A pair of California lawmakers has introduced a bill to raise retroactively the insurance limit on deposits held at IndyMac Bank, a move that could help former customers recover hundreds of millions of dollars lost when the thrift failed in July 2008.

The Investor Deposit Yardstick Act, introduced Thursday by Reps. Jane Harman, D-Venice, and David Dreier, R-San Dimas, would raise the deposit insurance limit from $100,000 to $250,000 for depositors at the Pasadena savings and loan.

According to the lawmakers, the bill could help 6,500 former IndyMac depositors recover $233 million.

“Our bill will restore to IndyMac customers what they suddenly lost in July 2008, and treat them as equals to other Americans whose savings were swallowed by the economic crisis,” Harman said in a statement.

IndyMac had become one of the nation’s largest independent mortgage originators, specializing in risky Alt-A loans, but was hammered by losses in the early days of the housing crisis. Regulators seized the institution in 2008 amid a catastrophic run on deposits, and the thrift’s assets were later sold to a group of investors who renamed the institution OneWest Bank.

Regulators initially estimated that as much as $1 billion in IndyMac’s deposits were above the insurance limit at the time of its failure, a number that was later reduced by about half.

Shortly after the failure, the federal government raised the deposit insurance limit from $100,000 to $250,000 – a change that will last through 2013 – but it was not applied retroactively.

In addition to IndyMac, the bill would apply to 1,500 depositors of five banks in other states that failed around the same time.