The city said thieves are removing access panels at the base of municipal lampposts and stripping the wiring, sometimes with the help of a car.
In recent months, the city calculates thieves have made off with 30 kilometers of wiring from lampposts at sports fields and along roads in industrial parks.
City spokesman Alain d'Entremont said in addition to the bottom line, it's having an impact on the city's recreational leagues.
"We're working with the different teams to re-schedule, either transfer to another site, maybe schedule it later in the season, but obviously these thefts do have an impact on our population," said d'Entremont.
George Bousquet was playing with son at Moussette Park Thursday, where it appeared copper wiring had been stripped from lamp posts. He shakes his head at the thefts.
"It definitely takes away from the citizens in this area, because of thieves that will stop everyone else from having fun," said Bousquet.
To prevent future thefts, the city is working to make the access panels more tamper proof, and is stepping up overnight patrols of sports fields.
It's also considering leaving field lights on all night, but d'Entremont said at the same time the city doesn't want the constant lighting to become a nuisance for neighbours.