A modern photo, taken from much the same vantage point, shows the submergence of the valley floor under the waters of the reservoir.

Hetch Hetchy Valley is a glacial valley in Yosemite National Park in California. It is currently completely flooded by O'Shaughnessy Dam, forming the Hetch Hetchy Reservoir. The Tuolumne River fills the reservoir.

The Hetch Hetchy Road drops into the valley at the O'Shaughnessy Dam, but all points east of there are roadless, and accessible only to hikers and equestrians.

History

The valley was called 'Hetch Hetchy' as early as the 1860s. The name means either 'acorns' or 'edible seeds' in the Native American Miwok language [1]. Acorns are indeed available in the valley, but rare elsewhere in the high country.

In 1903, San Francisco applied to the United States Department of the Interior to gain water rights to Hetch Hetchy. This provoked a 10-year environmental struggle with the Sierra Club. The environmentalist John Muir observed:

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.

Proponents of the dam said that the valley would be even more beautiful with a lake. Muir predicted (correctly) that this lake would deposit an unsightly ring around its perimeter, which would be visible at low water. The struggle ended in 1913, with the passage of the Raker Bill , which permitted flooding of the valley. It is said that the passage of the bill broke Muir's heart: he died the following year. Construction of the dam was finished in 1923.

Recent history of the dam and reservoir can be found in the O'Shaughnessy Dam article.

Geology

Like Yosemite Valley, Hetch Hetchy was also sculpted by glaciers as recent as 10,000 years ago. The more recent glacier there was larger than the one in the paleo-Yosemite Valley. However, today the Hetch Hetchy area is drier.

On the upper portion of the valley beyond the reservoir there is evidence of relatively young lava flows. One recent flow formed the Little Devils Postpile which, as the name suggests, is a smaller version of the Devils Postpile near Mammoth Lakes to the southeast. Both formations are great examples of columnar jointing , a phenomenon that results from contraction of basaltic lava as it cools (forming hexagonal columns).

Related topics

• Tuolumne River
• O'Shaughnessy Dam
• Yosemite National Park

External links

• Restore Hetch Hetchy web site
• Sierra Club on Hetch Hetchy
• Discover Hetch Hetchy - Environmental Defense
• San Francisco Public Utilities Commission, Department of Hetch Hetchy Water and Power
• Website for teen learning expedition to Hetch Hetchy - Synergia Learning Ventures
• U.S. Geological Survey Hetch Hetchy images - About 30 are available, from both before and after the construction of the dam.