Craig Manson, Brandon Middleton, San Francisco Chronicle January 8, 2009

There's great cause for concern over the biological opinion issued by the U.S. Fish and Wildlife Service in the form of a new rules to protect the delta smelt, a fish species that is listed as threatened under the federal Endangered Species Act. That's because millions of Californians depend upon the continued operation of two large irrigation projects for a reliable supply of water. And the scientific reasons for shutting them down to protect the smelt are dubious at best.

The two water operations in question, the Central Valley Project and the State Water Project, depend on pumps located at the southern end of the Sacramento-San Joaquin Delta, to move water flowing into the delta from Northern California to water users through Southern California and the Central Valley. Recent court decisions have identified the operations' pumps as a major cause of the smelt's decline, and the Fish and Wildlife Service's decision will force a dramatic reduction in pumping.

Obviously, protecting the delta smelt and other delta fish species is important. But unfortunately, the numerous farmers who will be severely affected by the water restrictions cannot take solace in knowing that their pain will be ameliorated by the delta smelt's gain.

There is little science to support the notion that pumping restrictions will solve the problem of the smelt's decline.

Myriad factors negatively affect the well-being of the delta smelt. These include, but are not limited to, a low food supply, presence of predatory fish and a toxic water habitat for the smelt. The pumps play a role through entrainment, meaning that smelt can sometimes get sucked into the pumps.

But the significance of this and how it affects the species is unknown. No one knows how many smelt are in the delta.

Moreover, no study has shown a definitive link between the pumps and smelt viability. As a federal judge overseeing litigation concerning the delta smelt has noted, there is no one cause for the smelt's decline. And yet, as a 2008 CALFED report indicates, the pumps are "blamed for many of the delta's ills," despite their being "no conclusive evidence that export pumping has caused population declines" of delta fish species.

Environmentalists contend that increased water pumping restrictions are necessary "to halt and reverse the trend toward species extinction, whatever the cost," in line with a 1978 Supreme Court decision on the Endangered Species Act. But even that dubious principle acknowledges that whatever is done on behalf of a threatened or endangered species should at least reverse a species' decline. In contrast, there is nothing close to a guarantee that increased pumping restrictions will help the delta smelt.

It would have been a pleasant surprise if the Fish and Wildlife Service had taken the above into account when it released its biological opinion. Much is at stake, as delta water deliveries help to sustain the state agriculture industry and play a key role in the state's energy, tourism and entertainment industries, not to mention everyday human activity.

It makes no sense to make the pumps the scapegoat for the delta smelt's decline, at the cost of threatening the water supply for millions of human beings.

Craig Manson is a professor at the University of the Pacific McGeorge School of Law and a former U.S. Department of the Interior assistant secretary. Brandon Middleton is an attorney with Pacific Legal Foundation ( www.pacificlegal.org).