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Vanda Felbab-Brown discusses the water-resource stressors evolving in U.S.-Mexican border areas, which have been experiencing water shortages for decades and will continue to experience them more and more as water availability greatly decreases and becomes more unpredictable. This piece was originally published by La Reforma's Mexico Today.

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For weeks, a water dispute between the Mexican government and Mexican farmers and between the United States and Mexico was brewing and escalating. October 24 was the deadline by which Mexico was supposed to have provided the United States with all of the water from the Rio Grande it owes the United States every five years. But this year's expected water delivery set off months-long protests in Chihuahua, where drought-stricken farmers took over the Boquilla dam and opposed the water disbursement to the United States, fearing that even more of their livestock and crops would perish. Unlike previous Mexican administrations that since mid-1990s habitually failed to deliver the Rio Grande water to the United States on time, President Andrés Manuel López Obrador (AMLO) has been determined to send the water to the United States. He even deployed the Mexican National Guard to confront the farmers and protestors, with the Guard killing one of them. At the last minute, a deal was struck between the two countries to resolve the latest immediate water crisis.

The recent tensions are merely the latest episode of accumulating water stress in the Rio Grande basin.Deep challenges of long-standing water overuse and depletion in the Rio Grande remain. The problemrequires comprehensive and innovative solutions as well as major changes to agricultural and other water-use practices on both sides of the Rio Grande basin to preserve adequate water supply for people, food production, economic activity, and a vital biodiversity-rich ecosystem and to prevent the emergence of systematic theft and smuggling of water that plagues countries such as Pakistan, India, Nigeria, and Brazil. The U.S.-Mexico collaboration on innovative solutions for the Colorado River provides an important example.

Two U.S.-Mexico treaties - one agreed to in 1906 and one in 1944 - govern the shares and distribution of water between the two countries from the Rio Grande River, known in Mexico as the Rio Bravo, and the Colorado River basins. The 1906 treaty deals with the northwest portion of the Rio Grande basin - until Fort Quitman - and specifies that the United States annually delivers 60,000 acre-feet (74 million cubic meters) of water to Mexico, but allows for reductions in drought years. Those reductions do not accumulate as a water debt the United States must pay up later. Between 1939 and 2015, there have been reductions in U.S. delivery one-third of the time, with only about 6 percent of the amount delivered to Mexico during a major drought in 2013.

Southeast downstream from Fort Quitman, the sharing of water in the Rio Grande watershed is governed by the 1944 Treaty on Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande. Administered by the binational International Boundary and Water Commission (IBWC), that treaty specifies that the United States must deliver a minimum of 1.5 million acre-feet of water to Mexico annually from the Colorado River. Meanwhile, Mexico must deliver to the United States a minimum of 350,000 acre-feet of water annually from the Mexican tributaries of the Rio Grande. But the water deliveries are measured in five-year cycles, giving Mexico the flexibility of not always having to deliver the full 350,000 acre-feet each year, particularly in drought years, but being obligated to deliver the full 1.75 million acre-feet by the end of the five-year cycle. In practice, Mexico has repeatedly missed making the water payment during the five-year cycle, letting it slip into the following cycle and paying up only after large storms replenished the water supply. In contrast, the United States allocates the Colorado water delivery to Mexico first, before internal U.S. allocations are made each year. (But for decades Mexico has complained about the salinity of the Colorado River deliveries, getting the United States to adopt various remedial measures.)

The water deliveries and their delays set off hot politics. In 2013, hammered by a major drought, Texan farmers were infuriated by the Mexican water disbursement delays - akin to the fury of the Chihuahua farmers suffering from the current drought there, with the difference being that international law was on the side of the U.S. farmers. Mexico then repaid the water debt in 2016, but has been running a major water deficit since. Yet because intense rainfall has brought plenty of water to Texas farmers this year, the U.S. pressure on Mexico has been nowhere as intense as during the 2013 drought (even though Texas governor Greg Abbott and a few other politicians tried to make political hay out of the approaching deadline). Nonetheless, with good justification, there were legal concerns about Mexico violating its treaty obligations for a second five-year cycle in a row.

On the Mexican side, the politics were hotter and more surprising. Although a populist nationalist politician, President López Obrador not only maintained his approach of yielding to the United States on issue after issue, but also criticized and dismissed the protesting Mexican farmers and blamed the social strife on " big agriculture." Big agriculture in Mexico is indeed a notorious thief of water, failing to pay water dues and depleting water in Mexico over allocated quotas. But small Mexican farmers are hurting from water stress and often have no voice in water policy decisions.

Unlike in the United States where both surface and ground water is owned by many entities (including state and local governments) and private actors (including individual and corporate land owners), in Mexico, water is owned by the Mexican state. The extremely complex system of water rights and their wide variation across jurisdictions on the U.S. side create lengthy and often difficult policymaking and enforcement tangles, but they also force water decision-making processes that involve consultation and problem-solving with all stakeholders. On the Mexican side, water decision-making is set by one institution - Comisión Nacional del Agua (Conagua) - and is heavily centralized, top-down, and insufficiently consultative and respectful of the interests of the varied stakeholders. As a result, some Mexican farmers do not even know that the 1944 treaty exists or what it says: Instead, they talk of water belonging to all.

