The Yosemite fire grew to more than 200 square miles Sunday, threatening two groves of giant sequoias as well as the Hetch Hetchy Reservoir supplying water and power to San Francisco, consuming some two dozen structures and threatening 4,500 more.
What’s called the Rim Fire is just 7 percent contained. And while its spread slowed somewhat Sunday, it continued to grow.
"This fire has continued to pose every challenge that there can be on a fire: inaccessible terrain, strong winds, dry conditions,” said Daniel Berlant, spokesman for the California Department of Forestry and Fire Protection. “It's a very difficult firefight.”
High winds are making that firefight even more challenging as ground-level blazes whip up to treetops, creating what are called crown fires.
"A crown fire is much more difficult to fight," said Mr. Berlant. "Our firefighters are on the ground having to spray up."
As the fire threat moved, some evacuation orders were lifted. But the San Jose Mercury News reports that residents were advised to clear out of several other settlements, including Tuolumne City and Ponderosa Hills, where homes are scattered throughout the woods.
The bulk of the fire is to the west of Yosemite National Park, and as of Sunday most of the park facilities in Yosemite Valley remained open to visitors, although officials closed some campgrounds and wilderness trails at higher elevations.
“Most of Yosemite National Park is not affected by the fire and is relatively smoke-free,” according to the park’s website. “The northern part of the park, including some areas along the Tioga Road, has some smoke. Conditions may change if winds shift.”
Park officials are taking special steps to protect the two groves of giant sequoias that the fire could threaten, reports KQED, the NPR affiliate in San Francisco. Crews have cleared brush from around the trees – some of which are believed to be 2,000 years old – and installed sprinklers in the Tuolumne and Merced groves just in case.
"All of the plants and trees in Yosemite are important, but the giant sequoias are incredibly important both for what they are and as symbols of the National Park System," park spokesman Scott Gediman told The Associated Press.
KQED also reports that as of Sunday the fire still has had no impact on the quality of water from the city's Hetch Hetchy Reservoir, which is inside the park.
More than 2.6 million people in the San Francisco Bay Area receive water from Hetch Hetchy. San Francisco gets 85 percent of its water from the reservoir, which is about four miles from the fire. The threat to Hetch Hetchy prompted California Gov. Jerry Brown to declare a state of emergency for San Francisco last week.
Two of the three hydropower facilities generating power downstream from the O'Shaughnessy Dam, which created the reservoir, have been taken offline because of possible damage. Surveys by power crews Saturday night found about 12 miles of power lines had been damaged, USA Today reported. So far, San Francisco has spent $600,000 purchasing power from other sources.
More than 2,800 firefighters are battling the blaze. As of Saturday, the cost to California agencies of fighting the Rim Fire had reached $7.8 million, 75 percent of which will be reimbursed by the Federal Emergency Management Agency.
The National Interagency Fire Center in Boise has added six new large fires to its list, two in California and one each in Idaho, Montana, Oregon, and Texas. The fire center reports that there now are 43 active large fires across the West covering more than 850,000 acres.
The report includes material from The Associated Press.