Randy Woodbury, director of public works, will leave that position Feb. 1 and become a water treatment plant operator trainee.
Woodbury announced Monday that he submitted a letter of resignation last week to Mayor Robert Kesicki, who accepted it.
One of the operators is retiring and the opening was posted, said Woodbury, who scored 97 on the civil service examination.
"This will continue my professional development in water treatment," he said.
Woodbury has been director of public works for five years during which he has been involved in the granulated activated carbon process that has improved water quality and improved the taste.