Systematically ignoring the needs of small Mexican farmers can thrust them into the hands of "water mafias" - criminal groups that siphon off water in particular localities and illegally sell it at inflated prices to industries, big agriculture, and marginalized users, whether slum residents or small farmers. Such water mafias operate from South and Southeast Asia to Africa and the Middle East to Latin America. In Mexico, water theft has been more disorganized, but large Mexican criminal groups, particularly those with experience in oil theft and illegal sale of gasoline, can easily expand into water theft and smuggling.

Despite the resolution of the current crisis, water stress is growing in the U.S.-Mexican border areas. The U.S. Southwest and Mexican states at the border have been experiencing water shortages for decades and will increasingly experience them as water availability plummets and becomes more unpredictable.

Agriculture takes up 75 percent of water consumption in the U.S. Southwest and on the Mexican side. Energy production, industry and water-thirsty fracking are other major draws. Water is also needed for human consumption, with the population in the Rio Grande and Colorado River Basins expanding dramatically in recent decades. Global warming has reduced water flows, as replenishing snow packs in mountainous headwaters melt earlier and faster and accumulate less. Global warming has also resulted in decreased rain and increased evaporation, intensifying droughts. Cumulatively, these changes have reduced water supply while demand has grown much beyond what was envisioned in 1944. The depletion is putting enormous stress on the water basins and has decimated the river ecosystems that are necessary for sustainable hydrological functioning of the basins.

In addition to being potentially in violation of the 1944 treaty prohibitions of unilateral erection of any obstruction of the Rio Grande's flow, the building of the border wall by the Trump administration is further hurting the rivers and basins and threatens dangerous flooding. The wall construction can also damage some of the 20 pan-border aquifers (not regulated by any treaty), already massively under stress by poorly monitored, poorly regulated and excessive use. The damage the wall construction has caused to the environmentally precious San Bernandino Springs and aquifer is a case in point.

The immediate resolution of the crisis is sound, and takes into account the needs of Mexican farmers: Mexico's water delivery schedule has become even more flexible and there is also new flexibility permitting that water for the United States can be made from a wider set of water sources, thus taking pressure off Chihuahua. The United States will also help supply water to Chihuahua when needed in drought emergencies.

Further collaboration and deep changes are needed. Much can be learned from the U.S.-Mexican collaboration on updating the water distribution from the Colorado River, known as Minute 323 of 2017 and Minute 319 of 2012 of the 1944 water treaty. They include a "Mexican Water Reserve" in Lake Mead through which Mexico can choose to delay the U.S. distribution of water to the country and store it in the United States, thus increasing water elevation at Lake Mead - an outcome beneficial to U.S. and Mexican users and the environment. With the water level at Lake Mead used as baseline for determining shortage conditions and cutbacks in distributions, Mexico now shares in the cutbacks along with Arizona, California, and Nevada. The negotiated Minutes also include a recognition of the natural environment as a water user ( a global breakthrough), and the provision of environmental flows to restore riverine habitats in Mexico, with the United States financing the flows and environmental restoration in exchange for water stored at Lake Mead. A Binational Water Scarcity Contingency Plan has also been established.In many ways, the Minutes are a hallmark of creative binational and subnational collaboration, and a non-zero-sum approach to commons issues.

Beyond learning from the management of the Colorado River, long-term sustainable solutions to water supply from the Rio Grande require a set of policy actions:

First, they require binational and subnational collaboration with all local, state, and federal stakeholders and establishment of common policy objectives and a joint understanding of ground realities.

Second, they require identification and development of new water sources, such as through desalination or conduction of water from more humid areas. Locating new water sources is often the preferred solution of water users and some water managers. It is necessary, but insufficient.

Third, and critically, water conservation and reuse must become key strategies at the Rio Grande and globally. This includes moving away from inefficient agricultural practices to water-savvy ones, such as the greater use of greenhouses and drip irrigation, and adopting Nature-Based Solutions.

Fourth, groundwater must stop being the undervalued, underpriced fallback to and enabler of surface water overuse and unsustainable economic practices. On neither side of the border, whether Arizona or Chihuahua, it makes sense to grow water-thirsty crops like pecans in the desert by flooding desert soil in prime heat times with water pumped out of poorly monitored and likely rapidly shrinking aquifers.

Fifth, studying, monitoring, and regulating aquifers and groundwater use, a domain in which California has taken initial baby steps, is necessary in each country separately and binationally.

Sixth, explicitly recognizing the water needs of ecosystems and the hydrological services they provide to nature and people is critical.

Seventh, to better align economic decisions with water sustainability, water must be adequately priced according to a pricing schedule escalating with water use; and serious, if very difficult, rethinking needs to be done about water rights allocation for groundwater.

Finally, such a commons approach to the Rio Grande water sustainability needs dedicated enforcement on both sides of the border: Usage and payments need to be policed, and water use violating regulations punished. Enforcing water regulations in turn requires technological innovation, increased resources for enforcement, and greater will to enforce regulations domestically, including through stiffer and reliably frequent penalties - as well as problem solving. It also demands joint determination to make binational and local arrangements work.

