A major fire in January at one of the world’s largest battery storage plants in Moss Landing showered 55,000 pounds of toxic metals across the landscape within a mile of the plant, a new scientific study has found.

Researchers from Moss Landing Marine Laboratories measured more than 100 locations at Elkhorn Slough, an expanse of sensitive marshes just north of the plant, and found high levels of nickel, cobalt and manganese on the top of the soil — all metals contained in the thousands of lithium-ion batteries that burned and which were spread in microscopic pieces through the billowing smoke that poured from the fire.

“It was like a dust,” said Ivano Aiello, a marine geology professor at Moss Landing Marine Labs who led the soils testing. “That’s what it was. A metal dust. It was like sugar dusting on a cake.”

The research, published Wednesday in the journal Scientific Reports, is the first independent study of the fire’s impacts published in a scientific journal.

“Metals came from the fire,” Aiello said. “There’s no doubt about that. They traveled. They are tiny. The smoke can travel really far. They can go everywhere, including your lungs. People who were breathing that air were breathing the air with metals.”

The dramatic fire at the 750-megawatt battery plant began on Jan. 16 and burned for two days. It caused the evacuation of 1,200 local residents and the closure of Highway 1 for three days. The flames quickly overwhelmed the fire sprinkler system at the plant, which is owned by Vistra Energy, a Dallas-based company, and located on the former site of a PG&E power plant that was build in the 1950s.

The fire raised major questions across California and the nation about the safety of battery storage plants. California has been approving hundreds of new storage plants each year since 2020 because they are key to expanding the state’s renewable electricity supply by storing solar power in the daytime and releasing it on the power grid at night. But the blaze exposed that battery storage plants can present a significant fire risk, and has prompted opposition in some communities where other plants are being proposed, most recently in Vacaville and Watsonville.

Since the fire, the U.S. Environmental Protection Agency has led cleanup efforts. Truckloads of the burned batteries continue to be removed from the wreckage and taken to a recycling plant in Nevada. That work is expected to continue for months. An investigation by the EPA and the California Public Utilities Commission into the fire’s cause continues.

The impact on humans and wildlife from the fire remains unclear.

The smoke spread over Monterey, Santa Cruz, San Benito and southern Santa Clara counties. EPA officials announced two days after the fire that monitors showed the air again in the area met federal health standards. Hundreds of local residents complained of respiratory problems and headaches after the fire. Multiple lawsuits have been filed against Vistra.

Researchers from Moss Landing Labs, which is affiliated with San Jose State University, along with the Monterey Bay Aquarium, Cal State University Monterey Bay and other institutions, have conducted early studies on clams and crustaceans in Elkhorn Slough, but say it is too early to tell how much of the material was ingested by animals at the bottom of the food chain and might migrate into birds, fish, sea otters and other wildlife that eat them.

Aiello estimated that altogether, roughly 2.2 million to 3 million pounds of burned battery material could have been carried into the smoke plume and spread over the wider area of farms, neighborhoods and the ocean.

“What we found in the marsh represents about 2% of what may have been released,” he said.

One key fact the scientists found: Elkhorn Slough quickly began to clean itself after the disaster.

Scientists compared soil samples they took in the marshes in 2023 before the fire with samples they took two weeks after the fire. They found the maximum concentrations of nickel in the soil increased 15-fold, from 246 parts per million in 2023 to 3,702 parts per million.

But a month after the fire, following rain storms and tides, the maximum concentration of nickel had fallen back to 339 parts per million. Similar trends were seen in manganese and cobalt. Much of the material is believed to have washed into Monterey Bay, where it would have eventually sunk.

“In some places the levels are still high,” Aiello said. “It’s not completely gone, but the majority of the sites show a return to almost baseline levels.”

Officials at Vistra said they are reading the study, and that company scientists are working with officials from Monterey County and other agencies to take their own water and sediment samples for a report that is expected out next year.

“The safety of our employees, the environment, and the surrounding community remains our top priority,” said Vistra spokeswoman Meranda Cohn. “We will continue to work closely with local officials and community partners in the Moss Landing community.”

Cohn noted that the state Department of Toxic Substances Control took 108 soil samples in May and June at 27 locations around the plant and nearby areas and concluded “widespread contamination above health-screening levels was not observed.”

Scott Murtishaw, executive director of the California Energy Storage Alliance, an industry group, said new plants are much safer than Moss Landing because the lithium-ion batteries are not clustered in one large building, but are located instead in dozens of containers outside, making the spread of fire much less likely.

“The largest fire I am aware of at a container-based facility was less than 2% of the size of the Moss Landing fire,” he said. “So we should never see that level of emissions from future incidents.”

Assemblywoman Dawn Addis, D-San Luis Obispo, said people living near the facilities remain concerned. A bill Addis introduced this spring in Sacramento to prohibit new battery storage plants near schools, homes, parks and businesses died after opposition from labor unions and the energy industry.

“The study confirms people’s worst fears unfortunately,” Addis said of the new research. “We need battery storage. It’s important. But it’s important local communities are safe. And we need to be vigilant.”

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