Democrats pointed the finger squarely at Snyder, who came into office in 2011 promising to run government like a business. They say his decision to skip over the democratic process and appoint emergency managers for struggling cities like Flint led to the crisis.
Both of those theories were played out several times over as Snyder and McCarthy spent five-plus hours fielding lawmakers' accusations about what went so terribly wrong in Flint. Here are the nine most contentious moments from the hearing:
1. Going after Snyder
The blame game started almost immediately, as Rep Elijah Cummings (Md.), the ranking Democrat on the committee, staked out Democrats' position for the hearing: Snyder, not the federal government, holds most of the blame for what happened.
"Gov Snyder's administration chose to switch to the Flint River for a source of water, not the EPA," he said. "Gov. Snyder's administration ignored warnings from the Flint water treatment plant supervisors not to go forward with the switch, not the EPA." And on he went.
"Gov. Snyder's administration caused this horrific disaster and poisoned the children of Flint."
2. Congress turns into a courtroom
Many lawmakers who questioned Snyder and McCarthy on Thursday have a background practicing law. The prestigious House Oversight and Government Reform Committee, which often holds contentious hearings that put witnesses on the hot seat, is one of the most high-profile places where they get to use their law background.
Congress turned into a TV courtroom drama when Rep. Matt Cartwright (D-Pa.), an attorney, questioned Snyder as if the governor were on the witness stand for a criminal trial and Cartwright was trying to pin him down for doing something wrong.
CARTWRIGHT: Governor Snyder, do you admit here today before this committee that you and your administration failed the people of Flint?SNYDER: I've made that clear in terms of my state of the state address where I said…(Cartwright cut him off.)CARTWRIGHT: And your own task force found that your Department of Environmental Quality was, quote, "Primarily responsible for the crisis in Flint." Do you also admit that here today?SNYDER: Yes, and I took actions immediately based on the recommendations. (Cartwright cut him off.)
It went on like this until finally Cartwright felt he had enough to make his point:
"Plausible deniability only works when it's plausible," he said, "And I'm not buying that you didn't know any of this until October 2015. You were not in a medically induced coma for a year. And I've had about enough of your false contrition and your phony apologies."
3. "Pages of edicts"
The committee's contentious environment also lends itself to theater and grandstanding. And there was plenty of that Thursday.
To make his point that Snyder's appointed Flint emergency managers were negligent when it came to the water crisis, Rep. Gerry Connolly (D-Va.) got illustrative. He asked his staff to appear behind him carrying two large, heavy-looking stacks of paper.
"These are the stacks of edicts issued by your emergency managers, not by the city council of Flint. Do you know how many of those 8,000 pages dealt with meaningful steps to protect the citizens of Flint?" he asked Snyder. Snyder said he didn't.
"Not one," Connolly replied, his point made.
The conversation devolved into, as the transcripts say, "unintelligible cross talk."
4. Republicans go after the EPA
Next, it was Republicans' turn to get visual. Rep. John Mica (R-Fla.) held up a report from EPA water expert Miguel Del Toral, who tried to raise the alarm to his superiors in early 2015 that there might be something wrong with Flint's water. Republicans argue the EPA failed to act on Del Toral's report in a timely manner; some even accuse EPA chief McCarthy and her staff of purposefully shushing him (an accusation EPA officials vigorously denied in hearings this week).
McCarthy said she wished her staff had taken control of the situation earlier but did not say she did anything wrong.
Republicans aren't convinced.
"Did you see this report?" Mica asked, holding up Del Toral's report. "A high school student could take this report and determine that kids were getting poisoned."
5. EPA tries to fight back
McCarthy maintained it wasn't her agency's fault they didn't step in to try to stop the flow of poisoned water to Flint homes for months. It was the state's, she said. "We were misled, we were kept at arms' length" by state environmental officials who didn't give them accurate information, she maintained.
Rep. Jason Chaffetz (R-Utah) was not impressed with her finger-pointing.
"Wow," he said, his normally raised voice lowering an octave. "You just don't get it. You still don't get it."
6. "You failed."
Things between Chaffetz and McCarthy escalated from there. One of the central disagreements between Republicans and EPA officials is whether the EPA even had the authority to step and take control of Flint's water.
EPA officials maintain they needed more evidence before they could do that; Republicans accuse the EPA of needlessly hesitating. That tension was borne out in this back and forth between Chaffetz and McCarthy. Chaffetz, his voice rising, called McCarthy's regrets "cheap," maintained she was "wrong" and said that she had "failed."
7. Disputing basic facts
Another disagreement between Republicans and McCarthy is whether Del Toral, the EPA water expert, got in trouble for bringing up potential problems with Flint's water. EPA officials have said they'd like to give Del Toral a medal for his investigation, but Rep. Tim Walberg (R-Mich.) maintained on Thursday the EPA disciplined him, pointing to emails released Tuesday where Del Toral felt he was being disciplined after releasing a draft copy of his report.
WALBERG: What about Mr. Del Toral? Who was disciplined?MCCARTHY: He was not disciplined...WALBERG: Oh, yes, he was.
McCarthy, who as a witness generally has to be deferential to lawmakers, was at a loss as to how to convince Walberg otherwise.
"Well, okay?" she replied.
8. Snyder: EPA emails make me "sick"
Aided by Republican attacks on the EPA, Snyder jumped in.
"When I read these things," he said, referring to emails between the EPA and Michigan's environmental agencies that discussed the problem but that he says didn't propose taking action, "I'm ready to get sick. We needed urgency, we needed action, and they keep on talking. And it's not about fighting; they're just not getting the job done."
McCarthy shifted in her chair and raised her hand to her mouth, as if to try to stop herself from interrupting the governor.
9. "You should be impeached."
When it came time for him to speak, Rep. Paul Gosar (R-Ariz.) was ready for a fight. He hit McCarthy for, as he saw it, being overly concerned with government regulations rather than helping real Americans.
"This is the same old crap," Gosar said. "Americans should be sick of this bureaucratic nepotism and you're the culture of problem. Not only am I asking you to be fired, if you're not going to resign, you should be impeached."
And this is the heart of the case with the Flint water issue: Was it the federal bureaucrats who messed up because bureaucracy is inherently slow and ineffective and possible evil? Or was it Snyder, who tried to run government like a business and fit a square peg into a round hole?
After three congressional hearings on Flint, including 10 hours this week alone, we don't seem much closer to an answer — at least not one everyone can agree on.