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Not dried up: US-Mexico water cooperation

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For weeks, a water dispute between the Mexican government and Mexican farmers and between the United States and Mexico was brewing and escalating. October 24 was the deadline by which Mexico was supposed to have provided the United States with all of the water from the Rio Grande it owes the United States every five years.

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The first story in The Guardians series about environmental justice. Provides powerful insight and personal stories about folks in Mexico facing the stark effects of the dried riverbed. Highlights the devastation of the loss of the river in Mexico and the work being done by locals to help combat this pressing issue.

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he temperature is rising toward 45C (113F) as young brothers Daniel and Dilan Rodríguez skip towards a bridge over the Colorado River in the Mexican border town of San Luis Río Colorado. But there is no water flowing through the channel of one of the world's mightiest waterways. The pair run down the river bank and cheerfully splash through stagnant puddles dotted about the riverbed.

"We wish we had a river, so we could swim, and jump and sail my cousin's boat," said Daniel, 12. "At least we have puddles to make mud balls, that can be fun."

Dilan Rodríguez, eight, fishing in the canal that runs adjacent to the dry Colorado River at the border of Mexico and the US on 6 September 2019. Photograph: Meghan Dhaliwal/The Guardian

The Colorado originates in the Rocky mountains and traverses seven US states, watering cities and farmland, before reaching Mexico, where it is supposed to flow onwards to the Sea of Cortez.

Instead, the river is dammed at the US-Mexico border, and on the other side the river channel is empty. Locals are now battling to bring it back to life.

There are few more striking examples of what has come to be known as "environmental injustice" - the inequitable access to clean land, air and water, and disproportionate exposure to hazards and climate disasters. Water in particular has emerged as a flash point as global heating renders vast swaths of the planet ever drier.

Today the Guardian is launching a year-long series, Our Unequal Earth, to investigate environmental inequalities and discrimination in the US and beyond. It will also reveal how the climate crisis is making things worse for activists and scientists on the ground.

"We've heard stories from my mum about how she used to play and swim in the Colorado River when she was little, but we've never experienced it," said Evelin Bautista, 14, who is a member of an indigenous tribe, the Cucapá, which means the River People. "I've heard that over the border, the water is so clear that they can even see the fish."

Indeed, a mere 30 miles north, over the border at Gateway park in Yuma, Arizona, siblings Damien Navarro, 12, and Dariana, eight, spent the day fishing, diving and swimming in the free flowing river.

David Barraga plays ball with his daughter Dariana and his stepson Damien in the Colorado River in Gateway park, Yuma, Arizona, on 7 September 2019. Photograph: Meghan Dhaliwal/The Guardian

"It's so hot, we come here all the time, the kids love the water, and we often catch catfish, bass and bluegill," said their father, David Barraga. "I didn't know there's no river in Mexico. Wow, that's a shame."

"At school in science we've been learning about drought, that the planet is getting hotter," said his son, Damien. "But we've never been told about the dam or the river in Mexico, maybe when we're older. It's really too bad for those kids."

Because the 1944 treaty did not allocate Mexico any water for the river itself, the channel is mostly dry. The loss of the river in Mexico has been devastating.

Nancy Saldaña, 54, an architect and activist in the Sonoran town of San Luis Río Colorado, recalls boat rides and fishing with her family during the 1980s, when the US occasionally released "extra" water to deal with heavy snow and rain that risked overwhelming its dams. Her mother, an evangelical pastor, conducted baptisms in the river until it disappeared.

"Taking away the river had a huge impact on us, it took away part of our identity. I felt anger, sadness and grief. My children had never seen the river flow."

The disparities on both sides of the border are stark.

In the US, the Colorado serves more than 35 million people, including several native tribes, seven national wildlife refuges and 11 national parks, and supports $26m tourism and recreational industries, as well as farming. California has rights to the largest quantity, with 4.4m acre-feet per year - or 29% of the total - while Utah is allocated 1.7m and Nevada 0.3m.

At the Morelos dam, located between Los Algodones, Baja California, and Yuma, Arizona, the river is diverted to a complex system of irrigation canals which nourish fields of cotton, wheat, alfalfa, asparagus, watermelons and date palms in the vast surrounding desert valley. This is good for farmers - and less so for ordinary Mexicans.

Following the dry riverbed south towards the Gulf of California evokes an eerie sadness. The sound of gunfire in one wide, dusty section led to a couple from San Diego hunting wild pigeons, and a bucketful of feathered corpses. A few miles west along dirt farm roads, dozens of herons, egrets and ducks were staking out a wonderfully lush wetland - though it is only an accidental byproductcreated by agricultural runoff from surrounding wheat and alfalfa fields.

The Colorado basin is one of 276 watersheds that cross international borders and Mexican supporters of the binational treaty argue that it resolved longstanding diplomatic disputes and enabled the region's economic development, even if there is mostly no longer a river in the channel.

"We're the only place in Mexico with a secure water supply, that is a privilege," said Francisco Bernal, the International Boundary and Water Commission (Cila) representative in Mexicali.

But the treaty didn't foresee prolonged drought, global heating and mounting demands. Now, water is running out, and things must change.

