The wildfire burning in the remote woods north of Yosemite National Park in California has grown rapidly since Friday to become one of the biggest fires in the state's history. Crispy dry conditions following an extra-dry winter as well as steady southerly winds have pushed the fire north- and westward, and as of Monday morning nearly 150,000 acres, or about 234 square miles, have burned or are on fire. It is only 15 percent contained, and pushing quickly toward the Hetch Hetchy Reservoir and O'Shaughnessy Dam, San Francisco's primary sources of water and power. Two of three hydroelectric power stations have been forced to shut down, and SF's public utility commission has begun buying power on the open market.

So far, they say, despite ash raining down on it, the water quality from the reservoir is still fine.

Though the fire is massive at this point, it's been burning in an area of remote, rugged terrain in the Stanislaus National Forest where there are few residences or towns, though it is edging closer to more populated areas. The terrain, which includes lots of steep river canyons, has made the fire harder to fight, and because it's densely forested there has been an effect known as a "crown fire" in which the blaze spreads from treetop to treetop, rather than along the ground. According to one report from the U.S. Forest Service yesterday, only about 23 structures have been destroyed, but it's unclear whether the buildings of Berkeley's Tuolomne Family Camp are included in that count. The 91-year-old, city-owned retreat was evacuated last week, and reportedly burned down on Sunday.

The fire is also threatening San Francisco's own Camp Mather, and it already blew through San Jose Family Camp, burning at least one building and a number of tents. See a map of the directions in which the fire is spreading here.

About 4,500 structures are threatened by the fire as it continues to grow, including 1,600 homes in Tuolomne City. And air quality north of the fire, in the Lake Tahoe basin and in the cities of Reno and Carson City, is not good.

Yosemite National Park remains open and, for the most part, the fire and smoke are heading away from the park thanks to southerly winds.

A State of Emergency remains in place, including the City of San Francisco, because of the Hetch Hetchy threat.

See some photos of the fire from over the weekend here. Below, some aerial footage of flying over the fire last Thursday.

[CBS 5]
[LA Times]

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