The Ohio River delivers billions of gallons past Louisville’s intake every day. Louisville Water Company continuously monitors that raw water for pH, odors, heavy metals and microbes — and, unlike many smaller utilities, it also routinely screens for PFAS (per- and polyfluoroalkyl substances). PFAS are a broad group of persistent chemicals used for decades in nonstick cookware, firefighting foams, cosmetics, food wrappers and other everyday products.
Studies have linked PFAS exposure to health concerns including some cancers, reduced immune response, higher cholesterol and developmental problems. These so-called “forever chemicals” break down very slowly and have been detected widely in soil, water and people’s blood across the U.S. Louisville monitors several PFAS, including HFPO-DA, better known by the trade name GenX.
In December 2024 Louisville technicians recorded a rise in GenX in raw Ohio River water to 52 parts per trillion (ppt), up from 3.4 ppt the month before. (A part per trillion is an extremely small concentration — one useful comparison is roughly one second in 32,800 years.) Although the absolute level was still low, the sudden jump prompted the utility to trace the source upstream.
Investigators followed the chemical past Cincinnati and through Appalachian terrain to a Chemours facility near Parkersburg, West Virginia — the Washington Works plant, which manufactures fluoropolymers and has a documented history of PFAS contamination dating to when the site was owned by DuPont. Louisville’s calculations indicated the December spike was consistent with publicly available Chemours discharge records.
Peter Goodmann, Louisville Water’s director of water quality and research, said the finding did not immediately suggest a short-term threat to customers: PFAS health assessments are tied to lifetime exposures, and Louisville’s treated drinking water tested below the federal limits in effect at the time of testing. He also noted that people encounter PFAS from multiple sources, including packaged foods.
Chemours has contested assertions linking its discharges to Louisville’s spike in filings connected to a separate lawsuit brought by a West Virginia environmental group. In those responses the company argued downstream sampling shows levels are “indisputably safe.” Chemours did not respond to NPR’s requests for comment for this story.
Federal PFAS standards have been developing amid political and legal debate. In 2024 the EPA finalized the first national drinking water standards for six PFAS, saying utilities that exceed them would need to take steps to reduce PFAS in treated water beginning in 2029. At that time the agency estimated up to about 10% of the roughly 66,000 public drinking water systems might need to take action, and a federal study suggested roughly 45% of U.S. tap water contains at least one PFAS.
After a change in federal leadership, EPA officials announced a revised approach: keeping limits for only two PFAS (PFOA and PFOS), dropping restrictions on the other four (including GenX), and giving systems until 2031 to comply with the remaining rules. That shift lowers the immediate regulatory burden for many utilities but leaves broader concerns about other PFAS unaddressed.
Enforcement and litigation have centered on whether permitted discharges and actual releases match up. Permits allow certain discharges at specified levels, but court filings and EPA enforcement actions contend Chemours repeatedly exceeded permit limits for GenX and PFOA. The West Virginia Rivers Coalition filed suit over the company’s discharges, and the EPA took enforcement action in 2023 alleging multiple permit violations at the Washington Works plant. Plaintiffs argued federal oversight and consent orders were not being aggressively enforced. In August, a federal judge, Joseph Goodwin, ordered Chemours to curtail over-polluting immediately; the company appealed. Environmental groups described the ruling as a win for public health and the Ohio River.
The Louisville episode illustrates how industrial releases upstream can quickly affect downstream source water. Even when a utility’s finished tap water tests below regulatory limits, contamination in the source complicates operations and planning. Higher concentrations in raw water can make compliance harder and more costly for treatment plants.
Removing PFAS from drinking water is technically possible but expensive. Louisville is investing roughly $23 million to upgrade its powdered activated carbon system, a common method for PFAS removal. Many smaller and rural utilities lack the financial and technical resources to install comparable treatment, which helps explain why federal timelines and regulatory debates remain contentious.
Advocates stress that permits effectively set allowable pollution levels, and preventing PFAS discharges in the first place is typically more effective and less costly than removing contaminants later. Goodmann and others argue future discharge permits should account for downstream treatment needs and public health, underscoring the role of source water protection.
Bottom line: Routine monitoring in Louisville detected a notable though still low spike in GenX in raw Ohio River water and traced it to upstream industrial discharges. Treated drinking water at the time tested below federal limits, but the incident highlights persistent challenges: PFAS are widespread and long-lasting, federal standards and enforcement are changing amid political and legal disputes, and removing these chemicals from drinking water requires costly upgrades many utilities may struggle to afford. Stronger source protection and enforceable limits on dischargers remain central to reducing long-term PFAS risks.