As Canada moves closer to legalizing marijuana, scientists and regulators in the U-S are warning that pot production isn't so green for the environment.

Growing pot indoors gobbles up electricity through the use of high-intensity lamps, air conditioners, dehumidifiers and more.

A peer-reviewed study in 2012 estimated that three per cent of California's power usage came from indoor marijuana operations.

And for the outdoor grow-ops, a 2015 study published by California's Department of Fish and Wildlife found that irrigation for marijuana farming is sucking some streams dry.

Lead author Scott Bauer says a marijuana plant needs 22 litres of water a day while a wine-producing grape plant uses about 12 litres a day.

Some Canadian marijuana companies are prioritizing sustainability, including Tantalus Labs that has one of Canada's first purpose-built cannabis greenhouses in Maple Ridge B-C.

Founder Dan Sutton says greenhouses harness the power of the sun instead of using artificial light.