Yosemite fire is 'highest priority' in nation

• Fire poses threat to San Francisco%27s water and electrical supplies
• Thousands of firefighters battling blazes across the West
• Fire not a threat to most-visited areas of Yosemite National Park

SAN FRANCISCO — A massive fire burning near Yosemite National Park continued its spread Sunday. More campgrounds were evacuated and firefighters worked to protect ancient giant sequoia groves. The fire was within a mile of the reservoir that supplies water to more than 2.6 million people in the San Francisco Bay area.

The Rim Fire reached almost 143,980 acres Sunday and was "very active on its eastern side," said Johnny Miller, an information officer with the unified fire command directed by Cal Fire and the U.S. Forest Service.

The towns of Tuolumne and Mi-Wuk Village and smaller communities between them were under voluntary evacuation Sunday, said Dick Fleishman with the U.S. Forest Service. Evacuation advisories were lifted for Pine Mountain Lake and Buck Meadows. "We still have homes that are risk," he said. An evacuation center was set up in the Sonora, Calif. for those who left their homes.

Local ham radio operators were providing community information in Sonora, Calif., where evacuees were being fed and housed. Carol Logue, with the Tuolumne County Amateur Radio Electronics Society, volunteered Sunday. She said the the smell of the fire was all around. "There's so much smoke it's really hard on people's lungs," she said. "You can get on the hilltops around here and see the fires."

Nearly 3,414 firefighters are battling the blaze, some from as far away as Florida, and more are being drafted to help, Miller said. As of 7 p.m. local time Sunday, the fire was 7% contained.

"It's the highest priority fire in the country right now because of its location, because Yosemite National Park is at risk. It's not just a national treasure, it's a world treasure," Fleishman said.

There were dozens of smaller fires burning across the West, officials said. The largest was the Beaver Creek Fire in Idaho, which has scorched 111,387 acres. It is now over 90% contained, according to the federal fire tracking site InciWeb.

California Gov. Jerry Brown has declared a state of emergency for San Francisco because the fire also threatens the city's water and electrical infrastructure.

"It's within a mile of Hetch Hetchy if not less," Miller said. Much of the San Francisco Bay area gets its water from the reservoir behind O'Shaughnessy dam. The famously pure water travels 160 miles entirely through gravity-fed pipes.

Officials don't have a clear idea of how Hetch Hetchy is faring, Medema said. An incident commander flew near the area Sunday morning but the smoke was so thick that the crew was unable to see the reservoir or surrounding area.

As of Sunday evening there had been no damage to the reservoir and the water was still clear and clean, despite fears that ash could fall into the reservoir and contaminate the water. "The turbidity levels are fine," said Fleishman, referring to a measurement of particles in the water.

If the reservoir were to be compromised the area would be able to get water from other nearby reservoirs owned by other counties with which it has emergency agreements, the San Francisco Public Utilities Commission said in a statement Sunday.

A secondary concern is the power generated by the dam, which creates the reservoir. It generates hydroelectric power used for some municipal buildings in the city, including San Francisco International Airport and San Francisco General Hospital.

The system has three powerhouses, two of which were taken offline Saturday because of possible fire damage. Repair crews begin making preliminary repairs to Kirkwood Hydroelectric Powerhouse on Sunday and are conducting additional damage inspections, according to the San Francisco Public Utilities Commission The third, Moccasin powerhouse, was still generating power Sunday, according to the Utilities Commission website.

Even if the powerhouses were all shut down there would be no loss of power in San Francisco. The city's electrical infrastructure is linked to the main electrical grid and it would simply purchase power to supplement the lost transmissions, officials said. Since the fire began Aug. 19 the city has so far purchased about $600,000 in supplemental power, the Public Utilities Commission website said.

The dam itself is impervious to fire. "It's a massive concrete structure and won't be harmed," Fleishman said. The concern is "mostly about the power lines and water quality."

As of Sunday the bulk of the fire was to the west of Yosemite National Park. Only "a very small piece" is in Yosemite, burning in the western side of the park in remote wilderness, said Tom Medema, a spokesman with Yosemite National Park.

"About 15,500 acres are in the park, that's about 10% of the entire fire," he said.

The fire is about 20 miles from the iconic Yosemite Valley, home to Half Dome, the Ahwahnee Hotel and Curry Village. "There is no imminent threat of any kind," Medema said.

It would take "days and days and weeks" for the fire to get that far. The park's hotels and campgrounds are full and aside from a slight tinge of smoke in the air it's impossible to tell there are fires, he said.

In Yosemite National Park, the White Wolf Lodge and the White Wolf campground were evacuated Sunday afternoon, said Tom Medema, a spokesman with Yosemite National Park. They are north of Yosemite Valley in the park's high country.

"The fire is not imminent there, but the smoke is such that the air quality is very poor, so we felt the need to close it down," he said.

Park officials are working to find other lodging for visitors from those areas.

Two other campgrounds, Yosemite Creek and Tamarack Flat, were not being evacuated but new campers are not being allowed, he said.

Park officials are also concerned about the safety of two groves of giant sequoiatrees, the Tuolumne Grove and the Merced Grove. These massive trees are some of the largest living things on Earth and some are believed to be more than 2,000 years old.

Both groves are surrounded by wilderness. Firefighters have built fire lines around the groves to protect them, clearing brush and undergrowth in a broad circle "so the fire that's creeping along the ground can't cross over," Medema said.

Although sequoia are naturally fire resistant due to their thick bark, "in a fire of this size you always want to have protective measures in place," he said.

Some historical buildings in the area are being protected by sprinkling the surrounding grounds with water. Firefighters are also wrapping the wooden shake roofs with aluminum fireproof material. "They look like baked potatoes," Medema said.

State Route 120 into the park from the west is closed, but all the other main park roads are open, Medema said.