A River Once Ran Through It

The Colorado River Delta was an oasis for wildlife and people until the water stopped flowing

  • Joby Warrick
  • Feb 01, 2002
Photo: EJIDO JOHNSON, Mexico.
In 1922, a few miles from this dusty farming village, a young forester named Aldo Leopold slipped his canoe into the lower Colorado River and quickly lost his way in a bewildering maze of green. "Verdant walls of mesquite and willow . . . a hundred green lagoons," the storied conservationist later wrote of the Colorado's lush delta. "The river was everywhere and nowhere."

Eighty years later, tracing the Colorado's path to the sea is just as bewildering, but it is anything but green. The semi-tropical marshes and wooded riverbanks have all but disappeared, replaced in many areas by a fissured moonscape of baked mud and desert weeds. And the Colorado itself--the great waterway of the American Southwest--is, in its final stages, a mere ditch in the sand.

"The Colorado ceases to exist here," says José Campoy, a Mexican biologist, as his Dodge Ram bounces over parched tidal flats that once oozed with life. "Every drop of water goes for cities, for farms. There is nothing left for nature, nothing for the river itself."

The transformation was gradual, yet astonishing when measured against the span of a single human life. Older villagers in Ejido Johnson still remember the wild river and emerald lagoons of Leopold's time, and some once made an easy living catching fish in the river's back channels. The 3,000-square-mile delta was then one of North America's most diverse ecosystems. At one time, it was home to as many as 400 plant species and an extraordinary array of birds, fish and mammals, ranging from the rare desert pupfish to coyotes and jaguars.

At the river's mouth in the Gulf of California, the daily churning of the tides blended fresh and salt water into the perfect nursery for tiny brown shrimp and the giant totoaba fish coveted by sportsmen.

That was before Hoover Dam. From the 1930s to the 1980s, ten major dams and dozens of irrigation canals, nearly all on the U.S. side of the border, reduced the river's flow to a trickle. These days, in normal years, the Colorado's last drops evaporate in the Sonoran Desert, miles before the river reaches the sea.

The dams aren't going away, but some now say it's time for the delta to reclaim a small piece of its natural inheritance. Armed with new scientific data, a coalition of university and government scientists, Native Americans and environmental groups (including NWF) are pressing the U.S. and Mexican governments to guarantee a minimum water flow for the Colorado's delta. Says Campoy, the Mexican government's chief scientist for the delta: "It's time to give a little bit back."

But to give water back to the delta, you first have to find it. In the thirsty Southwest, every drop of the Colorado River has been apportioned by treaties among more than a dozen national, state and tribal governments. Already, the agreements promise more water on paper than the river can deliver, but not nearly enough to meet the demands of booming Sunbelt cities.

"A lot of the U.S. agencies that manage the Colorado would tell you that they would like to see the delta ecosystem restored," says Kevin Doyle, director of habitat conservation programs in NWF's Western Natural Resource Center. "But that desire is confounded by the water demands that fuel the burgeoning growth of places like San Diego, Las Vegas and Phoenix, not to mention the need to restore the river's riparian areas on the U.S. side of the border."

The Colorado's final 100 miles from the U.S. border to the Gulf of California are a slow descent into one of the most hellishly dry places in the Western Hemisphere. Death from dehydration has long been a threat to tribes indigenous to the area. Historically, those tribes regarded the river as a symbol of life. Today their descendants' fates are intertwined with that of the Colorado in ways few could have imagined a century ago.

"The water sustained our lives and sustained our way of life," says Kermit Palmer, tribal administrator for the Cocopahs. Like those of many of the delta's Native Americans, the Cocopahs' fortunes have tumbled along with the river's in recent decades.

A generation ago, notes Palmer, more than 5,000 Cocopahs lived here, tied to villages and farms that traditionally drew sustenance from the river. "We fished, hunted, harvested native plants," he says. But now the Cocopah villages in Mexico are nearly deserted, most tribal members having moved away in search of work. Tribal leaders point to the shrinking Colorado, which these days is barely navigable by canoe. "Without water nothing is possible," Palmer says.