The population of Baja California grew from 1.67 million in 1990 to 3.5 million in 2018. Most of the river water still goes to farmers. Groundwater reserves are dwindling, pollution goes unchecked, and urban neighborhoods face shortages.

"If agriculture was forced to be more efficient there would be enough for everyone else," said Dr Jorge Ramírez, a leading water scientist at the Autonomous University of Baja California. "We have enough water, what we lack is planning. Water is the currency here and politics always wins."

In recent years, protests have erupted in response to allegations of corruption and poorly policed pollution standards that favor big landowners and water guzzling industries, such as a controversial US brewery under construction in the Mexicali valley.

In 2020, both countries will for the first time implement rationing. Mexico must cut usage by 3%. The US mustsave247m cubic metres. The plan would have been much stricter if not for record snowfall in parts of the Colorado basin last year.The reductions can only be accomplished if farmers waste less and participate in reforestation efforts.

Even so, scientists are optimistic that the delta can partially recover.

In the scorched and barren delta,visitors may encounter an incongruous sight: 700 acres of flourishing native trees and shrubs in three reforestation sites.

They are the product of what is called a "pulse flow".

In 2014, an environmental experiment driven by not-for-profits on both sides of the border resulted in 105,392 acres-feet (130m cubic metres) of extra water being released into Mexico over two months, simulating the natural spring floods of yesteryear.

The pulse flow bolstered parched wetlands and reforestation zones where native cottonwood and willow trees naturally germinated. And for a few days, for the first time in years, the river reconnected to the Sea of Cortez: fish stocks increased, dolphins returned and the number of migratory birds rocketed by 43%.

But for some scientists, the community response was perhaps the most surprising and satisfying. Thousands flocked to the river as it returned, briefly, to its former glory.

"I grew up with my mum's stories about the river in the old days, but couldn't believe it until I saw it myself," said Ulises Monroy Saldaña, 13. "I'll never forget putting my hand in the water for the first time: it was cold, but it felt so nice because it was so hot here."

Daniel Rodríguez was just seven years old, but still remembers the excitement of watching the river fill with water. "We'd come every day after school and keep jumping off the bridge until the police chased us away."

His grandmother, Lupe Aderete, 53, set up portable toilets for the massive influx of visitors. "It was beautiful to see the river alive again, everyone was so happy, and I made some extra money." She added: "It's not fair, the Gabachos [Americans] should leave some water for us.

The restoration site at Laguna Grande is a shady oasis of gangly cottonwood and willow trees surrounded by desert and farmland, visited by over 2,000 people last year.

Lupe Aderete at home in the neighborhood of Miguel Alemán, Baja California, on 6 September 2019. Photograph: Meghan Dhaliwal/The Guardian

"For most children, it's the first time they've seen a forest, and for the adults it brings back memories. Connecting to nature is emotional, and visitors cry all the time," said Gabriela González, education coordinator at the Sonoran Institute which runs Laguna Grande.

There's little or no chance that the river will ever flow freely again, but plans are afoot to repeat the pulse flow, this time flooding only the spots which most benefited last time. And there is hope of expanding native forests to create a green corridor withwetlands and lagoons channelling into the sea.

An indigenous community, the Cucapá, has been involved in dredging efforts, paid to shovel out thick mud to create connectivity channels that are crucial to sustainable ecosystems. Patches of native salty grass and flocks of raucous brown and white pelicans at the lower part of the estuary indicate that plentiful fish were swept in by recent high tides.

The next pulse flow should take place in 2021 or 2022. Regardless, this region will remain more desert than delta.

At home in Miguel Alemán, a poor makeshift neighbourhood with little shade, the Rodríguez brothers ditch their school stuff, grab a plastic bucket and rush back across the parched terrain to the concrete drainage canal running parallel to the littered riverbed.

They fearlessly dive into the polluted waterway, which emerges under the metal border wall, to cool down and catch some fish for dinner.
To contact Nina Lakhani, the Guardian's new environmental justice reporter, e-mail nina.lakhani@theguardian.com Design by Juweek Adolphe

This article was amended on 22 October 2019 to correct the spelling of Nancy Saldaña.

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The lost river: Mexicans fight for mighty waterway taken by the US

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he temperature is rising toward 45C (113F) as young brothers Daniel and Dilan Rodríguez skip towards a bridge over the Colorado River in the Mexican border town of San Luis Río Colorado. But there is no water flowing through the channel of one of the world's mightiest waterways.

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Provides a good picture of the Colorado River. Mentions the pulse flow as well as earlier history of the river. Includes insight from various environmentalists.

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The Colorado River once flowed with so much water that steamboats sailed on its wide, meandering stretches near the U.S.-Mexico border. When the environmentalist Aldo Leopold paddled the river's delta in Mexico nearly a century ago, he was filled with awe at the sight of "a hundred green lagoons."

Now, what's left of the river crosses the border and pushes up against the gates of Morelos Dam. Nearly all the remaining water is shunted aside into Mexico's Reforma Canal, which runs toward fields of cotton, wheat, hay and vegetables in the Mexicali Valley.

Downstream from the dam sits a rectangular lagoon that resembles a pond in a city park. Swallows swarm over the water, diving and skimming across its glassy surface. From here, a narrow stream the width of a one-lane road continues into a thicket, flanked by tall grasses.

