- This Week
Environmentalists want to tear down O'Shaughnessy Dam and restore the Hetch Hetchy Valley, but does their plan hold water?
08.09.11 - 2:03 pm | Rebecca Bowe |
Kolana Rock towers above Hetch Hetchy Reservoir in Yosemite National Park.PHOTO BY CHRIS ROBERTS
SFPUC spokesperson Tyrone Jue said Hetch Hetchy water does not require filtration "because basically, it's a giant granite basin there in the reservoir, so there's no sedimentation." He added that the water quality is exceptionally high. "It's high up in the watershed. The higher up in the watershed, the better it is."
Restore Hetch Hetchy has submitted a number of proposals to ensure that San Francisco could still receive adequate supplies without the reservoir, including constructing a new intertie at Don Pedro Reservoir, which lies downstream from Hetch Hetchy, to get drinking water supplies from there instead.
Under this scenario, the SFPUC would continue to get its water from the Tuolumne River — but it would have to build a new filtration system to treat it because the water quality would be worse and the city would lose its federal waiver.
That's an expensive consideration, particularly at a time when city coffers are depleted, critical services for vulnerable populations have been gutted, and taxpayers are wary of authorizing costly new endeavors.
Marshall defends the cost by asserting that the current system is flawed; the lack of filtration makes San Francisco's water more susceptible to contamination from nasty microorganisms like cryptosporidium and giardia, he says.
"San Francisco has a unique health demographic in that over 5 percent of the people that live in the city have compromised immune systems, if you just look at people who are HIV positive," he said. "Ultimately, San Francisco is going to be forced to filter its water, so why are we kicking this can down the road?"
But filtering water at the residential level would be far cheaper than tearing down the dam. Jue pegs the cost of a new filtration system at somewhere between $3 billion and $10 billion, but Marshall rejects that estimate as "just crazy."
So we called Xavier Irias, director of engineering at the East Bay Municipal Utility District. "Ten looks a little high, but the three sounds very credible," Irias said, acknowledging that there were many complicating factors that could affect cost. Ultimately, he said, the cost range could be anywhere from half a billion to the single-digit billions of dollars.
"With the filtration costs, not only are you talking about building a facility to filter the water, you're now talking about increased power consumption to basically power those filtration plants," Jue noted. "You'd have to start pumping water, which would require additional energy. And then on top of that, there's the long-term operation."
What's more is that the quantity of water that San Francisco now depends on wouldn't be guaranteed every year. According to an analysis done in partnership with the Environmental Defense Fund, reconfiguring the system to tap Don Pedro would result in 19 percent less water delivered from the Tuolumne in critically dry years, and similar losses would result from alternative proposals like tapping Cherry Reservoir, another storage facility in the SFPUC system.
Restore Hetch Hetchy has suggested that the shortfall could be made up in part with new water-conservation measures, something that cities arguably ought to be practicing anyhow since climate change threatens to bring about drier conditions in California's watershed. It could also place the city in the position of having to go to the open market to purchase water for customers — just as dwindling water supplies raise the temperature between cities and counties scrambling to secure reliable deliveries.
"The Hetch Hetchy water system is a fully owned public asset," Jue notes. "At a time when state and federal governments are struggling with even being able to close our budget deficits, to even look at dismantling an environmentally sound, cost-efficient water system that delivers water to 2.5 million people is sort of outrageous."
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