Where the water went is no secret. The river flows that once allowed the delta to blossom are now making other deserts green, from Southern California's Imperial Valley to the wheat and onion fields in northern Mexico. Technology and massive, government-financed water management projects have harnessed the river's power.

The scale of the engineering that took place from the 1930s to the 1980s is almost without parallel anywhere in the world. Great dams such as the Hoover and Glen Canyon serve both to control spring floods and to furnish electric power for the new cities of the Southwest. Eighty major diversion channels along the 1,400-mile river irrigate farms and supply water to nearly 30 million people, from Los Angeles to booming border cities such as Mexicali, Mexico.

But there are limits to the river's bounty, as governments quickly discovered. Beginning in the 1940s, disputes over water rights prompted a series of treaties that established quotas for water use. The current formula allows U.S. states to consume nearly 90 percent of the river's average flow; of the fraction that crosses into Mexico, virtually all of it is siphoned off to supply farms and cities close to the border. No water is allocated for the areas south of Mexico's Morelos Dam. And in most years that's what the delta gets. Nothing. In the trade-off between nature and progress, it's as though no one thought to deal nature in.

"What some people fail to realize is that more water for the delta would go beyond benefiting the ecosystem and the endangered species that are clinging to survival there," says Doyle. "The Sea of Cortez is a world-class fishery that has been impacted greatly by reduced and polluted river flows, and the entire region is a stopover on the Pacific Flyway that can only become more vibrant with water."

Along the tidal flats just upstream from the Colorado's mouth, the costs of the delta's deprivation are literally piling up. Immense piles of empty shells--the remains of a once-thriving native clam population--blanket the western-facing beaches and islands. Karl Flessa, a University of Arizona paleontologist who has studied the shells, calculates at least six billion clams were alive in the delta at any given time up until the 1930s. Today, he notes, it's hard to find any.

"I had never seen anything like it: The beaches and islands were covered with shells for 40 kilometers [25 miles]," Flessa recalls of his first visit to the delta. "But then I went out on the tidal flats and couldn't find a single living individual."

The "silence of the clams," as some scientists have called it, speaks powerfully about how the changes in the Colorado's flow altered the delta's ecology. Flessa, in a study published in December 2000, estimates that the delta's biological productivity is barely 5 percent of what it was before the dams. Reduced water flows are just part of the problem, he says. The river is saltier now, thanks to large volumes of wastewater from irrigation. And the dams have stripped silt from the river, depriving the delta of a major source of organic matter. 

END RESULTS: Western sandpipers flock to the shoreline (left) near the mouth of the Colorado, a vital stopover site for many birds during their migrations. Without a nourishing mix of fresh water from the river and salt water from the Gulf of California, adjacent offshore nursery grounds for shrimp and other marine life have declined in productivity. "Every drop of water goes for cities, for farms. There is nothing left for nature," says José Campoy, chief Mexican government scientist for the delta.

"Turning off the water supply of the Colorado River also turns off the supply of nutrients that reach the northern Gulf of California," Flessa says. "And that has probably had a big effect not just on clams but on shrimp and finfish in the area."

Flessa's research and several recent studies commissioned by environmental groups have provided the first before-and-after snapshots showing the impact of 80 years of water management on the lower Colorado. The river's delta ranked among "the most productive and diverse ecosystems in the world," according to a 2001 analysis commissioned by the David and Lucille Packard Foundation and the Ford Foundation. It's this lushness that Aldo Leopold captured in the account of his 1922 canoe trip:

"Fleets of cormorants drove their black prows in quest of skittering mullets; avocets, willets and yellow-legs dozed one-legged on the bars; mallards, wigeons and teal sprang skyward in alarm," Leopold wrote in 1948 in A Sand County Almanac. "At every shallow ford were tracks of burro deer. We always examined these trails, hoping to find signs of the despot of the Delta, the great jaguar."

The jaguars are gone now, along with many of the larger mammals present in Leopold's day. Today the delta's wildlife is confined to a few pockets of green: a half-dozen wetlands fed by wastewater or natural springs and a few stands of willow and cottonwood.

