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The Environmental Protection Agency director overseeing a region that includes Flint, Michigan, is stepping down after contaminated water in that city exposed residents to lead poisoning.

EPA Region 5 Administrator Susan Hedman offered her resignation effective Feb. 1, and the offer was accepted, the EPA said in a statement Thursday.

The agency said Hedman’s resignation was accepted “given Susan’s strong interest in ensuring that EPA Region 5’s focus remains solely on the restoration of Flint’s drinking water,” suggesting her position could be a distraction.

Related: Michigan Governor's Aide Called Flint Water Crisis 'Political Football'

Residents in the town of nearly 100,000 have been warned not to drink unfiltered tap water and the National Guard has been distributing bottled water in Flint. Water from the Flint River wasn’t properly treated, allowing lead to leach from pipes

The EPA on Thursday also announced an emergency order requiring that the state and city "take a series of immediate steps to address the drinking water contamination in Flint."

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It said the city and state’s response to the crisis has been “inadequate to protect public health.”

The EPA’s emergency order comes nearly four months after advocacy groups petitioned the agency to step in.

In October, the Natural Resources Defense Council, the American Civil Liberties Union and local groups petitioned the EPA to use its emergency powers to secure safe water in Flint. In December, EPA responded that it would “defer action” until the city had the corrosiveness of its water under control.

“The failure to act on it was bizarre and unacceptable,” said Henry Henderson, director of the NRDC’s Midwest program. “This action today reflects different thinking."

Related: Bad Decisions, Broken Promises: A Timeline of the Flint Water Crisis

As they waited for that response, the same advocacy groups filed notice that they planned to sue city and state officials for ongoing violations of the Safe Drinking Water Act. Henderson said he still believes the courts have a role to play in Flint.

"It's really good that EPA has shifted its position, but is it adequate to protect the public?" said Henderson. "We believe court supervision needs to take place."

Lead can cause mental and physical development problems in children. A first batch of tests detected high levels of lead in more than 40 children, and 10,000 children under 6 are being monitors, officials said.

State health officials denied there was a problem until a Virginia Tech professor in August found that tests showed elevated levels of lead in Flint's water, and a pediatrician in September reported that a comparison of blood tests showed lead poisoning in children.

Related: EPA Faults State 'Failures and Resistance' in Flint Water Crisis

But emails made public through record requests showed that EPA officials knew as early as February 2015 that Flint residents might be drinking lead-tainted water because of high levels found at a home.

Michigan Gov. Rick Snyder declared a state of emergency in January. He has apologized to the people of Flint and has vowed to fix the problem and support those affected.

President Barack Obama on Sunday signed an emergency declaration ordering federal assistance.