The Ohio River carries billions of gallons past Louisville each day, and the Louisville Water Company draws from that flow to supply the city’s tap water. Unlike many smaller utilities, Louisville’s team of scientists and technicians routinely tests for PFAS—alongside pH, odors, metals and microbes—giving the utility an ongoing picture of what’s in its source water.
PFAS (per- and polyfluoroalkyl substances) are a family of very persistent chemicals used for decades in products such as nonstick cookware, cosmetics, raincoats, food wrappers and firefighting foams. Some PFAS have been linked to health concerns including certain cancers, reduced vaccine response, higher cholesterol and developmental delays in children. Their chemical stability has earned them the nickname “forever chemicals,” and they now show up across soils, waterways and in the blood of most Americans.
Louisville monitors multiple PFAS, including HFPO-DA—commonly known by the trade name GenX. In December 2024 the utility detected a sharp, unexpected rise in GenX in raw (untreated) Ohio River water: 52 parts per trillion (ppt), up from roughly 3.4 ppt the month before. To convey scale, Louisville Water’s director of water quality and research, Peter Goodmann, compared one part per trillion to one second in 32,800 years; another visualization is one drop in 20 Olympic swimming pools.
Using upstream sampling and public discharge records, Louisville traced the increase past Cincinnati and into forested stretches of the river, ultimately linking the spike to publicly reported discharges from Chemours’ Washington Works plant near Parkersburg, West Virginia—about 400 miles upstream. The plant manufactures fluoropolymers used in semiconductors and has a long PFAS history: legal battles tied to the site’s DuPont-era operations raised decades-old toxicity concerns, and Chemours was spun off from DuPont in 2015.
Goodmann said the December spike aligned with Chemours’ public discharge records, but he did not believe local customers faced immediate risk. PFAS health assessments typically consider lifetime exposure, and Louisville’s finished drinking water—after standard treatment—tested below the federal limits adopted in 2024. Chemours has disputed that its discharges caused the spike and has emphasized that downstream finished water was compliant; the company declined to respond to an NPR request for comment.
Federal PFAS regulation is recent and evolving. In 2024 the EPA finalized national drinking water limits for six PFAS and required systems exceeding those limits to begin treatment by 2029. Earlier enforcement actions in 2023 flagged Chemours’ West Virginia plant for repeated permit violations for GenX and PFOA, prompting litigation by environmental groups led by the West Virginia Rivers Coalition. In 2024 the coalition sued again over continuing discharges, saying the EPA’s consent order was not being vigorously enforced. In August a federal judge ordered Chemours to stop exceeding permit limits immediately; Chemours appealed. In its legal filings the company acknowledged some permit violations while saying it was working with regulators on fixes and stressing finished-water compliance downstream.
Regulatory shifts followed political changes: after a re-election and a new EPA administrator, the agency chose to retain maximum contaminant levels only for PFOA and PFOS, dropping limits for four other PFAS including GenX, and extended compliance deadlines for the remaining rules to 2031, citing costs and burdens on smaller systems.
Removing PFAS from drinking water is technically and financially challenging for many utilities. Louisville is investing about $23 million to redesign its powdered activated carbon treatment system, a common method for PFAS removal. A federal study estimated roughly 45% of U.S. tap water contains at least one PFAS; when the 2024 rules were announced, the Biden administration estimated that up to 10% of the nation’s roughly 66,000 public drinking water systems might have PFAS levels high enough to require action.
Advocates argue that preventing PFAS from entering source waters is more effective and less costly than treating contamination downstream. Nick Hart, water policy director at the Kentucky Waterways Alliance, described regulatory permits as a “license to pollute,” noting that permit limits represent maximum allowable contamination rather than an absolute safety guarantee. Goodmann has urged regulators to consider the impacts on downstream treatment plants and communities when issuing or renewing permits for dischargers like Chemours, stressing that source-water protection reduces treatment burdens and risk.
Environmental groups called the court order in the Chemours case a win for public health and the Ohio River. Autumn Crowe, deputy director of the West Virginia Rivers Coalition, described the ruling as recognition of long-standing pollution and a step toward accountability.
Louisville’s routine PFAS testing allowed the utility to detect the spike, trace its likely source and confirm that finished water complied with then-applicable federal standards. That sequence highlights both the widespread reach of PFAS contamination and the practical, regulatory and financial challenges communities face in monitoring, treating and preventing these persistent pollutants from entering drinking-water supplies.