US public drops dams and goes with the flow

Knocking down dams is big business in the US - a bigger business than building them, in fact. That is largely because the US public has discovered a love for wild, untamed rivers whose flows are controlled by the rains rather than sluice gates, and where fish happily migrate up and downstream with the seasons. That public would dearly love to have more than the handful of such rivers now left to them.

When supply is short, the price Americans are willing to pay rises, and even the prospect of heavy bills for tearing down dams is no longer a deterrent to taxpayers. In the past six years, engineers have removed some 175 dams, large and small, from the paths of rivers as an exercise in environmental restoration. The recent removal of the Edwards dam on the Kennebec River in Maine on the east coast cost $3 million (£1.6 million). But the stakes are rising and now there is a move on the west coast to remove one of America's largest and most controversial dams, the O'Shaughnessy dam in the Hetch Hetchy valley, which supplies water and power to more than 2 million people in and around San Francisco.

The cost of dismantling this 100m structure and finding water and power from somewhere else would be a cool $8 billion, according to the city's engineers, who rather understandably oppose the move. But this is California and it could happen anyway.

And that is why this book on the dam's origins 90 years ago, subtitled "America's most controversial dam and the birth of modern environmentalism", matters. The Battle over Hetch Hetchy is a work of modern iconography as well as history. Water politics in California is a well-worked theme today. Mark Reisner's study Cadillac Desert is a classic of environmental writing, and the wider world has seen the blockbuster 1970s movie Chinatown , a story of corruption, criminality and the flooding of a valley to bring water to desert cities. But most of the stories, Chinatown included, have been about Los Angeles and southern California.

Until now we have heard less about the north of the state. But Robert Righter, a historian, Californian and drinker of Hetch Hetchy water from a young age, makes plain that the civic water wars there were no less bitter.

Without the flooding of the Hetch Hetchy valley, there would probably be no San Francisco today. After the 1906 earthquake, it was unclear if the place had a future at all until the dam was built. The dam was, in its day, second only to the Panama Canal in the pantheons of US civil engineering. But its construction was a cause célèbre for one reason. The Hetch Hetchy was inside Yosemite National Park. Construction was fiercely opposed by the big beast of early American environmentalism, John Muir, and his Sierra Club, who took the battle to Washington, where Congress eventually passed the Bill.

Righter tells the story of that campaign and the dam's construction through the people involved, headed by Muir and the dam's engineer, Michael O'Shaughnessy. It was a heavy defeat for environmentalists. Indeed, it took another half a century before Muir's successor David Brower returned to battle against the dam-building lobby to prevent the flooding of the Grand Canyon. Thankfully, he was successful. And from there a movement to prevent dam construction took hold in the US and around the world, which has in turn spawned a movement to begin their removal and the restoration of their rivers.

Fred Pearce is an environmental writer and the author of The Dammed .