Source of high PFAS levels in Muskegon Lake foam unknown, researchers say

Foam from Muskegon Lake contained over 4,000 parts per trillion of a synthetic chemical known to harm human and environmental health, researchers said on Monday . That's unusually high, but its cause and the implications of the event are still unclear.

The foam, sampled in mid-August, contained large concentrations of PFOS (perfluorooctane sulfonate), one of almost 15,000 chemicals in the PFAS family.

But the amount of PFOS in the foam may not reflect the water quality of the lake, said Alan Steinman, a research professor at Grand Valley State University's Annis Water Resources Institute.

"This was really an unusual event," he said. "It was almost an aberration." The institute monitors the lake for water quality issues, including PFAS. This sample wasn't collected as part of a study, he said.

"We saw the foam, we grabbed the foam," he said. "We weren't sure how long it would last."

Not all foam found on water surfaces is toxic. Some foam on lakes and rivers occurs naturally as biological matter breaks down.

PFAS foam tends to accumulate in large piles and may be whiter than other foam. The state has warned residents not to ingest or touch any foam they find.

Scientists are still studying what causes PFAS foam to form on water body surfaces. Factors include wind direction, treated wastewater discharge and oxygen levels in the water.

"We're racking our brains trying to figure out what the source was" for Muskegon Lake's foam, Steinman said. He declined to speculate.

"At this point, [it's] better to say we don't know than to give wrong answers," he said.

There are several potential sources of the chemical near the lake, according to a statement from Michigan's Department of Environment, Great Lakes and Energy and the Michigan PFAS Action Response Team (MPART):

"The Michigan PFAS Action Response Team is aware of the recent PFAS foam reports on Muskegon Lake and continues to investigate these sporadic foam events.

This is part of MPART's ongoing statewide effort to track the sources of these contamination which is often associated with the past use of class-B firefighting foam.

It is important to note that Muskegon gets its drinking water from Lake Michigan and the city's water has consistently complied with state regulations that place strict limits PFAS in drinking water.

MPART has received foam complaints in Muskegon Lake in 2020 and 2022. Like the recent reports, we have not yet been able to identify the source of these foam events as there a number of former industries along the Muskegon Lake shoreline that could have used PFAS foam for fire protection or in their industrial processes.

Although recreating in water containing PFAS is not considered harmful because the amount of PFAS is typically low, MPART and our agency partner, the Michigan Department of Health and Human Services, recommend that people avoid direct physical contact with any foam they encounter on lakes or rivers and rinse themselves and pets off after contact with foam."

The department wants residents to report foam they find on a Michigan water body that could contain PFAS. Verified reports inform where the state collects water samples to test for PFAS, according to MPART's website.

The foam on Muskegon Lake is one example of many PFAS contamination issues across the state, making it difficult for state regulators to address all of them, Steinman said. He reiterated the state's warnings to residents.

"If you see this massive foam that's accumulating, washing up somewhere on the lake shore, stay away from it," Steinman said. "You don't want to touch it. We can't say for sure that it's PFAS, but why take the risk?"