A former town manager of Cohasset has sued the municipality and its leaders, saying he was fired for blowing the whistle on allegedly improper ­actions by the chairman of the local Water Commission. 

Michael Coughlin’s suit asks a Norfolk Superior Court judge to reinstate him to his former job and award him damages to cover lost pay, benefits, and legal fees. His lawyer, Harold Lichten, said the total could amount to “hundreds of thousands of dollars.”