Glyphosate Spraying in California Forests Reaches Record Levels Amid Health Concerns

The U.S. Forest Service and private timber companies are applying glyphosate—Roundup’s active ingredient—on a scale described as a record for California’s public lands. In the Lassen National Forest alone, the agency plans to spray the herbicide across roughly 10,000 acres to clear brush that competes with newly planted trees. Analysis of more than five million pesticide reports shows that glyphosate applications across state forests have quadrupled over the past two decades, with the heaviest use near Yosemite, Lassen Volcanic National Park, and the Lake Tahoe region, including 75,000 acres burned by the 2021 Caldor Fire.

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Glyphosate has been at the center of litigation alleging cancer risk. In 2015, the World Health Organization’s International Agency for Research on Cancer classified it as “probably carcinogenic to humans.” Bayer, which acquired Monsanto in 2018, formed a subsidiary called Ruveon to manage its glyphosate-based business. The Forest Service’s reforestation strategy relies on glyphosate to eliminate competing brush, a practice justified by a 15-year-old agency study that cited peer-reviewed research later revealed to have been ghostwritten by Monsanto.

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• >5 million pesticide reports analyzed; glyphosate use in California forests has risen fourfold in the last twenty years.

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• Planned application on ~10,000 acres in Lassen National Forest.

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• Additional large-scale spraying documented near Yosemite, Lake Tahoe, and the 75,000-acre Caldor Fire scar.

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The Forest Service describes glyphosate as a “valuable tool” that “helps accelerate reforestation efforts” by removing brush that outcompetes young trees. The Environmental Protection Agency (EPA) has acknowledged that Monsanto engaged in ghostwriting and research misconduct but continues to cite studies concluding that glyphosate is “unlikely to cause cancer.”

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• Joe Van Meter, owner of Mill Creek Resort near Lassen, calls the herbicide “poison” and worries about exposure for his two-month-old child and other families.

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• Russell Nickerson, district ranger for Lassen National Forest, redirects detailed safety questions to the agency’s Washington office.

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• Members of Congress overseeing the Forest Service have submitted detailed inquiries demanding transparency about the spraying program.

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Field observations show stark contrasts: sprayed sections display dead bushes and cleared understory, while adjacent unsprayed areas exhibit natural regrowth of conifers. Residents who have endured recent wildfires now confront the prospect of long-lasting chemical residues in the very backyards where they rebuild.

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The Forest Service’s safety rationale rests on studies that have been retracted for “serious ethical concerns” and undisclosed Monsanto involvement. By contrast, the WHO’s classification labels glyphosate as a probable human carcinogen, while the EPA maintains it is unlikely to cause cancer. No recent independent safety assessment has been cited by the agency, leaving a gap between regulatory statements and independent health evaluations.

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• “They’re taking away the choice of being surrounded by a toxic chemical,” — Lake Tahoe

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Community opposition and congressional scrutiny continue, and legal challenges persist after a recent Supreme Court decision limiting state-labeling lawsuits against Bayer. The Forest Service has not announced any changes to its glyphosate program, and the investigation into the agency’s reliance on disputed studies remains ongoing.

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