Great Lakes show declining PFAS levels

Great Lakes fish are carrying lower levels of some PFAS chemicals than they did in earlier decades, according to a peer-reviewed study highlighted by Great Lakes Echo on May 17. The research drew on nearly 1,000 archived lake trout and walleye samples collected from 1975 to 2020 across all five Great Lakes. The authors found contamination peaked between the mid-2000s and 2010s in many places, then declined. Sarah Balgooyen, the lead author and a researcher at the Colorado School of Mines, said the results suggest fish are “safer to eat than they were even 10 years ago,” while cautioning that PFAS remain in the system. ### How did researchers measure a 40-year PFAS trend? The Journal of Great Lakes Research study used whole lake trout and walleye preserved through the U.S. Environmental Protection Agency’s Great Lakes Fish Monitoring and Surveillance Program. The paper says the sample archive let researchers quantify PFAS bioaccumulation from 1975 to 2020 rather than relying only on recent testing. Researchers tested 45 PFAS compounds and detected 15 of them in predatory fish, with eight found regularly, according to Michigan Public’s report on the study. (greatlakesecho.org) Wisconsin Public Radio reported that current and former EPA researchers in Duluth analyzed almost 1,000 samples from fish taken across all five lakes. ### What changed in the fish? Average PFAS levels in 2020 were the lowest seen since the 1980s, with differences by lake, Michigan Public reported. (sciencedirect.com) Great Lakes Now said contamination in archived tissue declined significantly since the late 2000s, after earlier peaks. Lake Erie showed some of the biggest swings. Wisconsin Public Radio reported concentrations there reached about 450 parts per billion before dropping to about 50 parts per billion in 2020. (michiganpublic.org) In Lake Michigan, levels peaked around 150 parts per billion and later fell to about 80 parts per billion, while Lake Superior peaked around 60 parts per billion and later fell to about 25 parts per billion. ### Why do scientists link the decline to older PFAS phaseouts? (michiganpublic.org) Balgooyen told Great Lakes Echo that manufacturers’ phaseout of long-chain PFAS chemicals made those compounds less likely to enter Great Lakes ecosystems. Wisconsin Public Radio similarly reported that declines in almost all lakes followed industry agreements in the early 2000s to phase out two of the most common PFAS chemicals, especially PFOS. (wpr.org) Balgooyen also told Michigan Public that the chemicals are not disappearing through breakdown in the lakes. “They’re just getting diluted out into the oceans,” she said, referring to Great Lakes outflow through the St. Lawrence Seaway. That means the study points to lower concentrations in fish, not elimination of PFAS from the environment. (greatlakesecho.org) ### Why does fish data matter so much here? PFAS build up readily in fish, and eating freshwater fish is a significant route of human exposure, Balgooyen told Michigan Public. Great Lakes Echo reported that fish are a useful indicator because they sit near the top of the freshwater food chain and can accumulate higher concentrations than other organisms. (michiganpublic.org) The Great Lakes serve as a food and water source for millions of residents, Great Lakes Echo reported. MPR News said health studies have linked PFAS exposure to weakened immunity and higher risks of some cancers, kidney and liver disease, and birth defects. ### Does this mean fish advisories are going away? Michigan Public reported that the findings offered hope that “do not eat” advisories could eventually be retired, but that was presented as a possibility, not a policy change. (michiganpublic.org) None of the reports reviewed said states had lifted existing advisories because of this study. As of the study’s publication in January 2026, the research showed lower bioaccumulative PFAS levels than a decade earlier, Balgooyen told Great Lakes Echo. (greatlakesecho.org) The next concrete step is not a new field campaign announced in the coverage, but continued use of the EPA fish archive and the Journal of Great Lakes Research paper as a baseline for future monitoring by researchers including Balgooyen and former EPA scientists. (michiganpublic.org)