Sacramento – After extensive and thorough investigations, CAL FIRE investigators have determined that 12 Northern California wildfires in the October 2017 Fire Siege were caused by electric power and distribution lines, conductors and the failure of power poles.
 
The October 2017 Fire Siege involved more than 170 fires and burned at least 245,000 acres in Northern California. About 11,000 firefighters from 17 states and Australia helped battle the blazes.
 
CAL FIRE investigators were dispatched to the fires last year and immediately began working to determine their origin and cause. CAL FIRE investigators continue to investigate the remaining 2017 fires, both in October and December and will release additional reports as they are completed. The cause of four Northern California fires were released on May 25.
 
Below is a summary of the findings from 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 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. 8and burned a combined total of 56,556 acres, destroying 1,355 structures. There were three civilian fatalities.
 
CAL FIRE investigators determined the Norrbom Fire was caused by a tree      
          falling and coming in contact with PG&E power lines.
 
          CAL FIRE investigators determined the Adobe Fire was caused by a eucalyptus           tree falling into a PG&E powerline.
 
 
          CAL FIRE investigators determined the Pythian Fire was caused by a downed   
          powerline after PG&E attempted to re-energize the line.
 
          CAL FIRE investigators determined 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’s investigations have been referred to the appropriate county District Attorney’s offices for review in eight of the 12 fires – Sulphur, Blue, Norrbom, Partrick, Pythian, Adobe, Pocket and Atlas – due to evidence of alleged violations of state law.
 
Californians are encouraged to remain vigilant and prepared for wildfire. For more information on how to be prepared, visit www.readyforwildfire.org or www.fire.ca.gov