Flint's former administrator says she was fired after discovering the mayor was trying to guide donors to a campaign fund instead of a charity for families with lead-tainted water.
Natasha Henderson filed a lawsuit Monday, claiming she was dismissed for being a whistleblower.
Henderson was hired when Flint was under state emergency management but was fired this year after a year on the job.
Her attorney, Katherine Smith Kennedy, says Henderson reported alleged wrongdoing by Mayor Karen Weaver to a city lawyer.
Henderson was dismissed in February.
The city council endorsed the decision in March.
Weaver's spokeswoman, Kristin Moore, says she can't comment on the lawsuit.
She referred reporters to attorney Kendall Williams, who didn't return a call seeking comment.
