The Colorado River has been dammed, diverted, and slowed by reservoirs, strangling the life out of a once-thriving ecosystem. But in the U.S. and Mexico, efforts are underway to revive sections of the river and restore vital riparian habitat for native plants, fish, and wildlife.

Last in a series republished from Yale Environment 360.

By Jim Robbins for Yale Environment 360
Photography by Ted Wood
Originally published February 14, 2019

From the air, the last gasp of the Colorado River is sudden and dramatic. The pale green river flows smack into the Morelos Dam on the U.S.-Mexico border, and virtually all of it is immediately diverted into a large irrigation canal that waters a mosaic of hundreds of fields — alfalfa, asparagus, lettuce, and other vegetables, their vivid green color clashing against the sere desert. The slender thread of water that remains in the Colorado’s channel continues to flow south, but is soon swallowed up by a sea of sand, far short of its delta, which lies 100 miles farther on.

The Colorado River once surged through the delta during high flows, carrying so much water at times that shallow draft steamboats chugged hundreds of miles up the river into the U.S. with loads of freight. The water in the delta nourished a vast fertile landscape, a fitting end to a river known as the Nile of North America.

“The river was everywhere and nowhere,” the naturalist Aldo Leopold wrote during a 1922 canoe trip to the delta, describing the waterway as it ebbed, flowed, braided, and stalled into pools, nourishing a rich and diverse ecosystem of “a hundred green lagoons,” a “milk and honey wilderness” with thick stands of cottonwoods and willows that provided habitat for hundreds of species of birds. The delta’s marshes, mudflats, and white sand beaches were home to clapper rails, bitterns, mallards, teal, and clouds of egrets.

Bobcats, puma, deer, and wild boar wandered the delta’s forests. Leopold was searching for the jaguar that roamed there, but didn’t see any.

Myriad species of fish swam in the river and in the brackish waters of the Gulf of California, including a relative of the white sea bass, the totoaba, which grew as large as 300 pounds. They were the buffalo of the sea, pursued for their meat and so plentiful that a whole fish sold for a nickel. Fishermen caught 4 million pounds a year in the early 20th century. Also harvesting the bounty of the delta were the indigenous Cocopah, who threaded the waters in dugout canoes and lived in round houses made of reed and brush.

As a natural river, before it was dammed, the Colorado was a massive, dynamic waterway. It flowed from elevations above 14,000 feet in the Colorado Rockies, then dropped to sea level, which meant that it moved at high water with tremendous force, liquid sandpaper carving out red rock canyons. It flooded the desert plains, carving new channels and braids with every inundation. When it receded, it left behind a mosaic of fecund marshes, wetlands, and ponds.

In its natural state, the Colorado had more extreme flows than any river in the U.S., ranging from lows of 2,500 cubic feet per second in the winter to 100,000 cubic feet per second in the summer. In 1884, an all-time historical peak flow reached 384,000 cubic feet per second in Arizona.

But extreme flows are too capricious to support a civilization, so over the past century or so humans have built a network of expensive dams and reservoirs, pipelines, canals, flumes, and aqueducts to tame and divert the flow. Yet these projects also strangled the life out of a once-thriving ecosystem. By design, the river will never again function as a free-flowing stream.

Can the Colorado flourish — to some degree and in some places — with the permission of engineers?

Now, however, experts and environmentalists are rethinking this technological marvel of a river, and looking at ways a natural Colorado can flourish — to some degree, and in some places — with the permission of the engineers. One of those places is in the delta.

The water that flowed in the once-lush delta has been replaced by sand, and the cottonwoods and willows have surrendered their turf to widespread invasive salt cedar and arrowweed. Without the river and its load of nutrients, marine productivity in the Gulf of California — where the Colorado River once ended — has fallen by up to 95 percent. But despite the dismal forecast for the future of water on the Colorado, some conservationists are hoping to return at least a portion of the delta to its former glory.

“We are trying to restore a network of sites that creates a functional ecosystem,” said Francisco Zamora, who manages the project for the Sonoran Institute. “We’ve acquired water rights, but use them for habitat instead of cotton or wheat.”

The delta is one of a disconnected series of restoration projects that government agencies, local groups, and environmental organizations are undertaking along the Colorado. Numerous efforts are focused on tributaries to the main stem of the river, seeking to enhance resiliency by increasing the flow of water and protecting and restoring riparian habitat for fish and other wildlife.

For example, a coalition of groups — including state agencies, nonprofits, and the Arizona cities of Buckeye and Agua Fria — have been removing invasive salt cedar, planting native species, and building levees to reclaim a 17-mile stretch of the Gila River. Invasive salt cedars are a region-wide problem on the lower Colorado, with a single tree sucking up 300 gallons a day. The invasive forest on this stretch of the river uses enough water to serve 200,000 households.

In the upper basin, meanwhile, a number of groups and local landowners are working to restore a 15-mile-long floodplain with globally significant biodiversity on a narrow section of the Yampa River, another Colorado tributary. Called Morgan Bottom, the section has been damaged by deforestation and poor agricultural practices, threatening bald eagles and greater sand hill cranes, as well as a rare riparian forest of narrowleaf cottonwood and red osier dogwood.

But there are limits to how natural the Colorado River can become, especially along the river’s main stem. “We should not kid ourselves that we are making it natural again,” said John Fleck, the director of the University of New Mexico’s water resources program and the author of a book about the restoration of the Colorado. “We are creating an intensively managed system to mimic some nature because we value it.”

Because of the Colorado’s extensive infrastructure, serious disruption of the river’s ecology is inevitable.

Indeed, some of the remaining naturalness on the Colorado is, paradoxically, because of the human-made system. “The geography of the Colorado gives it hope because L.A. and southern California, which everybody loves to hate, guarantee that a lot of water stays in the system through the Grand Canyon,” says Jack Schmidt, a professor at Utah State University and a member of the Colorado River Research Group. “The best friend endangered fish ever had in the Colorado River Basin is that giant sucking sound” of California withdrawing water.

