DENVER – A western Colorado sheriff’s deputy posting a notice about unpaid property taxes at a residence east of Montrose discovered a marijuana growing operation with plants and packaged marijuana worth an estimated $4.5 million.

The Denver Post reports three people were arrested Friday on suspicion of cultivation of marijuana.

Investigators believed they uncovered the operation just as the marijuana was being readied to be shipped out of state.

It took officers about 20 hours to load evidence into secure vehicles, including 1,500 pounds of plants of varying ages along with packaged marijuana.

While recreational use of marijuana is legal in Colorado, growers are regulated by the state. Officials believe the Montrose grow was illegal.