A River’s Return

A year ago, the Colorado River reached its delta for the first time in decades. Now resource managers, scientists, and environmentalists are considering the impact of that water —on people and place.

July 9, 2015

FeaturesIssue 13: July/August 2015

The pilot radioed to the airport tower—“2112 Cardinal ready to taxi for takeoff.” The plane’s wheels lifted from the ground and we were airborne. The sprawl of Mexicali dropped away. Agricultural fields broke sharply at desert dunes, and the metallic ribbon of the border wall appeared and disappeared in Hollywood-yellow sand.

At Morelos Dam, our pilot, Bob Allen, radioed to the American side to warn them of our approach. “We probably won’t cross over, but it’ll be close,” he said. The four-seat Cessna tipped, the wing outside my window shifting to a stomach-lurching 45-degree angle to the ground, and I gazed down at the beginning of the end of the Colorado River.

The Colorado has reached its delta in the Gulf of California only intermittently since the 1960s, the last time during the wet El Niño winter of 1997-98. Much fodder for despair has been found in the lower Colorado, labeled “utterly devoid of vitality” by Philip Fradkin in his 1981 book A River No More. But the river still has champions. In October 2002, 55 resource managers, scientists, and environmentalists met in Tijuana to discuss the region’s plight. They calculated that restoring just 1 percent of the river’s annual flow could help the delta revive. Francisco Zamora, director of the Sonoran Institute’s Colorado River Delta Legacy Program, called their report “a map of the possible”—a listing of riparian areas that could be protected or restored.

The map of the possible was now a real map, spread out below me in the floodplain. Between March 23 and May 18, 2014, the gates at Morelos Dam opened to release 105,000 acre-feet of water for a spring pulse flow, which mimics the surge of snowmelt that occurs on undammed rivers. An additional 53,000 acre-feet would replenish the Colorado’s base flow during a five-year pilot program. Together, this amount totals about 1 percent of the Colorado’s annual flow, spread out over a five-year pilot program. It was less than the scientists had recommended, but still a landmark moment: the first experimental release of water to the delta in history.

A single cottonwood at the Sonoran Institute’s Laguna Grande Restoration Site on the Colorado River. Laguna Grande is the largest restored site on the river south of the U.S.-Mexico border. This photo shows preparation work performed in anticipation of the pulse flow. January 2014

A single cottonwood at the Sonoran Institute’s Laguna Grande Restoration Site on the Colorado River. Laguna Grande is the largest restored site on the river south of the U.S.-Mexico border. This photo shows preparation work performed in anticipation of the pulse flow. January 2014

La Ciénega de Santa Clara, a 6,000-hectare wetland in Sonoran, Mexico. The largest wetland on the Colorado River Delta, it is maintained mainly by agriculture runoff from the Welton-Mohawk Irrigation and Drainage District in Arizona. January 2014.

La Ciénega de Santa Clara, a 6,000-hectare wetland in Sonoran, Mexico. The largest wetland on the Colorado River Delta, it is maintained mainly by agriculture runoff from the Welton-Mohawk Irrigation and Drainage District in Arizona. January 2014.

Below me, Morelos Dam stretched an L-shaped cement barrier over the river, white ribbons of water fluttering from the spillways. A broad canal diverted most of the water from the upright arm of the L, flowing perpendicular for 800 feet before bending at a 90-degree angle to run parallel to the riverbed. The canal carries Mexico’s allotment of the Colorado to the electric-green fields of Mexicali Valley, where farmers grow wheat, cotton, alfalfa, green onions, and asparagus.

I didn’t recognize the Colorado itself until Allen pointed it out to me: a narrow channel trickling out from the center of the dam, less than a quarter of the canal’s width. This was all that remained of the river that provides water to nearly 40 million people and 5.5 million acres of cropland. Millions more drink from the Colorado without knowing it, in the form of iceberg lettuce shipped from Yuma or strawberries from Imperial Valley. The water made a shockingly slender thread—but it hadn’t existed at all just a few weeks before.

Our plane circled Morelos Dam again and then winged south, following the Colorado. The river forms the border between Baja California and Arizona for the next 24 miles—though the water’s path no longer exactly follows the surveyors’ looping marks on maps. We were headed to see how far the water had made it, on its history-making trip back to the sea.

Early-morning. The Colorado River estuary was an important habitat for many species of fish and birds. The straight line in bottom left is a Sonoran Institute project to attempt to improve connectivity between the river and the gulf to improve habitat. January 2015. Aerial support by LightHawk.

Early-morning. The Colorado River estuary was an important habitat for many species of fish and birds. The straight line in bottom left is a Sonoran Institute project to attempt to improve connectivity between the river and the gulf to improve habitat. January 2015. Aerial support by LightHawk.