About a dozen miles farther south, the Colorado River disappears in the desert. Beside fields of alfalfa and green onions, the dry riverbed spreads out in a dusty plain where only gray desert shrubs survive.

Looking around at the barren floodplain during a visit in early March, Jennifer Pitt picked up a clamshell from the sandy, salt-crusted soil and held it in her hand. The intact clam was quarter-sized, its ivory shell marbled with brown and purplish lines. The halves were still fused together but soon broke apart, revealing dry silt inside.

Pitt said she wasn't sure how long ago the clam might have been alive - perhaps during floods in the 1980s, or if not, maybe during the 1950s, before the construction of Glen Canyon Dam choked the river's flow.

"That clam thrived sometime in the past when there was water still flowing," Pitt said. "It's a reminder this really was the Colorado River."

Pitt is director of the National Audubon Society's Colorado River program. She visited the delta with Gaby Caloca of the Mexican environmental group Pronatura Noroeste. The two co-chair a cross-border environmental work group that includes government officials and experts from both countries, and they're working together on plans to restore wetlands in parts of the Colorado River Delta.

These efforts to resurrect pieces of the delta's desiccated ecosystems face major challenges, including limited funds, scarce water supplies, and the hotter, drier conditions brought on by climate change.

But in the past decade, environmental groups have had success bringing back patches of life in parts of the river delta. In these green islands surrounded by the desert, water delivered by canals and pumps is helping to nourish wetlands and forests. Cottonwoods and willows have been growing rapidly. Birds have been coming back and are singing in the trees.

Pitt, Caloca and other environmentalists say they've found that even though there isn't nearly enough water available to restore a flowing river from the border to the sea, these modest projects planting trees and creating wetlands are showing promise. Even relatively small amounts of water are helping breathe life into parts of the delta.

And during the next several years, more water is set to flow to the restoration sites under a 2017 agreement between Mexico and the U.S.

Caloca pointed out the contrasts between wet and dry as she drove a Toyota pickup down roads flanked by farmlands.

Stopping at a bridge next to the border city of San Luis Río Colorado, the river channel below was a strip of dry sand crisscrossed with tire tracks. At a restoration site several miles away, cottonwood trees that were planted starting in 2014 have grown into a forest.

"We know we aren't going to be able to restore the delta to the way it was before, because it's impossible now," Caloca said. "But we know that with the restoration work we're doing, planting trees, creating pathways, it's working - even though we don't have water flowing there all the time."

'A hundred green lagoons'

The Colorado River begins high in the Rocky Mountains, where runoff from melting snow and rain pours into tributaries that wind through lush alpine valleys. From its headwaters in Colorado and Wyoming, the river basin fans out across 246,000 square miles to the Mexican border.

Over eons, the river carved the Grand Canyon and scattered billions of tons of sediment across its delta, flowing into the Sea of Cortez.

More than a century ago, the delta spread across 1.9 million acres in a watery oasis of wetlands, riparian forests and marshes that teemed with fish, birds, beavers, deer, bobcats and jaguars.

Leopold, the naturalist, saw that delta in 1922 when he canoed through it with his brother. He described their journey in his 1949 book "A Sand County Almanac."

On the map the Delta was bisected by the river, but in fact the river was nowhere and everywhere, for he could not decide which of a hundred green lagoons offered the most pleasant and least speedy path to the Gulf. So he traveled them all, and so did we.

The delta reminded Leopold of a biblical verse in Psalm 23: "'He leadeth me by still waters' was to us only a phrase in a book until we had nosed our canoe through the green lagoons."

They paddled through waters "of a deep emerald hue," hunted quail, and learned where to dig to find fresh water. Leopold described huge flocks of cormorants and egrets, and beside the river channel stood "a verdant wall of mesquite and willow."

Leopold never returned to the delta and didn't live to see his beloved green lagoons shrivel to dust.

In the decades after Leopold's visit, the Colorado's waters were dammed, diverted and routed in canals to farmlands and cities from Los Angeles to Phoenix.

The river's once-mighty floods - which had burst through canals and formed the Salton Sea in 1905 - were tamed by the dams.

And the delta was reduced to a shadow of its former self. The braided channels that were shaped by the flooding river have remained imprinted in the delta near the river's mouth by the Gulf of California. But the shore of the lower estuary, now starved of a river, has for years been sculpted more by the incoming and outgoing tides, which have left serpentine treelike patterns etched in the sands.

Pitt started analyzing ways of helping the delta's decimated ecosystems in 1999, when she began working on Colorado River issues for the Environmental Defense Fund. At the time, she said, environmentalists and water managers were talking on different wavelengths and the legal framework that governed water use along the river was widely perceived as being too inflexible to allow for changes that would remedy the delta's ecological health.

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Promoting the idea of environmental restoration projects in Mexico, Pitt said, "felt like tilting at windmills."

But over the years, conversations gradually shifted within the network of water managers and policymakers in the U.S. and Mexico who focus on the Colorado River.

A 2012 agreement between Mexico and the U.S. provided for an unusual experiment: a planned flood to rewet the delta.

