The fire in Butte County destroyed almost 15,000 homes and almost wiped out the town of Paradise, population 27,000, in the Sierra Nevada footballs.
The disclosure came on the same day the utility's new chief executive was testifying before a legislative committee in Sacramento.
An investigation into the cause of the fire began nearly immediately, with suspicion soon falling on power equipment operated by Pacific Gas and Electric (PG&E).
A Cal Fire spokeswoman said the investigators' report had been furnished to the Butte County District Attorney's Office for further review.
Named after Camp Creek Road near the first ignition point, the Camp Fire caused at least 85 civilian fatalities and several injuries to firefighters and residents.
When the fire began at those Pulga power lines, fire driven by strong winds quickly spread through dry grass and brush under "Red Flag" conditions.
Shares of San Francisco-based PG&E initially fell 3.1 percent in after-hours trading following release of the California Department of Forestry and Fire Protection (Cal Fire) statement announcing findings of its investigation of the blaze. Authorities said it was like no fire they had seen before.
Paradise sued PG&E in January seeking damages for the loss of infrastructure, land, property, trees, public and natural resources, and lost taxpayer resources. The cause of the second fire was determined to be vegetation into electrical distribution lines owned and operated by PG&E.
PG&E's bankruptcy reorganization plan is due by the end of May, but it has requested an extension until November.
California Gov. Gavin Newsom said in a Wednesday filing that PG&E shouldn't get an extra six months to reorganize.
The nation's largest utility filed for Chapter 11 bankruptcy in January as it faced tens of billions of dollars in potential liability costs related to wildfires in 2017 and 2018, according to The Associated Press.