Smoke is visible from a fire at a Moss Landing battery facility about 9:45 a.m. Friday from Merritt Street near Castroville. (Nik Altenberg — Santa Cruz Local)

Jump to:

• Air quality info
• How the fire started
• Health risks
• Pajaro Valley schools response
• Battery storage in California
• Evacuations and alerts in Santa Cruz County

A fire at a Vistra Corp. lithium battery facility broke out about 3 p.m. Thursday near Highway 1 and Dolan Road in Moss Landing. It was nearly fully extinguished by 10 a.m. Friday, but kicked up again around 12:30 p.m. for about an hour and remained smoldering at 3:45 p.m., firefighters and county officials said.

Firefighters said they could not use water to douse the flames because of the batteries’ composition. There were no injuries.

Santa Cruz County health officials said there was “no immediate threat” from smoke Friday morning. “Moderate” air quality is expected Friday and Saturday, according to the Monterey Bay Air Resources District. Hydrogen fluoride is a hazardous gas that can be emitted by a lithium battery fire, and none of the Vistra’s air monitors had detected the gas, officials said Friday morning. The pollutants are expected to break down within hours or days, experts said.

Teachers at Ohlone Elementary School in Royal Oaks reported “fumes” in the air Friday. “A lot of the kids are complaining that it smells really bad, and some students are starting to feel really sick,” said Janette Martinez, a second-grade teacher at Ohlone Elementary in Royal Oaks. “A lot of staff members were starting to get headaches and itchy eyes.” 

Santa Cruz County air quality information

Wind pushed smoke toward Prunedale Friday afternoon, said National Weather Service Meteorologist Rachel Kennedy. Friday night, light winds are expected to keep smoke close to Moss Landing, before they push smoke towards Monterey Bay tomorrow. Windy conditions are expected to pick up on Monday, but it’s uncertain in which direction winds will blow, Kennedy said.

“Sensitive groups, including those with respiratory difficulties, should continue monitoring local air conditions,” wrote Corinne Hyland, a spokesperson for Santa Cruz County Public Health, in a statement. 

“Sensitive populations and people who live closest to the fire should avoid outdoor activity, wear an N95 respirator or surgical mask, and seek medical help if respiratory symptoms worsen,” Hyland wrote. She described sensitive groups as “young children, older adults, pregnant people and people with respiratory conditions such as asthma or chronic obstructive pulmonary disease.”

“Residents who live closest to the fire should limit outdoor exposure, keep windows and doors closed, and adjust central air systems to recirculate indoor air or close outdoor air intakes to avoid drawing in smoky outdoor air,” Hyland wrote. 

• Air quality maps and forecasts can be found on the Monterey Bay Air Resources District website. 
• The free, nonprofit WatchDuty cellphone app for Apple and Android devices includes wind speed and direction maps overlaid with air quality and fire boundaries. 
• The Smoke Spotter app from the California Air Resources Board has maps of prescribed burns and smoke forecasts. 
• A National Weather Service map includes areas with fire weather warnings.

A Monterey Bay Air Resources Board map shows “moderate” air quality in yellow and “good” air quality in green as of 2 p.m. Friday. (Monterey Bay Air Resources Board)

A Watch Duty map shows air quality and wind velocity near the Moss Landing fire site on Friday morning. (Watch Duty)

How the fire started

Monterey County firefighters said the cause of the fire at the battery facility remained under investigation Friday morning.

At the same property in 2021, several batteries began overheating after the facility’s fire-suppression system was activated. Some of the pipes leaked and sprayed water on the battery racks, according to an internal investigation of the incident. Water can cause lithium batteries to overheat.

Brad Watson, a representative of the Irving, Texas-based-Vistra, said Friday that the company followed all regulations and had improved the system after the 2021 incident. 

The fire-suppression system “was water based and part of what we will be doing is studying and investigating why that didn’t work as designed. And that will be one of the many, many questions we will be going through to find out what happened here,” Watson said.

Mendoza, the fire division chief, said the firefighters who first arrived saw smoke coming from the building and at least one battery on fire. The fire-suppression system “was not sufficient, it was overridden and that led to fire overtaking the system and eventually overtaking the entire building,” Mendoza said.

Joel Mendoza, division chief of North County Fire Protection District of Monterey County, speaks at a news conference Friday morning in Castroville. (Nik Altenberg – Santa Cruz Local)

Health risks

Smoke from battery fires can include hydrogen, carbon monoxide and hydrogen fluoride, all of which can pose serious health hazards, experts said.

“The smoke is extremely toxic in battery fires,” said Dustin Mulvaney, a professor of environmental studies at San José State University. The pollutants are relatively short-lived, and will break down within hours or days, he said.

A potential long-term concern is the spread of heavy metals and PFAS, or “forever chemicals” from the smoke. More testing will be required to see if those could bring environmental or human health risks, he said.

Pajaro Valley school response

All Pajaro Valley Unified School District schools were open Friday but instructed staff to keep students inside and close windows and doors. After-school programs were canceled due to concerns about the smoke, said PVUSD Public Information Officer Alicia Jiménez.

Even though officials have said the air near the school is not toxic, “just considering the close proximity that our school site is to this power plant, that people still have to report to school, and parents still had to report their kids to school because then they would get an absence — it was crazy,” said Martinez, the Ohlone Elementary teacher.

“We’ll continue to go with what the county of Monterey says for our schools in that area and to ensure the safety of our students and staff and our families,” Jiménez said.

Battery storage in California

Moss Landing Power Plant used to be one of largest natural gas power plants in the state. Its natural gas systems have since been downsized, and the plant now hosts the largest battery storage facility in California.

“This particular battery system has one of the more energy-dense batteries,” Mulvaney said. “That means that there’s more energy packed into it, which also means it’s more susceptible to fires.”

“My first reaction is that it’s probably something that is less about negligence and more about just our learning curve of safety,” Mulvaney said. Batteries of this size “are not simple machines, and we don’t know all the ways they catch on fire.”

Battery storage is central to California’s strategy to reduce reliance on fossil fuels. Storage facilities allow renewable energy to be transported across the state and stored. But the Moss Landing fire could raise questions about how big those battery storage facilities should be, Mulvaney said.

Once started, battery fires are tough to extinguish — water just adds to the volatile chemical reactions and risks explosion, Mulvaney and firefighters said.

Evacuations and alerts in Santa Cruz County

• Identify your home and workplace’s geographical zone in Santa Cruz County and get details on current evacuation orders at protect.genasys.com/search.
• Register with Santa Cruz County’s emergency notification system CruzAware to receive texts, emails or calls about emergencies and evacuations.

• The Cal Fire incident report website has updates on fires and evacuations.
• Police in Santa Cruz, Capitola, Watsonville and Scotts Valley and some fire departments send Nixle text alerts to registrants during emergencies.
• UC Santa Cruz students, faculty and staff can receive emergency alerts from campus officials in its SlugSafe system.

Clarification: This story has been updated to clarify Dustin Mulvaney’s views on the battery fire.

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