In response to the revelation, Gov. Rick Snyder admitted his staff "let us all down" and added, "I'm responsible for that."
"That's where I am kicking myself every day. I wish I would have asked more questions and I wish I would not have accepted answers. That is the whole point. I won't let this happen again," he said. "There were red flags in these emails. ... We didn't connect all the red dots that I wish we would have.
"That is part of the cultural thing I want to address longer term within state government and in government in general," he said. "Let's work on getting better on connecting those dots moving forward."
The early warning was made on January 30, 2015, in an email from Brad Wurfel, then-spokesman of the state's Department of Environmental Quality, to David Murray, who was then a spokesman for the governor.
Wurfel wrote Murray: "And the reason is that I don't want my director to say publically that the water in Flint is safe until we get the results for some county health department epidemiological trace work on 42 cases of Legionaries' disease in Genesee County since last May. I'll explain more on the phone ... ."
Flint is located in Genesee County.
Murray was removed from his position as the governor's communications director this week,
a day before the governor released emails showing Murray had long known about the upswing in Legionnaires' disease cases. Murray now works as communications director for the Michigan Department of Talent and Economic Development.
Nearly a full year later, or last January 5, the governor declared a state of emergency for Genessee County
due to the lead contamination in Flint's drinking water. Flint had earlier been under a local emergency declaration since December 14.
More than a week after the state emergency declaration for the county, the governor announced the number of cases of Legionnaires' disease spiked in Genesee County
in the two years since Flint switched its water supply from the Great Lakes to the Flint River.
The increase cannot be directly attributed to the switch, and not all the people who got Legionnaires' were exposed to Flint water, state officials said.
From June 2014 to November 2015, at least 87 county residents developed Legionnaires' disease, compared to between 6 and 13 cases in the four preceding years, officials said. Ten patients died, officials said.
On January 16, President Barack Obama declared an emergency
in Michigan and authorized disaster relief in Genesee County.
Flint's state of emergency -- declared at municipal and state levels -- began years ago when the city suffered a financial emergency. The state took over the city's budget and decided to temporarily switch Flint's water source from Lake Huron to the Flint River to save money until a new supply line to Lake Huron was ready.
The river, however, was long-known as polluted. Locals call it the "General Motors sewer."
After the April 2014 switch, residents complained their water had problems. Virginia Tech researchers found the water was highly corrosive. A class-action lawsuit alleges the state Department of Environmental Quality didn't treat the water for corrosion, in accordance with federal law, and because so many service lines to Flint are made of lead, the noxious element leached into the water of the city's homes.
The city switched back to the Lake Huron water supply last October, but the damage was already done to the lead pipes. The state is now handing out filters and bottled water with the National Guard.
Earlier this month, Flint Mayor Karen Weaver said she wants the replacement of the city's lead pipes to begin immediately so that the community can have clean water as soon as possible. She urged Gov. Rick Snyder to pressure the state legislature to approve funding for the first phase of a $55 million lead pipe replacement plan.
The governor also favored speedy pipe replacement, but he said it's part of a multi-step process.