Delta Smelt Threatens Water Supply : Environment: A state agency says the tiny fish is nearing extinction. Saving it might force a reduction in shipments to Southern California.

SACRAMENTO —  In a serious challenge to California’s vast water supply system, a small fish found only in the Sacramento-San Joaquin River Delta is nearing extinction and should be listed as a threatened species, the state Department of Fish and Game has concluded.

The population of the Delta smelt, a three-inch fish that smells like cucumber, has fallen to an estimated 200,000--just 10% of the 2 million believed to have lived in the Delta two decades ago, said Lee Miller, an associate fishery biologist with the fish and game agency.

“They’re declining and they’re threatened,” Miller said. “The question is how probable it is that they go extinct, and I don’t think anybody knows.”

A declaration that the smelt is threatened could force water officials to cut back on the amount of water pumped out of the Delta to residents and farmers in Southern California.

“The only way to accomplish some of their plan (to save the smelt) would be a substantial reduction in diversions,” said Timothy Quinn, a director of the Metropolitan Water District. “That would have a devastating effect on us down here.”

The sudden decline of the smelt has revived discussion of building a “peripheral canal” around the Delta--a plan rejected by voters in 1982. Long advocated by water officials as a way of shipping water south, biologists said such a canal could decrease the danger to the smelt by bypassing the species’ habitat.

It is now up to the state Fish and Game Commission to decide whether to list the species as threatened. At the same time, the U.S. Fish and Wildlife Service is considering a petition filed by the American Fisheries Society requesting that the species be declared endangered. A finding by either agency that the species is threatened or endangered--an action that could be months away--would require the development of a plan to save it from extinction.

“The Delta smelt is now critically depleted and cannot long survive without the protection of the Endangered Species Act,” Don C. Erman, president-elect of the society, wrote in a letter to federal officials. “Recent drought conditions and an upsurge in new proposals for increased water contracts . . . place this species . . . in an ever-more precarious and endangered condition.”

The sharp drop in the Delta smelt population was discovered in studies conducted by the state Department of Fish and Game biologists and by biologists at UC Davis working under contract with the U.S. Fish and Wildlife Service.

“The numbers of smelt are now at their lowest levels ever recorded,” wrote scientists Peter B. Moyle and Bruce Herbold in a report to the federal agency in January, 1989. The smelt, they noted, was once one of the most common fish in the Delta.

Biologists for both the state and federal agencies concluded that the diversions of water from the Delta were a major factor in the population drop. A shortage of water in the Delta, they found, can affect the food supply of the species and disrupt the conditions necessary for successful breeding.

In years past, as many as a million smelt were caught in the fish screens at the pumping plants of the state and federal water systems near Tracy. Countless more were washed through the screens and into the aqueduct that carries water south. But in recent years, state Fish and Game biologist Miller said, few of the smelt have been found there.

“We don’t have hard and fast evidence to suggest that water export is the only cause for the decline, but it certainly looms largest as a major factor,” he said.

The nearly translucent fish with a steely-blue sheen is found as far up the Sacramento River as Isleton, as far up the San Joaquin River as Mossdale and as far west as Suisun Bay. It once thrived in the dead-end sloughs of the Delta and occasionally was discovered in San Pablo Bay near Richmond.

It is an important part of the Delta food chain and is fed upon by larger fish, including the striped bass, which itself has suffered a serious decline in numbers.

“They’re a unique little critter,” Miller said. “They’re a very interesting fish from a scientific point of view. They smell like cucumbers. When it’s caught in nets, you can smell the smelt before you even see one. . . . It has a silver stripe down the side. It’s quite a pretty little fish.”

The species is in an especially vulnerable position because it has a one-year life cycle. A change of conditions that disrupts breeding for one season could spell the end for the smelt, scientists say.

Officials with the State Water Project are hopeful that the smelt can be saved without drastic reductions in the amount of water sent south. Bob Potter, a deputy director of the state Department of Water Resources, suggested that reducing the diversion of water at key times to correspond with the tides or seasons could be sufficient.

“We might have the ability to adjust our operations,” Potter said. “But I don’t think anybody knows enough about the smelt and what’s bothering it to know what to do.”

But officials at the Metropolitan Water District, which supplies much of the Southland with water, were concerned that efforts to save the smelt could result in drastic shortages of water for Southern California.

“In the short run, the only way to accomplish it could be to shut down the export pumps to Southern California,” said the district’s Quinn, noting that well over half the agency’s water is pumped out of the Delta.

In the long run, he said, the way to save the smelt will be to build a new water project along the lines of the peripheral canal--an idea that has long been opposed by environmentalists.

“Metropolitan is concerned about solving these kinds of environmental problems in the Delta and elsewhere,” Quinn said. “But we strongly believe that we should accomplish those environmental protection goals in ways that don’t conflict with other water uses.”