Causes For 12 Northern California Wildfires Released

Sacramento, CA – CAL Fire released reports detailing what started 12 Northern California wildfires in the October 2017 Fire Siege. Many were caused by power lines, conductors and failure of power poles. CAL Fire is providing information to the appropriate county District Attorney’s offices to review eight of the 12 fires – Sulphur, Blue, Norrbom, Partrick, Pythian, Adobe, Pocket and Atlas – due to evidence of alleged violations of state law.

The October 2017 Fire Siege in Napa, Lake, Sonoma, Mendocino, Butte and Solano counties involved more than 170 fires and burned over 245,000 acres in Northern California. About 11,000 firefighters from 17 states and Australia helped battle the blazes but over 6,200 homes were destroyed and 40 lives were lost.

Summary of the 12 completed investigations:

The Redwood Fire, in Mendocino County, started the evening of Oct. 8 and burned a total of 36,523 acres, destroying 543 structures. There were nine civilian fatalities and no injuries to firefighters. CAL Fire has determined the fire started in two locations and was caused by tree or parts of trees falling onto PG&E power lines.

The Sulphur Fire, in Lake County, started the evening of Oct. 8 and burned a total of 2,207 acres, destroying 162 structures. There were no injuries. CAL Fire investigators determined the fire was caused by the failure of a PG&E owned power pole, resulting in the power lines and equipment coming in contact with the ground.

The Cherokee Fire, in Butte County, started the evening of Oct. 8 and burned a total of 8,417 acres, destroying 6 structures. There were no injuries. CAL Fire investigators have determined the cause of the fire was a result of tree limbs coming into contact with PG&E power lines.

The 37 Fire, in Sonoma County, started the evening of Oct. 9 and burned a total of 1,660 acres, destroying 3 structures. There were no injuries. CAL Fire investigators have determined the cause of the fire was electrical and was associated with the PG&E distribution lines in the area.

The Blue Fire, in Humboldt County, started the afternoon of Oct. 8 and burned a total of 20 acres. There were no injuries. CAL Fire investigators have determined a PG&E power line conductor separated from a connector, causing the conductor to fall to the ground, starting the fire.

The Norrbom, Adobe, Partrick, Pythian and Nuns fires were part of a series of fires that merged in Sonoma and Napa counties. These fires started in the late-night hours of Oct. 8 and burned a combined total of 56,556 acres, destroying 1,355 structures. There were three civilian fatalities.

• The Norrbom Fire was caused by a tree falling and coming in contact with PG&E power lines.
• The Adobe Fire was caused by a eucalyptus tree falling into a PG&E powerline.
• The Partrick Fire was caused by an oak tree falling into PG&E powerlines.
• The Pythian Fire was caused by a downed powerline after PG&E attempted to re-energize the line.
• The Nuns Fire was caused by a broken top of a tree coming in contact with a power line.

The Pocket Fire, in Sonoma County, started the early morning hours of Oct. 9 and burned a total of 17,357 acres, destroying 6 structures. There were no injuries. CAL Fire has determined the fire was caused by the top of an oak tree breaking and coming into contact with PG&E power lines.

The Atlas Fire, in Napa County, started the evening of Oct. 8 and burned a total of 51,624 acres, destroying 783 structures. There were six civilian fatalities. CAL Fire investigators determined the fire started in two locations. At one location, it was determined a large limb broke from a tree and came into contact with a PG&E power line. At the second location, investigators determined a tree fell into the same line.

CAL Fire investigators continue to investigate the remaining 2017 fires, both in October and December. The cause of four other Northern California fires; La Porte, McCourtney, Lobo, and Honey fire, was detailed here.