Yosemite’s Long-Lost Twin Could Be Resurrected
Yosemite’s Long-Lost Twin Could Be Resurrected - Environment - 05 November 2012
For a century, the Yosemite Valley’s beautiful “twin” has been drowned under 90 metres of water. A controversial project dammed the river that flows through the iconic Yosemite National Park, turning the 1180 square kilometre Hetch Hetchy valley into a giant reservoir. It now supplies most of the San Francisco Bay Area’s water and some of its hydropower.
This week, San Francisco will vote on plans to drain the reservoir and restore the valley to its original majesty. New Scientist looks at what might be achieved.
Why was Hetch Hetchy flooded?
In 1913, despite strident opposition from the nascent environmental movement, the US Congress voted to build a hydropower dam - the O’Shaughnessy Dam - across the Tuolomne River, which flows through what is now Yosemite National Park, and pipe its water to San Francisco 258 kilometres away. Spreck Rosekrans, policy director of Restore Hetch Hetchy, suspects that the bill was passed partly out of sympathy for San Francisco after its 1906 earthquake.
Hetch Hetchy has been flooded ever since, and now supplies 85 per cent of the city’s water. It is so pure, the city does not even filter it.
Wasn’t that rather destructive?
A project like this could never happen today, as Yosemite National Park is now protected from development. But the bill was controversial at the time, most famously opposed by naturalist John Muir. In his 1912 book The Yosemite, Muir wrote: “Dam Hetch Hetchy! As well dam for water-tanks the people’s cathedrals and churches, for no holier temple has ever been consecrated by the heart of man.”
The Sierra Club, which Muir co-founded, has campaigned to drain Hetch Hetchy over the past century, but chose not to involve itself in this year’s vote.