Hetch Hetchy is a valley near Yosemite. In 1913, congress gave permission for San Francisco to build the O'Shaughnessy Dam across Hetch Hetchy valley. The valley was filled with 300' of water that supplies San Francisco, San Mateo and Alameda counties. And power also is supplied by the water and the dam.
If the fire puts the pumps of the dam out of commission it may cause power and water disruption in the Bay Area. Since we live in Alameda County, I wonder if it will affect us much.
An interesting side note: San Francisco is suing Nevada for giving their criminals a one-way bus ticket to San Francisco to get them out of Nevada. Well, pay back! Nevada, especially Reno, is getting all the heavy smoke from the fire! Even Yosemite Valley hasn't been getting smoke up to this point!