Thursday, July 9, 2009

Dry forecast for California shapes plan for new water storage sites

Contra Costa Times (California): The San Francisco Public Utilities Commission is pursuing a plan to store water underground that can be pumped out in time to supply customers in a drought, given the uncertainty of California's water future. Officials say the natural groundwater aquifer that sits under north San Mateo County will someday be full enough to send 7.2 million gallons per day to SFPUC customers in San Francisco, San Mateo and Alameda counties and much of Santa Clara County for a period of seven and a half years, longer than the last historic drought period in California.

Global warming, and the resulting anticipated loss of Sierra snowpack that feeds the Hetch Hetchy reservoir, have played a part in the SFPUC's long-term planning for water security here in the Bay Area, said Ellen Levin, deputy manager of San Francisco's regional water system.

"We may be anticipating longer drought periods, and so having additional water supplies available to us protects our customers," said Levin. "We want to reduce the need to impose rationing on our customers."

At the heart of the proposal are the five San Mateo County cities — Daly City, South San Francisco, Colma, San Bruno and Millbrae — that already plumb the common groundwater basin they overlie for part of their water supply every year. They also use Hetch Hetchy water from the SFPUC. If these cities can promise to limit the water they draw from the groundwater basin in "wet" years, they will receive an equal amount of "surplus" water from Hetch Hetchy reservoir. Thus the groundwater basin will be allowed to naturally refill with rainfall until there is enough to draw on….

Hetch Hetchy Valley, 2009, © 2009 by Dan Lindsay, who has generously released this beautiful image into the public domain

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