Cause of Flat Fire still undetermined as containment efforts continue

PORTLAND, Ore. (KOIN) — With warm, dry and windy conditions expected later this week, firefighters in Central Oregon are working around the clock to contain the most recent wildfire to sweep through the region.

The Flat Fire has now burned an estimated 21,971 acres just two miles from the town of Sisters, Oregon, and is 7% contained. It has spread across Deschutes and Jefferson counties since it sparked on Aug. 21.

Despite some reports on social media and in other news outlets, the cause of the fire has not been determined.

“The fire is still under investigation and no cause has been determined,” Oregon State Fire Marshal Gert Zoutendijk told KOIN 6 News.

Wildland fires are categorized into three groups: lightning-caused, human-caused, and undetermined, Zoutendijk said. Even if a fire is classified as human-caused, it doesn’t necessarily mean a human started it. Faulty electrical equipment, for example, would be considered a human cause where a human didn’t actually start the fire.

The Jefferson County Sheriff’s Office also said no cause has been determined, but was able to confirm the fire started on private land.

The Flat Fire was first reported on Aug. 21, about three miles west of Lake Billy Chinook. The Emergency Conflagration Act was invoked on Aug. 22 to send more resources to battle the blaze. Still, the fire exploded in size over the weekend.

Four homes have been lost so far, officials said during an Aug. 25 community meeting at Sisters High School. More than 2,700 homes remain threatened, and more than 4,000 are still under some level of evacuation.

“This isn’t over just because of one day of good weather,” said Oregon State Fire Marshal Incident Commander Ian Yocum.

“We have critical fire weather coming this week, and we still have a lot of work to do around this fire,” he said.