O'Shaughnessy Dam

The O'Shaughnessy Dam is a dam on the Tuolumne River in the Hetch Hetchy Valley of California's Sierra Nevada mountains. The dam is located inside Yosemite National Park. It creates the Hetch Hetchy Reservoir.

The water is transported from the reservoir by the Hetch Hetchy Aqueduct. Hydroelectricity is also produced by Kirkwood Powerhouse and Moccasin Powerhouse, which have a capacity of 118 MW and 100 MW, respectively. Hetch Hetchy Reservoir is a municipal water supply and its water is not even filtered, so swimming and boating are prohibited. Fishing is allowed, but only from the shore of the Reservoir

The dam provides water and electricity to 2.4 million people in the city of San Francisco, San Mateo County, Alameda County, and the San Joaquin Valley. The power-generation facilities and transmission lines are concealed to protect the valley's famous scenery. The reservoir's capacity is 0.444 cubic kilometres (360,360 acre-feet).

The O'Shaughnessy Dam is quite near to Yosemite's western boundary, but the long, narrow, fingerlike reservoir stretches eastward for about 12.5 km (over 8 miles). Some of the former scenic beauty of the valley remains, though the fluctuating water level creates a conspicuous white band at the waterline.

Construction

The dam was proposed in 1903, when the city of San Francisco applied to the Department of the Interior for water rights in the area. The Sierra Club resisted for the next ten years. John Muir, its president and founder, declared, "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 Raker Act of 1913 left the dispute unsettled. Construction was completed in 1923. The dam then stood 111 metres (364 feet) high; its present height of 131 metres (430 feet) was achieved only later.

Subsequent disputes

However, the Raker Act specified that because the source of the water and power was on public land, no private profit could be derived from the development. The city of San Francisco, in violation of this provision ^*, sold the power to PG&E, which in turn sold it to the general public at a profit. Harold L. Ickes of Roosevelt's Interior Department tried for many years to enforce the Raker Act, but he was unsuccessful. Control of Hetch-Hetchy-generated power remains in the hands of the PG&E corporation.

The Sierra Club currently advocates removing the dam, but the city of San Francisco opposes, because the reservoir currently serves 2.4 million people, including parts of San Mateo County, Alameda County, and Silicon Valley. Deconstructing the dam would cost millions.

In 1987, the idea of razing the O'Shaughnessy gained an adherent from Don Hodel, then secretary of the Department of the Interior under President Ronald Reagan. Hodel called for a study of the effect of tearing down the dam. The National Park Service concluded that two years after draining the valley, grasses would cover most of its floor and within 10 years, clumps of cone-bearing trees and some oaks would take root. Within 50 years, vegetative cover would be complete except for exposed rocky areas: eventually a forest would grow, rather than the meadow being restored ^*.

Some people, such as Carl Pope (Director of the Sierra Club), stated that Hodel had political motives ^*. The imputed motive was to divide the environmental movement: to see residents of the strongly Democratic city of San Francisco coming out against an environmental issue. Then mayor of San Francisco and supervisor for the county of San Francisco, Dianne Feinstein said in a Los Angeles Times story in 1987: "All this is for an expanded campground? ... It's dumb, dumb, dumb." Hodel, now retired, is still a strong proponent of restoring Hetch Hetchy Valley and now-Senator Feinstein is still strongly against restoration.

External links

Dams in California | Yosemite | Sierra Nevada | Water in California

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Construction

Subsequent disputes

External links