There’s something profound about viewing a place from a great height. I flew that day with LightHawk, a nonprofit organization that mobilizes volunteer pilots to donate flights for conservation efforts. In the weeks leading up to my trip I skimmed through trillions of pixels compiled into time-lapse images from Landsat, a satellite program run jointly by NASA and the U.S. Geological Survey. Fast-forwarding through three decades, I saw the blue squares of recharge ponds appear, the geometric blossoming of agricultural fields, and subtle pale blocks where cities ate into mountainsides. I stood witness to the delta’s demise as green turned ashen gray.

Karl Flessa, a geoscientist at the University of Arizona, first saw the Colorado River from the air in the early ’90s. “I asked a friend who just got her pilot’s license to fly me over the delta,” he recalled. The view enthralled him. He returned on foot for a closer look: “The beaches were made of nothing but shells for as far as the eye could see. For a paleontologist, this was heaven.”

Reconnect: mid-May 2014, when the river reconnected with the tidal waters of the Upper Gulf of California for the first time in over a decade. Photo by Francisco Zamora Arroyo with aerial support by LightHawk.

Reconnect: mid-May 2014, when the river reconnected with the tidal waters of the Upper Gulf of California for the first time in over a decade. Photo by Francisco Zamora Arroyo with aerial support by LightHawk.

He could find no living specimen of the once-abundant clams. Solving this mystery dominated the next decade of his research, as he studied oxygen isotopes trapped in calcium carbonate shells, indicating whether the clam had grown in fresher or saltier water. Flessa’s sleuthing revealed that the delta’s productivity had fallen by 94 percent since the dam-building era of the 1930s. Almost no fresh water reached the gulf after the 1960s.

The delta’s fate rests almost entirely in human hands now, a legacy that began with the 1922 Colorado River Compact, which divvied up 16.5 million acre-feet of water—more water than the river carries in normal years—among seven U.S. states. In the U.S.-Mexican water treaty of 1944, the United States agreed to leave an additional 1.5 million acre feet in the river for Mexico, roughly 10 percent of the river’s long-term average. Almost all of Mexico’s allotment waters the fields of Mexicali Valley, where more than 15,000 farmers rely on the Colorado River for their livelihoods.

The need to balance the demands of cities, farms, and ecosystems drove the creation of Minute 319, an amendment to the Law of the River that allows the United States and Mexico to share both shortages and surpluses of Colorado River water. The agreement came at a time of deep concern over water, with California facing mandatory restrictions and Arizona officials predicting cutbacks to their Colorado River share as early as 2017. It was a strange time to consider restoring water to the environment, but that’s exactly what Mexico wanted to do. Minute 319 committed both nations to the experimental release of water to the Colorado’s final 75 miles.

The pulse flow came from Mexico’s allotment, stored temporarily in Lake Mead after an Easter Day earthquake in 2010 damaged irrigation infrastructure. The base flow (the year-round current normally fed by groundwater) was provided by the Colorado River Delta Water Trust, a binational coalition of environmental groups that purchases water rights from willing farmers. This water began irrigating trees in key restoration areas in December 2012, more than a year before the dramatic release of the spring pulse garnered the attention of national media.

Flessa now serves as co-chief scientist for the Minute 319 Science Team, which includes members of the Sonoran Institute, Nature Conservancy, U.S. Bureau of Reclamation, U.S. Geological Survey, University of Arizona, Universidad Autónoma de Baja California, and Pronatura Noroeste, a chapter of Mexico’s largest conservation organization. Their task is to evaluate the response of the ecology, hydrology, and biology of the region during the pilot program.

During the pulse flow, hundreds of people would come down to the water for spontaneous celebrations of the river’s return. There were food vendors, beer, barbeques, kids playing, friends kayaking. Once the water was gone, these celebrations ended. Photos courtesy of the Sonoran Institute. For more images of the pulse flow on the ground and in the air, visit Facebook.com/SaveTheColoradoRiverDelta

Officially, scientists aren’t tracking the social response to the restoration project, but some suspect it outstrips the euphoric response of cottonwoods. At San Luis Río Colorado, 20 miles downstream from Morelos Dam, hundreds of people gathered to watch the Colorado arrive. Flessa described the scene to me later: music blaring from the backs of pickup trucks, bottles of beer cracked open, and “literally a Mexican brass band” playing into the night.

The gathering began the day the gates at Morelos Dam opened. “Never mind that the water wasn’t arriving until Tuesday,” Flessa said. “They were having a good time.” Later, Flessa watched an elderly man help his mother bathe in the river beneath the bridge at San Luis, something she’d probably done as a girl. Nearby, children splashed and swam. Anyone below the age of 16 had never known the river as anything but dry.

Agriculture fields in Sonora, Mexico, abutting the Colorado River, separated by an irrigation canal carrying Colorado River water. Sierra de Los Cucapah is in the background. Aerial support by LightHawk. Much of the winter greens consumed by people throughout the United States are grown in this region, including lettuce, kale, chard, onions, and cilantro. It is all irrigated with Colorado River Water. January 2015.

