Transcript for The Great Web of Water, segment 09 of 12


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To see the west side of the San Joaquin Valley, we go two hundred miles northwest to the Sacramento San Joaquin delta region. In this tangle of waterways, much of the land is at or below sea level. Levees protect the area from inundation. The Delta Cross Channel shunts surplus Sacramento River water, otherwise headed for the Pacific Ocean, into the delta. The forty-eight mile Contra-Costa Canal takes water to farms, homes, and factories east of San Francisco. A larger amount will go to the San Joaquin Valley, but first a giant screen blocks the way of migrant fish.

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They'll be trucked to safety because up ahead is the churning heart of the Central Valley Project which turns the old dream of lifting water into the San Joaquin Valley into everyday fact. Power from CVP dams comes to Tracy Pumping Plant. The power is used to drive great pumps. The pumps lift the water up this hill, one mile, to the little house at the end of the line. The water moves through three buried pipes, each fifteen feet wide, starting at the distant pumping station.

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Now go back to go, the pumping plant. The total lift is one hundred ninety-seven vertical feet. The horsepower available, one hundred thirty-five thousand. Beside this road, underground, thirty-four thousand gallons, one hundred forty-four tons per second, struggle up toward the little house on the hill.

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The little house on the hill is actually the air exhaust valve of the mammoth system that gives birth to the majestic Delta-Mendota Canal. The canal now snakes down the east slope of the Diablo Range, which hasn't a single permanent stream in its one hundred fifty mile length. With imported surface water, however, the land produces exuberantly. The Delta-Mendota and the state's California Aqueduct run side by side approaching San Luis Reservoir, used jointly by the CVP and the state water project. Surplus winter water from the north stored here sustains canal flow in summer. The Pacheco Tunnel will carry water to the San Felipe Division west of the dry Diablos.

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From O'Neil Forebay, a part of the San Luis Complex, the Delta-Mendota swings southeast across the valley to the San Joaquin River. The canal serves a million acres of land. At Mendota Pool, one hundred eleven miles from Tracy, the east and west sides of the web of water are linked. Northern water replaces that taken from the San Joaquin River by the Madera and Friant-Kern Canals upstream. This maintains irrigation downstream.