Part I: a journey down the aqueduct
By Greg Reis
Editor’s note: The following article is the first in a series of four which will take a close look at the sources and infrastructure of Los Angeles’ water. Understanding where your water comes from, how it gets to you, and the associated consequences and trade-offs lie at the heart of responsible water use. We begin the series right here in the Mono Basin with water diverted from Parker, Walker, Rush, and Lee Vining creeks.
Deep under the Mono Craters water rushes through a dark carbon dioxide-filled tunnel as more water trickles in to add to the flow. Eleven miles of tunnel later, the water spills through a flume, back into bright sunlight, through watercress beds, and into the slow-moving Upper Owens River. Water from Grant Lake Reservoir on Rush Creek has just flowed through an active chain of volcanoes.
Once in the Upper Owens, the water meanders past yellow-headed blackbirds, grazing cows, and anglers, finding its way to Crowley Reservoir. Here the 16,000 acre-feet (AF) from the Mono Basin sits with up to 167,000 AF of water native to the Owens River watershed, waiting for L.A.’s water demand to determine when it will make the rest of the trip.
On its way again it rushes into penstocks—big, metal pipes—alongside the Owens Gorge that carry it to turbines which generate electricity. Thanks to precedent-setting cases at Mono Lake, the Owens River at the bottom of the gorge once again carries some water. After the water is released from Pleasant Valley Reservoir, it meanders in the Owens River past Bishop and Big Pine on the floor of the Owens Valley. Soon it reaches Tinnemaha Reservoir, where it reflects herds of Tule Elk before being released back into the Owens River for a short final distance before it is diverted into a canal at Aberdeen.
As the open canal moves south, it slowly moves farther from the Owens River and begins contouring the side of the Alabama Hills near Lone Pine. High on the side of the valley it passes Owens Dry Lake—now being partially flooded to control the terrible dust storms. After passing through the Cottonwood Treatment Plant, it sits in the Haiwee reservoir before being sucked into pipes that use gravity and siphons to cross the Mojave Desert. In a tunnel it crosses the San Andreas fault, an active geologic feature like the Mono Craters. It sees the light of day once again at the Owensmouth Cascades before ozonation, filtration, chlorination, and distribution into the city’s municipal water system.
The 16,000 AF of water from the Mono Basin is currently 3% of L.A.’s annual 600,000 AF supply, and when combined with an average of 350,000 AF of water from the Owens Valley, the Los Angeles Aqueduct accounts for 60–70% of the city’s supply. In the past this supply has been as high as 84% in wet years and as low as 16% in dry years. The capacity of the aqueduct is 560,000 AF per year, and reservoir storage capacity is 325,000 AF. Evaporation from these reservoirs is significant, consuming about 5% of the city’s water supply. The water exceeds almost all drinking water standards (see page 9), which makes it more valuable than L.A.’s other sources of water.
The cost of this water to the city is the managment of 315,000 acres of watershed lands in the Eastern Sierra, property taxes, and maintenance and operation of the aqueduct. Since the water generates over 1 billion kilowatt-hours of electricity at 11 powerplants on its way downhill, selling this power—enough for 220,000 homes for one year—more than pays for these operations costs. The larger cost of this water to all of us comes in terms of the negative environmental, cultural, and health impacts that excessive diversions have caused in the Eastern Sierra.
This aqueduct is the connection between Mono Lake and the city of Los Angeles. Tenuous in places, a thin lifeline across a vast desert for 3.8 million people each using an average of 136 gallons of water a day, yet very real and very powerful.
Further reading about the Los Angeles Aqueduct: Water and Power, by William L. Kahrl; Storm Over Mono, by John Hart; Cadillac Desert, by Marc Reisner.
Greg Reis is the Committee’s Information Specialist. In Part II, he will examine the local sources of water on which L.A. has depended since it was a small, remote Mexican pueblo surrounded by cattle ranches.
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