Restoring Yosemite’s Hetch Hetchy Valley could cost billions |

Restoring Yosemite’s Hetch Hetchy Valley could cost billions

Terence Chea
Tim Connor / Environmental Defense / The O'Shaughnessy Dam spans the Hetch Hetchy reservoir in Yosemite National Park.

SAN FRANCISCO (AP) – It would cost between $3 billion and $10 billion to tear down a massive dam and restore Hetch Hetchy Valley in Yosemite National Park more than 80 years after it was flooded, a state report said Wednesday.

The valley, once described by conservationist John Muir as “one of nature’s rarest and most precious mountain temples,” was plugged in 1923 to provide drinking water, irrigation and hydropower to the Bay Area and Central Valley.

The study by the state Department of Water Resources made no recommendations on what to do next, but said further investigation should include participation by other stakeholders including the federal government, which oversees the national park in the Sierra Nevada.

Environmentalists have sought for decades to remove the 312-foot O’Shaughnessy Dam, but opponents say draining and restoring the submerged valley carries too high a price at a time when California has more pressing infrastructure needs.

Hetch Hetchy Reservoir on the Tuolumne River generates 1.7 billion kilowatt-hours of electricity and provides drinking water to 2.4 million San Francisco Bay area residents.

The restoration campaign gained new momentum two years ago when Environmental Defense published a study arguing that water quality and supply could be maintained if the dam was removed.

That report, along with requests by state lawmakers, prompted Gov. Arnold Schwarzenegger to direct the state water agency to analyze previous studies by environmental groups, academic researchers and the U.S. Interior Department.

The study released Wednesday highlighted the technical and legal challenges associated with dismantling the dam, draining the reservoir and replacing the water storage and electricity they provide. The cost would depend on how those issues are addressed.

“This is a very ambitious project,” said Gary Bardini, the state’s chief hydrologist.

The study’s authors said more in-depth studies would be required if the public wanted to pursue the idea. The project goes beyond the state’s jurisdiction and would likely require approval by Congress, they said.

Supporters said the study showed that restoring the glacially carved valley was possible, and called on state and federal leaders to move ahead with further studies.

“This study confirms that it is within our reach to restore Yosemite Valley’s lost twin without compromising California’s long-term water and power supply,” said Assemblywoman Lois Wolk, D-Davis.

But opponents said the study showed that the project was unwarranted at a time when California needs to increase its water and energy supplies.

“Draining the reservoir would be far too expensive and leave the state vulnerable to both drought and blackout,” Sen. Dianne Feinstein said.

Susan Leal, general manager of the San Francisco Public Utilities Commission, said the report “confirms our worst fears about the enormous costs and monumental risks to the Bay Area’s water and power supply that could come from draining Hetch Hetchy.”

Despite strong opposition, environmentalists said the study was a step in the right direction.

“We have a long way to go,” said Tom Graff, regional manager of Environmental Defense. “But restoring Hetch Hetchy Valley as a second Yosemite Valley is eventually going to happen.”

On the Net:

State Department of Water Resources:

Support Local Journalism

Support Local Journalism

Readers around the Lake Tahoe Basin and beyond make the Tahoe Tribune's work possible. Your financial contribution supports our efforts to deliver quality, locally relevant journalism.

Now more than ever, your support is critical to help us keep our community informed about the evolving coronavirus pandemic and the impact it is having locally. Every contribution, however large or small, will make a difference.

Your donation will help us continue to cover COVID-19 and our other vital local news.