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Impacts of Illegal Outdoor Marijuana Growing Operations


Impacts of Illegal Outdoor Marijuana Growing Operations

Although most of us never come in contact with illegal outdoor marijuana growing operations, they are present and active in remote areas throughout the Russian River watershed. These operations are found on both public and private land. The number of grow sites and the size of the operations are increasing, and so is the impact to the environment and local water resources. This article is intended to raise awareness about the harmful ecological impacts on the Russian River watershed from illegal, unregulated, outdoor marijuana growing operations. 

California’s drought is having a huge impact on our rivers, streams, and wetlands. As streams and rivers run dry, the fish and wildlife that depend on these water sources are fighting to survive. 

There are huge differences between the environmental impacts of personal-use gardens, commercial-size grows, and the large-scale cartel grows, with not all contributing to the environmental problems. Unfortunately, there are illegal marijuana growers that operate with little or no regard for the environmental impacts of their operations, especially the large scale growers whose operations are controlled and funded by drug cartels. Habitat destruction, pollution, and even poaching are huge concerns in these growing areas.  

In terms of the larger operations, the problems arise even before the ground is prepared for these illegal grows and continue through to the harvest. Roads are often cut to access illegal grow sites. Trees, brush, and other vegetation may be cleared to make room for these operations. Unregulated road construction can cause erosion and increased sediment loads to the nearby waterways. 

These operations use pollutants such as herbicides, used to kill competing plants, and pesticides, which kill off animals and insects that might graze on the marijuana plants. In addition, poisons that are banned from use in the United States may be applied to the site. Toxins used on site can end up washing into waterways or leaching into groundwater.

Rodenticides (rat poison) are also often used in an attempt to kill forest creatures that might gnaw on irrigation piping or come into contact with the plants. Rodenticides used on large illegal marijuana grows have been connected to poisoning the Pacific fisher, which is a proposed threatened species by the U.S. Fish and Wildlife Service and is a member of the weasel family that inhabits closed-canopy forests and feeds on everything from birds to small mammals to fruits and mushrooms. 

The Pacific fisher, birds of prey, and other wildlife populations depend on smaller creatures, such as rodents and squirrels, for their food source. Rodenticides do not always kill the target pest right away; therefore, any predator that eats a live poisoned creature will be ingesting the poison as well. This is a serious threat to many species of wildlife, including endangered species. 

When large illegal grow sites are discovered by authorities or found abandoned, they often require government resources and staffing for clean-up. Garbage, human waste, hazardous materials, and fertilizers are usually found littering the landscape. As the illegal grows continue to flourish, more and more government resources are required for identification and eventual clean-up. 

The North Coast Regional Water Quality Control Board recently adopted California’s first regional water quality regulatory order to protect the environment from discharges of waste associated with cannabis cultivation. 

The public can help by educating friends and neighbors about the issues and by reporting water quality violations to local law enforcement or directly to the North Coast Regional Water Quality Control Board at (707) 543-7128 or email

This article was authored as a collaborative effort by RRWA.  RRWA ( is an association of local public agencies in the Russian River Watershed that have come together to coordinate regional programs for clean water, fisheries restoration, and watershed enhancement.