Widespread protection efforts are focused on native fish in the Colorado. The river once was home to an unusual number of endemic fish. But dams, irrigation, and the introduction of bullhead, carp, and catfish did them in. While the upper basin still has 14 native fish species, the lower basin, according to one study, “has the dubious distinction of being among the few major rivers of the world with an entirely introduced fish fauna.”

The Colorado pike minnow — something of a misnomer for a fish that historically grew to 6 feet in length and weighed up to 80 pounds — once swam through the entire system from Wyoming to Mexico. It is now listed as endangered, with two distinct populations remaining in the upper Colorado and the Green River.

The humpback chub lived in various canyon sections, and though once seriously endangered, it has fared better in recent years through transplantation efforts, growing from 2,000 to 3,000 fish to 11,000. Officials say it may soon be taken off the endangered list.

Razorback suckers, once common, are now rare. The bonytail, a type of chub that is one of North America’s most endangered fish, no longer exists in the wild. A handful of these fish exist in hatcheries, and attempts are underway to restock them in the river throughout the basin.

Because of the Colorado’s extensive infrastructure, serious disruption of the river’s ecology is inevitable. Dams trap most of the river’s sediment in reservoirs, which means there is no material to rebuild beaches, sandbars, and important fish habitat downstream.

Dams also deprive the river downstream of nutrients, such as phosphorous and nitrogen, and stratify water temperatures. The native fish in the Colorado adapted to a wide range of temperatures, from cold to very warm. They also evolved to tolerate high flood flows along with extremely dry periods. Now, the water is cold in the summer for miles below the dams, and the humpback chub and other fish that had adapted to a range of water temperatures and flows suffer.

Something called hydro-peaking also has had serious impacts on the food web. Dams generate power according to demand. As people come home from work and switch on the stove, air conditioning, and lights, demand soars and dams release more water to produce power. “Prior to the construction of dams, there were almost no major daily changes in river levels,” said David Lytle, a professor of integrative biology at Oregon State University. When fluctuations in water levels occur, they “can interrupt the egg-laying practices of some species. It’s a serious problem.”

Paradoxically, two of the Colorado’s most important wetlands are the product of runoff from irrigation.

Insects lay their eggs just below the water level, and if levels drop rapidly it can dry them out. A recent study found that below the Hoover and Glen Canyon dams, there was a complete absence of stoneflies, mayflies, and other species — insects that are vital food for fish, bats, birds, and other creatures.

Because of the ecological effects of the Glen Canyon Dam, the Grand Canyon stretch of the Colorado is one of the least productive sections of river in the world. The Colorado here will always be highly unnatural, a novel, human-created ecosystem with some natural elements.

Today, there is a large and growing backlash against dams in America and elsewhere as the immense damages they have inflicted on rivers become manifest. Few dams, though, are as reviled as the Glen Canyon, which was built in 1963 and took 17 years to fill Lake Powell.

Before the Glen Canyon was dammed, those who saw it say it was not unlike the Grand Canyon, with towering walls of red, tan, and ochre. Early Native American sites were plentiful. Environmental activist Edward Abbey decried the dam, and in his novel the Monkey Wrench Gang fantasized about using houseboats packed with explosives to blow it up. In 1981, members of Earth First!, a radical environmental group with a connection to Abbey, rolled a black plastic “crack” down the face of the dam to symbolize its demise.

Removing the dam was part of the reason the Glen Canyon Institute was formed, but activists have now dropped that idea, says Rich Ingebretsen, a Salt Lake City physician who founded the group. Today, he advocates draining Lake Powell to fill Lake Mead, which is downstream and where the need for water is by far the greatest. The “Fill Mead First” campaign would restore a free-running Colorado River to what was once Lake Powell.

“You’d get much of Glen Canyon back,” said Ingebretsen. “A free-flowing river through the Grand Canyon means you’d restore the river — riparian zones, animals that belong there, a beautiful canyon with arches and bridges and waterfalls. Much of that would come back very quickly.” There would also be increased water in the river, he says, because so much of the Colorado is now lost from Lake Powell; scientists estimate that the lake loses three times Nevada’s allotment of water because of evaporation. As levels in Lake Mead drop due to prolonged drought, a growing number of people are taking this idea more seriously.

Paradoxically, two of the Colorado River’s most important wetlands for wildlife are the product of runoff from irrigated farm fields — and are now at risk from a changing climate and agreements to reduce water use.

In the Sonoran Desert of northwestern Mexico, the 40,000-acre La Cienega de Santa Clara wetland was inadvertently created in the 1970s when U.S. officials built a canal to dispose of salty wastewater from agricultural fields in Arizona. As the water began spilling into the desert, myriad forms of life began to appear. Now its cattail-studded marshes and mudflats are considered one of the most important wetlands in North America, home to 280 species of birds — including the endangered Ridgeways rail — on what was once hard-baked desert.

The largest project to restore some semblance of nature on the Colorado is in the delta.

Meanwhile, in California, the Salton Sea was once a shallow inland lake whose levels routinely fluctuated. In 1905, an effort to increase Colorado River flow into the Imperial Valley led farmers to allow too much river water into their irrigation canal, overwhelming their system; for two years the water poured into the 35-mile-long, 15-mile-wide Salton Sea and expanded it.

But as less water becomes available to agriculture and rising temperatures cause more water to evaporate, scientists are concerned that these wetlands will dry and shrink faster than they already have. A 2003 agreement, for example, allows agricultural water in the Imperial Valley to be sent to San Diego for municipal uses. That could cause water levels in the Salton Sea to drop by more than 40 percent, dramatically reducing bird habitat and increasing toxic dust because wetlands would dry out. Local, state, and federal officials have devised a plan — still not fully funded — to restore 15,000 acres of wetlands, at a cost of more than $700 million.

The largest project to restore some semblance of nature to the Colorado River, though, is in the delta. An unusual agreement in 2012 between the U.S. and Mexico, called Minute 319, mandated that the two countries would provide water and funding to revive sections of the delta and release a one-time pulse of 105,000 acre-feet to again connect the river to the delta temporarily. Scientists would then study the effects.