A flood demonstrates potential

In the spring of 2014, a surge of water poured through the gates of Morelos Dam on the border. That "pulse flow" of 105,000 acre-feet of water brought back a flowing river in areas that had been dry since floods in the late 1990s.

Crowds of jubilant revelers gathered by the resurrected river. They dipped their feet into the water and waded in.

Some danced on the banks and drank beer. Others tossed nets into the water and pulled out flapping fish.

Two days after the water started to flow, Pitt joined her colleague Osvel Hinojosa Huerta on a canoe trip to survey newly formed marshes near the border. She was surprised and thrilled when up ahead of their canoe, she spotted the dark head and back of a beaver. It swam ahead of them just long enough for her to snap a couple of photos, and then it disappeared.

She wondered how that beaver had reappeared there so quickly, in a river that had long been a parched channel.

Pitt said one of her favorite photos during the celebrations captured a Mexican man, wearing a pressed shirt, slacks and dress shoes, as he bent down and touched the surface with an open hand.

As the river continued to flow, Pitt stepped into a raft by the dam in the town of Los Algodones and floated 24 miles downstream to the bridge in San Luis Río Colorado.

When she returned last month and stood on that same bridge, Pitt looked down at the sandy riverbed. "During the pulse flow," she said, "this was full bank to bank."

That spring, the surge of water coursed all through the twists and turns of the delta for eight weeks, traveling about 100 miles from the border until it reached the sea. Then the experiment was over, and the water retreated.

While the river's brief return was widely praised as an achievement of cross-border cooperation, many environmentalists acknowledged they couldn't hope to get so much water flowing perpetually.

Even so, the pulse flow gave Mexican and U.S. officials a visual demonstration of the potential of restoration efforts - an example that nudged them toward budgeting water for the environment as they negotiated a new Colorado River agreement.

"I think having that river flowing piqued people's interest," Pitt said. "It opened people's imagination to the idea. It gave them a vision of the Colorado River here that has energized these restoration efforts."

When representatives of the governments signed the next deal in 2017, it cleared the way for smaller but substantial flows to expand several habitat restoration sites.

The agreement, called Minute 323, acknowledged that the work group led by representatives from both countries had recommended goals including expanding the habitat areas from 1,076 acres to 4,300 acres, and setting aside an annual average of $40 million and 45,000 acre-feet of water for environmental restoration in the delta.

The deal included pledges for about half that much water, a total of 210,000 acre-feet through 2026 - enough water that if spread across Phoenix would cover two-thirds of the city a foot deep. This water - averaging 23,000 acre-feet a year - represents a small fraction of the 1.5 million acre-feet that Mexico is entitled to each year under a 1944 treaty, and an even smaller fraction of the larger allotments that California and Arizona take from the river upstream.

Mexico and the U.S. each agreed to provide a third of the water, while a coalition of environmental nonprofits pledged to secure the remainder. Each government agreed to contribute $3 million for restoration projects and $3 million for research and monitoring work.

So far, environmental groups have been buying water in Mexico through a trust and pumping it from agricultural canals into three restoration areas. More water is scheduled to be delivered by the two governments over the next several years, including water the U.S. plans to obtain by paying for conservation projects in Mexico.

When the infusion comes, the wetlands and newly planted forests will get a bigger drink.

"We are scaling up," Pitt said from the backseat, while Caloca drove through farmlands toward one of the restoration sites.

A forest springs up in the desert

The Colorado River's historic floodplain spreads across much of the Mexicali Valley. In the upper delta near the Arizona border, west of the channel where the pulse flow roiled through in 2014, an old meander of the river forms a sweeping scar in the desert.

Though the floodwaters missed this area near the town of Colonia Miguel Alemán, the swollen river soaked into the soil and boosted groundwater levels. That same year, workers hacked through thickets of invasive salt cedar trees and began planting native trees in the dry soil.

Those saplings have since bloomed into a forest of cottonwoods and willows. Some trees now stand about 40 feet tall.

Leading a tour of the site, Alberto Ruiz of Pronatura Noroeste showed off a nursery where a worker with a hose was watering hundreds of tiny trees, including honey mesquites, ironwoods, and willows.

The site covers about 330 acres. Ruiz said a "restoration brigade" of about two dozen employees has been watering trees, working on the irrigation system, and preparing to plant more.

Walking past spraying sprinklers, Ruiz stopped at a ditch where water was gushing out of a plastic pipe. He proudly pointed to rows of tall cottonwood trees, their leaves rustling in the breeze.

Six years ago, he said, there was nothing here.

"We've transformed it in a very short time. The trees grow very well," Ruiz said. "They don't need large amounts of water to achieve all this."

As he walked into the forest, the air grew cooler and dry leaves crunched underfoot.

A black net was strung up between the trees. Caught in its strands, like flies in a spiderweb, were several birds.

A hummingbird struggled against the net, its tiny wings ensnared. A warbler squirmed upside down, straining its neck and watching the visitors with beady black eyes.

Stefanny Villagomez, a biologist, carefully removed birds from the nets one by one, slipping them into white cloth bags.

At her work table beside a pond, she held an Audubon's warbler and looked closely at its gray and yellow feathers. A healthy male, she said. Using pliers, she clipped a metal band around one leg while the bird's feet grasped at the air.

