FLBS Monitoring Finds PFAS and PPCPs in Flathead Watershed

Recent monitoring conducted by the University of Montana’s Flathead Lake Biological Station has revealed the presence of per- and polyfluoroalkyl substances (PFAS) and pharmaceuticals and personal care products (PPCPs) in waters of the Flathead Watershed.

“Detection of these compounds is not entirely surprising given results elsewhere,” said FLBS Director Jim Elser. “But confirming their presence in the Flathead, even at these low levels, is still a matter of concern.” 

PFAS are a class of synthetic chemicals distinguished by the exceptionally strong bond between fluorine and carbon atoms. This bond imparts high levels of chemical stability, durability, and resistance to degradation, thus the term “forever chemicals”.

As a result, PFAS are widely used in hundreds of industrial processes and consumer products, including carpets, clothing, food packaging materials, wire and cable coatings, pesticides, and herbicides. In total, there are around 15,000 different PFAS compounds.

PFAS were detected in water at all FLBS sampling locations in the Fall of 2025, which included sites in Flathead Lake, the Flathead River, the Swan River, and Stoner Creek. Of the 40 PFAS compounds targeted for analysis, ten were detected. Of those ten, three were found at quantifiable levels that were above laboratory reporting limits. For compounds with established thresholds for safe drinking water, concentrations were low and well below those standards.

“Right now, PFAS concentrations are not at levels to cause direct concern about human health but they should motivate us to find out more about where they are coming from and to continue surveillance,” Elser said. “Unfortunately, that is very challenging because analysis of PFAS in water samples is extremely expensive.” 

To this point, all PFAS and PPCP compound sampling and analyses conducted by FLBS have been made possible by philanthropic support.

For most PFAS compounds, thresholds for safe concentrations for drinking water have not been established. PFAS exposure may lead to various health effects, including decreased fertility, developmental effects or delays, increased cancer risk, immune impairment, hormone disruption, and increased risk of obesity. Additionally, the short and long-term ecological impacts of PFAS compounds are poorly understood.

In a separate FLBS study, PPCPs were analyzed in water samples collected from Ashley Creek, two sites in Flathead Lake, and two sites in Whitefish Lake.

Chemicals used in PPCPs and their degradation byproducts are chemically persistent and are being increasingly detected in waterbodies all over the world. They include caffeine, prescription and non-prescription drugs, consumer products (e.g., lotions, soaps, and sunscreen), and controlled substances.

PPCP compounds were detected at all sampling sites. These detections provide indicators of wastewater, human waste, and/or improper disposal of these products; and may help us determine hotspots of sewage and/or septic inputs.

Like many PFAS compounds, thresholds for safe concentrations of PPCPs in drinking water have not been established and the ecological impacts of PPCP compounds are poorly understood—especially regarding their effects on humans and aquatic organisms in combinations and under natural conditions.

FLBS scientists also emphasize the need for expanded monitoring and research to better understand the human health and ecological implications of PFAS and PPCP compounds in our waters.

“In the Flathead we need to work together to get a better perspective on the distribution of PFAS and PPCPs in various streams, rivers, and lakes in our watershed,” Elser said, “and then work together to reduce or eliminate the sources that are introducing them to our ecosystems.”