A California Battery Plant Burned. Residents Have Gotten Sick, and Anxious.

The vast farmlands just off the coast of California’s Monterey Bay are usually quiet during the winter, when there are no crops to pick.

This winter, a different kind of stillness has taken hold. First, fears of immigration raids paralyzed the immigrant communities that make up the agricultural work force. And now, anxiety has spread over what some in the region believe is a sprawling and silent environmental disaster.

Last month, a battery-storage plant went up in flames and burned for days, prompting the evacuation of more than 1,000 residents and shutting down local schools. The plant, located in Moss Landing, an unincorporated community in Monterey County, is the largest facility in the world that uses lithium-ion batteries to store energy. Residents have reported feeling ill, and many of them worry that the fire polluted the air, soil and water with toxins.

“Now you don’t see anybody walking outside because it’s terrifying, everything that’s going on,” said Esmeralda Ortiz, who had to evacuate from her home in Moss Landing after the plant began burning on Jan. 16.

She noticed an odd metallic odor as she and her two young children fled. She said she later took her children to the doctor after they complained of headaches and sore throats, symptoms she also had. Eventually, her children felt better, but Ms. Ortiz said she worries about the potential long-term health effects and whether the strawberry fields where she and her husband plan to work during the harvest have been contaminated.

No homes were damaged in the fire, which unfolded more than 300 miles north of the devastating Palisades and Eaton fires in the Los Angeles area. For weeks, residents, officials, researchers and environmental and public-health experts have been trying to understand the scale of damage, but so far there have been few answers. What was unleashed by the plumes of smoke from thousands of burning lithium-ion batteries? And where did it go?

“A lot of people are concerned about the ingestion of heavy metals,” said Brian Roeder, who moved his family into a rental home for the next month after they felt ill at their home in Prunedale, about eight miles southeast of the fire.

“Most people can’t do that,” Mr. Roeder, 62, said of temporarily relocating. “But we have a 7-year-old and we’re like, ‘We got to get him out of here.’”

Vistra, the Texas-based energy company that operates the plant, said there were approximately 100,000 lithium ion battery modules inside the storage facility and that most of them had burned. The company said an exact accounting had yet to be done, because crews were still prohibited from entering the facility to do a visual inspection.

Tests conducted by a state agency, the Department of Toxic Substances Control, detected cobalt, nickel, copper and manganese — heavy metals found in lithium ion batteries — at wide-ranging levels in soil sampled at eight sites near the plant and up to roughly five miles away from it. Officials said the data was preliminary and still needed to be thoroughly analyzed. Tests of the local drinking water found the presence of the metals but at safe levels. Air quality monitoring has not detected heavy metal particles or hydrogen fluoride, a gas associated with the batteries, county officials said.

In a separate study, researchers at San Jose State University’s Moss Landing Marine Laboratories in the Elkhorn Slough Reserve, an estuary next to the battery facility, found that the levels of cobalt, nickel and manganese had significantly increased in topsoil samples in the area compared to levels from studies conducted before the fire.

The results of soil testing by the state agency and the university lab were cited in a lawsuit filed on behalf of four residents by a legal team that includes the environmental activist Erin Brockovich.

The suit alleged that the amount of cobalt, manganese, nickel and copper in the preliminary state data exceeded federal Environmental Protection Agency risk levels for residential soil, including for children. The lawsuit claimed the facility’s fire-suppression system was deficient. It was filed against Vistra as well as other defendants, including the state’s largest utility company, Pacific Gas & Electric, which operates another energy storage facility at the Moss Landing plant.

Vistra declined to comment on the lawsuit. The company said in a statement that it was working closely with local officials and community partners. “We have and will continue to do everything we can to do right by our community and are working in concert with federal, state and local agencies to ensure public health and safety,” Vistra’s statement read.

PG&E said it was reviewing the complaint.

Mr. Roeder has helped lead residents in collecting more than 100 of their own soil samples for testing. The preliminary results detected varying concentrations of lithium, cobalt, nickel or manganese as far as 46 miles away.

Haakon Faste, 47, who lives in Ben Lomond, a mountain community roughly 25 miles northwest of the plant, recalled a metallic taste in the air in the days after the fire broke out on Jan. 16. He and his wife experienced a number of symptoms: sore throat, headaches, bloody noses.

“It feels like you’re breathing — I don’t know if it’s like breathing acid or it’s like the air is so incredibly dry that it burns deep down into your lungs, so it hurts to swallow,” Mr. Faste said.

The couple evacuated and moved to a short-term rental. Trips to urgent care have yielded few answers about what may have sickened them.

People who inhale high concentrations of heavy metals experience profound health effects, said Dr. Justin Colacino, an associate professor of environmental health science at the University of Michigan School of Public Health. Throat irritation, lung inflammation and difficulty breathing can occur with heavy-metal inhalation, and manganese can have neurological effects if inhaled at high levels.

“If people in the community are reporting these, that would be consistent with what we know from folks that breathe in metals like this in an occupational setting where the levels tend to be high,” Dr. Colacino said.

Even without a full understanding of the environmental and health effects, the fire has raised questions about the safety of energy storage technology that California is relying on to meet its ambitious timeline for a clean-energy future. The Moss Landing Power Plant has stood tall over the region since 1950, generating gas-powered electricity for the state’s grid. Vistra’s lithium-ion battery facility went online at the site in 2020, in an expansion approved by the California Public Utilities Commission.

Facilities like the one in Moss Landing store excess energy collected during the day and release it as electricity into the grid at night. Presented as a step toward a carbon-free future, the expansion received little attention or resistance from the public or from interest groups, said Glenn Church, a county supervisor who represents northern Monterey County.

“We are right now in a place where government does not have the knowledge to regulate this technology and industry does not have the know-how to control it,” Mr. Church said.

When a lithium-ion battery catches fire, industry best practice is to let it burn. Dousing it with water is ineffective and can cause a chemical reaction.

“I know of no other industry that does that,” Mr. Church said of letting the material burn.

He is pushing to keep the facility off line until there is a full accounting of the cause of the fire and its fallout. In addition, Dawn Addis, the state assembly member who represents the central coast, has introduced a bill to require local input in the permitting process and new regulations for new energy storage facilities. And the utilities commission has proposed the implementation of new safety rules.

The depositing of heavy metals onto soil carries added implications for a region known for growing strawberries and other produce, and for the workers who pick the fruit.

At a forum on immigrant rights hosted by the local school district in nearby Castroville in late January, many hands shot up when the presenter asked how many farmworkers were in the room.

“People are in a such big moment of stress that they say it’s one thing and another,” Maria Tarelo, who works packing berries, said of the fears of federal raids and the battery plant fire.

Ms. Tarelo has advised her fellow workers to take precautions by wearing masks and gloves, as they face the potential of working land that could turn out to be hazardous to their health. For many men and women who labor in the fields, the pressing concern is that contaminated crops could result in less work.

“Then we don’t have anything to pay for food or rent,” Ms. Tarelo said. “Sometimes, no matter the state of the environment, we have to go work.”