Third in a series.

At the genesis of the California Aqueduct near Tracy, a tumbleweed bears testimony to the truth that lies south. To the west of Interstate 5, parched golden grass covers desolate hills, broken only by newly planted cherry orchards. To the east, the Central Valley appears green.

In ancient times, this was an inland sea, infusing the soil with salt. In the 1800s, the Valley alternated between flooding in spring and desiccation in summer. Today, dust rises with the barest breeze across newly harvested fields. A few forlorn tomatoes share the plowed earth with drip tubing waiting to be recycled. I'm tempted to help myself to a tomato. In the distance, a lake shimmers across a width of incredibly flat land to the southwest – a mirage.

When optimistic settlers first walked this land, they saw potential in the dry, fertile soil. They dreamed of harnessing water and developing land. They envisioned new towns and farms, despite the extreme seasons.

The southwest quadrant of the Central Valley gets so little rain that it's classified as desert. The Coast Range receives far less precipitation than the southern Sierra, where even the once flowing San Joaquin River has been diverted to a trickle. Land has been plowed and planted, but salt and drainage remain the nemesis. Only fresh water can leach soil for growing – fresh water from Northern California and the Delta.

Nowhere is the lush density of the Valley more apparent than from a low-flying classic crop-duster. In every direction, we see water transported by gravity, by pumps, in sinuous rivers and straight channels, wide and narrow. It flows to dairies, orchards, field crops, carp farms, water treatment plants, towns and golf courses.

Almonds, pomegranates and cherries are high-value crops that demand a lot of water. In fields and orchards, each drop is shepherded with the latest technologies that capitalization loans can buy. A farmer stands in the shade of his almond trees next to computerized irrigation systems. A hand-held device communicates conditions beneath the soil as sensors monitor precise conditions to deliver water, fertilizer and pest control efficiently to each root system. Conserving, drop by drop, in the last five years, GPS and drip irrigation systems have been their savior.

A century ago, the Valley supported only cotton, wheat and cattle. Since then, we've engineered a colossal, agriculturally productive industrial landscape to tame the proclivities of nature's extremes. State and federal agencies, scientists, policymakers, water districts and contractors bring clean, controlled water to tap, field and habitat.

The aqueduct heads south, joined by Kern River systems. It passes an extinct lake in the Tulare basin that was drained by man but not forgotten by nature. Farms terminate abruptly at the first of three facilities that pump water 2,000 feet over the Tehachapi Mountains. In my mind, the aqueduct and ascending pipes are like an optical phenomenon – an illusion that there's enough water to both domesticate a desert and to flow uphill. The California Aqueduct crests the mountains and cascades into the Southland.

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