A colleague wrote down details on a clipboard, and then Villagomez held up the bird and it flew off.

"We have been seeing that some of the birds are spending months in the area," Villagomez said.

Surveys have found many more birds are arriving in the forest, often stopping during their migrations. At first, biologists had seen only 13 species of birds, and now they've counted 110 species.

Villagomez has spotted house finches carrying bits of vegetation to make a nest. There are also orange-crowned warblers, verdins, Abert's towhees, ash-throated flycatchers, blue-gray gnatcatchers, Anna's hummingbirds, Cassin's vireos, Bullock's orioles, Gila woodpeckers, and northern flickers.

All across North America, scientists have found widespread declines in bird populations over the past 50 years. But in this patch of the delta, migratory birds are finding a rare oasis.

"They need to rest. They need to eat. And these places are providing that for them," Villagomez said. "These areas are really important."

Helping reconnect nature

Rows of tall cottonwoods at the Miguel Alemán restoration site form a green wall next to the desert. On the outer edges of the oasis, water drips from irrigation lines below scraggly mesquite saplings.

Caloca's group plans to start another 345-acre site, called Janitzio, just upstream along an S-curve in the river channel. They plan to create a pond and a marsh, and plant willows, cottonwoods, mesquites and palo verdes.

These sorts of forests once were nourished by shallow groundwater. But the absence of a flowing river, compounded by pumping from nearby wells, has led to declining groundwater levels in this part of the upper delta.

Where the water table lies too deep for trees' roots to reach, a steady stream of river water from canals is needed to irrigate the budding forests.

Downstream, the dry riverbed meanders for miles through farm fields.

Then, in the central delta, water reappears in ponds surrounded by forests. Here, agricultural runoff contributes to higher groundwater levels and helps sustain the wetlands.

At the Laguna Grande restoration area, American coots bob in open water fringed with cattails. Next to the wetlands stand towering cottonwoods that were planted nearly a decade ago.

"I love the sound, the wind in the trees," said Gabriela González, an environmental education coordinator for the Tucson-based Sonoran Institute, which manages the site.

Walking through the forest, she said this 700-acre wilderness has become a haven for animals from bobcats to beavers. She pointed out a stump that had been whittled down by a gnawing beaver.

The way nature has bounced back in this stretch of the delta, she said, demonstrates how cooperative work by environmental groups can pay off in areas that once were widely considered lost.

"It's possible to restore ecosystems that have been damaged for so many years," González said. "It's making this river corridor be alive again."

González and her colleagues regularly welcome schoolchildren and families to Laguna Grande on weekends. The kids are often excited, she said, because for many of them it's their first time walking in a forest or seeing animal tracks in the sand.

Older Mexicans who grew up in the area tend to respond differently. For them, seeing water in the delta again can open a window to a past they thought was gone for good.

"We get a lot of people who get very emotional when they see this place because it reminds them of how it used to be when they were small, and then they stopped seeing the forest or the river run," González said.

"For them it's very, very personal," she said. "The river is what made these communities grow, and it's bringing back a little bit of their identity."

ON THE RIVER: Steamboats once sailed on the Colorado River near Yuma

Flying over the delta

In the future, Pitt hopes more of the delta will look like Laguna Grande - a series of wetlands and forests with flowing stretches of river at least part of the year.

"The idea is to bring connectivity back for the Colorado River," Pitt said, by expanding the network of restoration sites across the delta.

Caloca agreed, saying the long-term goal is to "see the entire corridor of the Colorado River restored in a way that's a bit more complete."

To get an aerial view of the restoration areas, they climbed aboard a Cessna at Mexicali's airport and asked the pilot to fly along the river's path.

A storm the day before had unleashed a downpour, and Pitt said parts of the river channel seemed wetter than usual. But south of Morelos Dam, the river still vanished in the desert sands.

Caloca pointed excitedly when the rows of trees appeared at Miguel Alemán beside the dry channel.

Then the riverbed snaked on, a dusty artery passing through green fields.

In the central delta, lush vegetation emerged. Stretches of blue water shimmered in the sun.

The plane circled and headed south for the lower delta.

Approaching the shore of the Sea of Cortez, aquamarine fingers of saltwater reached into the estuary.

Flocks of birds soared over the marshes. The tidal flats extended in a vast plain framed by ocher mountains.

"When you're up here, you get a sense of the scale, how big the estuary of the delta was," Pitt said. "You feel the absence of the river down there."

Circling back toward the north, the plane flew over a wetland called the Ciénega de Santa Clara. Usually sustained by salty irrigation drainage from Arizona farms, the wetland had been starved of water for four months while a bypass drain underwent repairs.

With water now flowing to the wetland again, shallow pools glistened in the dry, brown vegetation.

After the flight, Caloca said she, too, was struck by the vastness of the estuary where the river once flowed.

"You see that we've lost a big part of the habitat," she said. But Caloca also came away feeling encouraged and optimistic about how quickly the restoration areas have grown.

"You can see the changes," Caloca said. "It makes you think restoration is possible."

The three nonprofits that are managing the habitat areas are among six Mexican and American environmental groups participating in Raise the River, a partnership that promotes efforts to restore the delta.