Agriculture fields in Sonora, Mexico, abutting the Colorado River, separated by an irrigation canal carrying Colorado River water. Sierra de Los Cucapah is in the background. Aerial support by LightHawk. Much of the winter greens consumed by people throughout the United States are grown in this region, including lettuce, kale, chard, onions, and cilantro. It is all irrigated with Colorado River Water. January 2015.

Ecologists chose a few special places along the lower Colorado to focus their efforts to restore the long cottonwood-willow galleries that grace desert streams. The primary focus, Laguna Grande, is a 1,200-acre land grant from the Mexican government secured by the Sonoran Institute and Pronatura Noroeste. They hope to restore 750 acres of riparian habitat within Laguna Grande before the end of the five-year pilot program.

In advance of the pulse flow, ecologists bulldozed through thickets of exotic saltcedar trees and cleared areas for the cottonwood and willow seeds to land. They planted seedlings by hand in some areas, broadcast seeds in others, monitored birds, and measured groundwater levels. Just six weeks after the simulated flood, researchers spotted two-inch high seedlings of willow and cottonwood pushing up through the riverbank debris, slender sprouts of optimism.

Saltcedar sprouted as well in the wake of the pulse flow, an undesirable but somewhat inevitable result. It’s too soon to know if willows and cottonwoods will be able to compete with the exotic trees. Flessa noted that the restoration of native vegetation was most effective in areas where the ground had been “pre-scoured” with bulldozers, since the flood itself was not large enough to sweep clean the riverbanks and make a landing pad for seeds. “Instead of water doing the work, people did the work,” he explained. “That’s probably an efficient use of water, and of people, too.”

One immediate response to the flood was an increase in migratory birds. Birds have remained abundant in the river corridor over the last decade, but diversity has declined. Birds accustomed to farm fields and urban areas moved in, while native species that rely on riparian habitat and open water vanished. Scientists need time to determine the long-term effects of the experimental release on bird populations. Hydrologic responses were clearer: the water table near the river rose rapidly after the flood, and then dropped again. Much of the water released from Morelos Dam infiltrated to the aquifer, where it remains available to trees.

Perhaps the most charming preliminary result from the experiment came from the Landsat 8 satellite, which has trained its imaging spectroradiometer on the river corridor since 2000. The satellite charted an increase in plant stress in the years leading up to the pulse flow. After the flood, Landsat 8 measured a 36 percent increase in “greenness” compared with the previous year.

The upper estuary of the Colorado River is where the river historically met the Gulf of California. Sierra de Los Cucapah is in the background. January 2015. Aerial support by LightHawk.

The upper estuary of the Colorado River is where the river historically met the Gulf of California. Sierra de Los Cucapah is in the background. January 2015. Aerial support by LightHawk.

Each shovelful of soil is an act of faith. There’s no guarantee that water will continue to flow in the lower Colorado. At the close of the Minute 319 pilot program, the United States and Mexico will re-enter discussions about the delta’s fate. “I think a lot of people want to do it again,” Zamora said. “Are we going to be able to do it again? We don’t know. But at least it’s different from five years ago. Now a lot of people are very supportive and willing to come back and talk about it.”

That’s a sea change in western water politics, which more often involves maelstroms of contention and dispute. The region’s decades-long drought has brought former antagonists to the negotiation table. Drought engenders change. It requires that we tackle the daunting task of deciding what we value, and make difficult choices that will shape the future.

The view from above—if not as intimate as the celebration in San Luis Río Colorado, where people touched and tasted the water—offers, quite simply, perspective. Americans didn’t think to hold an Earth Day until after Apollo astronauts transmitted home a photograph of our planet suspended like a Christmas ornament in space, delicate as a soap bubble, swaddled in clouds.

I asked Flessa what he’d do if money and time didn’t limit the restoration work, expecting to hear something about purchasing more water, collecting more satellite data, or planting more trees. He was quiet for a moment. “There’s a railroad bridge a bit upstream from the Sonoran Institute’s restoration site,” he said finally. “I’d love to see a park at the site. It wouldn’t take much water to increase the water level there, and there’s shade, something that’s important to that part of the world. It’s an optimal place for people to reconnect to their river.”

Residents of San Luis Río Colorado, Sonora, view the Colorado River near the peak of the pulse flow. Many people in this community have never seen water in the river. April 2014.

Residents of San Luis Río Colorado, Sonora, view the Colorado River near the peak of the pulse flow. Many people in this community have never seen water in the river. April 2014.

“The whole idea about the delta restoration is that it’s not just about trees and birds and groundwater,” he added. “It’s really about the people.”

Scientists still have much to learn from the experiment about the intricate workings of the groundwater table, the needs of trees and birds and beavers. But it has already proven that we can design water policies to bend gracefully to environmental ethics in the decades ahead. Cities and farms can begin to look at ecosystems with new eyes: not as an intolerable competitor for water in an arid land, but as the provider of everything we will ever eat, drink, build, create, or imagine. ✜

Melissa Sevigny is a science writer from Tucson. She writes more about western water politics and river restoration in Mythical River, forthcoming from the University of Iowa Press.







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