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Are We Ready to Kiss Our Big Dams Goodbye?

San Francisco's major source of drinking water comes from Yosemite's Hetch Hetchy, but there's a growing campaign to have the reservoir drained and returned to the park.

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"The best physical solution in dry years to get enough water is to have San Francisco and its customers invest in groundwater storage in the Central Valley," said Restore Hetch Hetchy's policy director Spreck Rosekrans. In wet years, he says, the city would move water to the water bank, and during dry years that banked water would be available as a trade -- agricultural communities nearby would have the water to pump for irrigation and in turn they would give up some of their rights to Tuolumne River water that San Francisco could use.

Is There the Will or the Way?

Since 1987, seven different reports have examined the feasibility of eliminating Hetch Hetchy reservoir and restoring the valley. The most recent and comprehensive, done by the California Department of Water Resources in 2006, examines all the previous studies and comes to the conclusion that there are still too many unknowns. The authors write:

This final report is a comprehensive analysis of Hetch Hetchy Valley restoration studies. But even as a comprehensive analysis, we find, first and foremost, that much study remains to be done because there are major gaps in vital information. For example, objectives for replacing the water supply for the Bay Area, dam removal methods and impacts, and considerations of the public use and benefit of a restored Valley remain largely undefined. Another critical, missing element is a formal public involvement process to engage agencies, Native American tribes, stakeholders and other interested parties in this issue...

The state concludes that the existing body of work--including its own--is insufficient to support sound public policy decision-making at this time; in fact, most of the work to date is not even at the "concept level." However, the state found no fatal flaws in the restoration concept that would preclude additional study.

The problem is, there isn't really an easy solution to coming up with the additional water needs that Hetch Hetchy currently fills. Don Pedro dam, the closest large reservoir, is actually jointly owned by the Turlock and Modesto irrigation districts, although the SFPUC has a stake in the reservoir from having financed part of the construction of Don Pedro in 1971. The irrigation districts though, appear to have little interest in wading into discussions about removing O'Shaughnessy Dam. They released a statement saying, "It does not make sense to the districts that a water-short state that desires to reduce its carbon footprint would seriously entertain the idea of removing a 360,000 acre-foot storage reservoir," the San Francisco Chronicle reported.

The two other "upcountry" reservoirs are Lake Eleanor and Cherry Lake, which are currently used for hydroelectric power and are not used for drinking water, says SFPUC's Kastama. "The next largest drinking water reservoir after Hetch Hetchy is Calaveras," said Kastama. "But it holds 32 billion gallons, against 117 billion gallons that Hetchy does." So an upgrade there to accommodate the extra capacity would be massive.

Without an easy way to increase storage in an existing facility the city would be faced with other potentially more costly and complicated options. The idea of water "banking" using underground storage has been done before in California, but not without complications -- the most notorious being the Kern Water Bank at the southern end of the San Joaquin Valley, which was built with public money but is now owned and controlled by rich agribusiness interests. Banking water in the Central Valley, where water resources are a source of continued strife between agricultural and environmental interests, could mean a tangle of politics, not to mention the fact that parts of the Central Valley's aquifers are undrinkable because of contamination from farming operations.

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