The head of the Michigan health department was charged Wednesday with involuntary manslaughter, the highest-ranking member of Gov. Rick Snyder's administration to be snagged in a criminal investigation of Flint's lead-contaminated water.

Nick Lyon is accused of failing to alert the public about an outbreak of Legionnaires' disease in the Flint area, which has been linked by some experts to poor water quality in 2014-15. If convicted, he could face up to 15 years in prison.

Mr. Lyon also is charged with misconduct in office for allegedly obstructing university researchers who are studying if the surge in cases is linked to the Flint River.

The state's chief medical officer, Dr. Eden Wells, is accused of obstruction of justice and lying to an investigator.

Lyon's failure to act resulted in the death of at least one person, 85-year-old Robert Skidmore, special agent Jeff Seipenko told a judge.

The charges were read in court by Mr. Seipenko, a member of the state attorney general's team. Lyon and Dr. Wells were not in court. A message seeking comment was left for Lyon's attorneys. Wells' lawyer was not immediately known.

Flint began using water from the Flint River in 2014 while under state emergency management, but did not treat it to reduce corrosion. Lead from old plumbing leached into the water system.

Some experts also have linked the water to Legionnaires' disease, a type of pneumonia caused by bacteria that thrive in warm water and infect the lungs. People can get sick if they inhale mist or vapor, typically from cooling systems, some reports say.

There were nearly 100 cases in the Flint area, including 12 deaths, in 2014 and 2015.

Lyon was personally briefed in January 2015 but "took no action to alert the public of a deadly" outbreak until nearly a year later, Seipenko said.

Lyon has admitted that he was aware of the Legionnaires' outbreak for months but wanted to wait until investigators in the state Health and Human Services Department finished their own probe.

He told state lawmakers that experts likely wanted to "solve the problem" before they raised it with senior officials in the Snyder administration. The investigation, he said, "wasn't one that was easily solved."

Michigan Attorney General Bill Schuette has now charged 15 current or former government officials in an ongoing probe that began in early 2016, including two emergency managers whom Snyder appointed to run the impoverished city of roughly 100,000 residents.

In May, Mr. Schuette dropped a misdemeanor charge against a Flint official who cooperated after pleading no contest to willful neglect of duty. And in March, Corrine Miller – the state's former director of disease control – was sentenced to probation and ordered to write an apology to residents after pleading no contest to willful neglect of duty.

Seipenko said Wells told an investigator that she had no knowledge of the outbreak until late September or early October 2015.

"This was clearly a false statement," he said, saying she knew as early as March 2015.