San Francisco Reservoir Pelted with Yosemite Fire’s Ash

San Francisco officials said they are increasing the transfer of water from the city’s main reservoir in Yosemite National Park as a fast-moving forest fire pelts the lake with ash.

The fire, which has scorched an area the size of the city of Chicago, was less than two miles from the Hetch Hetchy Reservoir. The lake, about 160 miles (260 kilometers) east of San Francisco, supplies 85 percent of the city’s water and its hydroelectric plants power San Francisco International Airport, San Francisco General Hospital and the city’s transit system.

San Francisco was already moving water out of the lake and into some of its other reservoirs before the fire started because Hetch Hetchy was near capacity, Charles Sheehan, a spokesman for the San Francisco Public Utilities Commission, said in a telephone interview.

“There is ash all throughout the region and there is ash at the reservoir but the condition of the water is mostly clear,” he said. “Water quality has not been affected and we continue to deliver water from Hetch Hetchy.”

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 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.

“This is something we typically do, transferring water from one reservoir to another and we were doing this prior to the fire,” Sheehan said. “We increased the water transfer from Hetch Hetchy but it was already ongoing.”

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