{"id":41369,"date":"2026-04-08T00:01:52","date_gmt":"2026-04-08T04:01:52","guid":{"rendered":"https:\/\/beyondpesticides.org\/dailynewsblog\/?p=41369"},"modified":"2026-04-07T14:54:07","modified_gmt":"2026-04-07T18:54:07","slug":"u-s-geological-survey-finds-pfas-pesticides-in-california-streams","status":"publish","type":"post","link":"https:\/\/beyondpesticides.org\/dailynewsblog\/2026\/04\/u-s-geological-survey-finds-pfas-pesticides-in-california-streams\/","title":{"rendered":"U.S. Geological Survey Finds PFAS Pesticides In California Streams"},"content":{"rendered":"

(Beyond Pesticides<\/em>, April 8, 2026) Researchers at the U.S. Geological Survey (USGS) assessed pesticide and PFAS (per- and poly-fluoroalkyl substances) contamination in ten agricultural streams in the San Joaquin and Sacramento Valleys (Central Valley) in 2024, detecting 60 pesticides, synergists, and associated transformation products, including 12 fluorinated pesticides (<\/span>Dithiopyr<\/span><\/a>, <\/span>Trifluralin<\/span><\/a>, <\/span>Fluridone<\/span><\/a>, <\/span>Oxyfluorfen<\/span><\/a>, <\/span>Penoxsulam<\/span><\/a>, <\/span>Flubendiamide<\/span><\/a>, <\/span>Bifenthrin<\/span><\/a>, <\/span>Flonicam<\/span><\/a>, <\/span>Indoxacarb<\/span><\/a>, Cyhalothrin, <\/span>Fluopyram<\/span><\/a>, and <\/span>Penthiopyrad<\/span><\/a>) that meet the Organisation for Economic Cooperation and Development (OECD) definition of qualifying as PFAS. It is alarming to learn that \u201cthe OECD fluorinated pesticides were generally detected more frequently and at higher concentrations\u201d relative to the 48 other compounds.<\/span>\u00a0<\/span><\/p>\n

Relatedly, research finds products containing three of the detected pesticides (<\/span>Methoxyfenozide<\/span><\/a>,\u00a0<\/span>Imidacloprid<\/span><\/a>, and\u00a0<\/span>Piperonyl\u00a0Butoxide<\/span><\/a>) associated with various PFAS, and according to the authors, there are a handful <\/span>of active ingredients, such as the insecticide Methoxyfenozide<\/a> and the fungicide Azoxystrobin<\/a>, detected in 100 percent of collected samples. Their entire findings were published in <\/span>Environmental Science & Technology Letters<\/span><\/i><\/a>\u00a0<\/span><\/i>in March 2026.<\/span><\/p>\n

This research is critical to our understanding of the pervasiveness and ubiquity of multi-chemical pollution that impacts one of the most productive agricultural regions in the country. The regions encompassing these two valleys make up just one percent of total U.S. farmland, yet produce eight percent of total agricultural production by output, including 4 in 10 of the country\u2019s fruits and nuts, according to <\/span>USGS<\/span><\/a>. Unfortunately, the chemical-intensive status quo has led to significant evidence of off-target pesticide drift into community members\u2019 <\/span>households<\/span><\/a>\u00a0and\u00a0<\/span>schoolyards<\/span><\/a>,\u00a0emphasizing the\u00a0dangers of\u00a0<\/span>bioaccumulation<\/span><\/a> from resulting acute and chronic exposure to local communities and ecosystems, not to mention the downstream effects of residues that are spread in the supply chain across the U.S. and the globe. In this context, organically managed systems, as defined by the <\/span>Organic Foods Production Act,<\/span><\/i> have created a blueprint for least- and non-toxic pest management systems that ban the spread of toxic inputs (synthetic pesticides, fertilizers, PFAS, biosolid sewage sludge, and antibiotics and animal growth hormones for livestock). <\/span>\u00a0<\/span><\/p>\n

Methodology\u00a0and Results\u00a0
\n<\/strong>“The objective of this study was to evaluate pesticide applications as a source of PFAS in streams draining agricultural regions in California: San Joaquin Valley and Sacramento Valley,\u201d says the USGS researchers. They continue: \u201cSites across the San Joaquin Valley and Sacramento Valley were sampled for 183 pesticides and pesticide transformation products (TPs) and 57 individual PFAS.\u201d <\/span>\u00a0<\/span><\/p>\n

Ten sites were selected across the Central Valley, with water samples gathered in May and July 2024. The sites were chosen based on two criteria: \u201cminimal nonagricultural influences\u201d to otherwise explain the source(s) of contamination and substantial levels of the pesticide product Intrepid 2F (methoxyfenozide), citing previous research finding \u201cthe presence of perfluorobutanesulfonate (PFBS)\u201d in the formulation. The most recent pesticide data is from peak applications in 2021, collected by the <\/span>California Department of Pesticide Regulation (DPR),<\/span><\/a>\u00a0operating\u00a0on the assumption \u201cthat 2022 pesticide use data (the most recent year available) are representative of the 2024 pesticide data.\u201d\u00a0A\u00a0range of agricultural products (alfalfa, rice, tomatoes, nuts, etc.)\u00a0are grown on the sites,\u00a0information that\u00a0assisted\u00a0in\u00a0determining\u00a0relevant pesticides to\u00a0test for.\u00a0<\/span>\u00a0<\/span><\/p>\n

There was no rain to impact pesticide residue data gathered in this study across both valleys in the days leading up to water sample collection in July 2024, with San Joaquin Valley experiencing less than 2.5 centimeters of rainfall the day before water testing in May 2024; Sacramento Valley also faced no rainfall in the days leading up to the May 2024 sample gathering. Researchers used various techniques to isolate and determine individual compounds (pesticides, PFAS, etc.), involving liquid and gas chromatography-tandem mass spectrometry (LC-MS\/MS and GC-MS\/MS). Across the ten sites (creeks and streams), summary data were developed, including \u201ctotal PFAS concentration, total pesticide concentration, total OECD fluorinated pesticide concentration, PFAS counts, pesticide counts, and pesticide use (kg) normalized by watershed area (km<\/span>2<\/span>).\u201d<\/span>\u00a0<\/span><\/p>\n

There are some\u00a0additional\u00a0notable findings from this study, including site-specific findings:\u00a0<\/em><\/p>\n