In 2014, for the first time in decades, the river flowed again in Mexico — for eight weeks. San Luis Rio Colorado — once a Colorado River town, but now a dusty desert settlement — became a river town for two months, to the delight of locals, many of whom had never seen the river. The pulse offered a glimpse of what reclamation efforts might look like. “It gave us an idea of how the river behaves, and the best sites for restoration,” said Zamora.

Minute 319 and its 2017 replacement, Minute 323, have funded the restoration of sections of the river. A group of nonprofits — including the National Audubon Society, the Sonoran Institute, The Nature Conservancy, and a Mexican group called Pronatura Noroeste — is working on a project called Raise the River to revive a significant swath of the delta.

In 2008, the group secured rights to 1,200 acres along the desiccated river channel. Since then, local residents have torn out acres of salt cedar and planted irrigated fields of cottonwood, willow, and other endemic species — more than 200,000 trees in all. A small supply of water mandated by the treaty, along with excess water that flows off of irrigated fields, have been dedicated to the restoration.

On a recent visit, I joined Zamora and botanist Celia Alvarado on a short boat ride to Laguna Grande, a 6-mile section of restored river and estuary. We skimmed across still water the color of weak tea, minnows darting away from our paddles. Thick groves of cottonwoods and willows lined the river. Zamora remarked that bobcats and beaver lived there now, along with blue grosbeaks and yellow-billed cuckoos. “Impacting the target species is key,” he said.

And what about the jaguar? I asked. It has not returned, he said. Will it come back?

“Yes,” said Zamora, smiling. “Someday. If they allow me to introduce them.”

 

Back to Part I: The West’s Great River Hits Its Limits: Will the Colorado Run Dry?
 

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Once criticized for being a profligate user of water, fast-growing Phoenix has taken some major steps — including banking water in underground reservoirs, slashing per-capita use, and recycling wastewater — in anticipation of the day when the flow from the Colorado River ends.

Fourth in a series republished from Yale Environment 360.

The Central Arizona Project canal carries water from the Colorado River to neighborhoods in North Phoenix. TED WOOD

By Jim Robbins for Yale Environment 360
Photography by Ted Wood
Originally published February 7, 2019

The Hohokam were an ancient people who lived in the arid Southwest, their empire now mostly buried beneath the sprawl of some 4.5 million people who inhabit modern-day Phoenix, Arizona and its suburbs. Hohokam civilization was characterized by farm fields irrigated by the Salt and Gila rivers with a sophisticated system of carefully calibrated canals, the only prehistoric culture in North America with so advanced a farming system.

Then in 1276, tree ring data shows, a withering drought descended on the Southwest, lasting more than two decades. It is believed to be a primary cause of the collapse of Hohokam society. The people who had mastered farming dispersed across the landscape.

The fate of the Hohokam holds lessons these days for Arizona, as the most severe drought since their time has gripped the region. But while the Hohokam succumbed to the mega-drought, the city of Phoenix and its neighbors are desperately scrambling to avoid a similar fate — no easy task in a desert that gets less than 8 inches of rain a year.

“We are fully prepared to go into Tier 1, 2, and 3 emergency,” said Kathryn Sorensen, Phoenix’s water services director, referring to federally mandated cutbacks of Colorado River water as the levels of Lake Mead, the source of some of the city’s water, continue to drop. And what of the dreaded “dead pool,” the point at which the level in the giant man-made lake falls so low that water can no longer be pumped out?

“I can survive dead pool for generations,” says Sorensen, pointing to a host of conservation and water storage measures that have significantly brightened the city’s water outlook in an era of climate change and drought.

These days, Phoenix’s alternative water supplies are not dependent on the Colorado. But there’s a caveat. Phoenix may have enough water to secure its near-term future, but it still needs to build $500 million of infrastructure to pipe it to northern parts of the city that now rely on Colorado River water. And Phoenix may need the water sooner than it planned. “You could hit dead pool in four years,” Sorensen said. “That’s worst case.”

Many cities and towns in the Southwest — including Los Angeles, San Diego, and Albuquerque — are trying to figure out solutions to a dwindling Lake Mead, the key reservoir on the Colorado. One of the most ambitious efforts is a new $1.35 billion, 24-foot-wide tunnel — the so-called Third Straw — that Las Vegas drilled at the very bottom of Lake Mead to function like a bathtub drain. Las Vegas gets 90 percent of its water from the Colorado via the lake, which is located just east of the gambling and tourist mecca. In 2000, as the lake’s level dropped, the city placed a second, deeper straw to replace the original outtake. As the region moved into its second consecutive decade of drought and lake levels continued to drop, Las Vegas officials got more nervous and the third straw was completed in 2015; it should continue to siphon off water unless the lake dries up completely.

Supplying enough water to sustain a city this size in the desert has long been controversial.

In Arizona, the modern equivalent of the Hohokam irrigation system is the 17-foot-deep and 80-foot-wide concrete aqueduct called the Central Arizona Project, which carries water from the Colorado River to Phoenix, Tucson, and elsewhere. It was a feat of engineering when it was finished in 1993, snaking across the sere desert landscape for 336 miles as it pumps water up 2,900 feet in elevation. So much power is needed to flush this water along its route that the massive coal-fired Navajo Generating Plant was built to provide it.

Supplying enough water to sustain a city this size in the desert has long been controversial, and as Phoenix and its neighbors continue their unrelenting sprawl — Arizona’s population has more than tripled in the past 50 years, from 1.8 million in 1970 to 7.2 million today — the state has often been regarded as the poster child for unsustainable development. Now that Colorado River water appears to be drying up, critics are voicing their “I told you so’s.”

That’s a bad rap though, at least for Phoenix, according to Sorensen. The city is prepared to carry on with business as usual even if the last of the Colorado River water evaporates into the desert sky, depriving Phoenix of 40 percent of its water supply. City officials have been busy planning for this eventuality, and much of the responsibility for that has fallen to Sorensen.

As she stands behind her large desk on the 9th floor of the municipal building in the heart of downtown Phoenix, surrounded by windows that look out on glass office towers gleaming in the desert sun, Sorensen deftly handles questions about the city’s water future. On her desk sits a crystal ball, a joke gift that she says she wishes was real. She’s proud of the work she has done since she was appointed in 2013 — before that she served four years as head of Mesa, Arizona’s water department — although she admits it has been a challenge.

