Photo by Associated Press
The massive Rim Fire that has torched parts of Yosemite National Park and threatens scores of homes in the pristine northern California mountains has swelled to nearly 180,000 acres.
The 11-day-old fire grew by almost 20,000 acres since Monday to an area of about 280 square miles, forcing mandatory evacuations near Yosemite Park south of Highway 120. Firefighting crews were securing fire lines along the southwestern and northeastern edge of the blaze. The fire was about 20% contained Tuesday.
About two dozen structures have been destroyed, and about 4,500 are under threat.
More than 3,700 firefighters are battled the biggest wildfire on record in California's Sierra Nevada. Airborne tankers, including DC-10s and C-130 cargo planes carrying fire retardant are treating areas in the fire's path.
Weather conditions forecast for Wednesday may bring challenges in the morning as heavy smoke is expected to settle low to the ground, limiting visibility, said National Weather Service meteorologist Matt Mehle. Higher humidity expected in the afternoon could help dampen the flames, he said.
The area scotched in Yosemite National Park doubled to about 64 square miles, but it remains in backcountry. Most of the park remains open to visitors.
As Labor Day weekend nears, Park Service officials are eager to get the word out that it's business as usual in the country's first national park, which sprawls over 750,000 acres and soars from bear-stalked meadows to 13,000-foot granite peaks with celebrated names like El Capitan and Half Dome.
Apart from slightly thinned out crowds - noticeable everywhere from half-filled trolleys that tour the valley floor to some empty benches during ranger presentations - the park so far shows little trace of the inferno that burns some 20 miles to the north.
Yosemite park officials cleared brush and set sprinklers on two groves of giant sequoias that were less than 10 miles away from the fire's front lines, said park spokesman Scott Gediman. While sequoias have a chemical in their bark to help them resist fire, they can be damaged when flames move through slowly with such intense heat.
Crews spent Monday bulldozing firebreaks to protect Tuolumne City, several miles from the fire's edge.
Yet as flames lapped at the edge of the main water reservoir that supplies San Francisco, fears that the inferno could disrupt water or power to the city diminished.
"It looks great out there. No concerns," Glen Stratton, an operations section chief on the blaze, said of the Hetch Hetchy Reservoir.
Crews remained confident they could protect hydroelectric transmission lines and other utility facilities at the reservoir.
Utility officials monitored the basin's clarity and used a massive new $4.6 billion gravity-operated pipeline system to move water quickly to reservoirs closer to the city.
Ash from the fire has been raining onto the reservoir, but has not sunk as far as the intake valves, which are about halfway down the 300-foot O'Shaughnessy Dam. Utility officials said the ash is non-toxic but that the city will begin filtering water for customers if problems are detected.
Power generation there was shut down last week so firefighters would not be imperiled by live wires. San Francisco is buying replacement power from other sources to run City Hall and municipal buildings.
Meanwhile, biologists with the Forest Service are studying the effect on wildlife. Much of the area that has burned is part of the state's winter-range deer habitat. Biologist Crispin Holland said most of the large deer herds would still be well above the fire danger.
Biologists discovered stranded Western pond turtles on national forest land near the edge of Yosemite. Their marshy meadow had burned, and the surviving creatures were huddled in the middle of the expanse in what little water remained.
"We're hoping to deliver some water to those turtles," Holland said. "We might also drag some brush in to give them cover."
Wildlife officials were also trying to monitor at least four bald eagle nests in the fire-stricken area.