Of all the federal judges who have recently presided in California, none has had more impact on California water issues than just-retired U.S. District Court Judge Oliver W. Wanger of Fresno.

Appointed by President George H.W. Bush in 1991, Wanger was at the center of highly contentious rulings on federal water contracts, endangered species protections and disputes over toxic drainage.

On numerous occasions, the Westlands Water District – the nation's largest agricultural district by value of crops – was a party in those cases, and several times Wanger issued rulings favorable to this powerful water agency.

Last December, for instance, Wanger invalidated a federal biological opinion intended to protect Delta smelt but opposed by Westlands and other contractors because of its proposed limits on water pumping from the Sacramento-San Joaquin Delta. Westlands praised Wanger in a press release, saying his "balanced and carefully articulated ruling marks another impact victory for good science and public interest."

Wanger retired at the end of September, but not before verbally blasting federal scientists from the bench, calling one a "zealot" and suggesting that the other distorted the truth. His ruling in that case, which threw out a biological opinion intended to protect salmon, delighted water contractors, with Westlands General Manager Thomas Birmingham stating, "the court got it right again."

Now we learn that Wanger, two months after stepping down from the bench, is going to work for Westlands. He will serve as the water district's lawyer in a case where environmental groups are claiming that interim water contracts for Westlands and other contractors violate state environmental law.

Technically, Wanger does not appear to be in violation of ethics rules for ex-judges by agreeing to take this case. That's because the lawsuit doesn't involve a case he previously ruled upon. It involves alleged violations of a state statute, as opposed to the federal statutes that were heard in Wanger's court. Nonetheless, his decision to work for Westlands throws into question his past impartiality, since he was at the center of so many cases involving this water district and previously ruled on similar lawsuits involving federal statutes.

It also doesn't help that on Oct. 3, just three days after Wanger left the bench, a major Westlands landowner emailed an invitation to growers announcing that Wanger would be the guest speaker at a political event for a local supervisor who used to clerk for Wanger. "Judge Oliver Wanger has been key in supporting Valley agriculture and its lawful access to essential water!," said the flier sent by Westlands grower Mark Borba.

To be sure, in his 20-year career, Wanger issued rulings that went against Westlands, particularly one in late 2007 that determined that federal agencies had failed to adequately protect Delta smelt. That ruling resulted in a reduction of water pumping from the Delta during an already dry year, creating hardship and protests in the San Joaquin Valley and new rounds of litigation.

Still, if he were truly interested in protecting his legacy as a judge, Wanger would have shied away from work with Westlands, environmental advocates or any group that previously appeared regularly before him. By taking a case for this water district, which already has several other former federal employees on its payroll, he has undermined the credibility of many of his past court decisions.

Given that credibility was already in short supply as state and federal officials try to resolve water conflicts in the Delta, Wanger hasn't done Californians any favors.

© Copyright The Sacramento Bee. All rights reserved.