The Phoenix Water Services Department is one of the nation’s largest, with 1.5 million customers spread out across 540 square miles. It maintains 7,000 miles of water lines and 5,000 miles of sewer lines.

The Salt River is the single biggest source of water for metro Phoenix, and provides about 60 percent of its needs. It is a large desert river, some 200 miles long, that begins at the confluence of the snow-fed White and Black rivers, is joined by a series of perennial, spring-fed streams, and then meets the Verde River east of Phoenix.

Just after the turn of the 20th century, the first of four dams was constructed on the Salt for a growing Phoenix, and today those reservoirs are Phoenix’s main water supply. However, Phoenix’s north side gets only Colorado River water, and should that source dry up one day, constructing infrastructure to connect north Phoenix to new sources of water would cost a half-billion dollars. Funding for such a project would hardly be a fait accompli; in late December, the Phoenix City Council rejected a water rate increase to pay for the infrastructure expansion. The Salt and Gila rivers also may someday be severely impacted by climate change. “They could be affected by a mega-drought,” said Andrew Ross, a sociology professor at New York University and author of Bird on Fire: Lessons from the World’s Least Sustainable City. “They are in the bullseye of global warming, too.” Perennial streams could dry up and snowfall in Arizona’s White Mountains could dwindle, as it has done in the Rockies, further depriving the rivers of a steady supply of water.

“We’ve decoupled growth from water,” says a city official. “We use the same amount of water we did 20 years ago.”

Beyond the Salt River, Phoenix has undertaken some innovative water strategies. Among the first of these was the Arizona Water Bank. California is entitled to 4.4 million acre-feet of water a year from the Colorado, but because Arizona was not using its full allotment of 2.8 million acre-feet, its excess water was being slurped up by a perpetually thirsty California. So the water bank, a unique system of underground storage, was created in 1996 as a way to store Colorado River water that the state couldn’t use, rather than letting it flow through to California. It turned out to be a prescient move, but not for the reason it was created. In that era, few people foresaw the crash of the Colorado River system.

Arizona has since created seven water banks, largely in empty underground aquifers. A series of large pools has been built above the aquifers and, as water is pumped into them, it slowly leaches through a layer of gravel and rock and fills the aquifer. So far the water banks have cost the state $330 million, storing 3.6 million acre-feet in 28 sites across three counties — more than a year’s worth of Colorado River water.

One of the largest water banks is 40 miles west of Phoenix near the tiny town of Tonopah, Arizona. The nearly $20 million facility has 19 infiltration basins covering more than 200 acres. It was constructed alongside the Central Arizona Project canal, and a pipe delivers 300 cubic-feet-per-second of Colorado River water a day to fill the basins.

In addition, other aquifers underneath Phoenix are brimming with 90 million acre-feet of water, some natural and some pumped in — enough to last the city for years. One problem is that much of it is contaminated, both from natural sources of arsenic and chromium and from the city’s many Superfund sites, which include manufacturing sites polluted by industrial solvents and unlined landfills that contain hazardous waste. But Sorensen dismisses the cleanup challenges as surmountable. “As long as the contamination isn’t nuclear, we can fix it,” she says. “What matters here is that the water is wet.”

Phoenix also recycles almost every bit of wastewater that journeys through its system. The vast majority of it — more than 20 billion gallons of recycled water a year — goes to cool the Palo Verde Nuclear Power Plant. Another 30,000 acre-feet is traded to an irrigation district as gray water to use on agricultural fields and the district, in turn, sends potable water from the Salt River to the city.

And the city is working on “toilet-to-tap” technology aimed at someday making sewage water so clean it will be drinkable. The technology for recycling wastewater into drinking water exists, but is only used in a few places, including San Diego. Arizona says it will play a role in its water supply some day — if, that is, the city can sell the idea to consumers.

Desalinization of seawater has long been floated as a possibility for Arizona, and much of the U.S. Southwest, and officials say it too will be part of Arizona’s water mix — someday. The process, which forces water through an extremely fine filter, is energy-intensive, extremely expensive, and a major environmental problem because of the waste it generates. Nonetheless, Arizona sits on top of 600 million acre-feet of brackish water, and officials have also considered treating water from the Gulf of California, nearly 200 miles to the southwest.

For now, though, Phoenix appears to have positioned itself well for a new era of drought. Sorensen credits the people of Phoenix for adapting to the desert by using far less water per capita. “We’ve decoupled growth from water,” she said. “We use the same amount of water that we did 20 years ago, but have added 400,000 more people.” In 2000, Some 80 percent of Phoenix had lush green lawns; now only 14 percent does. The city has done this by charging more for water in the summer. Per capita usage has declined 30 percent over the last 20 years. “That’s a huge culture change,” Sorensen says.

In fact, the decoupling of water from growth through conservation has taken place throughout the Lower Colorado Basin. “Actual municipal water use across the basin, with the exception of Utah, is declining, even as population rises,” said John Fleck, director of the University of New Mexico Water Resources Program. “Albuquerque has built its long-range plan around conserving more than its demand for decades to come, and Las Vegas’ demonstration of its ability to use less water is stunning.”

But while Phoenix and Las Vegas are pursuing conservation strategies as a partial solution to the withering of the Colorado River, others entities in the region aren’t. Much of conservative Arizona is in denial about what the potential drying of the West may mean, if they recognize it at all. “We’re just starting to acknowledge the volatile water reality,” said Kevin Moran, senior director of western water for the Environmental Defense Fund. “We’re just starting to ask the adaptation questions.” Ross, of New York University, argues that the biggest problem for Arizona is not climate change, but the denial of it, which keeps real solutions — such as reining in unsustainable growth or the widespread deployment of solar energy in this sun-drenched region — from being considered. “How you meet those challenges and how you anticipate and overcome them is not a techno-fix problem,” he said, “It’s a question of social and political will.”

All these well-intentioned measures may fall far short of being able to cope with a full-blown climate crisis.

