The General Services Administration has instituted oversight measures to prevent field offices from wasting taxpayer money, the agency’s acting administrator and inspector general told two Senate panels Wednesday.

GSA regional budgets and contracting authority are now overseen by officials in Washington, the acting administrator, Daniel Tangherlini, told the Senate Environment and Public Works Committee.

A confusing administrative structure and poor oversight of budget and contracting allowed the GSA’s Pacific Rim region to spend more than $800,000 on a 2010 employee training conference, Tangherlini said.

“What we need to do is create the appropriate sets of checks and balances, the appropriate sets of oversight systems, clear lines of accountability to make sure this kind of thing can’t happen again,” he said.

In separate testimony before the Senate Appropriations subcommittee on financial services, Tangherlini said many of the agency’s problems stemmed from a 2009 decision to give regional public buildings and acquisitions commissioners more autonomy over their budgets.

Paul Prouty, the acting GSA administrator who made that decision, was one of 10 employees placed on administrative leave, Tangherlini said. Prouty is the public buildings commissioner for the Rocky Mountain region, based in Denver, a position he also held before his tenure as acting administrator.

Sen. Barbara Boxer (D-Calif.), who chairs the Environment and Public Works Committee, focused on the fixes the GSA had instituted.

Senators were pointedly critical of the waste of taxpayer dollars, and they directed criticism at officials such as Jeffrey E. Neely, the GSA official at the center of the scandal who invoked his Fifth Amendment right to remain silent and attended only Monday’s hearing. But overall the sessions were less charged than those conducted by House panels Monday and Tuesday, during which lawmakers sometimes offered whithering condemnation in bellowing tones.

“I don’t want to just dwell on the conferences,” Boxer said.

Boxer did note GSA’s scandal-prone history, however. In the late 1970s, GSA came under federal investigation for contracting abuse that cost billions. Administrator Jay Solomon resigned over the scandal. In 2006, a GSA official was implicated in the Jack Abramoff lobbying scandal, and Administrator Lurita Doan resigned in 2008 after allegations of contract abuse.

Inspector General Brian Miller offered an explanation.

Bank robber “Willie Sutton was asked, ‘Why do you rob banks?’ ” Miller told the public works panel. “He said that’s where the money is. Part of the reason there is a lot of crime, fraud, waste and abuse at GSA is because a lot of money flows through GSA.”

Miller’s office is investigating allegations of bribery and kickbacks within the Pacific Rim region. But the problems may be more systemic across the GSA, Miller said.

“Every time we turn over a proverbial stone, we find 50 more, and we find things crawling out from under them,” Miller said. “I don’t know what we’re going to find but it hasn’t been pretty.”

Sen. John Barrasso (R-Wyo.), who sits on the public works committee, asked Tangherlini whether GSA had outlived its usefulness.

“Having a single accountable agency that can aggregate the expenses of the government and use the scale of the government to get the best possible price for the government, I think that has value today,” Tangherlini said.