 -- An administrator for the Environmental Protection Agency has resigned amid the crisis over Flint, Michigan's toxic drinking water, said the agency, which also blasted the state and city's responses as "inadequate."

The news about Region 5 administrator Susan Hedman came Thursday, one day after Michigan Gov. Rick Snyder released all of his emails from 2014 and 2015 tied to Flint. Her resignation will take effect Feb. 1.

"EPA Region 5’s focus remains solely on the restoration of Flint’s drinking water," a statement from the EPA read.

Hedman oversaw regulations in Michigan, Ohio, Illinois, Indiana, Wisconsin and Minnesota.

"EPA has determined the State of Michigan and the City of Flint’s responses to the drinking water crisis in Flint have been inadequate to protect public health," the agency said in a statement.

The EPA said there are "serious, ongoing" concerns with delays, lack of adequate transparency, and capacity to safely manage the drinking water system in Flint. The agency stressed the importance of "restoring public confidence that the ongoing drinking water crisis in Flint will be promptly and fully remedied."

Since December, the EPA has been working with the National Drinking Water Advisory Council to develop strategies for alleviating the water crisis.

Elevated lead levels were found in the water supply in Flint after the city switched from the Detroit water line to save money in 2014 and began drawing water from the Flint River.

Improperly treated water from the Flint River allowed lead to leach into the water until the city switched back to Detroit's supply in October.

The U.S. Department of Health and Human Services has been designated to lead federal efforts in Flint's recovery efforts.