Firefighters Report Steady Gains Against Mosquito Fire, Now State's Largest Blaze of the Year

Firefighters reported major progress on Thursday against the Mosquito Fire, preventing fast-moving flames from entering a small Sierra foothill community west of Tahoe, even as the blaze surged to become the state's largest of the year.

Conditions were “looking a whole heck of a lot better,” Cal Fire spokesperson Scott McLean said of the eight-day-old conflagration that has grown to more than 64,000 acres, with some 11,500 residents in Placer and El Dorado counties under evacuation orders. The fire is now 20% contained.

Nearly 6,000 structures in the area are threatened with more than 45 homes and other buildings destroyed so far.

Crews on the ground continued to build up containment lines around the south and east sides of the fire while water-dropping helicopters knocked down hot spots after the fire roared back to life on Tuesday, burning structures near the small town of Foresthill.

According to a report from Cal Fire, today’s priorities remain securing each of the three corners of the fire. Southwest winds have been favorable for the communities along Volcanoville Road, but firefighters remain in the area to ensure the fire does not spot across containment lines.

Stronger winds have been predicted for this weekend ahead of an incoming system that is expected to include some rainfall, Cal Fire officials said.

"We had three burn operations going last night on the fire," Cal Fire Operations Section Chief Don Fregulia said on Thursday morning. "We did some defensive firing along the Deadwood Road to really build the corner. We know that the North Fork of the American River is a high-value asset that has not seen a fire in a very long time. So, we really want to keep it from going to the north along with the Interstate 80 corridor."

Fregulia said firefighters at Foresthill tried to contain the fire all the way to a nearby river, but conditions weren't favorable, so they held off and hoped to complete the operation today. In the southeast, firefighters were able to bring the fire to Wentworth Springs Road near Stumpy Meadows Reservoir with no concerns or holding issues.

Firefighters prepared to actively engage in structure defense along the edges of these communities should the fire make similar runs as on Tuesday, Cal Fire said. The area is full of extremely dry fuels that were rapidly igniting, challenging both firefighters on the ground and in the air.

Jonathan Pangborn, fire behavior analyst with Cal Fire, said the weather continues to present challenges.

"We still have the winds out of the southwest pushing to the northeast," he said. "They're not dramatically strong, but they're strong enough to give clear air. What that means is that it's going to continue to have potential for progression out in this northeastern portion of the area of the fire."

Similar conditions are expected over the next few days, which could lead to more spotting, Pangborn said, referring to small blazes outside that main fire perimeter that are sparked by windblown embers.

The Mosquito Fire is one of several large fires currently burning across the state. Climate change has made the West warmer and drier over the last three decades and will continue to make weather more extreme and wildfires more frequent and destructive. In the last five years, California has experienced the largest and most destructive fires in its history.

This story includes reporting from The Associated Press and KQED's Spencer Whitney and Attila Pelit.