TRAVERSE CITY, Mich. — A regional director of the U.S. Environmental Protection Agency resigned Thursday in connection with the drinking water crisis in Flint, Mich., and EPA chief Gina McCarthy issued an emergency order directing state and city officials to take actions to protect public health.

EPA said in a statement that Susan Hedman, head of the agency’s regional office in Chicago whose jurisdiction includes Michigan, was stepping down Feb. 1 so it could focus “solely on the restoration of Flint’s drinking water.”

High levels of lead have been detected in the impoverished city’s water since officials switched from the Detroit municipal system and began drawing from the Flint River as a cost-saving measure in April 2014. Some children’s blood has tested positive for lead, a potent neurotoxin linked to learning disabilities, lower IQ and behavioral problems.

While much of the blame has been directed at Gov. Rick Snyder and state officials, particularly the Department of Environmental Quality, some have faulted the EPA for not acting more forcefully.

The EPA said McCarthy had sent a memo to all staff members establishing a policy assessing and responding to “critical public health issues.”

The agency also released a letter from McCarthy to Snyder outlining terms of her emergency order.

The EPA “is deeply concerned by continuing delays and lack of transparency,” it said, describing the measures as “essential to ensuring the safe operation of Flint’s drinking water system and the protection of public health.”

Michigan officials said they still aren’t certain whether there’s a link between a drinking water crisis in Flint and an increase in local cases of Legionnaires’ Disease.