Hetch Hetchy pipeline scheduled for maintenance in San Mateo County

The Hetch Hetchy pipeline, which provides water to more than 2.8 million Bay Area residents, will shut from Jan. 3 to March 8 to allow for annual maintenance improvements. The project is a part of the San Francisco Public Utilities Commission’s and BAWSCA’s $140 million project to repair, upgrade and rehabilitate a 19-mile stretch of the mountain tunnel, the Moccasin Powerhouse and Reservoir and the San Joaquin Pipeline that is in need of repairs.

Sandkulla said the project won’t impact customers’ water rates or service. The project will be funded by preexisting water rates, two-thirds of which BAWSCA is responsible for, and the projects are conducted during the winter because demand for water is low during that time, she said.

Still, Sandkulla urges people to turn off automatic timers for their lawns and gardens and be aware of how much water they consume because the county is relying on its local water storage.

“We are still in a drought despite the heavy rain,” Sandkulla said.

The Hetch Hetchy system consists of more than 280 miles of pipelines, more than 60 miles of tunnels, 11 reservoirs, five pump stations and two water treatment plants, which deliver approximately 260 million gallons of water per day. 

Roughly 85% of the water comes from Sierra Nevada snowmelt, traveling 160 miles from gravitational pull from Yosemite to the San Francisco Bay Area. The remaining 15% is captured from rain runoff that flows to the Alameda and Peninsula watersheds. After the Loma Prieta earthquake, in 1989, and the drought in the 1990s, it became apparent the aging water system was in need of an overhaul, according to BAWSCA.

Joseph Sweiss, spokesperson for SFPUC, said the pipeline is shut down, inspected and repaired as needed.

“We live off of our local water supply every winter and take the upcountry system offline for maintenance,” Sweiss said.

While the pipeline is being repaired, the winter rain has been building on existing water levels at the Hetch Hetchy drainage basin. Craig Shoemaker, meteorologist for the National Weather Service, said water levels at the drainage basin are doing really well.

He has reasonable confidence that January will be an active wet month, which will add to water levels and help alleviate drought concerns.

“Generally, a lot of the sites are 150-200% compared to normal levels down there,” Shoemaker said. “It’s been wet over the Central Sierra and these coming rain systems are definitely helping.”