Michigan Gov. Rick Snyder (R) and EPA Administrator Gina McCarthy testified in front of the House Oversight Committee on March 17, and things got a little heated. (Peter Stevenson/The Washington Post)

Michigan Gov. Rick Snyder (R) and EPA Administrator Gina McCarthy testified in front of the House Oversight Committee on March 17, and things got a little heated. (Peter Stevenson/The Washington Post)

The head of the Environmental Protection Agency and the governor of Michigan faced calls to resign from angry lawmakers Thursday, as a congressional oversight committee bore in on which level of government was most responsible for the contamination of Flint’s water supply.

Repeatedly shouting at EPA Administrator Gina McCarthy, Rep. Jason Chaffetz (R-Utah) faulted her for failing to require the Michigan Department of Environmental Quality to move more quickly after lead was discovered in the tap water of some Flint homeowners.

“If you want to do the courageous thing, like you said [former EPA Midwest region head] Susan Hedman did, you, too, should resign,” Chaffetz thundered.

When McCarthy tried to explain the limits of the EPA’s power under the law, Chaffetz repeatedly cut her off. “Well it failed,” he yelled. “You failed.”

But Michigan Gov. Rick Snyder (R) received his own blasts of criticism, some of it sarcastic, when Democrats were asking the questions. “Plausible deniability only works when it’s plausible,” Pennsylvania Rep. Matt Cartwright told Snyder as he pressed why the governor was slow to act. “You were not in a medically induced coma for a year.

“We’ve had enough of your false contrition and your phony apologies,” Cartwright said. “You’re doing your dead level best to spread accountability. ... You need to resign, too.”

This second of two contentious hearings on lead in Flint’s water followed the same pattern as the session Tuesday, with a federal official blaming the state for causing the disaster and the governor pointing the finger at the EPA for moving too slowly in its oversight role. Sharp questioning from members of the House Oversight and Government Reform Committee broke down mostly along partisan lines. Republicans targeted McCarthy and the EPA; Democrats slammed Snyder and the state.

But not in every case. With hundreds of people from the Flint area in attendance, Rep. Tammy Duckworth (D-Ill.), who’s running for the Senate, told Snyder that if McCarthy should resign, he should, too.

McCarthy reviewed the state’s efforts to engage the state and force a quicker response throughout the second half of 2015, saying that her agency’s staff “begged” the Michigan Department of Environmental Quality to address the growing lead threat. At every turn, she said, the state agency dragged its feet in responding.

But like Hedman on Tuesday, McCarthy repeatedly declined to admit that EPA had done anything wrong. That drew several comparisons with Snyder from lawmakers, who forcefully pointed out that the governor has admitted wrongdoing.

“Were we late in getting it done? Yes,” McCarthy said. “Were there consequences to that? Yes.” But she said EPA staffers, from Hedman on down, worked “very hard” with state environmental officials to solve the crisis starting last summer and throughout the fall.

[EPA official resigns as agency intervenes in Flint water crisis]

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In her opening testimony, McCarthy had placed blame for the Flint water crisis squarely on Michigan, saying a state-appointed emergency manager made the decision that led to the contamination and that the state bureaucracy approved it.

“The crisis we’re seeing was the result of a state-appointed emergency manager deciding that the city would stop purchasing treated drinking water and instead switch to an untreated source to save money,” she told the committee as its hearing opened. “The state of Michigan approved that decision.”

McCarthy acknowledged that “in hindsight, we should not have been so trusting of the state for so long” when it assured EPA that action was taken to prevent lead from leaching into drinking water. The state’s environmental quality department admitted in October that it had not ensured that corrosion control chemicals were added to the water as they should have been.

“We missed the opportunity late last summer to quickly get EPA’s concerns on the public’s radar screen. That I regret,” she said.

For his part, Snyder said “systemic failures” at the state’s environmental protection agency led to the catastrophe. But he repeated his message that “a failure of government at all levels” resulted in the catastrophe. He also insisted that a water specialist at the federal Environmental Protection Agency was “silenced” when he tried to warn about the lead contamination in February 2015.

“I do want to thank Miguel Del Toral, a water specialist at the EPA, who spoke up early about the crisis,” Snyder said. “Tragically, his superiors at the EPA told local leaders in Flint to ignore his call for action.”

Hedman, former head of the EPA’s Midwest region, repeatedly denied muzzling or retaliating against the scientist when she testified before the same panel Tuesday.

Snyder pledged to hold those responsible accountable, noting that “bureaucrats created a culture that valued technical compliance over common sense — and the result was that lead was leaching into residents’ water.”

Some officials, including Democratic presidential candidates Hillary Clinton and Bernie Sanders, have called on Snyder to step down. Some Flint residents want him jailed. Three recall efforts are seeking his removal, and a special prosecutor is investigating the disaster to determine whether criminal charges are warranted.

Residents’ tap water was tainted when the city began using the Flint River as its source in April 2014, and state environmental officials failed to ensure that anti-corrosive chemicals were added to the supply. That caused lead to leach from aging pipes. Anyone who drank the water — including nearly 9,000 young children, the most vulnerable population — was exposed.

At Snyder’s order, the city of about 95,000 people switched back to Lake Huron water in October, but unfiltered tap water is still not safe to drink.

[Did Flint’s contaminated water cause deadly outbreak of disease?]

On Wednesday, the EPA released thousands of pages of emails about the Flint debacle. One suggests that McCarthy grew concerned in late September after receiving a memo from Hedman.

“Seems like the Flint lead issue is really getting concerning,” McCarthy wrote to Hedman and other agency officials on Sept. 26 as she called for a meeting on the subject. “This situation has the opportunity to get very big very quickly.”

The emails detail the EPA’s efforts to work with the state Department of Environmental Quality and the city as the crisis mushroomed. In October, the emails show, the EPA began to receive requests from citizens groups and at least one lawmaker to intervene using its emergency power.

But it didn’t take that action until Jan. 21, when it found that Flint’s water posed “an imminent and substantial endangerment to the health” of the people drinking it. McCarthy accepted Hedman’s resignation the same day.