Illegal Cannabis Cultivation on California National Forests

Hazmat disposition is prepared and readied to clean the illegal pesticides and herbicides used in an illegal marijuana site on the Inyo National Forest in 2022. (All photos USDA Forest Service)

Background

Illegal cannabis cultivation is an escalating problem in California’s national forests. 

Cannabis (or marijuana) use is legal in 38 states, 18 of which allow “legal recreational” use, including California, and nearly all have cannabis cultivation activity on National Forest System lands. For instance, California has the largest legal cannabis market in the world, with more than $5 billion in sales in 2021.

That being said, it’s important to understand the Forest Service is a federal agency and the land we manage is federal land. Therefore under federal law, cultivation or the use of cannabis on federal lands is illegal.  

Our national forests are priceless treasures held in trust for the public to enjoy for generations to come. But these assets are being destroyed by criminal organizations that cultivate millions of marijuana plants on these lands each year for profit. The growing scientific evidence showing the depth and scale of this destruction to the forests, wildlife, and waterways is a wake-up call that we must heed.

A Forest Service employee hikes near an illegal marijuana grow site on the Six Rivers National Forest in 2017.

What is the Forest Service Doing

Every year, acres of cannabis (or marijuana) are illegally planted throughout the nation’s pristine national forests; and every year, dozens of Law Enforcement and Investigations officers within the USDA Forest Service are charged with conducting cannabis enforcement operations by utilizing prevention, investigation, interdiction, eradication and reclamation strategies in partnership with our Federal, State, County, and Local Law Enforcement agencies.

While law enforcement have worked for years to eradicate these illegal cannabis grows, emerging data continues to show how they cause far-reaching harm to the environment, disrupt nature’s benefits, and threaten public safety.

Since 2021, the U.S. Forest Service has cleaned up more than 80 illegal cultivation sites in California national forests.

Forest Service personnel, joined by representatives of other federal and civilian partners, cleaned more than 6,000 pounds of trash and 7,000 pounds of irrigation pipes from an illegal marijuana cultivation site on the Lassen National Forest in 2016.

How to Spot an Illegal Grow

In national forests, cannabis grow sites tend to beplaced in sensitive and remote areas where visitors are unlikely to stumble upon. Southern or western slopes are preferred, but grow sites can be found in any type of terrain, habitat or even elevations as high as 9,000ft . However, there are times grow sites are planted along roads or freeways on steep hillsides where brush and trees hide the marijuana plants from the public view. Forest Service employees working in the field or fighting fires may enter areas where cannabis is actively being grown. The dangers of encountering cannabis growers or entering a grow site cannot be overemphasized. Be aware of your surroundings, and look for signs of human activity in isolated areas. If you suspect you may be near a cannabis grow site, be quiet and leave the area immediately—do not venture or explore further into the site.

Informal, unmarked, hiking trails may be a sign that you are approaching a grow site. Other signs include:

• PVC (plastic) pipes, hose lines, drip irrigation lines, water reservoirs or cisterns in the stream channel or remotely in the forest, gardening supplies, or gardening tools.
• Containers for fertilizers, insecticides, and animal poisons.
• Signs of established camping, cooking, and sleeping areas.
• Structures in remote locations.
• Trash or garbage in remote locations—especially if the trash contains canned goods or other heavy items not common in the backcountry
• Propane bottles or tanks. Growers use propane to avoid smoke from campfires.
• Sights or sounds of human activity in remote forest areas.
• People sitting on cutbanks or hillsides along remote forest roads. They may be growers waiting for food drops or supplies.
• Food cached near trailheads or alongside roads.
• Individuals with firearms when hunting seasons are closed.
• Pungent strong odor. Marijuana plants can have a strong smell, especially on hot days.
• Signs of cultivation or soil disturbance in forested areas.
• Areas cleared of brush or timber, especially in isolated areas.
• Paper cups, chicken wire, or plastic sheets. These are often used for starting and protecting plants

If you come across a cannabis grow site, do not enter the area. Quietly leave the same way you came in.

Don’t

• Look around or explore.
• Take a sample.
• Take a GPS location while you are in the grow site.
• Use your camera, radio, or cell phone while you are in the grow site.

Do

• Return to your vehicle and leave as soon as possible.
• Call 911 and report your location when you are a safe distance away and sure you are not being watched.

Forest Service law enforcement officers prepare trash to be evacuated out of a marijuana grow site by helicopter on the Inyo National Forest in 2022.

In the News

• Six-Year Study Shows Downstream Contamination from Illegal Cannabis Grow Sites
• 'We're one cigarette away': Illegal marijuana farms pose wildfire risk in California's parched national forests (NBC News Dec 2021)
• Illegal marijuana farms in Orange County show how toxic danger is spread through national forests (OC Register Oct 2021)
• Klamath National Forest first in nation to remove all identified illegal marijuana grows (KTVL CBS July 2021)
• Illegal marijuana grows creating devastating environmental damage in national forests (ABC Denver July 2021)

Resources

Illegal Cannabis Cultivation Impacts Scientific Papers/Resources (PDF 179 KB)