LANSING, Mich. — High-ranking officials in Governor Rick Snyder’s administration were aware of a surge in Legionnaires’ disease potentially linked to Flint’s water long before the governor reported the increase to the public last month, internal e-mails show.

When he disclosed the spike in Legionnaires’ cases on Jan. 13, Snyder said he had learned about it a couple days earlier. But e-mails obtained by the liberal group Progress Michigan through public records requests show Snyder’s own office was aware of the outbreak since last March. At the time, others in the administration were scrambling to respond to suggestions that bacteria in the city’s new water source, the Flint River, could be the culprit.

The outbreak was also well known within state agencies, according to e-mails obtained separately by various news organizations. Together, the e-mails offer more evidence that some state officials were dismissive of county health authorities who raised concerns about the safety of the community’s drinking water.

‘‘The increase of the illnesses closely corresponds with the timeframe of the switch to the Flint River water. The majority of the cases reside or have an association with the city,’’ Jim Henry, Genesee County’s environmental health supervisor, wrote March 10 to Flint leaders, the city’s state-appointed emergency financial manager, and the state Department of Environmental Quality, known as the DEQ.

‘‘This situation has been explicitly explained to MDEQ and many of the city’s officials,’’ Henry said in the e-mail that was forwarded by the Department of Environmental Quality to a Snyder aide three days later. ‘‘I want to make sure in writing that there are no misunderstandings regarding this significant and urgent public health issue.’’

Legionnaires’ disease is a pneumonia caused by bacteria in the lungs. People get sick if they inhale mist or vapor from contaminated water systems, hot tubs, or cooling systems.

There were at least 87 cases across Genesee County during a 17-month period, including nine deaths, but the public was never told about the increase when it was happening — even after an initial wave of more than 40 cases was known by early 2015.

The back and forth behind the scenes occurred while residents were complaining about poor water quality, even before lead contamination became an extraordinary health emergency roughly six months later.

The e-mails reveal tension between the county health department, which was on the front line of the Legionnaires’ outbreak, and the city and state about how to investigate the disease. The e-mails also show some angst in the Snyder administration over the controversy.

Brad Wurfel, who was the Department of Environmental Quality’s spokesman at the time, informed Snyder’s director of urban initiatives, Harvey Hollins, about a ‘‘significant uptick’’ in Legionnaires’ cases but said it was ‘‘beyond irresponsible’’ for Henry to link the disease to the river without an adequate investigation. He copied Dan Wyant, director of the Department of Environmental Quality at the time, on the e-mail.

Wurfel noted that the county had resubmitted an open records request to the city for water testing results and other information because of what Henry called the city’s ‘‘lack of cooperation.’’

Wurfel said it would be ‘‘highly unlikely’’ to find Legionella bacteria around the water treatment plant. However, he acknowledged the accusation about a link to the river was serious and said all agencies should come together ‘‘asap to share what information we have and develop a response/screening strategy before the weather gets warm again.’’

Both Wyant and Wurfel resigned Dec. 29.

Snyder spokesman Dave Murray, citing the large executive office staff, said this week that the Republican governor only learned about the Legionnaires’ outbreak days before he publicly disclosed it — despite Hollins being flagged 10 months earlier. Snyder’s former chief of staff, Dennis Muchmore, has said neither he nor Snyder knew but they should have been told earlier.

Lonnie Scott, executive director of Progress Michigan, said the e-mails expose ‘‘another glaring example of Governor Snyder saying one thing and e-mails really revealing something different.’’ The group, which has asked Snyder to release staff e-mails that are exempt from the Freedom of Information Act, is still reviewing thousands of pages of state e-mails related to Flint’s water.