So, for now, Arizona’s rampant growth continues. To the west of Phoenix a new tech city is emerging. Mt. Lemmon Holdings, a subsidiary of computer magnate Bill Gates’s investment firm, Cascade Holdings, has plans to built a “smart city,” for example, on the outskirts of Phoenix near the town of Buckeye. The new city, on 24,000 acres — about the same size as Paris — would have infrastructure for self-driving cars, hi-tech factories, and high-speed public wi-fi.

Meanwhile, the so-called Sun Corridor — 120 miles of Sonoran Desert between Phoenix and Tucson — is seen as the state’s next burgeoning megalopolis. It’s one of the fastest-growing regions in the country and its population of more than 5.5 million — anchored by Phoenix in the northwest and Tucson to the southeast — is expected to double by 2040.

And what about the water for this growth? Under state law, a developer must prove it has a 100-year supply for any new housing development. The primary solution for that has been for the Central Arizona Groundwater Replenishment District to fill or replenish aquifers where growth is planned — and the source for that is the precarious Colorado River water.

 

Read Next: Restoring the Colorado– Bringing New Life to a Stressed River
 

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Communities along the Colorado River are facing a new era of drought and water shortages that is threatening their future. With an official water emergency declaration now possible, farmers, ranchers, and towns are searching for ways to use less water and survive.

Third in a series republished from Yale Environment 360.

By Jim Robbins for Yale Environment 360
Photography by Ted Wood
Originally published January 31, 2019

From the air, the Grand Valley Water Users Association canal — 10 feet wide and 8 feet deep — tracks a serpentine 55-mile-long path across the mountain-ringed landscape of Mesa County, Colorado. It’s a line that separates parched, hard-baked desert and an agricultural nirvana of vast peach and apple orchards and swaying fields of alfalfa.

The future of this thin brown line that keeps the badlands of the Colorado desert at bay, however, is growing more uncertain by the day.

Since 2000, the snow that blankets the Colorado Rockies each winter — the source of most of the river’s water — has tapered off considerably. Last year it was less than half of normal. So far, the farmers here have gotten their share of water, but this year could bring the first emergency declaration by water administrators. That would mean that some “junior” water users — those whose allocations came later — may have to forego their share in favor of senior users.

The nearly two decades of low snowpack is being called a drought, and tree rings show it’s the most severe in over 1,200 years. The term drought, however, implies it will end someday. But there are serious questions about whether this is a drought or a permanent drying of the West due to a changing climate.

If the water crisis deepens, farmers could see their neighbors start to disappear as farms and ranches are abandoned.

Few doubt that things are building toward crisis. Last year junior water users on the Yampa River, a tributary to the Colorado, were forced to face the new reality when officials ordered them to stop taking their allocated water and allow it to flow to senior users downstream. In places, the river channel was dry; fishing and float trips were also halted.

As things get tighter throughout the Colorado River Basin, irrigators, who control 80 percent of the water on the river, fully expect others to come looking for their water. One place that has been preparing a strategy to try and head off a raid on its water is in Mesa County in western Colorado.

“There is not an active attack on our water at this time,” said Mark Harris, general manger of the Grand Valley Water Users Association and a farmer himself, as we walked along a row of peaches in a sea of orchards near Palisade, Colorado. “But we do have a huge target on our back. The crisis will require draconian measures that will savage ag. If municipalities run out of sanitary water or fire water, those steps are going to have to be taken.”

The Grand Valley Water Users Association was founded in 1905 as part of the U.S. Bureau of Reclamation. It operates the canal, as well as 150 miles of pipe and open ditch that carry water to a little more than 23,000 acres of land. Without water to service this network — and with only 9 annual inches of precipitation — a new dust bowl could be in the offing.

Water law in the West is based on something called the Prior Appropriation Doctrine, or “first in time, first in line.” While water is a public asset, rights to it were promised to those who came West to homestead, ranch, and grow crops in the late 19th and early 20th centuries. They have the most senior rights, and these are considered private property rights, enshrined in law. The rights of cities and towns are usually junior to these senior rights, and junior users stand to lose out first if cutbacks are mandated. However, cities and towns have considerable political and economic heft, especially in metropolitan areas in the Lower Basin, such as Phoenix, Las Vegas, and Los Angeles. The fear is that the policy of “first in time, first in line” could be discarded in a time of emergency and replaced with one that adheres to a different adage — “water flows uphill toward money.”

The water that many farmers and ranchers use on the Colorado is now cheap. Senior users like those in the Grand Valley pay from $25 to $50 for an irrigated acre for the season. A hundred acres of, say, alfalfa, the single largest crop along the river, needs up to 2 feet of water per acre. Water to irrigate for the season then, would cost the farmer about $2,500 to $5,000. The net profit from the hay is about $300 an acre, so the farmer would make about $30,000 on the 100 acres after costs.

Currently water is selling on the open market for about $200 to $250 an acre-foot for a season, well above what farmers in the Grand Valley are paying. The rules of the Grand Valley Water Users Association do not permit separating water from the land; but if the exigencies of the drought were to cause the rules to change, on today’s market the value of the water from those 100 acres would be worth about $40,000 for a season. In that case, farmers could make more money selling their water rights than by continuing to farm. And if the crisis were to deepen and junior users such as the city of Denver were to lose their water and needed to look elsewhere, the lease price of an acre-foot for the season could go as high as $1,000, some experts say. That would mean farmers could make $100,000 annually by selling their water rights and fallowing their 100 acres.

“We don’t want an unfettered free market for water,” said Harris. “That would be a disaster,” with a range of unintended consequences.While many farmers could do well financially in the advent of a crisis, those who continued farming would see their neighbors start to disappear as farms and ranches were abandoned. And if the crisis was prolonged or permanent, and more and more water was siphoned off to cities, it could threaten the very existence of farming communities around the basin.

It’s happened on a large scale before — most famously in California in the Owens River north of Los Angeles in the early 1900s, as depicted in the fictional 1974 film “Chinatown.” William Mulholland, head of the Los Angeles Department of Power and Water, secretly began buying up ranch and farmland with water rights along the Owens River in the eastern Sierras. Officials then built an aqueduct and piped that water to Los Angeles to fuel the city’s growth. The Owens Valley is now mostly arid.

