San Francisco Public Utilities commissioners were updated Tuesday afternoon about the damage and repair efforts at the Hetch Hetchy water and power facilities after the massive "Rim Fire" burned through the Yosemite area.
Hetch Hetchy provides 100 percent of the water supply used by Los Altos Hills.
Water quality was unaffected with the turbidity, or cloudiness, continuing to fall within state-mandated levels.
The fast-moving fire prompted fire crews to drop retardant but to protect the water quality none of the retardant was dropped near the O'Shaugnessy Dam at the reservoir.
Ash has not been an issue for water quality at the surface level or when taken from a depth of 160 feet.
The fire that started Aug. 17 at the Stanislaus National Forest spread into Yosemite National Park and has charred more than 254,000 acres. It has been 80 percent contained and full containment is not expected until Sep. 20. It is the third largest fire in California history.
SFPUC deputy general manager Michael Carlin explained at the commission meeting Tuesday afternoon at San Francisco City Hall that only 1 percent of the Hetch Hetchy watershed was affected by the fire.
Since firefighters gained the upper hand, SFPUC crews have been able to access the facilities and assess the damage. SFPUC general manager Harlan Kelly said Mayor Ed Lee and SFPUC staff took a helicopter ride to see the "devastation" of the fire.
Kelly credited the U.S. Forest Service, local firefighters and other agencies that came together and "helped us through to where we are today."
"We are grateful to all the firefighters on the ground," Carlin said.
The Hetch Hetchy provides water and other services to 2.6 million Bay Area residents.
Carlin said he was proud to report that there was no disruption to water and power service to Bay Area customers at any point.