The Environmental Protection Agency on Thursday ordered the city of Flint and the state of Michigan to treat, test and report on the beleaguered municipality’s water supply, in an emergency directive issued because their responses to a lead crisis in the water there “have been inadequate to protect public health.”

EPA Administrator Gina McCarthy also accepted the resignation of Susan Hedman, the agency’s top official for the region that includes Flint, where 100,000 people are unable to drink the water that comes into their homes because of elevated levels of lead.

President Obama also sharply criticized Michigan officials for failing to respond more quickly to the crisis, saying that “our children should not have to be worried about the water they’re drinking in American cities.”

Obama’s remarks, to a meeting of the U.S. Conference of Mayors in Washington, came one day after Michigan Gov. Rick Snyder (R) released 273 pages of emails about the Flint crisis.

The Obama administration said it would speed delivery of $80 million to Michigan to help repair the city’s water system. Old pipes there began leaching dangerous amounts of the heavy metal after Flint switched its water source to the Flint River in 2014 in an effort to save money. The city switched back last year to receive its water from Detroit’s municipal system, but the contamination problem remains.

“EPA finds that water provided by the city to residents poses an imminent and substantial endangerment to the health of those persons,” said Cynthia Giles, assistant administrator in the EPA’s Office of Enforcement and Compliance Assurance. And that will continue, she added, “unless preventive actions are taken.”

The move is the most aggressive taken to date by the federal government in the ongoing crisis. Tests have shown that some children in Flint have elevated levels of lead in their blood, which puts them at risk for developmental delays and other health problems.

The EPA cited its “serious, ongoing concerns with delays, lack of adequate transparency, and capacity to safely manage the drinking water system.” But the agency’s action comes four months after the ACLU of Michigan, the Natural Resources Defense Council and Flint residents petitioned it to intervene.

Long-time resident Rhonda Kelso, who is part of a class-action lawsuit over the tainted water, said Hedman’s resignation does little to resolve the crisis. “The water that’s coming out of the pipes is still poison to drink,” said Kelso, 52, who is using her tap water only to flush her toilet. “It doesn’t make our water clean. We want safe, affordable water.”

Giles gave the city and state — which is led by a Republican governor, Rick Snyder — a day to agree to comply with the order. She demanded water-quality measurements and results of lead testing within 10 days.

In at least one case, testing by the state turned up lead levels that were elevated but lower than those found by independent experts from Virginia Tech. Some critics have alleged that was because water-quality personnel told residents to flush their systems for several minutes before they took measurements.

The EPA also ordered that water treatment with anti-corrosive chemicals and chlorine continue.

Residents of Flint, Mich., complained of persistent problems with their water since the city switched the supply in April 2014. On Jan. 13, officials announced a spike in cases of Legionnaires’ disease in the area. (AP)

Snyder said earlier this week that he was making the emails related to the issue public to give residents “answers to your questions about what we’ve done and what we’re doing to make this right.”

But the emails only generated more controversy. They showed that even as Flint residents were growing increasingly outraged over the lead that had seeped into the city’s water supply, state authorities were dismissing their complaints and questioning research showing that elevated lead levels were poisoning their children.

At one point, a top aide said that state officials thought that people in Flint were trying to turn the issue into a “political football” and shift blame. A message with background information from the Michigan Department of Environmental Quality discussing the water situation acknowledged that Flint had a “tremendous need to address its water delivery system.”

The emails only cover correspondence sent to and from Snyder’s email address regarding Flint, and so they provide an incomplete picture of how the official response unfolded in Michigan. But they illuminate how top officials responded to a concern that has, in recent weeks, emerged as a national scandal.

Dennis Muchmore, at the time Snyder’s chief of staff, wrote in September that state officials in two agencies felt that “some in Flint are taking the very sensitive issue of children’s exposure to lead and trying to turn it into a political football” and pointing blame at the state level.

Muchmore wrote that “the real responsibility” was on the local level, but continued that “since the issue here is the health of citizens and their children we’re taking a pro-active approach” in responding.

Brady Dennis and Juliet Eilperin contributed to this report.