Beyond the impact on the rural social fabric, dewatering agricultural areas in the Colorado Basin would cause other serious problems, from reducing food security, to less open space if the land were developed for housing, which would release the carbon sequestered in farm fields and eliminate wildlife habitat.

In the Grand Valley, some farmers are being paid to leave their land fallow and keep the water they would have used in the river.

That’s why places like the Grand Valley are taking unprecedented measures. “It’s time for preparation,” said Harris. “Preparation not panic, it’s a delicate balance.”

The Grand Valley Water Users Association has partnered with The Nature Conservancy, which is taking a lead role in helping agricultural interests find ways to survive the future, here in Mesa County and elsewhere in the Colorado River Basin.

In the last several years, an array of projects has been initiated around the basin — from western Colorado, to central and southern Arizona, to the upper Green River of Wyoming, to the borderlands of Mexico — to try to find solutions and, if they work, scale them up all along the Colorado. The Nature Conservancy, for example, has helped create a water bank here in the Grand Valley. Under a two-year pilot program, some farmers are paid to fallow their land — not grow anything on it — and leave the water they would have used in the river.

So far, Grand Valley farmers have fallowed 2,200 acres, which has enabled them to leave 6,000 acre-feet of water flowing in the Colorado. They were compensated for the loss of their crops, plus paid a premium for participating. Saving that water also helped the local irrigation district meet its obligations under the Endangered Species Act to protect fish by keeping more water in the river.

“We created a contract between all these states and Mexico that the hydrology doesn’t support,” said Taylor Hawes, head of the Colorado River program for The Nature Conservancy, referring to the 1922 Colorado River Compact which governs the allocation of water. “Ag and the environment will be the big losers if things continue, so we’re creating a more flexible system that adapts to the reality of our hydrology. Our goal is that whatever solutions we come up with for people also work for nature.”

The states of the compact are also working to find solutions. The Upper Basin states — Utah, New Mexico, Colorado, and Wyoming — have instituted a multi-faceted conservation program that tests ways to reduce water use, including fallowing land with compensation, irrigating crops with less water, and cutting back on municipal water use. The Lower Basin states — Nevada, Arizona, and California — are funding a host of initiatives; the city of Needles, California, for example, was given $500,000 to tear up sod at the city golf course and install drought-tolerant landscaping

The Lower Basin states are also working on a Drought Contingency Plan. As drought conditions continue to worsen, they are coming up with ways to voluntarily give up hundreds of thousands of acre-feet of water to keep Lake Mead, the key reservoir on the Colorado, above crisis levels. This would avoid the imposition of an officially declared emergency, which would force these states to make even larger cuts.

Farmers in Arizona’s Verde Valley are swapping out fields of alfalfa and replacing it with barley, which uses about half the water.

In Arizona’s Verde Valley, between Phoenix and Flagstaff, a different approach is being used. The Verde River is small, but a rare perennial desert river, borne of mountain springs in Arizona’s central highlands — a true oasis. It’s a tributary to the Salt River, which flows into the Gila River and on to the Colorado. It’s hard to overestimate the importance of desert rivers like this to biodiversity — 90 percent of all wildlife in deserts is found within a mile of a river. It’s also a critical water source for metro Phoenix.

A decade ago, The Nature Conservancy’s Kim Schonek came to the Verde Valley to work with local farmers to improve the river’s flow. The meandering, cottonwood tree-lined river is home to several endangered species, including the southwestern willow flycatcher and the loach minnow and spike dace, desert fish that are adapted to natural flows.

The project’s goal is to keep the flows no lower than at least 30 cubic feet per second or so, about a third of its natural level, but high enough to protect species. “We’re trying to re-establish the natural flow regime to the Verde,” says Schonek. “At that level, you have water in all your riffles and no stagnant pools, and that’s good for fish.”

The Nature Conservancy raised money from Coca-Cola, PepsiCo Recycling, Boeing, and other companies in Phoenix, as well as the city itself, all of which get water from the Verde and who have a stake in a more secure supply. With this funding, they are doing things such as updating irrigation technology to keep more water in the river.

Some of the fixes were simple. There were old-fashioned hand-cranked headgates along the river that farmers used to open or close by turning a wheel on top. Notoriously inefficient, the whole flow of the river was often diverted, and sections were inadvertently dried up for miles. The cantankerous headgates have been replaced with $40,000 electronic ones that neither the farmers nor the ditch companies could afford on their own.

“I used to have to go out at 2 in the morning and close that gate,” said Claudia Hauser, whose family has the largest agricultural holdings in the valley and has partnered with The Nature Conservancy to conserve water. “Now I can do it from the house with my phone.”

Other strategies have been more challenging. The Hausers are part of an experiment to swap out 144 acres of alfalfa and replace it with barley. Not only does barley use about half the water of alfalfa, it uses that water in the spring when the flows are high and doesn’t take water out of the river during critical summer periods. The Nature Conservancy has also raised money to build a small barley malting facility, Sinagua Malt, to get the malt ready for beer brewers. Local breweries have snapped up this malt and use it for their beer, and the fact that it is helping save the Verde has become a marketing point. “It’s the essence of naturalism and conservation that truly excites this brewery!” the Arizona Wilderness Brewing Company boasts on its homepage.

Zach and Heather Hauser — part of the same Verde Valley farm family as Claudia — have also removed a field of alfalfa that was nourished by flood irrigation and replaced it with a higher value pecan orchard, using micro-jets that spray water in a circle around each tree. It was paid for by one of the project’s corporate donors. It not only saves a good deal of water, it’s better for the orchard than flooding and creates a more uniform crop. “Alfalfa is a huge issue for the West,” says Schonek, “because so much is grown and it takes so much water.”

The funding has also allowed the Hausers to install drip irrigation to raise their watermelons and their locally-renowned sweet corn — so good, it’s said, that many people eat it raw — with a lot less water.

The city of Phoenix, which sources water from the Salt and the Verde, is contributing to these conservation initiatives. It pays for forest thinning to prevent wildfires so the river won’t be inundated with post-fire ash and mud and become unusable for the city’s water supply.

