The Ohio River sends billions of gallons past Louisville’s pumping station every day. Louisville Water Company constantly tests that raw water for pH, odors, heavy metals and microbes — and, unlike many smaller utilities, regularly checks for PFAS (per- and polyfluoroalkyl substances), a class of long-lasting chemicals used for decades in nonstick pans, firefighting foam, cosmetics, food wrappers and other products.
Studies have linked PFAS to health risks including certain cancers, reduced immune function, high cholesterol and developmental delays. These “forever chemicals” break down extremely slowly and now contaminate soil, water and people’s blood across the U.S. One PFAS the Louisville team monitors is HFPO-DA, commonly known by the trade name GenX.
In December 2024 Louisville technicians detected a spike in GenX in raw Ohio River water: 52 parts per trillion (ppt), up from 3.4 ppt the month before. (A part per trillion is an extremely small concentration — one analogy is one second in 32,800 years.) Although still low in absolute terms, the change prompted the utility to trace the source upstream. The team followed the chemical past Cincinnati and through Appalachian forests to a Chemours factory near Parkersburg, West Virginia, about 400 miles upstream — the Washington Works facility that makes fluoropolymers and has a documented history of PFAS pollution dating to DuPont’s earlier ownership.
Louisville’s calculations showed the December spike corresponded to publicly available Chemours discharge data. Peter Goodmann, director of water quality and research at Louisville Water, said he was not immediately concerned for customers’ short-term safety: PFAS risks are evaluated over lifetime exposure, and Louisville’s treated drinking water tested below upcoming federal limits. He also noted people get exposed to PFAS from multiple sources including food packaging.
Chemours has disputed links between its discharges and Louisville’s spike in filings for a separate lawsuit brought by a West Virginia environmental group. In responses to that suit, the company asserted downstream sampling shows levels are “indisputably safe.” Chemours did not respond to NPR’s requests for comment for this story.
Federal PFAS rules: evolving and contested
The EPA finalized the first-ever national drinking water standards for six PFAS in 2024. Those limits require utilities that exceed them to take steps to reduce PFAS in treated water beginning in 2029. When the Biden administration announced the rule, it estimated up to 10% of the roughly 66,000 public drinking water systems could need to take action, and a federal study suggested about 45% of U.S. tap water contains at least one PFAS.
After a subsequent change in administration, EPA leadership announced it would retain limits for only two PFAS (PFOA and PFOS) and drop restrictions on the other four, including GenX, while also giving systems until 2031 to comply with the remaining rules. That shift reduces the regulatory burden on utilities in the near term but leaves many concerns about other PFAS unaddressed.
Enforcement and litigation around Chemours
Under current permits, companies may legally discharge certain chemicals into rivers, but court filings and EPA actions say Chemours repeatedly exceeded permit limits for GenX and PFOA. The West Virginia Rivers Coalition filed suit in 2024 over the company’s discharges. The EPA took enforcement action in 2023, alleging multiple permit violations at Chemours’ West Virginia plant. Plaintiffs argued the EPA’s consent order was not being vigorously enforced.
In August (year in filing), a federal judge, Joseph Goodwin, ordered Chemours to immediately curtail over-polluting; the company appealed. The West Virginia Rivers Coalition called the ruling a victory for public health and the Ohio River.
Implications for utilities and communities
Louisville’s December spike illustrates how upstream industrial discharges can quickly affect downstream water supplies. Even when finished tap water tests below regulatory limits, source-water contamination complicates utilities’ operations and planning. Elevated source concentrations can make it harder and costlier for water treatment plants to meet standards.
Removing PFAS from drinking water is possible but expensive. Louisville is investing roughly $23 million to upgrade its powdered activated carbon system, one method for removing PFAS. Smaller and rural utilities may struggle to afford such infrastructure, which partly explains the federal timeline extensions and the controversy over regulatory scope.
Advocates emphasize that permitting is effectively a license to pollute at specified levels, and that preventing PFAS from entering rivers in the first place is more effective and less costly than removing them later. Goodmann and others argue future permits for polluters should account for downstream water treatment needs and public health considerations, reinforcing the importance of source water protection.
Bottom line
Louisville’s routine monitoring caught a sharp but still low spike in GenX in raw Ohio River water and traced it to upstream industrial discharges. Treated drinking water remained below the federal limits in place at the time of testing, but the incident underscores ongoing challenges: PFAS are widespread and persistent, federal standards and enforcement are evolving amid political and legal disputes, and removing these contaminants from drinking water requires costly upgrades that many utilities may struggle to afford. Source protection and stricter, enforceable controls on dischargers remain central to reducing long-term risks from PFAS.