The Colorado River Runs Dry

Dams, irrigation and now climate change have drastically reduced the once-mighty river. Is it a sign of things to come?

Reservoirs along the river may never rise to previous levels. Utah's Lake Powell has a "bathtub ring" that rises at least 70 feet above the water. (Peter McBride)
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From its source high in the Rocky Mountains, the Colorado River channels water south nearly 1,500 miles, over falls, through deserts and canyons, to the lush wetlands of a vast delta in Mexico and into the Gulf of California.

That is, it did so for six million years.

Then, beginning in the 1920s, Western states began divvying up the Colorado’s water, building dams and diverting the flow hundreds of miles, to Los Angeles, San Diego, Phoenix and other fast-growing cities. The river now serves 30 million people in seven U.S. states and Mexico, with 70 percent or more of its water siphoned off to irrigate 3.5 million acres of cropland.

The damming and diverting of the Colorado, the nation’s seventh-longest river, may be seen by some as a triumph of engineering and by others as a crime against nature, but there are ominous new twists. The river has been running especially low for the past decade, as drought has gripped the Southwest. It still tumbles through the Grand Canyon, much to the delight of rafters and other visitors. And boaters still roar across Nevada and Arizona’s Lake Mead, 110 miles long and formed by the Hoover Dam. But at the lake’s edge they can see lines in the rock walls, distinct as bathtub rings, showing the water level far lower than it once was—some 130 feet lower, as it happens, since 2000. Water resource officials say some of the reservoirs fed by the river will never be full again.

Climate change will likely decrease the river’s flow by 5 to 20 percent in the next 40 years, says geoscientist Brad Udall, director of the University of Colorado Western Water Assessment. Less precipitation in the Rocky Mountains will yield less water to begin with. Droughts will last longer. Higher overall air temperatures will mean more water lost to evaporation. “You’re going to see earlier runoff and lower flows later in the year,” so water will be more scarce during the growing season, says Udall.

Other regions—the Mediterranean, southern Africa, parts of South America and Asia—also face fresh-water shortages, perhaps outright crises. In the Andes Mountains of South America, glaciers are melting so quickly that millions of people in Peru, Bolivia and Ecuador are expected to lose a major source of fresh water by 2020. In southwestern Australia, which is in the midst of its worst drought in 750 years, fresh water is so scarce the city of Perth is building plants to remove the salt from seawater. More than one billion people around the world now live in water-stressed regions, according to the World Health Organization, a number that is expected to double by 2050, when an estimated nine billion people will inhabit the planet.

“There’s not enough fresh water to handle nine billion people at current consumption levels,” says Patricia Mulroy, a board member of the Colorado-based Water Research Foundation, which promotes the development of safe, affordable drinking water worldwide. People need a “fundamental, cultural attitude change about water supply in the Southwest,” she adds. “It’s not abundant, it’s not reliable, it’s not going to always be there.”

Mulroy is also general manager of the Southern Nevada Water Authority, which serves two million people in greater Las Vegas. The city is one of the largest in the Colorado River basin, but its share of the river is relatively small; when officials allocated the Colorado’s water to different states in 1922, no one expected so many people to be living in the Nevada desert. So Nevadans have gotten used to coping with limitations. They can’t water their yards or wash their cars whenever they like; communities follow strict watering schedules. The water authority pays homeowners to replace water-gulping lawns with rocks and drought-tolerant plants. Golf courses adhere to water restrictions. Almost all wastewater is reused or returned to the Colorado River.

In 1922, conservationist Aldo Leopold paddled a canoe through the great delta at the mouth of the Colorado River. He wrote about a “wealth of fowl and fish” and “still waters...of a deep emerald hue.” In Leopold’s time, the delta stretched over nearly 3,000 square miles; today, it covers fewer than 250, and the only water flowing through it, except after heavy rains, is the runoff from alfalfa, lettuce and melon fields and pecan orchards.

The river has become a perfect symbol of what happens when we ask too much of a limited resource: it disappears. In fact, the Colorado no longer regularly reaches the sea.