The efforts here are paying off. “We floated the river all year this year,” said Schonek, noting the increase in the flow from the conservation measures. “You couldn’t have done that five years ago.”

Groundwater, too, is an issue that environmentalists are looking to address along the Colorado and its tributaries. The Nature Conservancy has a groundwater-focused project in southern Arizona to protect the San Pedro, the longest undammed free-flowing river in the Southwest and home to an astonishing array of biodiversity: nearly 400 bird species, several dozen reptile and amphibian species, 84 mammal species, including jaguars, and a suite of terrestrial and aquatic endangered species. The San Pedro — one of only two major rivers that flow north out of Mexico into the United States — flows into the Gila, a major tributary to the Colorado.

Groundwater pumping for homes and farms are reducing the San Pedro’s flows so that some sections of the river have dried up, which is impacting biodiversity. Among other strategies, The Nature Conservancy has, with partners, purchased properties that capture stormwater runoff and funnel it into zones where it can seep into the ground and recharge groundwater supplies.

“The important thing now,” said Hawes of The Nature Conservancy, “is to look for innovative ways to reduce demand and learn to live within our water budget.”

 

Read Next: In Era of Drought, Phoenix Prepares for a Future Without Colorado River Water
 

 

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With the Southwest locked in a 19-year drought and climate change making the region increasingly drier, water managers and users along the Colorado River are facing a troubling question: Are we in a new, more arid era when there will never be enough water?

Second in a series republished from Yale Environment 360.

By Jim Robbins for Yale Environment 360
Photography by Ted Wood
Originally published January 22, 2019

In the basement of the University of Arizona’s Laboratory of Tree-Ring Research, the fragrant smell of pine hangs in the air as researchers comb through the stacks of tree slabs to find a round, 2-inch-thick piece of Douglas fir.

They point out an anomaly in the slab — an unusually wide set of rings that represent the years 1905 to 1922. Those rings mean it was a pluvial period — precipitation was well above average — and so the trees grew far more than other years.

“In 1905, the gates opened and it was very wet and stayed very wet until the 1920s,” said David Meko, a hydrologist at the lab who studies past climate and stream flow based on tree rings. “It guided their planning and how much water they thought was available.”

The planning was that of the states that share the water of the Colorado River. Worried that a burgeoning California would take most of the water before it was fairly divvied up, representatives from the other Colorado River Basin states, presided over by U.S. Secretary of Commerce Herbert Hoover, came together in 1922 to develop an equitable apportionment. They looked at flow measurements and figured that the river contained an average of 15 million acre-feet. They divided the Colorado River states into two divisions – the upper basin and the lower basin, with the dividing line in northern Arizona near the Utah border. The upper basin states — Utah, Wyoming, Colorado, and New Mexico — agreed not to take more than a total of 7.5 million acre-feet and to allow the other half to flow south to the lower basin. The agreement they signed was called the 1922 Colorado River Compact, also known as the Law of the River.

The 1922 compact, though, is based on a premise that the tree rings in the University of Arizona lab now show is false. The river’s long-term average flow is about 12 to 15 million acre-feet, in a good year. Meanwhile, the lower basin states — Arizona, California, and Nevada — use 7.5 million acre-feet, and in 1922 no one factored in evaporative losses from the desert sun at the yet-unbuilt Lake Mead reservoir, which amount to another 1.2 million acre-feet, or the water taken up by plants. Nor did anyone factor in a subsequent 1944 treaty that requires the United States to provide 1.5 million acre-feet to Mexico. A conservative estimate on how much Colorado River water is actually used is 20 million acre-feet.

This over-appropriation is problem enough, but in recent years the river’s flow has been dwindling. The region is locked in a 19-year-long drought, the most severe in 1,250 years. And it may continue much longer. The tree ring data shows that there have been numerous multi-decadal or mega-droughts in the basin in the last 1,000 years. The prospect that drought could be the new normal for the region is creating a good deal of anxiety along the Colorado.

“Many water managers like me are struggling at not panicking,” said Mark Harris, general manager of the Grand Valley Water User’s Association in Grand Junction, Colorado. In his farm cap and jeans, Harris is a no-nonsense type, not given to hyperbole. This year, though, some “junior” water users on the Yampa River, a tributary to the Colorado, were told they would not get their water because others had priority, the first time that has ever happened, and late-season water flows near Grand Junction were near crisis levels. “The crunch is here,” Harris said. “It’s here, and it will stay here. We will never be out of the woods, we are in the woods forever.”

Another low-snow winter would trigger the first emergency declaration in the basin, forcing states to deal with water cutbacks.

Never has the question of “what will the winter be like?” loomed larger than it does this year in the Colorado River Basin. If it is anything like last year (when about two-thirds of the usual snow fell) and many other low snow years since 2000, it will trigger the first emergency declaration in the basin, which could force states to deal with cutbacks in the water they are appropriated. And even if it is a big snow year, it will likely only delay what now seems inevitable.

The last time Lake Mead was full was 1983. Since then it has slowly declined. It is now 40 percent full: 1,082 feet above sea level. It may never be full again, experts say. If it drops 7 feet, to 1,075 feet, it will trigger the first Tier 1 water cutbacks. A flyover reveals a giant white ring all the way around the lake’s 112-mile-long perimeter, dramatically showing how far water levels have dropped.

There are three levels of cutbacks. When Lake Mead falls to 1,050 feet, a Tier 2 crisis occurs, and Tier 3 at 1,025. At each level, states in the lower basin have to give up more of their water. Lake Mead would have already hit 1,075 feet and a First Tier declaration if it weren’t for the fact that farmers, ranchers, and many others have been working to avoid an emergency by keeping more water in the river through conservation efforts. For example, in 2017, state, federal, municipal, and private entities funded the purchase of 40,000 acre-feet from the Gila River Indian Community to be left in Lake Mead in perpetuity as part of a system conservation agreement.

