Police have broken up nine grow-ops in the Calgary area and seized more than $17 million worth of marijuana, officials said on Thursday.

Officers seized more than 13,500 plants and 44 kilograms of harvested marijuana, along with growing equipment.

The operations were set up by two organized crime groups working in collaboration, officials said.

More than 80 criminal charges have been laid against nine people, said officials with  Alberta Law Enforcement Response Team's (ALERT) Green Team South, which ran an 18-month investigation leading up the bust.

Two of the grow-ops were in Okotoks, one in Strathmore and the rest were in Calgary.

Some of the homes had been rented by people posing as legitimate families. After using false names and counterfeit identification on the rental agreement, the suspects then converted the properties to grow-ops, police said.

"This investigation confirmed that most large marihuana grow operations are connected to organized crime," said Staff Sgt. Tom Hanson.

"Nearly all of the properties had dangerously compromised electrical and natural gas utilities, exemplifying the hazards inherent in many grow operations we dismantle."

Two grow-ops dismantled in rural Alberta in 2010 are also believed to be connected to these two groups, police said.