FRESNO -- Oliver W. Wanger, the often larger-than-life federal judge who has presided over some of this region's most high-profile cases, is stepping down after two decades.

Wanger, 70, is taking the rare step of leaving the bench and returning to private practice. His last day at Fresno's federal courthouse is Sept. 30, a Friday. The following Monday, he'll hang out his shingle as a partner at the newly created firm of Wanger Jones Helsley.

"I am going to be a lawyer," Wanger said. "I'm going back to the other side of the bench."

Wanger said he's frustrated by the Fresno court's growing caseload and Congress's unwillingness to add judges here.

Wanger -- who sent his resignation letter Wednesday to Anthony W. Ishii, the chief judge for California's eastern federal judicial district -- plans to be much more than a trial lawyer.

The notorious workaholic still plans to offer his services as a defense attorney, but he also plans to teach, advise trial lawyers and local governments, and be an expert witness. He also will hear civil cases as a private judge.

And he no longer expects to be addressed as "Judge Wanger." Instead, he'll once again be "Ollie Wanger."

Wanger's resignation letter says his "intent was lifetime service."

Five years ago, he took "senior status," a change that could allow him to move into semiretirement, reduce his caseload and keep his existing salary. The move also allowed Congress to appoint someone to fill his former slot as a full-time jurist.

But instead of moving into semiretirement, he kept his entire caseload. And as his caseload grew even more, he became increasingly frustrated that Congress wouldn't create more judgeships.

On Wednesday, he also hinted that compensation is an issue, though he added he was "not complaining in light of what everybody else in our society is going through."

District court judges, who have lifetime appointments, earn $174,000 annually. But Wanger said raises have been nonexistent and cost-of-living adjustments have been sparing.

Wanger's departure will be felt at Fresno's federal courthouse, observers say.

"It's a huge loss of institutional knowledge -- and also the loss of his work ethic," said Carl Faller, a local defense attorney who formerly worked as a federal prosecutor. "I think it will be very tough on the judges that remain to pick up the slack for someone who has been a massive part of that bench for so many years."

Wanger, for instance, has been the main judge overseeing the ongoing Sacramento-San Joaquin Delta water wars between farmers and other water users and environmentalists. In the middle are the delta smelt and endangered salmon -- as well as reams of complicated state and federal water law.

Ishii said Wanger "was unmatched in his passion for justice, fairness and upholding the rule of law."

Then there's the caseload. Wanger's 1,200 cases will have to be split between Lawrence J. O'Neill and Ishii, who are Fresno's two remaining judges.

Two decades of service

Wanger, a Republican, was nominated in 1991 by then-President George H.W. Bush and confirmed unanimously by the Senate.

A native of Los Angeles, Wanger earned a law degree at the University of California at Berkeley's Boalt Hall School of Law.

In 1967, he came to Fresno as a deputy district attorney. He eventually left for private practice. When he was nominated to the federal bench, he was a partner at McCormick, Barstow, Sheppard, Wayte & Carruth, one of the city's most prominent law firms.

As a judge, Wanger has overseen some of Fresno's most celebrated cases, including the Operation Rezone political corruption cases in the 1990s and, more recently, a lawsuit brought by nine homeless residents in Fresno who said the city destroyed their personal property without giving them a chance to reclaim the items. Wanger ruled in favor of the homeless.

A battle of wills

It was the latter case that helped spark a public feud between Wanger and then-Fresno Mayor Alan Autry, who said the judge should "enter the real world and find out the real truth."

At one point, Wanger ordered Autry into his court, saying the mayor had challenged "the integrity of the United States Court."

Wanger has sometimes gone to great lengths to explain decisions and the law behind them.

He appeared before farmers -- some of them hostile over his smelt and salmon decisions -- to explain water law at a Madera County Farm Bureau meeting.

"He is a natural teacher and a tireless worker with the goal of justice always at the forefront of everything he has ever touched," said O'Neill.