Sep. 9—Pacific Gas and Electric Co. said Thursday that the U.S. Forest Service has placed caution tape around the base of one of its transmission poles in the area where the Mosquito Fire started, as part of an investigation into the fire's origin.
In an incident report to the California Public Utilities Commission, PG&E said that it "has observed no damage or abnormal conditions to the pole or our facilities ... has not observed down conductor in the area or any vegetation related issues. Our information reflects electrical activity occurred close in time to the report time of the fire."
The company said the investigation is ongoing.
Fire officials have said the origin of the fire, which began Tuesday evening near OxBow Reservoir east of Forest Hill in Placer County, is under investigation. The fire exploded to 6,870 acres Wednesday with no containment as of Thursday morning, and continued to grow, threatening several small communities and critical infrastructure in the steep, dry forested hills of Tahoe National Forest. State mapping data put the fire at 13,700 acres as of 6 p.m.
Gov. Gavin Newsom called a state of emergency for the fire and the Fairview Fire in Southern California, which together have forced tens of thousands of people from their homes.
The developments in the Mosquito Fire came as California's record-breaking heat wave kept the state on edge another day Thursday. A massive pyrocumulus cloud above the fire continued growing, wildfire smoke began to affect air quality across a large area and officials pleaded with residents to conserve power yet again.
Residents of several communities in Placer County were ordered to evacuate, including Michigan Bluff and parts of Foresthill, with the Georgetown area under evacuation warning.
On Thursday afternoon, hot, dry conditions pushed the Mosquito Fire into El Dorado County, with officials there saying it was moving quickly toward Volcanoville.
About 1,000 structures in Placer County were in jeopardy — including dams, transmission lines, a hydroelectric powerhouse and cellular and microwave transmission towers, according to a statement from Cal Fire. Community drinking water supplies were endangered, Cal Fire said.
Smoke from the Mosquito Fire was expected to push eastward Thursday night and into the interior portion of the state with the Sierra Nevada foothills being most affected, Sacramento-based National Weather Service meteorologist Sierra Littlefield told The Chronicle.
"In the overnight hours starting around midnight, we'll start to see smoke settle into areas in the Sierra and then slowly make its way down drainage valleys into the foothills and eastern portions of the Central Valley in the Sacramento region," Littlefield said.
A Flex Alert was issued by the California ISO for 3 p.m. Thursday — an hour earlier than other alerts during the heat wave — because it was unclear how the smoke would affect renewable energy sources such as solar, the grid operator's chief operating officer Mark Rothleder said.
Joel Umanzor (he/him) is a San Francisco Chronicle staff writer. Email: firstname.lastname@example.org
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