A century ago the great conservationist John Muir fought his last great battle: a doomed effort to prevent San Francisco from damming the Hetch Hetchy Valley, roughly the northern third of Yosemite National Park.

Today, Muir's philosophical descendants are aggressively pushing to return the valley to its natural state by either removing the O'Shaughnessy Dam or at least draining the valley to restore the flora and fauna that once lived there.

The effort not unexpectedly faces a virtual flood of opposition by San Francisco water district and city/county officials and has been vehemently opposed by U.S. Sen. Dianne Feinstein. San Francisco officials have thus far turned a deaf ear to suggestions they at least study the idea, according to group officials.

Feinstein once called it "the worst idea since selling arms to the Ayatollah." But her office did not respond to an email request for a current position.

Some opponents scoff at the proposal as a pipe dream. But if it is a pipe dream, the pipes rival the size of the giant ones that bring water to much of the Bay Area, including Palo Alto and many other cities in the region.

A severe drought year may not be the most opportune time to float the concept. But for longtime Palo Altan Peter Van Kuran, a retired marketing and business manager, restoring Hetch Hetchy Valley is a cause well worth pursuing. He serves as treasurer for the Berkeley-based Restore Hetch Hetchy, under Executive Director Spreck Rosekrans — who has been almost as diligent as Muir himself in pushing the restoration idea. Rosekrans works from a modest office in Berkeley adorned with photos of Hetch Hetchy Valley as it once was.

The group was formed as the Hetch Hetchy Restoration Task Force in 2000 in the Merced living room of Marsh Pitman, a Sierra Club member. Rosekrans became executive director in 2011. He formerly was on the staff of the Environmental Defense Fund.

Those involved did "under the radar" research and outreach prior to going public, he said.

A major boost came when the Sacramento Bee did a major article outlining water-resource alternatives; the article won a Pulitzer Prize.

A large part of today's incentive for restoration is that when the dam and the Hetch Hetchy reservoir were authorized by President Woodrow Wilson in 1913, as the Raker Act, the Hetch Hetchy Valley was already part of Yosemite National Park. It was considered the "second Yosemite Valley" in its pristine grandeur and sweep of granite walls, waterfalls, plants and animals. It earlier had been the seasonal home of native Americans for an estimated 6,000 years.

But the 1906 earthquake and fire had created an intense awareness of the unreliability of existing water-supply systems, and San Francisco leaders urgently began lobbying for rights to Sierra Nevada mountains' water. The city's allies and supporters began a multi-year effort to gain rights to develop the Tuolumne River, which feeds Hetch Hetchy reservoir and other reservoirs and facilities that are part of today's water system — transporting the water through the massive aqueduct that feeds the water temples in Sunol and Woodside and the Crystal Springs Reservoir above Redwood City.

An excellent history of the struggle can be found on Wikipedia. And a full outline of the Restore Hetch Hetchy proposal, including comparative photos, is at hetchhetchy.org. The proposal is to create a low-intensity version of the Yosemite Valley, absent the commercialization and development that exists there today. What Muir called "the bathtub ring" on the granite walls, caused by the drowning of the dark lichen once there, would eventually fade as the lichen returns, perhaps with some human assistance, Rosekrans said.

Van Kuran said he moved to Palo Alto in 1968 to attend the Stanford Graduate School of Business and spent 37 years working for Silicon Valley companies in sales and marketing, most notably for Tandem Computers, now part of HP Inc.

He said he discovered Yosemite National Park through attending the High Sierra Summer Camp and has had a "lifelong love of Yosemite," with its hundreds of miles of trails through the valleys and Tuolumne Meadows region.

"I was always aware of the big reservoir, which is a huge violation of the national park system," he said.

Some years back Van Kuran came across a performance in Yosemite by actor Lee Stetson, who does a high-end recreation of John Muir that includes among various tales his efforts to preserve the integrity of the park against sheep — "four-footed locusts," he called them — and against San Francisco's plan to dam the Hetch Hetchy Valley.

Stetson is scheduled to perform at the group's annual dinner in March in Berkeley, Van Kuran noted.

Van Kuran said he sees strong support for restoring Hetch Hetchy in the Palo Alto region, even though nearly all its water comes from the Hetch Hetchy system.

"I think the sentiment is moving toward restoration," he said, as information gets out that there are other storage facilities in the system and that the region would still get the same high-quality Sierra granite water.

"It's still from the Tuolumne River, just stored in different places," he said. The reservoir behind O'Shaughnessy Dam "is actually quite small" compared with other reservoirs, with just over 360,000 acre-feet behind the 430-foot-high dam. Even so, it is the largest of the city's eight reservoirs in its system.

If the dam were to be left in place and the reservoir drained, it would be unsightly but could be a large "monument to an albatross," he said.

A 2012 vote in San Francisco on restoring the valley failed, with just 22 percent support. Even officials of communities served by Hetch Hetchy water were nervous about the outcome and the future of a dependable high-quality water supply.

Restoration advocates have now turned to the courts, contending that the approval of the Raker Act violated California's constitution and the fundamental intent of the national parks. Support has come from several sources and includes several former state officials, Rosekrans said.

John Muir would be proud.

Former Weekly Editor Jay Thorwaldson can be emailed at [email protected]