Overview of the Hetch Hetchy Water System

(KTSF by Jessie Liang)

Water is the source of life and the most critical resource in our lives. Our Hetch Hetchy Water Special Report will help you understand our water source and supply that serves 2.5 million people in the Bay Area. Of the three water agencies that serve the Bay Area, the San Francisco Public Utilities Commission (SFPUC), the Santa Clara Valley Water District and the East Bay Municipal Utilities District (EBMUD), the SFPUC covers the largest population. Do you know where these 2.5 million people get their drinking water from daily? Let’s see how some San Franciscans answer the question:

“Drinking water? I don’t know.”

“I don’t know. Maybe from a reservoir?”

“It’s Hetch Hetchy water.”


Yes. The 26 cities and water agencies in the Bay Area rely on the snowmelt in the Sierra mountains in Nevada that flow down the Tuolumne River from Yosemite National Park, delivering water to the Bay Area residents, including the 800,000 San Francisco residents and the 1.7 million people in San Mateo County, northern Santa Clara and southern Alameda counties.

But why do we get water from a remote area of Yosemite National Park?

SFPUC General Manager Ed Harrington said, “The Spring Valley Water Company started in San Francisco back in the 1800s. They had water from the peninsula watershed that came to San Francisco.”

San Francisco at the time saw its population booming and water supply became an issue. In 1899, the American Geological Institute suggested building a dam in the Hetch Hetchy Valley inside Yosemite National Park. The 3-day fire resulting from the 1906 earthquake was a catalyst to building a new water system.”

SFPUC spokesman Tyrone Jue said, “The most devastating part of the earthquake was that 50 % of the city was burned to the ground because of lack of water to fight the fire. That really drove the public sentiment and the nation to allow us to look at the alternative water site such as the Hetch Hetchy Reservoir.”

In May 1908, the federal Interior Department approved the Hetch Hetchy construction. Two years later, San Francisco voters passed a $45 million bond measure for financing the project. The initial design for the system was completed in 1912.

Within ten years or so, early environmentalist and Sierra Club founder John Muir launched his national anti-dam campaign. Restore Hetch Hetchy Executive Director Mike Marshall said, “The Sierra Club created a national group with the help of over 200 newspapers, to oppose destroying the Valley.”

After numerous hearings, Congress passed the Raker Act in 1913 approving the building of the Hetch Hetchy Dam. Construction started in 1914 and finished 9 years later. Michael O’Shaughnessy was the chief designer and architect for the project. The dam was named after him and became his legacy. In October 1934, Hetch Hetchy water finally flowed from Yosemite National Park to the Pulgas Temple, built near the Crystal Springs Reservoir.

The Moccasin power house up north was completed in 1925 and to this day, generates hydroelectricity for the Hetch Hetchy system. The city bought out the Spring Valley Company, officially owning and running the system, which is considered a construction miracle of the 20th century.

It is a spectacular water supply system. Its gravity-fed design without any pumping device goes through some 160 miles of pipes and has delivered pristine water to the San Francisco Bay area for over 70 years. How is the water transported, treated and turned into drinking water for residents?

(Copyright 2012 KTSF.  All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)
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