Invasive plants, such as salt cedar and cattails, now dominate the delta, a landscape of seemingly endless mud flats where forests used to stand. And in the Gulf of California itself, shellfish, shrimp and waterfowl have declined dramatically as fresh water has dried up.

Peter McBride has spent two years photographing the great river, paddling a kayak through its headwaters, flying in small planes over cities and fields, rafting through the Grand Canyon and using his own two feet to traverse the delta. In his career, McBride, who lives near Basalt, Colorado, has taken pictures in 50 nations on six continents for magazines, books and films, but he relished the chance to turn his camera on the river that fed his childhood home, a Colorado cattle ranch. “I never knew much about where the river went and where it ended,” he says. In his work, McBride depicts not only the extraordinary scale of the human impact on the river but also the considerable beauty that remains.

McBride knew the delta was suffering, but he was surprised when he visited it for the first time. “I spent two weeks walking the most parched, barren earth you can imagine,” he recalls. “It’s sad to see the mighty Colorado River come to a dribble and end some 50 miles north of the sea.”

Sarah Zielinski is an assistant editor for Smithsonian. Peter McBride’s book The Colorado River: Flowing Through Conflict will be published in November 2010.

In a potash mine near Moab, Utah, the water is dyed blue to speed evaporation. (Peter McBride)
Reservoirs along the river may never rise to previous levels. Utah's Lake Powell has a "bathtub ring" that rises at least 70 feet above the water. (Peter McBride)
South of Kremmling, Colorado, an oxbow reflects a harsh sun. (Peter McBride)
Pistachio trees are irrigated in Arizona. (Peter McBride)
A boat casts a forlorn shadow in a dry river channel 25 miles from the river's historical end at the Gulf of California. (Peter McBride)
A Cocopah Indian surveys what was once the tribe's traditional fishing grounds. (Peter McBride)
Jonathan Waterman, entering the delta, paddled the length of the Colorado River. (Peter McBride)
Like many Western communities, Las Vegas has limited watering and restricted the planting of grasses. (Peter McBride)
Greater Phoenix continues to expand into the desert. The population of the American West is expected to grow, putting added pressures on dwindling water resources. (Peter McBride)
Photographer Peter McBride, who lives near Basalt, Colorado, has taken pictures in 50 nations on six continents for magazine, books and films, but he relished the chance to turn his camera on the river that fed his childhood home, a Colorado cattle ranch. (Peter McBride)
The Grand Canyon as seen above Phantom Ranch, looking toward the Little Colorado. (Peter McBride)
An aerial view of Lake Mead and the Hoover dam. (Peter McBride)
Once the largest dam in the world, the Hoover dam continues to provide power and water to Las Vegas. Behind the dam, Lake Mead shows the dramatic drop in water levels—now 130 feet lower than it was in 2000. (Peter McBride)
The river has been running especially low for the past decade, as drought has gripped the Southwest and demand for water continues. (Peter McBride)
Enforced catch and release measures mean this rainbow trout is headed back to the upper stretches of the river. (Peter McBride)
In the Imperial Valley, feedlots are still abundant and utilize a large supply of water. The dwindling Colorado is a growing concern for ranchers and farmers in the region. (Peter McBride)
Horse farms and other businesses depend on the river for survival. 70 percent or more of the Colorado is siphoned off to irrigate 3.5 million acres of cropland. (Peter McBride)
With over 150 golf courses and a continuing expansion into the desert, greater Phoenix continues to be a large consumer of water. (Peter McBride)
The Colorado River winds through Rocky Mountain National Park. (Peter McBride)
The Colorado meanders for nearly 1,500 miles across seven states. Over the past century, the river has been diverted for drinking water, industry and agriculture. (Guilbert Gates)
About Sarah Zielinski
Sarah Zielinski

Sarah Zielinski is an award-winning science writer and editor. She is a contributing writer in science for Smithsonian.com and blogs at Wild Things, which appears on Science News.

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