The giant rim fire raging through Yosemite has tripled in size since Aug. 21, burning about 149,000 acres and approaching the vicinity of the Hetch Hetchy Reservoir, the source of San Francsico’s water supply, according to the San Francisco Public Utilities Commission.
In an update, the SFPUC noted that the city’s water system has not been impacted but is being closely monitored for changes to water quality.
“Currently, some ash has fallen onto the surface of the reservoir, but there has been no impact to the quality of water, which is being withdrawn from the reservoir at a depth of 260 feet,” The SFPUC noted in an update on Aug. 27. “All turbidity (the amount of suspended particles in the water) instrumentation continues to be within normal operating parameters.”
There has been no interruption to municipal electric service – although two hydroelectric powerhouses, Holm and Kirkwood, have been out of commission since last Monday due to the rim fire. Crews succeeded in making some repairs on Kirkwood Aug. 26 in preparation for power restoration.
The SFPUC has been making up the difference in power generation by tapping a power bank and making supplemental power purchases on the open market – a pricey alternative that's cost the city around $600,000 so far, according to an Aug. 26 update.
A video of the rim fire shot from a Cal FIRE plane. The blaze has increased considerably in size since Aug. 22 when this footage was captured.