Hetch Hetchy Reservoir

In 1966, exactly fifty years ago, a 6-foot diameter pipeline was snaking its way through Milpitas as part of a second line in the San Francisco water system that begins at Hetch Hetchy reservoir in Yosemite National Park. Today land in Milpitas covering the pipeline has been preserved as open space areas, and some as part of our municipal parks.

The Hetch Hetchy Water Project was originated partly in response to the tragic scarcity of water that made fighting the fires caused by the great 1906 earthquake so difficult. Work began in 1914 with the installation of a railroad line for transporting construction materials to that remote area.

Construction of the O’Shaughnessy Dam began in 1919 and was finished in 1923. On October 28, 1934 – twenty years after the beginning of construction of the Hetch Hetchy Project – a crowd of 20,000 San Franciscans gathered to celebrate the arrival of the first Hetch Hetchy water in the city.

After passing through several powerhouses, Hetch Hetchy water flows in the 167-mile Hetch Hetchy Aqueduct that travels across the Central Valley. Upon reaching the Bay Area near Fremont, the aqueduct splits into four pipelines. All four pipelines cross the Hayward fault. Pipelines 1 and 2 cross San Fran-cisco Bay south of Dumbarton Bridge, while pipelines 3 and 4 cross at the south end of the Bay. In the Bay Area, Hetch Hetchy water is stored in several local facilities, including Calaveras Reservoir, Crystal Springs Reservoir, and San Antonio Reservoir.

Today the Hetch Hetchy water system serves as the primary water source for the City and County of San Francisco as well as several surrounding municipalities in the greater San Francisco Bay Area. The dam and reservoir (combined with a series of aqueducts, tunnels, hydroelectric plants, as well as eight other

storage dams) comprise the system known as the Hetch Hetchy Project, which provides 80% of the water supply for 2.6 million people.

The aqueduct delivers an average of 31,900,000 cubic feet per day to residents of San Francisco, San Mateo, Santa Clara, and Alameda Counties. It provides about 55% of the water that Milpitas uses under ordinary conditions, and more under drought conditions.

Water from Hetch Hetchy is some of the cleanest municipal water in the United States.

National Parks System founder John Muir was heartbroken that the Tuolumne River in the beautiful Hetch Hetchy Valley was dammed up to make this reservoir, and over the years since his time, park and nature activists have repeatedly requested that the dam be removed, but fewer such requests have been heard due to the recent drought that has affected so many Californians.

by tmhs October, 2016