Wildfire near Yosemite threatens San Francisco’s power supply; giant sequoias

Fire crews are struggling to gain control over a massive wildfire, which exploded into Yosemite on Friday and threatened the power supply into San Francisco.

As of Sunday morning, only seven percent of the 203-square-mile fire had been contained.

By Monday at 11:30 Pacific time, the fire was 15 percent contained.

Johnny Miller with the California Department of Forestry and Fire Protection's public information bureau told the Los Angeles Times that counts as progress considering the challenges of fighting a fire on rugged terrain.

“Everything is looking as good as it possibly can for this stage of the fire,” he said. “We’re making good progress.”

The fire is threatening 4,500 homes and has already destroyed 23 structures.

Authorities are also making preparations to protect the region's giant sequoia trees, laying sprinklers and cutting brush.

California Governor Jerry Brown declared a state of emergency for the city and county of San Francisco on Friday, warning that the fire had damaged the electrical infrastructure serving the area.

Two of the San Francisco Public Utilities Commission's three hydroelectric power stations were shut down as well as transmission lines to the city.

San Francisco is buying its power on the open market and so far there have been no reports of blackouts.

There is no word on when the two power stations will be restored.

"We are making progress but unfortunately the steep terrain definitely has posed a major challenge," said Daniel Berlant, a spokesman for the California Department of Forestry and Fire Protection, said Saturday.

The fire is also moving rapidly toward the Hetch Hetchy Water and Power System, which supplies about 85 percent of San Francisco's total water needs.

The San Francisco Public Utilities Commission, owner reservoir, re-iterated earlier that water quality and delivery were not affected.

More than 3,670 firefighters were working on containing the blaze on Monday.

The fire remained about 20 miles away from Yosemite Valley, the heart of the park's tourist center, Yosemite spokesman Scott Gediman told Reuters.

Gov. Brown visited the area Monday and met with fire officials and first responders. “This is something that we have to live with — it may even get worse in years to come — but California will be ready for it,” Brown said at a news conference.