Monday, March 10, 2008 | Another fish species found in the Sacramento-San Joaquin River Delta appears headed for the state’s endangered species list, a step that could further limit water delivery from one of Southern California’s major drinking water sources.

The listing of the longfin smelt as a candidate species under the state’s Endangered Species Act could reduce water exports from the delta in the same way as its cousin, the now-infamous delta smelt, already has. The longfin is afforded the act’s protection while being considered for listing, a step that could be made permanent within a year by the California Fish and Game Commission.

The immediate impact on San Diego’s water supply is uncertain and will depend on when the longfin smelt migrates through the delta this autumn and what protections are in place when it does. Regardless of its supply impact, many say the fish’s listing is a reminder that the San Diego region, which imports 90 percent of its water from outside sources, cannot continue to rely on the Sacramento-San Joaquin River Delta in its current state.

“It’s another uncertainty in terms of how long you have to move water out of the delta,” said Ken Weinberg, director of water resources at the San Diego County Water Authority. “More than anything, it’s a reminder of how precarious a place it is to be the state’s main water supply system.”

When the winter snows blanketing the Sierra Nevada melt, the runoff cascades into rivers that flow west toward San Francisco Bay, beneath the Golden Gate and out to the Pacific Ocean. If that snowmelt were a train, the delta would be its tracks.

As an eight-year drought has set in on the Colorado River, the region has increasingly relied on the delta and the State Water Project, the series of dams and aqueducts that pump water south to provide its water. In some years, Southern California has gotten as much as 70 percent of its water supply from the delta, which satiates the thirst of 23 million Californians and 2 million acres of agriculture.

The water project’s massive pumps, which sit near the delta’s southern fringe, pull billions of gallons of water up into an aqueduct that winds 444 miles before feeding the San Luis Reservoir, which then delivers water south to Los Angeles and San Diego. Fish can get sucked into the pumps and crushed.

A growing number of species found in the delta have shown precipitous population declines at the same time the state has increased its reliance on the delta as a water source. If the longfin smelt is given endangered species status, it would be the sixth fish found in the delta to receive the designation from the state or federal government. The longfin’s proposed listing lines up another struggling fish in front of the pumps, so that even if the delta smelt goes extinct, pumping restrictions would stay in effect.

Tina Swanson, senior scientist for The Bay Institute, a Bay Area environmental group that petitioned for the longfin’s listing, said its decline “reminds people we’re not talking about just one fish. It’s not one little fish against everything else. It’s the whole ecosystem telling us that it’s in crisis. It’s about all the fish.”

Scientists suggest that if both smelt species go extinct, the pumping restrictions won’t. Other endangered fish such as the Chinook salmon would be next in line to require pumping restrictions. Bill Bennett, a research ecologist at the Center for Watershed Sciences at University of California, Davis, said the Chinook salmon’s spring and winter runs, both protected under the federal Endangered Species Act, are struggling.

“They appear to be taking the hardest hit,” he said. “Other species are more resilient (than the two smelt species), but you’ll start to see these others click off.”

The Bay Institute and other environmental groups have litigation pending before U.S. District Judge Oliver Wanger challenging the validity of a federal permit that allows the State Water Project’s exports to impact the two Chinook salmon runs. The groups filed a similar suit on the delta smelt, which thrust the smelt into the public spotlight last summer, when Wanger sided with environmentalists and invalidated the permit allowing the project’s pumps to impact the tiny fish. That decision led to the current restrictions on water exports from the delta.

The delta smelt has been held up as the poster child to exemplify the degrading ecosystem in the delta, a 738,000-acre area roughly one-fourth as large as San Diego County. The delta smelt is found only in the triangle-shaped area bounded by Tracy, Antioch and Sacramento. For better or worse, the delta is its aquarium.

Protections for the delta smelt have already caused delta water exports to be cut this year by 250,000 acre feet, enough water to supply 500,000 homes for a year. Reductions were first triggered on Christmas Day and were ratcheted up two weeks ago when a dead female delta smelt was found near the pumps that send water to Southern California, said Carl Torgersen, chief of State Water Project operations and maintenance.

Longfin smelt have different migration patterns than their cousin, which could expand the timeframe when pumping restrictions are possible. While delta smelt can trigger reductions from mid-December to mid-June, the longfin smelt migrate past the pumps as early as November, Bennett said.

The longfin smelt, a four-inch-long pink-tinted fish, doesn’t spend its whole life in the delta, though scientists say it suffers from the stress it experiences while living there. Longfin smelt live longer than delta smelt and aren’t solely dependent on the delta for food or refuge. They migrate into the delta in the autumn to spawn and leave in the spring, traveling to San Francisco Bay and as far as the Pacific Ocean.

That makes diagnosing the reasons for the longfin smelt’s decline more difficult, Bennett said, because it spends time away from the delta’s stressors. “You open yourself up to a host of other things that we’re not looking at as closely,” he said.

Still, its population has sharply dropped in recent years. A four-month long state survey for the fish found nearly 2,000 longfin in 2006 and 129 in 2005. Last year, the same survey found 13. And it didn’t find any 1-year-olds, raising concerns among scientists that next year’s population levels could drop further. The fish live to be two years old and spawn in their second year.

“It really looks like last year was a disaster for them,” said Bruce Herbold, a U.S. Environmental Protection Agency biologist. “It’s really disturbing, because we won’t have any adults next year.”

The longfin smelt’s population tends to dip in dry years, Herbold said. During the 1987-1992 drought that struck California, the fish’s population dropped significantly. But it bounced back, something scientists say will be harder this time around.

In the 16 years since the drought ended, an invasive clam has reduced the amount of food in the delta. The State Water Project’s pumps have increased the amount of water sucked out of the delta, a process that traps and crushes fish. The pumps and clams have been cited as major factors in the delta smelt’s decline.

“We’ve made the delta a very different place than it used to be,” Bennett said. “It’s little wonder that the native fishes there aren’t doing well.”

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