Researchers investigating the long-term effects of the 2025 firestorms on L.A.’s beaches have found that rarest of things: good news.
In the year following the Palisades and Eaton fires, levels of harmful metals like lead in coastal sand and seawater have remained far below California’s limits for safe drinking water and the U.S. Environmental Protection Agency’s safety thresholds for aquatic life.
“We’re not seeing any evidence for harm in the ecosystem or harm for human health,” said Noelle Held, a University of Southern California marine biogeochemist and principal investigator for the CLEAN Waters project, which is measuring post-fire water quality.
The Palisades and Eaton fires burned more than 40,000 acres and destroyed at least 12,000 buildings, blanketing the ocean in ash for up to 100 miles offshore. Heavy rains a few weeks later washed the charred remnants of plastics, batteries, cars, chemicals and other potentially toxic material into the sea and up onto beaches via the region’s massive network of storm drains and concrete-lined rivers.
Initial testing by the nonprofit environmental group Heal the Bay in the weeks after the fires documented a spike in lead, mercury and other heavy metals in coastal waters. Concentrations of beryllium, copper, chromium, nickel and lead in particular were significantly above established safety thresholds for marine life, prompting fears for the long-term health of fish, marine mammals and the marine food chain.
For their most recent study, Held’s team analyzed seawater samples collected along multiple locations on five different dates between Feb. 10 and Oct. 17 in 2025, along with sand collected in August.
Seawater lead concentrations were highest in the month after the fire and in October, when the season’s first major rain had just washed months’ worth of urban pollution into the ocean.
Even at their peak, lead levels 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.
While levels of iron, manganese and cobalt were higher in sampling locations near the Palisades burn scar than they were in other areas, even there they remain well below concentrations that could pose harm to human or marine life.
For beach sand collected in August, lead levels never topped 14 parts per million at any location, significantly below both the current California residential soil standard of 80 parts per million and 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 recent findings are consistent with water quality tests the State Water Resources Control Board conducted earlier in 2025. A board spokesperson said those found both higher relative concentrations of metals closest to the burn scars and no overall evidence that post-fire pollution poses an ongoing threat to human health.
Yet the need for continued testing remains. Officials struggled to answer questions about post-fire beach safety in part because of a lack of historical data on pollution levels, a pitfall researchers would like to forestall before another disaster arrives.
Future rainstorms could also continue to wash metals into Will Rogers Beach and the Rustic Creek outfall, both of which are near the Palisades burn scar, CLEAN Waters warned.
“Post-fire impacts can change over time, depending on rainfalls, runoffs and sediment movements,” said Eugenia Ermacora, manager of the nonprofit Surfrider Foundation’s L.A. chapter, which has partnered with Held’s team to collect samples. “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.”
