Maribyrnong Council is looking for the people responsible for stealing nine steel drainage pit grates across the city.
The drainage pits had been left open and unprotected prior to council officers erecting temporary hazard barriers for safety.
"These thieves are putting our residents at risk," said mayor John Cumming.
"The grates are not cheap to replace either. Each one will cost ratepayers $500, with installation costs on top of that."