But now, the "Peripheral Canal" plan is back on the drawing board of state government officials, including Gov. Jerry Brown—and the Golden Gate Salmon Association, based in Petaluma, wants to see the project halted before it destroys one of the West Coast's largest runs of Chinook salmon.

"These are critical times, in the next year or two, for what the Bay-Delta and its salmon will look like for the rest of our lives," says Victor Gonella, founder and president of the Golden Gate Salmon Association. "It's a rare time. We're sitting here while our future is shaping up."

Chinook salmon spawn in many watersheds along the West Coast, as far north as Alaska's Yukon River. The Sacramento River is the southernmost stronghold of the species, but its salmon runs have seen a roller-coaster ride in the last decade between record high and record low levels. Experts largely agree that water conditions, including flow rates of the river and Delta, where baby salmon spend their first months of life, have a direct effect on salmon abundance.

State and federal records show a long-term average spawning return of the fall-run Chinook, the most historically abundant of the Sacramento's four distinct runs of salmon, to be between 300,000 and 400,000 fish. But 2009's record low of 39,000 spawners came after water-pumping rates from the Delta jumped by 20 percent, to all-time high levels, from 2003 to 2006.

Fishermen fear that the proposed canal is likely to cause an overall decrease in water-flow rates, causing a decline in salmon numbers.

"[Gov.] Brown needs to scrap the 'Peripheral Canal' until further notice," says Mike Hudson, a commercial fisherman in Oakland. Hudson says the current fishing is as good as it has been in at least five years, but adds that he isn't confident about the future. "Along the entire West Coast we have managed to stop overfishing. Now, if we could only stop overfarming we'd have it made."

Peter Moyle, a fisheries biologist at UC Davis, says that the current system for water removal from the Sacramento River, which involves two giant pumps in the Delta, reverses the entire flow of the estuary system when the pumps are operating at full force. This phenomenon confuses young salmon trying to migrate out to sea, Moyle says. Many become lost or stranded in sloughs, where they make easy pickings for predators. Others are sucked directly into the pumps and killed. Moyle says the canal, which would draw water from a location far upstream of the Delta, could be beneficial for the Delta habitat since the reverse flow effect would no longer occur.

But he says that a healthy salmon population requires a minimum amount of water flowing through the Delta and out to sea.

"A conveyance in any form will be positive from a native fish perspective only if it is connected to no net increase in diversion [of water]," Moyle says.

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