Researchers have found unexpectedly positive results in the aftermath of the devastating January 2025 Palisades and Eaton wildfires that swept through Los Angeles County: levels of harmful metals in coastal waters and sand remain below established safety thresholds.
The findings, released by the University of Southern California’s CLEAN Waters project, offer a rare bright spot following the fires, which burned over 40,000 acres and destroyed at least 12,000 buildings, according to reporting at the time. The blazes blanketed the ocean in ash, raising initial concerns about widespread contamination.
“We’re not seeing any evidence for harm in the ecosystem or harm for human health,” said Noelle Held, a marine biogeochemist and principal investigator for the CLEAN Waters project. Her team analyzed seawater samples collected from multiple locations between February 10 and October 17, 2025, as well as sand samples collected in August of that year.
Initial testing by the environmental group Heal the Bay immediately following the fires did detect a spike in heavy metals, including lead, mercury and others. Concentrations of beryllium, copper, chromium, nickel and lead were significantly above established safety thresholds for marine life, prompting fears for the long-term health of the marine ecosystem.
However, Held’s team found that even at their peak, seawater lead concentrations barely surpassed 1 microgram per liter – well below the U.S. Environmental Protection Agency’s aquatic life safety threshold of 8.1 micrograms per liter. Levels of iron, manganese, and cobalt were elevated near the Palisades burn scar, but remained below levels considered harmful.
Sand samples collected in August showed lead levels never exceeding 14 parts per million, significantly below California’s residential soil standard of 80 parts per million, and even below the stricter 55 parts per million standard proposed by environmental health researchers. “This isn’t something we would flag if we were testing your soil in your yard,” Held said.
The State Water Resources Control Board conducted its own water quality tests in 2025, reaching similar conclusions: higher concentrations of metals near burn scars, but no overall evidence of an ongoing threat to human health, according to a board spokesperson.
Despite the encouraging results, researchers emphasize the necessitate for continued monitoring. The Los Angeles County Board of Supervisors launched a public survey on March 11, 2026, to gather feedback from residents impacted by the fires, as part of an independent After-Action Review conducted by the McChrystal Group. The survey, open through April 24, 2026, seeks input from those who evacuated, experienced property damage, or utilized disaster services.
Eugenia Ermacora, manager of the Surfrider Foundation’s L.A. Chapter, which partnered with Held’s team on sample collection, noted that post-fire impacts can change over time depending on rainfall and sediment movement. “It’s not just about the fires, but it’s about urbanization and how much our city needs to continue the work of doing testing in the water,” she said. NASA also analyzed the fires, creating visualizations of fire behavior, black carbon dispersal, and air quality effects, as part of its 2025 Year in Review series.
Researchers also pointed to a lack of historical data on pollution levels as a challenge in assessing post-fire safety, a gap they hope to address before future disasters occur. Potential future rainstorms could also continue to wash metals into areas like Will Rogers Beach and the Rustic Creek outfall, both near the Palisades burn scar, CLEAN Waters warned.