Yosemite wildfire update: Fire containment shrinks, but hope grows to save giant sequoias

Warm overnight temperatures did little to help firefighters working to contain the Washburn Fire in Yosemite National Park, which grew to more than 3,200 acres by Tuesday morning – an increase of almost 900 acres, or 40%, from 24 hours earlier.

But fire crews expressed confidence on Monday night that they would save Mariposa Grove, an iconic stand of hundreds of mature giant sequoia trees, some of which are thousands of years old, near the southern entrance to the park.

About 650 personnel from the National Park Service and other firefighting agencies are now engaged in trying to gain containment of the fire. Tuesday morning’s report from the National Interagency Fire Center indicates that containment is now estimated at about 22% – meaning that containment lines have been carved out around 22% of the fire’s perimeter.

That’s a slight decrease from the 25% containment reported Monday afternoon.

“The fire was active last night and with the current warming trend, increased fire activity is expected for today as well,” according to Tuesday morning’s situation report.

Matt Ahearn, deputy operations chief with the state interagency team that is managing the firefighting effort, said Monday was marked with more than a dozen small spot fires that cropped up west of Highway 41, the largest of which was about a half acre in size. All of those, he said, were quickly knocked down by fire crews.

Crews were employing backfires on Monday to create low-intensity burns and guide the fire westward from Mariposa Grove toward Wawona Road. Tuesday’s plans called for using drone aircraft to monitor for more spot fires along the western edge of the fire. “That’s a priority today, to hold the fire east of 41,” Ahearn said.

At the northwest edge of the fire, Ahearn reported that flames had progressed to the Studhorse Trail near Wawona. By early Tuesday, he added, firefighters were able to nudge the fire’s progress to the south fork of the Merced River and bolster control lines around Wawona.

“We still have structure defense in place (in Wawona); we’re going to keep that in place while we have fire backing off and burning out along the lines,” Ahearn said.

In Mariposa Grove, in addition to crews working to build protective lines, a temporary sprinkler system was set up to help protect the giant sequoias. The sprinklers increase the humidity in the grove.

That system, along with previous prescribed burns and other projects to reduce the volume of fuel and debris on the ground within the grove, are helping to reduce the danger to the massive trees.

The Mariposa Grove remains closed until further notice, and the community of Wawona remains under an evacuation order. Wawona Road (Highway 41) is closed from the park’s south entrance near Fish Camp to Henness Ridge Road.

At the northern end of the fire, flames have burned down a slope to the Merced River’s south fork, and a few spit fires had cropped up north of the river.

Hotshot crews were quickly sent hiking into those areas to throttle those outbreaks. “We still have a major priority of holding fire in the south fork and will be checking that throughout the day,” Ahearn said.

The area where the fire is burning does not offer many natural barriers that help firefighters gain ground for containment, such as bare rock outcroppings. That is requiring hand crews and bulldozers to carve out containment lines within the forest and prepare for potential spread of the fire.

The northeastern edge, where containment lines have not yet been built, has already crossed over beyond the park boundary into Madera County and the Sierra National Forest. That appears to represent the greatest opportunity for flames to spread.

Ahearn said contingency crews have been deployed to the Long Meadow area “where we are wrapping the Biledo Cabin system this morning and connecting contingency lines and coming up with a backup plan” if the fire continues to expand.

Hotshot crews are also being sent to the Star Mine area south of the Merced River’s south fork. “They’re going to be looking out past Mount Raymond and figuring out a plan to bring containment lines back down to the South Fork of the Merced,” Ahearn added.