California has been plagued by wildfires for years. How often is arson the cause?

San Bernardino County authorities announced this week that a 34-year-old man was arrested and accused of starting the Line Fire that burned over 37,000 acres of land in San Bernardino County.

How often is arson responsible for wildfires in California?

What do the numbers show?

Gianni Muschetto, chief of staff of Cal Fire, said about 10 to 15 percent of wildfires over the past five years were caused by arson.

Citing published data from 2022, he said there have been 358 arsons in the state this year, burning about 12,000 acres, and each time putting firefighters and citizens at risk.

“This is not an accident and it is not a lightning strike. It is a reckless or malicious act,” Muschetto told LAist.

He mentioned the Park Fire, which fire officials say was started in July by a man accused of pushing a burning car into a ravine near Chico. It is reportedly the fourth-largest wildfire in state history.

The fire destroyed nearly 430,000 acres of land in Butte and Tehama counties.

“None of us will live to see these forests return to what they once were,” Muschetto said.

What are the most common causes of forest fires?

Wildfires can be started by natural causes such as lightning strikes, but they are more often caused by humans. According to the National Park Service, nearly 85% of wildfires in the United States are caused by human activity.

Firefighters often point out that people can inadvertently ignite dry brush by not building campfires, having machinery running (such as a broken lawn mower), or discarding lit cigarettes.

Sometimes, however, it is not an accident but arson.

In 2022 and 2021, Cal Fire identified arson as the cause of more than 350 fires per year, according to the department's most recent released data. Arson was the cause more often than campfires, playing with fire, electricity, lightning and smoking.

But it was less than some other causes, like burning debris. In one of those years, 2021, there were more vehicle-caused fires — 419 — than arson.

Cal Fire authorities had more recent data on arrests related to arson. These arrests almost doubled last year compared to five years before. Last year, there were 111 arrests on suspicion of arson in Cal Fire areas. In 2018, there were 61.

During that five-year period, the most arrests related to arson occurred in 2022, when there were 162, according to Cal Fire.

Muschetto attributed the higher numbers in part to video evidence recorded on cell phones and surveillance cameras in private homes.

“This will enable us to identify the cause of the fire much better than before,” he said.

How can a suspected arson be reported?

The public can call Cal Fire Hotline if you suspect arson. The phone number is 800-468-4408.

Callers can remain anonymous.

What arrests have been made for arson?

Line fire — Justin Wayne Halstenberg, a 34-year-old contract contractor from Norco, was arrested Tuesday on suspicion of setting the fire that burned thousands of acres in LA and San Bernardino counties.

San Bernardino County Sheriff Shannon Dicus said Halstenberg is suspected of intentionally setting the fire and investigators are looking into the possibility that he is responsible for other fires. The sheriff said automatic license plate readers picked up the license plate of a vehicle linked to Halstenberg near where the Line Fire started.

Dicus declined to provide details on how the fire was started, pointing out that the investigation is still in its early stages.

Halstenberg is expected to appear in court on Friday.

Park fire — Ronnie Dean Stout II, 42, was arrested on suspicion of arson in connection with the massive fire that broke out near Chico.

Cal Fire said a man they identified as Stout was seen pushing an already burning car into a ravine in an area called Alligator Hole. The car plunged 65 feet down an embankment, spreading flames that eventually burned more than 400,000 acres of land and destroyed more than 700 structures.

According to The Sacramento Bee, Stout pleaded not guilty and denied pushing the car down the hill – he said it rolled over.

Fire in El Dorado — A San Bernardino couple who set off pyrotechnics during a gender reveal party in 2020 and accidentally ignited the fire that led to the 22,000-acre El Dorado fire were convicted in February.

The fire killed one US Forest Service firefighter and injured several others. Five homes were destroyed.

Refugio Manuel Jimenez Jr. pleaded guilty to manslaughter and was sentenced to one year in prison and two years' probation. He was also sentenced to community service, according to the LA Times.

Angelina Jimenez pleaded guilty to three counts of negligently causing a fire on another's property and was sentenced to one year of probation. She was also sentenced to community service.

Where can I find resources about wildfires?

For more wildfire coverage, visit our LAist newsroom.