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SF advances plans to blend Hetch Hetchy water with groundwater

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The San Francisco Public Utilities Commission wants to use recycled water to irrigate Golden Gate Park and fill park lakes as well as irrigating two public golf courses. (Cindy Chew/S.F. Examiner file photo)

San Francisco’s plan to mix groundwater with Hetch Hetchy drinking water advanced Wednesday along with a plan to use recycled water for Golden Gate Park irrigation.

The proposal comes as California’s ongoing drought is pushing cities across the state to do more to conserve water and to increase use of recycled water in place of potable water.

The San Francisco Public Utilities Commission’s plan to use recycled water for irrigation purposes at Golden Gate Park, which currently uses groundwater, and to start using groundwater under the western aquifer for drinking water was supported Wednesday by the Board of Supervisors Budget and Finance Committee.

The Waterside Recycled Water Project will produce an average of 1.6 million gallons per day of recycled water at the treatment facility at the existing Oceanside Water Pollution Control Plant, where sewage would be treated for irrigation at Golden Gate Park and delivered through 7.7 miles of newly installed piping.

Per the proposal, water would be used to fill park lakes, irrigation of both the Lincoln Park and Presidio golf courses and possibly water uses at the San Francisco Zoo and toilet water at the California Academy of Sciences and the De Young Museum.

The committee Wednesday authorized the agency to spend $120 million of the total $180 million project cost, which was previously placed on reserve.

The committee also supported the agency’s groundwater supply project, which would ultimately pump about four millions gallons of water per day from the Westside Groundwater Basin aquifer.

“We are going to start out pumping slowly a million gallons per year and slowly ramp it up to make sure that as we develop the groundwater that it doesn’t cause any other unintended consequences either sea water intrusion or potential subsidence,” said Steven Ritchie, SFPUC assistant general manager of the water enterprise. “We want to be very careful.”

Ritchie said the mix of groundwater with the Hetch Hetchy drinking water will be around 10 percent to 13 percent for about 40 percent of the customers in San Francisco. “It will be a very high-quality water,” Ritchie said.

Before voting, Supervisor Katy Tang noted how some water customers are put off by the blending plan.

“I know that some folks have a very negative reaction to the potential blended water coming forth, but certainly we all understand our true need to be able to diversify our water sources,” Tang said.

Laura Tam, a policy director at the public policy think tank SPUR, said the project was vital. “It is important that we diversify our water supply to meet the goals of a sustainable city,” Tam said. “We have a wonderful supply in Hetch Hetchy but we could be doing more to supply local groundwater as well as recycled water. San Francisco is one of the last cities in the Bay Area to actually develop recycled water.”

The SFPUC oversees the distribution of some 60 million gallons of water to customers in The City daily from the Hetch Hetchy reservoir, 167 miles away from San Francisco along the Tuolomne River, which is filled by the Sierra Nevada melting snowpack.

A civil grand jury report released Tuesday analyzed San Francisco’s water supply amid a drought and a development boom.

“The Jury was satisfied with SFPUC water stewardship (monitoring, treatment, protection and distribution), as well as the near-term supply/demand outlook,” the report said.

The report’s conclusion was based in part on the SFPUC projecting it can manage up to 8.5 more years of drought without “drastic rationing,” the projects that advanced Wednesday and how “thanks to conservation programs, more efficient fixtures and enthusiastic public cooperation, a San Franciscan currently uses less than half the water of an average Californian (44 vs. 94 gallons per day).”

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