After decades of worry about “forever chemicals” in the Great Lakes, a sweeping new analysis of lake trout and walleye suggests the worst years are in the rearview mirror. PFAS levels in fish across the basin appear to have dropped from decade-high peaks, a trend scientists call encouraging even as health officials remind anglers that local tests and fish-consumption advisories still rule the dinner table.
The study examined nearly 1,000 archived lake trout and walleye collected between 1975 and 2020 and screened for 45 different PFAS compounds, according to a paper in the Journal of Great Lakes Research. The samples are part of the EPA’s long-running Great Lakes fish monitoring program, stored at the agency’s Duluth lab and documented in its quality-assurance plan. Lead authors report that, across the basin, PFAS concentrations in fish peaked roughly between 2007 and 2017 and by 2020 had declined toward levels last seen in the 1980s.
What The Samples Show Lake By Lake
The comeback story is not uniform. Lake Erie and Lake Ontario posted the highest PFAS concentrations in fish, with Lake Erie samples topping out near 450 nanograms per gram before dropping to about 50 ng/g by 2020. Lake Michigan peaked around 150 ng/g and had eased to roughly 80 ng/g by 2020. Lake Superior’s high point was much lower, near 60 ng/g, sliding into the mid-20s by 2020. Researchers stress that these declines are uneven and that hot spots linger in the most heavily populated stretches of shoreline. Those lake-by-lake figures were reported by Michigan Public Radio and corroborated by Urban Milwaukee.
Why Levels May Be Falling
Study authors point to two main reasons for the downward trend: changes in industrial chemistry and the lakes’ own ability to dilute and flush contaminants. Major manufacturers began phasing out older, long-chain PFAS such as PFOS-type compounds in the early 2000s, according to company filings, and many later signed on to voluntary reduction efforts. Once those chemicals stopped flowing in at the same rate, the ecosystem started to respond. "The ecosystem responded very quickly to these changes in industrial production," lead author Sarah Balgooyen told Great Lakes Now. Natural mixing and turnover in the lakes then helped push concentrations down toward older, lower baselines.
What Anglers Should Know
For people who fish the Great Lakes, the findings are welcome news, not a green light to fry up unlimited fillets. State health and natural-resources agencies still lean on location- and species-specific advisories, which can be stricter in areas that remain contaminated. Officials with the Wisconsin Department of Natural Resources and state health agencies told WPR that they are reviewing the study and expect to roll out updated consumption guidance later this spring. Under recently adopted best-practice thresholds, the DNR treats fish with PFOS above about 40 parts per billion as unsafe to eat. For now, the standing advice applies: check the latest advisories for the lake and species you plan to eat, especially if fish is a regular part of your diet.
Regulatory Backdrop
On the regulatory front, the federal government has been tightening the screws on PFAS exposure. In 2024, the EPA finalized a national drinking-water regulation for several PFAS compounds and set enforceable maximum contaminant levels, including 4 parts per trillion for PFOA and PFOS. The agency also designated PFOA and PFOS as hazardous substances under CERCLA, a move that expands monitoring, can speed up cleanups and makes it easier to hold polluters financially responsible.
Researchers and outside toxicologists see the new fish data as a rare environmental bright spot that still comes with caveats. "It’s promising that levels have gone down on some of these ones that we know we’re concerned about," study co-author Gerald Ankley told WPR. At the same time, he noted that it is not yet clear whether concentrations in many waters are low enough to lift existing advisories. The bottom line for anglers is unchanged: enjoy the catch, but keep an eye on local fish advisories and state guidance, especially if those fillets are a regular feature on your dinner plate.
