Pacific Gas & Electric Co. power lines that came into contact with trees caused four Northern California wildfires that burned more than 14 square miles last fall and incinerated 134 buildings, state fire officials said Friday.
The California Department of Forestry and Fire Protection indicated that three of the fires might have been prevented if PG&E had made a greater effort to keep trees clear of its power lines.
Cal Fire said it is turning those findings over to prosecutors in Nevada and Butte counties, where the blazes occurred.
PG&E said it is reviewing the agency's conclusions, adding that safety remains its paramount goal.
"Based on the information we have so far, we believe our overall programs met our state's high standards," the utility said in a statement.
PG&E said it inspects and monitors every overhead electric transmission and distribution line at least once a year under its Vegetation Management Program.
No one was killed or injured by the four fires the agency addressed Friday.
The blazes, in largely rural areas, were among more than 170 that broke out across California in October, consuming more than 380 square miles of forest, farmland and vineyards. Some of those fires were deadly.
Devastating damage occurred in Northern California's wine country, where dozens of lawsuits seeking tens of millions of dollars have been filed against PG&E.
Cal Fire said it is continuing to investigate the other fires and will release its findings as they become available.
The La Porte fire in Butte County covered 13 square miles and destroyed 74 structures. It was blamed on tree branches falling onto power lines, but investigators concluded that there were no violations of state law and that PG&E was not to blame in the blaze.
But the Honey fire, also in Butte County, was caused by inadequate clearance of tree branches near PG&E power lines, the agency concluded.
In Nevada County, which encompasses California's Sierra Nevada gold country, two fires burned across a mile and a half, destroying 60 structures.