East Bay residents may notice water changes as SFPUC tests backup supply

Some East Bay residents might notice that their water has a different taste or odor over the next few days while the San Francisco Public Utilities Commission prepares for tests of a recently repaired backup water supply.

The SFPUC, which supplies water to 2.6 million resident in Bay Area counties, will be drawing water exclusively from local reservoirs, including the Calaveras Reservoir and San Antonio reservoirs in Alameda County and the Crystal Springs reservoir on the Peninsula, from today through Wednesday.

Starting Wednesday, the agency will begin drawing water from the Lower Cherry Aqueduct System, a backup water supply that was badly damaged in the 2013 Rim Fire. Customers will receive a blend of water from the Lower Cherry system and local reservoirs until Nov. 16 while the agency conducts tests to make sure repairs are complete and the system is fully functional.

About 85 percent of the water provided by the SFPUC normally comes from the Hetch Hetchy Reservoir on the Upper Tuolumne River Watershed. It is carried to the Bay Area via a system of aqueducts.

The agency owns other reservoirs, however, including Lake Eleanor and Cherry Reservoir, also in Tuolumne Court, which are normally used to generate electricity and satisfy legal requirements for water flow.

The reservoirs have historically been used to supply backup drinking water supplies during a drought year via Cherry Creek and the Lower Cherry Aqueduct, but that system had not been used since 1988. Even before the fire, it had fallen into disrepair due to age, SFPUC officials said.

The repaired aqueduct system will give the SFPUC access to more than 200,000 acre feet of water in drought years, officials said.

Unlike Hetch Hetchy water, which does not need to be treated or filtered, water from Lower Cherry Aqueduct will be treated at the Sunol Valley Water Treatment Plant.