Siskiyou County Declares Emergency Over Toxic Pesticides at Illegal Cannabis Operations

YREKA, Calif. — The Siskiyou County Board of Supervisors unanimously declared a local state of emergency Tuesday to address what officials describe as an escalating public health crisis from dangerous pesticides discovered at illegal cannabis cultivation sites throughout the region.

Resolution No. 25-109, passed 5-0 on July 1, responds to the widespread presence of highly toxic, foreign-manufactured pesticides that illegal growers are using as fumigants by burning sawdust-like materials infused with chemical cocktails in aluminum cans placed throughout enclosed growing structures.

Since 2023, approximately 176 investigations conducted by the county’s Code Enforcement and Environmental Health divisions have revealed what officials call “widespread blatant misuse” of highly toxic Chinese-labeled pesticides, along with Thai-labeled and Spanish-labeled products. County laboratory analysis has identified at least 27 different pesticides in various mixtures, with individual illicit products containing between 3 to 13 different chemicals.

Of particular concern, nine of the identified pesticides behave similar to chemical warfare nerve agents by attacking the central nervous system, three are listed as California Toxic Air Contaminants, six are designated as groundwater pollutants, and nine are listed as California Proposition 65 carcinogens.

The illegal pesticides include substances never approved for use in the United States, such as chlorthiophos, diafenthiuron, fenobucarb, fuberidazole, isoprocarb, procymidone, and tridemorph. Others were once approved but later banned due to health and safety concerns, including dinoseb and hexachlorobenzene.

The emergency declaration highlights increasing dangers to first responders, including sheriff’s deputies, firefighters, emergency medical personnel, and environmental response teams who encounter these substances during enforcement operations. Recent weeks have seen increased responses from fire departments at contaminated sites where pesticide-laced materials were actively burning, creating volatile organic compounds and hazardous materials incidents.

“Many illicit cannabis operations are hostile to responders, booby-trapped, structurally unsound, or deliberately designed to evade detection, creating volatile and life-threatening conditions,” the resolution states.

The contamination poses particular risks to the county’s water resources. Under the Sustainable Groundwater Management Act, four of Siskiyou County’s groundwater basins are designated as medium priority, including the Shasta, Scott, and Butte Valley subbasins. Contamination could jeopardize the county’s compliance with state water quality standards and potentially trigger state intervention.

The emergency declaration authorizes several immediate actions:

• Formation of a coordinated, multi-agency emergency response task force
• Allocation of emergency resources to equip and train first responders with appropriate HAZMAT protective equipment
• Collaboration between county agencies and state and federal partners including the DEA, EPA, and CalEPA
• Development of public education campaigns about the hazards
• Pursuit of mutual aid, technical assistance, and emergency funding

The county is requesting both concurrence from the California Office of Emergency Services and a state emergency proclamation from Governor Gavin Newsom to support local mitigation and enforcement efforts.

According to CalEPA, these Chinese-labeled pesticide fumigant products have been found in 18 counties throughout California, with Siskiyou County leading in quantity, variety, and frequency of observation.

The resolution emphasizes that it remains unknown what toxic gases are produced when burning mixtures of these illegal pesticides that are not permitted for use as fumigants, creating additional uncertainty about exposure risks.

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