Apparently, Caltrans isn't the only state agency that needs thorough scrutiny. Evidence is mounting that the state Department of Toxic Substances Control could use a good scrubbing as well.

The Sacramento Bee's Jim Sanders reported Thursday that the agency has spent more than $100 million in public money since 1987 to clean up 1,700 contaminated sites across California, but has yet to bill the polluters.

Earlier in May, the department's chief deputy director, Odette Madriago, resigned and announced her retirement at the end of the year after the Fair Political Practices Commission opened an investigation into a complaint that she has a financial stake in companies the agency regulates.

These revelations embolden critics who say that while California has among the nation's strongest environmental protection laws, it has some of the weakest enforcement due to DTSC's shortcomings. It does make one wonder: What other problems might there be?

A full-blown independent financial audit may be the best way to find out. Among those calling for that review is Consumer Watchdog, which in February issued a six-month study, "Golden Wasteland," calling for sweeping reforms in the agency and a crackdown on "serial polluters."

DTSC told The Sacramento Bee's editorial board that it will cooperate with any audit ordered by the Legislature or the executive branch. Already, there's an outside review underway of the often slow permitting process, and the Senate Office of Oversight and Outcomes is looking into Consumer Watchdog's claims.

It is encouraging that DTSC Director Debbie Raphael is trying to fix the agency's flaws and promises to restore public confidence. While disputing much of Consumer Watchdog's report, she has acknowledged that when she took over in May 2011, key decisions had been put off, the agency lacked accountability and it must improve on permitting and enforcement.

The scope of the uncollected reimbursements came to light after Raphael noticed a December 2011 report and sought more information. The agency says the issue was identified as early as 1992 and was raised multiple times, but that previous top officials took little action. Raphael created a cost recovery team that DTSC says has reduced the backlog of unpaid bills and increased the collection rate in the past 18 months.

Besides $102.7 million that hasn't been billed, $45 million more has been billed but not yet collected. Another $37 million is tied up in litigation or negotiations. That includes the single largest unpaid bill, $31.1 million for a BKK Corp. landfill in West Covina in Los Angeles County.

While the agency initially provided only a few examples to The Bee, it since has released a full list of unpaid bills. (You can view it at dtsc.ca.gov/CostRecovery.cfm).

Coming clean on this problem is a good step, but the job isn't done.