YOSEMITE -- Prompted by this week's air quality emergency, Yosemite National Park officials are sidestepping a longtime policy to allow natural wildfires to burn out on their own.
Instead, park firefighters are working to extinguish a week-old blaze that's charred about 300 acres of remote wilderness.
Yosemite officials expect the fire to be out by Monday.
Although the Bald fire poses no direct threat to people or property -- the usual threshold as to when the park will extinguish a fire -- park officials say smoke from the growing fire is enough to warrant putting it out.
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"We always consider the big picture when we're deciding how to respond to a fire, and we're always concerned with air quality both in the park and in the surrounding communities," Yosemite spokeswoman Adrienne Freeman said. "With the other fires in the state right now, we're worried about the cumulative effect."
Smoke from the massive Moonlight fire, which has burned 31,294 acres in the Plumas National Forest since Monday, has blanketed the Central Valley and Bay Area for several days. That fire is about 16 percent contained, according to the California Department of Forestry and Fire Protection.
The Like fire burning in Henry W. Coe State Park in eastern Santa Clara County and western Stanislaus County has blackened 37,660 acres. That fire, which is 45 percent contained, is contributing to the valley's problems because the wind direction has shifted, air quality officials say.
Considering the other fires' impact, Freeman said, park officials decided late Wednesday to extinguish the Bald fire, which was ignited by a lightning strike Aug. 30.
The Bald fire is minuscule by comparison, but park officials say it could spread quickly. The fire is about three miles east of Bald Mountain in a remote area.
"This is nothing compared to the other fires going on in other parts of the state," Freeman said. "But to allow it to grow could mean that we'd be contributing to all the smoke that's already out there."
Because park officials have been managing the Bald fire since it started, Freeman said, it's largely contained. She said about 50 firefighters, mostly from Yosemite's own crews, began working to extinguish it early Friday.
Besides the Bald fire, three other fires are burning in the park. Freeman said there are no plans to extinguish them, because they aren't believed to be contributing to air quality problems.
The Babcock fire, just north of Merced Lake, has burned about 220 acres since it was ignited -- also by a lightning strike -- in early July. Because that fire is at a higher elevation surrounded by granite, Freeman said there is little chance of it spreading.
Brenda Peeler, who owns a bed and breakfast about 12 miles outside of Yosemite's south gate, said she saw little evidence of the fires until Friday.
Freeman said some visitors to northern areas of the park might see plumes of smoke, but that the fire isn't otherwise affecting tourists. "Everything is open," she said.
Naturally ignited wildfires are common in the 747,000-acre Yosemite National Park. Historically, the park has worked to put out all fires. In the 1970s, however, park officials adopted a policy of allowing natural fires -- those not started by humans -- to burn out on their own.
Natural fires, which usually are lower in intensity, are an important part of a forest's ecosystem, experts say. That's because they burn underbrush and forest waste that, if left unchecked, can fuel catastrophic fires later. Natural fires also deposit nutrients back into the soil to promote new, healthy growth.