Water Resources Division Annual Report FY 2016-2017 | Page 6

Local Water Supplies
For the past decade, the SFPUC has been implementing a Local Water Program. This Program provides
conservation assistance, promotes recycled water to meet the City’s most significant irrigation needs, mandates
non-potable supplies for toilet flushing in new developments and develops local groundwater to enhance the
City’s drinking water supply sustainably now and into the future.
SAN FRANCISCO GROUNDWATER SUPPLY PROJECT
The San  Francisco Groundwater Supply Project is a forward-looking project that allows us to supplement our
drinking water sources by blending a small amount of local, high-quality groundwater with water from the Regional
Water System.
The SFPUC is completing construction on four of the six wells planned to extract water from the Westside
Groundwater Basin, as well as over five miles of pipelines to distribute the groundwater to local reservoirs for
blending. Two groundwater wells will also serve as emergency drinking water supplies following an earthquake or
other natural disaster, and will include a distribution system to fill emergency water tankers.
The project is pumping groundwater from wells that are 270 to 460 feet deep. The pumped groundwater is treated
and then blended with the Regional Water System supplies in the Sunset and Sutro Reservoirs before entering the
distribution system. Water from these reservoirs is distributed to over half the City, based on the elevations and
pressure zones of the reservoirs.
The SFPUC will be adding an average of up to 1 mgd of groundwater to our Regional Water System supply –
that’s about 3% of the volume in the reservoirs. Over the next several years, we will incrementally build up to an
average of 4 mgd of groundwater in San Francisco, which will represent approximately 13% of the water in the
Sunset Reservoir.
The project is currently in the start-up phase of implementation, and the individual wells and the blended water at
the reservoir outlets are sampled and analyzed regularly. All water served by the SFPUC will continue to meet or
surpass all drinking water standards set by the California State Water Resources Control Board, Division of Drinking
Water (State Water Board) and the Environmental Protection Agency. For more information about groundwater or
to view our water quality reports, visit sfwater.org/sfgroundwater.
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