A report released Monday by Environmental Defense is the latest attempt to sway public opinion in favor of draining Hetch Hetchy Valley and restoring to nature what conservationist John Muir called Yosemite Valley's little brother -- a "precious mountain temple" and "grand landscape garden" that now lies under 300 feet of water.
The authors of the report, "Paradise Regained," argue that water quality, supply and storage, as well as power generation, could be maintained if the Hetch Hetchy Valley, in the Sierra Nevada mountains about 160 miles east of San Francisco, were drained and restored. The study proposes a variety of alternatives for the San Francisco Bay area and the Central Valley if the O'Shaughnessy Dam were taken down.
The report comes as the Bay Area embarks on a $3.6 billion expansion and retrofit of the Hetch Hetchy water system, which seismologists warn could leave millions without drinking water if a major earthquake strikes.
"We have an amazing opportunity to return Yosemite's second crown jewel to the American people," said Tom Graff, Environmental Defense's California regional director. "It's not technically or institutionally simple, but we think it can happen if federal, state and regional agencies cooperate."
Hetch Hetchy was named after the grass native to its valley. The system provides some of the nation's highest quality drinking water to more than 2.4 million residents in San Francisco and its fast-growing suburbs in San Mateo, Santa Clara and Alameda counties.
"In a state that has faced repeated droughts and is desperate for water sources, I believe this would be a terrible mistake," Sen. Dianne Feinstein, D-Calif., said in a statement.
The first serious look at restoring Hetch Hetchy came in the mid-1980s when Interior Secretary Donald Hodel commissioned a study that concluded the valley would return to life within a decade if the dam were taken down. But the idea was shelved after it encountered intense opposition from powerful water interests.
Over the past year, the campaign to restore Hetch Hetchy has gained momentum with a University of California, Davis study published on alternative water sources, and a recent series of editorials in the Sacramento Bee advocating the valley's restoration.
Environmental Defense decided to conduct its own study after San Francisco officials declined to do a joint study two years ago.
The report concludes that the Bay Area could receive a majority of its drinking water and hydropower by using other reservoirs on the Tuolumne River. In especially dry years, water supplies could be obtained by boosting Bay Area storage capacity and water purchases from agricultural districts, as well as storing water in underground reservoirs.
The San Francisco Public Utilities Commission, which manages the Hetch Hetchy water and power system, released a statement saying it was sympathetic with the study's goals, but urged caution.
"The report today paints a very optimistic and rosy picture of the minimal impact on the Bay Area," commission spokesman Tony Winnicker said. "The reality is much more complicated. At what cost does it all happen? And who's going to pay?"
Environmental Defense says its report is only meant as a starting point for discussion. The group hopes federal, state and local agencies will agree to a more comprehensive study that could put a price tag on the project.
"Imagine the opportunity to allow nature to recreate another place like Yosemite Valley. Why not at least take a look?" said Ron Good, executive director of Restore Hetch Hetchy. "It was done by humans. It can be undone by humans."
By Terence Chea