DETROIT (Reuters) - Quality problems prompted two of Michigan Governor Rick Snyder’s top lawyers to urge that Flint be moved back to the Detroit water system just months after a decision to draw water supply from the Flint River, according to emails released on Friday.

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Several critics have called for Snyder to resign over concerns about the state’s poor handling of the crisis, and the governor said Friday he felt regret every day.

Flint switched its water supply from Detroit to the Flint River in April 2014 in a bid to cut costs when the city was under a state-appointed emergency manager.

While the city switched its water source back to Detroit in October 2015, corrosive water from the river had already leached lead from city pipes, posing a serious threat to public health.

Snyder’s aides discussed Flint’s water quality problems as early as autumn 2014, with one calling the situation “downright scary,” about a year before the switch back to the Detroit system was finally made. The Detroit Free Press and Detroit News earlier reported about the emails, which were released by the governor’s office.

“That’s where I’m kicking myself every day,” Snyder said after signing a $30 million supplemental bill to reimburse Flint residents for their water bills. “I wish I would have asked more questions.”

Snyder, scheduled to testify to Congress on March 17, has repeatedly apologized for the state’s poor handling of the crisis.

Liberal group Progress Michigan again called for Snyder to resign, citing the emails.

“There’s no reasonable person who can believe at this point that every top adviser to Rick Snyder knew that there was an issue, but Snyder knew nothing,” said executive director Lonnie Scott, who also called for Snyder’s resignation.

Valerie Brader, Snyder’s senior policy adviser, addressed problems over the quality of Flint River water in an email to the governor’s chief of staff, Dennis Muchmore, and others on Oct. 14, 2014.

She argued Flint should be returned to the Detroit water system, citing bacterial contamination and reduced quality that prompted General Motors to switch away from the river due to rusted car parts.

Michael Godola, then the governor’s legal counsel, responded, calling the Flint River as a water source “downright scary.”

On Friday, State Representative Sheldon Neeley of Flint asked Attorney General Bill Schuette for his legal opinion on whether an official withholding information that leads to death or harm can be charged criminally.