Though small, these scattered oases play a critical role, supporting more than 160,000 shorebirds and 60,000 waterfowl, and at least a dozen endangered and threatened species. "Even today," says the Packard-Ford report, "the ecological resources of the delta are impressive."

But for how much longer?

It looms on the desert horizon like a mirage, but in fact La Cienega de Santa Clara is even weirder than that. It is a huge semi-tropical swamp in the middle of one of North America's driest, hottest places: a natural wonderland created entirely from wastewater.

"You go from desert and sand dunes to this: an oasis in the middle of nowhere," says Campoy, nodding toward a curtain of green that rises jarringly from a landscape of sunbaked monotony. On closer inspection, the 50,000-acre Cienega--"wetlands" in Spanish--reveals itself to be a vast river of cattails and reeds, broken at intervals by watery passages navigated by ducks and geese. Here, Campoy says, migrating birds return to feed, drawing larger predators such as eagles and bobcats. These days, the area also attracts cash-paying visitors: bird-watchers from the North.

By far the largest intact marsh in the delta today, the Cienega was created accidentally when agricultural wastewater, originating from farms in the United States, began pooling around a natural depression in the desert in 1977. By the time it was first spotted on satellite photos two years later, the Cienega covered thousands of acres and was becoming, by default, a magnet for the region's wildlife. Today, this happy accident is the world's most significant repository for two endangered creatures, the Yuma clapper rail and the desert pupfish.

Despite its origins, the Cienega is now a powerful symbol for supporters of delta restoration--a reminder of what the delta was in the past and could again become. At the same time, says Campoy, it is a symbol of what the delta stands to lose if water pressures in the United States prompt farmers and cities to tap into the delta's last remaining water sources.

For the Cienega, the immediate threat is the possible loss of the irrigation wastes that have sustained it for 24 years. This chemical-laden water, which flows through a 50-mile canal from Arizona's Mohawk Valley, is too salty for irrigation. One proposal being considered by federal officials would divert the water instead to an Arizona desalting plant.

Other delta habitats face a more immediate threat: a sharp curtailment in the "surplus flows" that flood the lower Colorado in wet years. The 1980s and 1990s witnessed an unusual number of surplus flows, thanks to El Niño and heavier-than-normal snowpack at the Colorado River's mountain source. Scientists linked the surpluses to an increase in fish production during those years.

Even an occasional flood would ensure the survival of the delta habitats that revived in the recent spate of wet years. But environmentalists charge that a new water-sharing agreement approved by the U.S. Department of the Interior last January could torpedo the delta's chances of getting any surplus flow. Under the agreement, California would be allowed to draw down the level of Lake Mead, the reservoir behind Hoover Dam, to meet its water needs for the next 15 years. If Lake Mead is no longer full, chances are that no water will flow south toward Mexico and the delta.

Though encouraged by the blossoming of the Cienega, Campoy doubts the delta will ever witness such a feast, or that the paradise of Leopold's day will return in his lifetime. But the scientist would settle for a subsistence diet to prevent one of the Southwest's special places from disappearing for good.

"Are we wise enough to set aside a flow and create habitat?" asks Campoy. "We're talking about the world's most managed river. But can we manage it for nature?"

Joby Warrick is a staff writer for The Washington Post.



Combating Invasive Species

In recent decades, much of the riparian habitat along the lower Colorado River and its delta has been invaded by exotic species that have displaced native plants. One fast-growing nonnative tree called saltcedar, for example, has caused severe erosion and increased flooding along the river. Its deep roots suck up vast amounts of water that would otherwise support habitat for the southwestern willow flycatcher and other endangered species. Finding solutions to the ecological problems caused by such exotics is a NWF priority. To learn more, see http://www.invasivespecies.gov.

Recognizing that North America is, in fact, one continuous habitat, NWF has also initiated a new program, Partnership for Wildlife, to provide educational and advocacy expertise to conservation groups in Mexico. The program was created in response to requests from Mexican groups that seek to adopt NWF's grassroots approach to conservation.

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