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Wildfire continues to threaten ancient sequoias in Yosemite National Park

4-foot sprinklers are helping, the U. S. Forest Service says, but high temperatures are keeping Mariposa Grove and the Wawona-area trails closed.

A Northern California wildfire continued its destructive march Monday toward a grove of ancient sequoia trees in Yosemite National Park as the Washburn Fire grew to more than 2,300 acres.

Using a 4-foot-tall sprinkler system to ward off damaging flames and maintain much-needed moisture in the air, firefighters worked to create a perimeter around about 500 mature sequoias in the park's Mariposa Grove.

The Washburn Fire, on the western flank of the Sierra Nevada, was 25% contained by Monday evening. Nearby Wawona remained under threat as high temperatures scorched the region.

There have been no reports of severe damage to any named trees, including the 3,000-year-old Grizzly Giant.

“Right now the sprinklers are doing a lot of good,” U.S. Forest Service spokesman Stanley Bercovitz said. 

Image:
A firefighter protects a sequoia Friday as the Washburn Fire burns in Mariposa Grove of Giant Sequoias in Yosemite National Park, Calif.Noah Berger / AP

Asked whether firefighters had made protecting certain trees a priority, Bercovitz simply said: “That’s like asking who’s your favorite child.”

Mariposa Grove and Yosemite Valley have been protected since President Abraham Lincoln signed legislation in 1864. The grove has a long history of prescribed burning, which greatly reduces the negative impacts of high-severity fires, the National Park Service said in a statement.

The giant sequoias, native in only about 70 groves spread along the western slope of the Sierra Nevada, were once considered impervious to flames, but they have become increasingly vulnerable as wildfires, fueled by a buildup of undergrowth from a century of fire suppression and the impact of drought worsened by climate change, have become more intense and destructive.

Lightning-sparked wildfires over the past two years have killed up to a fifth of the estimated 75,000 large sequoias, which are a major draw for tourists. 

“Fortunately there has not been any erratic winds that have affected fire behavior,” fire information officer Marc Peebles said. “We do have the high pressure that’s over the top of the fire, which is causing the increase in temperatures. However, we do get a decent amount of humidity at night, which moderates fire behavior, which allows our night shift firefighters to do good work.”

The area in the southern part of Yosemite was closed to visitors, but the rest of the national park remained open.

Image: Firefighters conduct early morning backfiring operations near the South Entrance on July 11, 2022 in Yosemite National Park, Calif.
Firefighters conduct early morning backfiring operations Monday near the South Entrance in Yosemite National Park, Calif. National Park Service / Getty Images

A heat advisory was issued for the Central Valley sprawling below the Sierra, while up in the fire area, a high temperature of 88 degrees was forecast for the village of Wawona, where hundreds of tourists and residents were forced to evacuate Friday.

There was no obvious natural spark for the fire, which broke out Thursday next to the park’s Washburn Trail. Visitors walking in the grove reported smoke.

Image: Viewed from Oakhurst in Madera County, Calif., a plume rises from the Washburn Fire burning in Yosemite National Park on July 8, 2022.
Viewed from Oakhurst in Madera County, Calif., a plume rises from the Washburn Fire in Yosemite National Park on Friday. Noah Berger / AP

A fierce windstorm ripped through the grove more than a year ago, toppling 15 giant sequoias, along with countless other trees.

The downed trees, along with massive numbers of pines killed by bark beetles, provided ample fuel for the flames.

Image: Seen from unincorporated Mariposa County, Calif., a helicopter drops water on the Washburn Fire burning in Yosemite National Park on July 9, 2022.
A helicopter drops water on the Washburn Fire in Yosemite National Park on Friday.Noah Berger / AP

So far this year, more than 35,000 wildfires have burned nearly 4.7 million acres in the U.S., according to the National Interagency Fire Center, well above average for both wildfires and acres burned.