During the past month, the coronavirus outbreak has affected work at the restoration areas. Managers of Pronatura Noroeste have scaled back their operation and are having five employees take turns watering trees. Most employees are staying home, and bird surveys have been canceled this spring.

In the long term, water scarcity across the Colorado River Basin may pose challenges for the environmentalists' work in the delta.

The legal framework that divides the river among seven states and Mexico was established during much wetter times nearly a century ago, starting with the 1922 Colorado River Compact. That and subsequent agreements have allocated more water than the river can support in an average year, leading to chronic overuse and falling reservoirs.

Two decades of mostly dry years have taken a toll, and climate change is adding to the strains. Scientists have found that hotter temperatures are already sapping the river, and that the Colorado could lose about one-fourth of its flow by 2050 as temperatures continue to climb.

The three states that depend on water from Lake Mead - Arizona, Nevada and California - signed an agreement last year aimed at preventing the reservoir from falling to critical lows. Arizona and Nevada are taking less water this year under the deal, and Mexico is contributing under a separate accord by leaving some water in Lake Mead.

Pitt said the cooperative U.S.-Mexican dialogue on the river during the past decade stands in sharp contrast to the situation years ago, when the two sides didn't have much if any diplomatic conversation "as this violence was perpetrated on the ecosystem" and the delta was left dry.

"The fate of the delta will always rely on U.S.-Mexico cooperation," Pitt said.

In the long run, she said, successfully reconnecting habitats along the river will require sustaining and building those connections between policymakers on both sides of the border, and making it a priority to bring back a few more of the delta's green lagoons.
Reach reporter Ian James at ian.james@arizonarepublic.com. Follow him on Twitter: @ByIanJames
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How a trickle of water is breathing life into the parched Colorado River Delta

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The Colorado River once flowed with so much water that steamboats sailed on its wide, meandering stretches near the U.S.-Mexico border. When the environmentalist Aldo Leopold paddled the river's delta in Mexico nearly a century ago, he was filled with awe at the sight of "a hundred green lagoons."

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PBS report from a few weeks ago concerning the extreme stress on the river that will require cutbacks in water deliveries this year for the first time ever.

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Unrelenting drought leaves millions who rely on Colorado River facing an uncertain future

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The Colorado River is a critical resource for the western U.S. But a megadrought, one significantly exacerbated by climate change, is jeopardizing the river’s future and threatening to upend how its water is used and longstanding agreements between states. Miles O’Brien reports as part of our covera…

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The Good Neighbor Environmental Board report that gives a sense of the breadth and variety of governmental environmental efforts to assist in boundary region responses to climate change.

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A video narrated by Robert Redford discusses the pulse flow from an environmentalists perspective.

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RENEWAL - A Reborn Colorado River Once Again Finds Her Path to the Sea

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This video provides a good sense of the impact of the pulse flow, including a local Arizona view. Emphasizes how the Colorado River is part of the identity of the people who reside in the region.

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The report prepared after the "pulse flow" was executed back in 2014 (i.e., a release of a very substantial amount of water over a several week period to see whether it would find its way to the Gulf of Mexico, and assess what impact that might have on restoring the environment in the river delta in Mexico).

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Absolute change (in USD million, indicated by the bars) of Germany’s imports and exports by regions in 2050 due to labour productivity losses as compared with the baseline (SSP2); relative change of external trade balance (in %) is also indicated; climate projections: HadGEM2-ES for RCP4.5, climatic period 2050 (Ø2036–2065).

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For example, ripple effects on the global economy were estimated to have reduced Japan’s fourth quarter 2011 manufacturing production index by 2.4% (UN-ESCAP, 2012). The causes of the disastrous flood impacts are multi-faceted, but point to an imperative to build enhanced resilience into those components where impacts were propagated. However, superimposed on all of these immediate challenges is the spectre of a changing climate and associated sea-level rise, with the expectation of more frequent and severe events of this kind occurring in the future (Promchote et al., 2016).

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In 2011 Thailand experienced the longest duration flooding event in its recorded history (158 days), resulting in more than 800 deaths and affecting 13.6 million people in the country itself (Promchote et al., 2016). Devastating as these floods were for Thailand, the impacts beyond its borders were equally notable. The Bangkok region is home to large industrial parks that host numerous high value manufacturing concerns, many also located close to coastal port facilities to reduce transportation costs. Seven parks were badly affected, leading to enormous losses in the automobile and electronics industries (primarily Japanese companies), due to inundation of plants supplying key components to manufacturers in Thailand, throughout Asia and beyond. The implications of these severe inundation events at critical nodes in highly inter-connected global supply chains led to impacts that propagated far beyond the borders of Thailand. For example, ripple effects on the global economy were estimated to have reduced Japan’s fourth quarter 2011 manufacturing production index by 2.4% (UN-ESCAP, 2012). The causes of the disastrous flood impacts are multi-faceted, but point to an imperative to build enhanced resilience into those components where impacts were propagated. However, superimposed on all of these immediate challenges is the spectre of a changing climate and associated sea-level rise, with the expectation of more frequent and severe events of this kind occurring in the future (Promchote et al., 2016).