(Adds fire reaching reservoir, updates acreage burned, adds
By Laila Kearney
SAN FRANCISCO Aug 27 One of the largest
California wildfires on record roared deeper into Yosemite
National Park on Tuesday, frightening away many late-summer
visitors and reaching a water reservoir that serves as the
primary water supply for San Francisco.
The so-called Rim Fire, which is burning mainly in the
Stanislaus National Forest west of Yosemite, nearly doubled its
footprint in the park overnight and the sprawling blaze later
crept closer to thousands of homes west of the park.
Officials said ash had drifted onto the surface of the Hetch
Hetchy Reservoir, which supplies water to San Francisco some 200
miles (320 km) to the west, but testing of samples showed water
quality remained healthy.
After advancing on the reservoir for several days, the
flames reached the shores of the artificial lake, officials
said. But the San Francisco Public Utilities Commission said in
a statement there was "little risk for direct impacts" on the
reservoir because of the rocky terrain and lack of brush
If the water should become fouled by too much ash and soot
and require filtration, it can be diverted through a treatment
plant near San Francisco before being delivered to customers,
officials from the Public Utilities Commission said.
Meanwhile, a firefighting force of some 4,100 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 on Monday, containment lines had been established
around 20 percent of the fire's perimeter, nearly triple
Sunday's figure, though the overall area of the blaze continued
to grow as much of the firefighting effort focused on structure
"The lines are being built miles long, and in some areas 12
(bulldozer) blades wide," said Daniel Berlant, a spokesman for
the California Department of Forestry and Fire Protection.
Fire managers were looking forward to a cooling trend
forecast for the end of the week, which Berlant said "would
bring some much-needed relief."
The blaze was among the fastest-moving of dozens of large
wildfires raging across the drought-parched U.S. West.
More favorable weather this week in the Pacific Northwest,
including lower temperatures, diminished winds and even some
rain, helped firefighters gain an upper hand on a number of
stubborn blazes in Oregon and Washington state.
Those gains freed up some fire crews and other thinly
stretched resources, leading federal fire managers to lower the
nation's wildfire threat index a notch.
"Things are really getting rosier," said Ken Frederick, a
spokesman for the National Interagency Fire Center, a support
center for wildland firefighting, in Boise.
BUFFER ZONES AROUND HOMES
The Rim Fire has charred nearly 184,500 acres (about 75,000
hectares) - an area larger than the land mass of Chicago - since
it erupted on Aug. 17, most of that in the Stanislaus Forest.
It ranks as the biggest California wildfire since October
2007, when the Witch Fire torched nearly 198,000 acres (80
ha)and more than 1,600 structures in San Diego County, and the
sixth-largest in state history, according to the records of Cal
Fire, a state government site.
Firefighters hacking through dense, dry brush and trees to
create clearings in the rugged terrain rushed to improve 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.
As of Tuesday, the blaze had scorched more than 40,000 acres
of Yosemite, forcing the closure of some campgrounds in the more
remote northern part of the park and the main entrance road from
the San Francisco Bay area. (www.nps.gov/yose/index.htm)
Tioga Road, the second of four access routes to Yosemite
National Park is scheduled to be closed on Wednesday for fire
crews to build containment lines along the road before flames
can reach it, said Yosemite spokesman Tom Medema.
The vast majority of the 1,200-square-mile park, including
the Yosemite Valley area renowned for its towering rock
formations, waterfalls, meadows and pine forests, remained open
to the public and free of smoke. But late-summer crowds were
notably diminished, park officials said.
"There are still people here, but there's definitely fewer
visiting than there normally would be for this time of year, and
that just happened within the last couple of days," said park
spokeswoman Kari Cobb. "It's just the northern part of the park
Some 4 million people visit Yosemite each year, most of them
during the peak months of June through August, she said.
The Rim Fire, named for a Stanislaus National Forest lookout
point called Rim of the World, has already damaged two of the
three hydropower generating stations, linked to the Hetch Hetchy
Reservoir, that supply electricity for all of San Francisco's
public facilities, such as hospitals and firehouses.
The city has been drawing on reserve power stored for
emergencies and purchasing additional electricity on the open
market to make up for the difference.
The cause of the blaze remained under investigation.
(Reporting by Laila Kearney; Additional reporting by Laura
Zuckerman in Idaho and Alex Dobuzinskis in Los Angeles; Writing
by Steve Gorman; Editing by Cynthia Johnston and Christopher