California wildfire burns deeper into Yosemite National Park
Sprawling blaze creeping closer to thousands of homes

One of the largest California wildfires on record roared east into Yosemite National Park on Tuesday, frightening away many late-summer visitors, while the sprawling blaze also crept closer to thousands of homes west of the park.
The so-called Rim Fire, which has burned for 11 days mainly in the Stanislaus National Forest west of Yosemite, nearly doubled its footprint in the park overnight after encroaching on a reservoir that serves as the primary water supply for San Francisco some 320km to the west.
Video: Ancient sequoia trees could be affected by California wildfires
Officials said some ash from the fire had drifted onto the surface of the Hetch Hetchy Reservoir, but testing of samples taken from the artificial lake showed that water quality remained healthy.
If the water should become fouled by too much ash and soot and require filtration, it can be diverted through a treatment plant near San Francisco before being delivered to customers, officials from the city Public Utilities Commission said.
