PFAS from Pesticides Found Widespread in California Water

Per- and polyfluoroalkyl substances—known as PFAS or “forever chemicals”—are contaminating California’s surface water and sediment at levels that should alarm agricultural communities and regulators alike. New analysis from the Environmental Working Group (EWG) documents the persistent presence of pesticide-derived PFAS compounds across the state’s waterways, a finding that raises urgent questions about farming practices and the chemicals being distributed across the agricultural landscape.

PFAS compounds are part of a class of synthetic chemicals used in a range of industrial and consumer products. But what makes this discovery particularly troubling is that many of these compounds originate from agricultural pesticides—chemicals deliberately applied to farmland and often carried into surface water through runoff, soil erosion, and groundwater movement. Once in the environment, PFAS don’t break down. They accumulate in water, soil, and living organisms, which is why they’ve earned the nickname “forever chemicals.”

The Scope of Contamination

California’s agricultural heartland—the Central Valley, responsible for a quarter of the nation’s food supply—is particularly vulnerable to PFAS contamination. The state’s intensive farming practices, which rely on synthetic pesticides to manage pests across millions of acres, have created conditions where these chemicals migrate readily into waterways. EWG’s analysis found PFAS pesticides widespread in California waterways and sediments, indicating the contamination is not isolated to a few hotspots but is systemic across the state.

The problem is compounded by agriculture’s dependence on water. Farmers irrigate with surface and groundwater that, in many regions, is already contaminated. This means PFAS compounds are being cycled back into the soil year after year, accumulating in sediment and groundwater where the chemicals can persist for decades.

Health and Environmental Stakes

PFAS chemicals are classified as probable human carcinogens and have been linked to serious health effects including liver damage, thyroid disease, weakened immune function, and certain cancers. For farmworkers and rural communities whose water sources depend on wells and surface intakes in contaminated areas, exposure is not theoretical—it’s daily.

Agricultural communities face a particular bind. Farmworkers often have limited access to clean water, relying on farm-provided water systems that may pull from contaminated sources. Rural wells in farming regions frequently have no regulatory oversight or testing requirements, meaning families may drink PFAS-laced water without knowing it.

Regulatory Gaps and Farmer Liability

Federal regulation of PFAS has lagged dangerously behind scientific evidence of harm. The EPA has proposed drinking-water standards for just a handful of PFAS compounds, leaving hundreds of other variants unregulated and unmonitored. Individual states, including California, have begun to fill the gap with their own rules, but these are often toothless without enforcement resources.

What’s particularly galling for farmers: regulations surrounding pesticide use focus almost entirely on target-organism toxicity—will it kill pests without immediately poisoning the applicator? They rarely account for the fate of synthetic compounds in the environment over decadal timescales. A pesticide approved and legally applied decades ago may now be recognized as a persistent environmental contaminant, yet the farmer who applied it faces no liability, nor do the companies that manufactured and marketed it.

What Needs to Change

Addressing PFAS in California’s agricultural water requires action at multiple levels:

• Pesticide policy reform: California should accelerate review and restrictions on PFAS-containing pesticides, prioritizing phaseouts of known persistent compounds and funding transitions to less persistent alternatives.
• Water monitoring: Agricultural regions need mandatory testing and reporting of PFAS in surface water, groundwater, and soil, with public access to the data.
• Farmworker protections: Regulations must ensure farmworkers have access to clean drinking water and protective equipment, with hazard disclosure for any field exposure.
• Remediation research: State and federal investment in cleaning up contaminated water and soil in agricultural regions is overdue.

For now, California’s agricultural heartland remains a PFAS hotspot, with compounds that were never supposed to degrade persisting in the state’s waters and accumulating in the bodies of the people who grow America’s food.

Related reading: Learn more about how consolidation in agriculture exacerbates environmental harms in the meatpacking monopoly and food safety. And for context on how agricultural debt ties farmers’ hands when it comes to sustainable practices, see the farm bankruptcy debt crisis.