State Rep. Rick Hansen has asked the state's legislative auditor to investigate how Minnesota's pollution regulator handled a key water quality permit for PolyMet Mining's proposed copper mine.

Hansen, a DFLer from South St. Paul, chairs the Legislative Audit Commission as well as the House's Environment and Natural Resources Finance Division.

The allegations about how the Minnesota Pollution Control Agency handled the permit requires "an independent, nonpartisan, third-party investigation into the agency to ensure the public's trust in our state's ability to protect water quality and the environment," he said Monday.

Hansen's statement said the legislative auditor will start up the review immediately.

The Office of the Legislative Auditor is an influential watchdog with broad authority to audit and evaluate a range of entities, including state government agencies, and investigate allegations of wrongdoing or misuse of resources.

Its auditor, Jim Nobles, could not immediately be reached for comment.

Via e-mail, MPCA spokesman Darin Broton said MPCA Commissioner Laura Bishop "supports a more transparent permitting process and is working with the office of legislative auditor to meet its request."

The development follows revelations last week, via a leaked e-mail, that a then-MPCA assistant commissioner asked her counterparts at the U.S. Environmental Protection Agency (EPA) not to file their written comments on PolyMet's water quality permit during Minnesota's public comment period. This had the effect of keeping the federal regulators' considerable criticisms of the permit out of the public record.

The MPCA issued the permit last December.

The e-mail was dated March 13 of last year and was written by Shannon Lotthammer to EPA Region 5 Chief of Staff Kurt Thiede. It was released last week by the union representing career employees of the EPA Region 5 office in Chicago, which oversees Minnesota's enforcement of federal pollution laws.

The EPA's Office of Inspector General has also opened its own investigation.

The EPA has said that its actions were consistent with the federal Clean Water Act. It has also said that its agreement with the MPCA, which governs the process, doesn't require it to submit its comments in writing.