The Rim Fire grew today to about 150,000 acres (60,600 hectares) or 234 square miles and was 15 percent contained, according to the California Department of Forestry and Fire Protection, which has command of the fire crews. About 3,400 personnel were fighting the blaze, which erupted Aug. 17 and threatened 4,500 structures.
The fire was less than two miles from the Hetch Hetchy Reservoir at 9:15 a.m. local time, said Harlan Kelly Jr., general manager of the San Francisco Public Utilities Commission. The lake, about 160 miles (260 kilometers) east of San Francisco, supplies 85 percent of the city’s water and powers San Francisco International Airport, San Francisco General Hospital and the city’s transit system.
“We are trying to protect as many facilities around our watershed and trying to minimize the damage,” Kelly said today in an interview. “As far as the water is concerned, our major concern is the ash getting into the water system. We have not started to see signs of the ash.”
The commission deactivated electrical transmission lines and two of three hydroelectric power plants in the area of the fire on Aug. 19 and had spent $600,000 buying replacement electricity, according to a statement yesterday.
In addition to tapping wholesale power markets, the utility is borrowing from a “piggy bank” with PG&E Corp. (PCG) to make up for 110 megawatts out of service because of the fire. That represents 69 percent of the agency’s 160 megawatts of supplies in the area.
It will take several days after the fire is out to bring back the transmission lines, requiring the city to continue buying power, Kelly said. He said he couldn’t estimate how much power costs may climb.
The Hetch Hetchy system serves 2.6 million water customers in San Francisco and the Bay Area. Water flows from the reservoir, more than 3,000 feet above sea level in the Sierra Nevada Mountains, through tunnels to San Francisco.
San Francisco’s water system has supplies in Bay Area reservoirs and is linked with the East Bay Municipal Utilities District and the Santa Clara Valley Water District, according to the commission.
Most of Yosemite National Park wasn’t affected by the fire and is relatively smoke-free, according to the park’s website.
Outside the park, the fire destroyed most of the structures at the city of Berkeley’s Tuolumne Family Camp, which has operated since 1922, according to a statement on the city’s website. The camp, about seven miles west from the park entrance, was evacuated Aug. 20.
The Rim Fire is not threatening the state’s high-voltage transmission lines and power supplies remain adequate, Steven Greenlee, a spokesman for the California Independent System Operator, which manages the state’s power grid, said by e-mail.
PG&E had 158 customers without power as of 9:30 a.m. local time, said a spokeswoman, Nicole Liebelt. The utility had shut a power line at the request of the fire incident command, Liebelt said. PG&E has been unable to assess damage to the company’s equipment due to safety concerns, she said.
Several large fires damaged utilities in Southern California in recent months.
A blaze that spread across almost 30,000 acres north of Los Angeles in June triggered “multiple forced outages” on lines that connect to Northern California and the Pacific Northwest, according to the California Independent System Operator Corp., which manages the state’s power grid.
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