Medical marijuana growers in California are depleting the state's northern rivers to feed their pot farms in what is being called a "full-scale environmental disaster," the Associated Press reported.

Not only are they draining the water supply, but most of the marijuana grown in the state's north is not even used for personal medical use, wildlife officials say.

"Whether it's grown quasi legally under the state's medical marijuana laws, or it's a complete cartel outdoor drug trafficking grow site, there is extreme environmental damage being done at all levels," Fish and Wildlife Lieutenant John Nores, head of the department's Marijuana Enforcement Team, told the AP.

Officials are fighting back against what they say is a growing demand for pot sales in California and beyond. That includes Lake County Supervisor Denise Rushing, who supports a motion to ban marijuana from being grown outdoors in well-populated communities.

"People are coming in, denuding the hillsides, damming the creeks and mixing in fertilizers that are not allowed in the U.S. into our watersheds," Rushing told the AP.

Scot Bauer, a biologist who studied the effect of marijuana farms on several bodies of water, estimated that 30,000 plants are being grown in each of the state's river systems- with each plant using nearly 6 gallons of water daily, the AP reported.

Marine-life officials say the pot farms are drying up the rivers and streams in the Mendocino County forests, thus affecting the salmon, steelhead and other fish that live there. Lake Humboldt has also seen its water levels drop.

"We didn't know they could consume all the water in a stream," Bauer told the AP.

But pot growers say they are not to blame for endangering the salmon. The fish were already affected by years of overfishing and tree cutting in the area, the AP reported.

Pot farmers said they will continue to supply medical marijuana as long as patients continue to demand it. But they will also continue to operate in secret out of fear of federal prosecution, officials say.  

"Patients who cannot grow their own medicine can rely on our farmers to provide them with the best holistic medicine that is naturally grown, sustainable and forever Humboldt," the Humboldt county-based Tea House Collective told the AP.