Transcript for Yosemite Fire Triples in Size
Now, we turn to the out-of-control wildfire burning outside of yosemite national park. California's governor declaring a state of emergency. And this morning, big questions about whether the fire could threaten water and power supplies for san francisco. Abc's neal karlinsky is in groveland, california. Reporter: The news out here just keeps getting worse. But one estimate, this fire has grown to 80,000 acres. That's five-times the size it was just 48 hours ago. A fire now as big as all of sacramento. The rim fire is now so big -- the bulk of the efforts to stamp it out is being made by a massive aerial assault. Even as firefighters in the path of the flames are sweating the smallest details. You heard about the tankers. Reporter: Going yard-to-yard, and fighting this fire, one house at a time. What do you think? That's pretty dispensable, yeah. Reporter: No matter what officials say. Residents can see this fire for themselves. And they're nervous. Very freaky. You just see it this close. The first time I've had it this close to the house before. Yeah. It's pretty scary. Reporter: This is classic structure protection. You have ground fire crews. And on the roof of the house, they've coated it in flame retardant. That's what this orange stuff is. Because the fire is so enormous, there is concern it could burn power and water lines, feeding san francisco 150 miles to the west. Utility officials say that threat is highly unlikely. But contingencies are being considered. Because this fire is so unpredictable and so hungry. Packed up and got things ready to leave as soon as we need to. Reporter: There are now 1,000 firefighters working this blaze around the clock. Many protecting homes just like this one. But as is usually the case, it is the weather that will dictate where this goes now.
This transcript has been automatically generated and may not be 100% accurate.