Authorities have arrested two women and seized over $900,000 worth of marijuana and drug paraphernalia from an illegal grow up in Calgary.

The Alberta Law Enforcement Response Teams (ALERT) uncovered a sophisticated grow op on February 25, seizing 743 plants.

A search of the home discovered a three stage grow op on the main level.

Building inspectors and Alberta Health Services have since deemed the home unfit for human habitation.

“Based on the presence of mould in the home, it would appear this grow-op has been in operation for some time,” said Sgt. Len Dalton in a release. “People underestimate the damage grow-ops can do to a home. Besides mould, there are fire risks, electrical issues, and crime-related violence.”

Two women, Tan Le, 50, and Thuy Nguyen, 49, were arrested at the home.

They are charged with production of marijuana and possession of marijuana for the purpose of trafficking.

Police say the operation was one of the largest for the year for their section.

Since April 2013, ALERT has dismantled more than 50 grow ops in Southern Alberta and seized over $20M worth of plants.