Forestland in Plumas County, California, sprayed with glyphosate, shown in August, 2025. More than four years after the Dixie Fire, nothing grows here but replanted conifer trees.Scott Anger
Two members of Congress have sent a letter to US Forest Service Chief Tom Schultz calling on the agency to justify its actions following an investigation by Mother Jones that found glyphosate—the controversial key ingredient in the herbicide Roundup—was being sprayed in record amounts on public lands.
“Given the recent scientific disputes, retracted studies, and litigation surrounding glyphosate due to serious ecological and health harms, we are deeply concerned by the alleged use of the herbicide and lack of information available regarding current and planned use,” wrote Reps. Chellie Pingree (D-Maine) and Jared Huffman (D-Calif.).
Rep. Chellie Pingree: “It’s bullshit. I’m really mad.”
While glyphosate is more well-known for its use in agriculture, its fastest-growing use in California—where our investigation analyzed more than 5 million state pesticide records—is on forestlands. Private timber companies and the Forest Service have been dousing hundreds of thousands of acres of the state’s forests in the herbicide, especially areas affected by wildfires.
Local communities have struggled to understand where the agency is spraying. In one case, the Forest Service published maps showing where it had sprayed glyphosate in the Lake Tahoe area, including at the ski resort Sierra-at-Tahoe, a full year after the work was done.
“It’s bullshit. I’m really mad,” Congresswoman Pingree told me when asked about the Forest Service spraying in environmentally sensitive areas.
The lawmakers’ letter calls on the Forest Service to publish a database showing its herbicide use across the country, and to report what safety measures it has put in place—such as monitoring waterways and soils for contamination—following its use of Roundup and other glyphosate-based products.
They also wondered about potential harms to humans: “Have there been any reported worker illness incidents, accidental exposures, or contamination complaints associated with glyphosate applications?” the letter asks.
Our investigation found that workers hired to spray Roundup on the El Dorado National Forest in 2021 were covered in Roundup, including directly on exposed skin, and that they were not wearing the required protective equipment nor did they have the state-required training, according to a report by a county inspector.
Bayer, the German company that manufactures Roundup, provided a statement that “regulators, including the EPA, EU, and others around the world, have repeatedly concluded that glyphosate-based products—which are the most widely used and extensively studied products of their kind—can be used safely according to the product label directions.”
Glyphosate is at the center of several legal, scientific, and political controversies. Bayer is on the hook for more than $12 billion in legal payouts to people who say exposure to the chemical made them sick. The World Health Organization classified glyphosate as a probable carcinogen in 2015, and the Environmental Protection Agency says the herbicide likely harms 93 percent of endangered species. The EPA last approved the chemical’s safety in 1993. A more recent review in 2020 that found it was safe was overturned two years later by the 9th Circuit Court of Appeals, which determined the agency had not fully assessed the risks to human health or the environment.
The Forest Service says it is using the chemical at record levels in California because it is the least expensive way to help conifer trees—the ones with pine needles—grow back after wildfires. The often stated goal of these Forest Service herbicide projects is to regrow trees more expeditiously. This helps the agency meet its desired forest density for future timber sales, according to hundreds of pages of Forest Service documents reviewed in our investigation. (The agency is part of the US Department of Agriculture and manages many of the nation’s public forests, similar to how a farmer oversees rows of corn: optimizing the land for higher yields, lower costs, and greater revenue.)
In 2025, President Trump issued an executive order for the Forest Service to increase timber sales by 25 percent, while the administration has cut the agency’s staffing. In 2026, Trump called for an increase in the domestic production of glyphosate.
Spraying glyphosate and other herbicides both before and after replanting conifer trees results in the death of all other plants that reemerge after fires.
In their letter to the Forest Service, Reps. Pingree and Huffman urged the agency to consider “safer or more sustainable approaches to forest management.” With such indiscriminate spraying of glyphosate,“you’re talking about just wiping out all biology, you know, just like all life forms. It’s bonkers,” Pingree told Mother Jones. “If there’s one thing we learned from Rachel Carson [author of Silent Spring] in the sixties it’s that we have to look at the cumulative impact, both on humans, but also the species and the food chain, and the loss of diversity.”
