One of the largest wildfires in California history roared deeper into Yosemite National Park on Tuesday while flames of the sprawling blaze crept closer toward thousands of homes outside the park, fire officials said.
The blaze, which has burned for 11 days mainly in the Stanislaus National Forest adjacent to Yosemite, nearly doubled its imprint in the park overnight after encroaching on a reservoir that serves as the primary water supply for San Francisco some 200 miles to the west.
The fire had ravaged 282 square miles by Tuesday, the biggest in the Sierra’s recorded history and one of the largest on record in California.
A firefighting force of some 3,700 personnel, backed by teams of bulldozers and water-dropping helicopters, continued to make headway in their drive to encircle and suppress the flames.
By late Monday, containment lines had been established around 20 percent of the fire’s perimeter, nearly triple Sunday’s figure, though the overall footprint of the blaze continued to grow as much of the firefighting effort focused on structure protection.
“We are making progress,” said Daniel Berlant, a spokesman for the California Department of Forestry and Fire Protection, adding that fire managers were looking forward to a cooling trend toward the end of the week. “That would bring some much-needed relief,” he said.
As of Tuesday morning, the blaze had scorched some 42,000 acres of Yosemite — almost double the number from late Monday. The fire has forced the closure of some campgrounds in the northern part of the park and the main entrance road from the San Francisco Bay area.
Firefighters hacking through dense, dry brush and trees to create clearings in the rugged terrain rushed on Tuesday to shore up buffer zones around some 4,500 homes threatened by the blaze on its northwestern flank, Berlant said.
Most of those dwellings have been ordered evacuated or were under advisories urging residents to leave voluntarily or be ready to flee at a moment’s notice. The fire has already destroyed dozens of homes and cabins, Berlant said, but no serious injuries have been reported.
The blaze was among the fastest-moving of dozens of large wildfires raging across the drought-parched U.S. West. The fires have strained resources and prompted fire managers to open talks with Pentagon commanders and Canadian officials about possible reinforcements.
The blaze was just 40 acres when it was discovered near a road in Stanislaus National Forest on Aug. 17, but firefighters had no chance of stopping it in the early days.
Fueled by thick forest floor vegetation in steep river canyons, it exploded to 10,000 acres 36 hours later, then to 54,000 acres and 105,620 acres within the next two days. On its 11th day it had surpassed 179,400 acres, becoming the seventh-largest California wildfire in records dating to 1932.
Now the so-called Rim Fire ranks as the biggest California wildfire since October 2007, when the Witch Fire torched nearly 198,000 acres and more than 1,600 structures in San Diego County, and the sixth-largest in state history, according to CalFire records.
A constant slow warming across the Sierra Nevada, unnaturally long intervals between wildfires and two years of drought have all combined to turn the Rim Fire into an inferno chewing up the rugged landscape on the edge of Yosemite National Park, forestry experts say. For years forest ecologists have warned that Western wildfires will only get worse.
“Every year the summer temperatures are a little warmer, hence the conditions for burning are a little more auspicious,” said Hugh Stafford, an ecologist with the U.S. Forest Service in California. “People can deny it all they want but it’s happening. Every year the fuels are a little bit drier.”
The Rim Fire’s exponential growth slowed only after hitting areas that had burned in the past two decades, and Stafford says that shows the utility of prescribed and natural burns that clear brush and allow wildfires to move rapidly without killing trees.
“If you look at the Sierra Nevada as a whole, by far the largest portion hasn’t seen a fire since the 1910s and 1920s, which is very unnatural,” Stafford said. “This one isn’t stopping for a while.”
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