Rim wildfire threatens San Francisco water, power

A huge wildfire near Yosemite National Park in California was 20 percent contained by Monday night, but continued to threaten San Francisco's water supply, with flames within a mile of the park's Hetch Hetchy Reservoir, where 85 percent of the city's water comes from. The menacing blaze, which has burned 160,980 acres since it began Aug. 17, is also endangering several towns near the park and the Golden State's historic giant sequoias.

While containment of the so-called Rim Fire has increased from seven percent earlier Monday morning, San Francisco water authorities were scrambling to fill area reservoirs with water from Hetch Hetchy, the source of San Francisco's famously pure drinking water before ash tainted water supplies, Harlan Kelly Jr., general manager of the city's Public Utilities Commission, said. 

The city's hydroelectric power generated by the system has been interrupted by the fire, forcing the utility to close two plants and spend $600,000 supplying electricity from other sources.

Ash from the fire has been falling on the reservoir, but so far hasn't sunk far enough to reach intake pumps, Kelly said. Water quality in San Francisco, where a state of emergency is still in place, remained good on Monday.

Officials, however, warned that the blaze was so hot that it could send sparks into untouched areas.The fire near one of the country's most popular national parks also edged closer to some of the giant sequoia trees that are among the largest and oldest living things on earth. They were being sprinkled for protection.

"This fire has continued to pose every challenge that there can be on a fire," said Daniel Berlant, a spokesman with the California Department of Forestry and Fire Protection. "It's a very difficult firefight."

Despite that, the tourist destination of Yosemite Valley remained open to the public, clear of smoke and free from other signs of the fire, which has become one of the biggest in California's history, helped by inaccessible terrain, strong winds and bone-dry conditions. 

Hundreds of firefighters were digging trenches, clearing brush and fighting back blazes to keep the raging wildfire, north of Yosemite, out of several mountain hamlets.

Statewide, more than 8,300 firefighters are battling nearly 400 square miles of fires. The U.S. Forest Service says about 4,500 structures are threatened by the fire. 

Al Jazeera and The Associated Press