Last August, the U.S. Bureau of Reclamation issued a report on the water future of the region. The agency’s predictions were sobering. By May of this year, the bureau forecast the level will dip just below 1,075 feet, and at the beginning of 2020, the level is expected to drop to 1,070. By the summer of 2020, the prediction is 1,050 feet, almost Tier 2. If these predictions come true, users will have to begin giving up their water allotments, starting with the most junior.

If water levels continue to drop, sinking below 1,050 feet, Hoover Dam — which impounds Lake Mead and provides power to millions of people in Southern California, Nevada, and Arizona — will stop generating electricity, as water levels will be too low to flow through it. And should Lake Mead keep dropping all the way to 895 feet, it will fall below the level at which water can be piped out — the dreaded “dead pool.” Moreover, because Lake Mead is funnel-shaped, the lower it gets the faster it drops. At some point there is the likelihood that the lower basin will force the upper basin to send water to meet its obligations — a compact call — something that’s never happened before.

A few wet years in a long dry spell would be critical these days to keep the Colorado from completely drying up.

All of this is uncharted crisis terrain. “If the drought is multi-decadal the system will fail,” said Jack Schmidt, a professor of watershed science at Utah State University. “But nobody knows what failure means.”

Arizona officials have a sense of it and are coming to grips with the reality. They are the most junior users in the Lower Basin and a Tier 1 shortage would mean Arizona would have to start cutting allocations to users. “If the current climate trend continues,” said Kathryn Sorensen, director of the Phoenix Water Services Department, “you could have ‘dead pool’ in four years. That’s worst case.” Should that happen, the whole region, she says, would be thrown into crisis.

If these were normal times, past droughts might give us a sense of what might be in store. The climate information stored in tree rings show that the longest drought in this region occurred in medieval times and lasted for 62 years — with no very wet years in between the dry ones. A few very wet years in a long dry spell would be critical on the Colorado these days to keep it from completely drying up.

But it may be even worse than that. This drought is unusually hot. “Temperatures keep going up,” said Meko, of the University of Arizona tree ring lab. “We keep breaking records year after year. It’s additional stress on the water system.” Meanwhile, the two driest years all the way back to the 1200s occurred in 1996 and 2002. “It’s a little worrisome to see the most extreme years right near the present,” he said.

“Droughts impacted by warmer temperatures will be more severe,” says Connie Woodhouse, who also studies climate at the tree ring lab. “A lack of precipitation is one thing. But when a drought happens and temperatures are warmer, the precipitation deficits are exacerbated. You have more evaporation, more ground heating, and it impacts the snowpack.”

From 2000 to 2014, flows in the river were 19 percent below the averages in the previous years, and a third of that loss was caused by high temperatures, according to researchers Jonathan Overpeck of the University of Michigan and and Brad Udall at the Colorado Water Insitute at Colorado State University, in an often-cited paper about the unprecedented nature of this drought and what it means for the future.

The biggest impact of high temperatures is something called runoff efficiency — the amount of stream flow that results from precipitation. Right now about 15 percent of the water in the snow in the watershed makes it into the river. The other 85 percent soaks into the ground, evaporates, or is taken up by plants. As it gets warmer, runoff efficiency is decreasing. Shorter winters mean the ground has less snow cover and is darker, so it warms up more and sooner, which means snow melts faster and more water evaporates and is taken up by plants in a longer growing season. The Colorado River Research Group, 10 veteran academics who study the Colorado, call this most alarming change to the physical environment.

The alarm is palpable among water managers throughout the Southwest. They see the writing on the wall.

Warmer temperatures also mean that of the precipation that does come, more of it will fall as rain instead of snow. The Colorado’s engineering infrastructure was built around the natural long-term storage that snowpack provides, but rain pulses quickly through the system.

Meanwhile, the rapid development of everything from housing developments to solar installations in the Southwest has created more dust particles which go airborne and settle on to the snow fields of the Rockies, five to seven times as much dust as was seen a century ago. The darker snow melts sooner and faster, a phenomenon that costs the river about 5 percent of its flow. And as the drought continues, there’s more dust from more dry ground and that creates more dust.

As the flow of the Colorado diminishes, more water users will be forced to turn to groundwater pumping.The news on that front, though, is also problematic. In a 2014 paper, researchers at the Global Institute for Water Security, which uses a satellite to measure large-scale changes in groundwater by measuring changes in gravitational pull, found that from 2004 to 2013, the loss of groundwater from pumping was 6.5 times greater than the total loss of water from Lake Powell and Lake Mead. “Everybody knows that groundwater will become progressively more important,” said Jay Famiglietti, the institute’s director. “The problem is groundwater is rapidly disappearing so we shouldn’t depend on it being there.”

However the biggest cloud looming over the Colorado River Basin is whether the region is entering a completely new era, a permanent change as opposed to a temporary one, caused by a planet being rapidly warmed by human activity. “Is this a drought or is this aridification of the Southwest and Colorado River Basin?” asked the University of Michigan’s Overpeck, who has long studied the Colorado.

Like Overpeck, many experts believe the drying up of the Colorado is being driven by a changing climate. “It’s going to get drier and drier,” he said. “It could mean a hell of a lot less water in the river. We’ve seen declines of 20 percent, but it could get up to 50 percent or worse later in this century.”

If climate change is locked in, he said, what is going on now is not a new normal, but a stop along the way to a yet-drier new normal somewhere in the distant future. “In that case, every year will be a new reality,” he said. “The aridification of the Southwest will continue as long as we put greenhouse gases into the atmosphere. We need to stop burning fossil fuels and that will help stop the decline in the river flow.

“And even if we did that, there’s warming baked in,” he said. “It would continue for another decade and then stabilize. Then we will get the new normal. And it will be at that level of warmth for centuries.”

That’s why the alarm is palpable among water managers in the Southwest. They see the writing on the wall, and there are few skeptics about climate change among them. The plight of Cape Town, South Africa, which came to the brink of a water system crash last year, is on many people’s minds along the Colorado River.

This era of drying is especially serious because so much — some 40 million people and an economy that includes the world’s fifth largest, in California — is riding on the flow of the Colorado. The specter of a region facing an existential crisis because of a warming climate becomes more real every day. “If you can see it, you should plan for it,” Phoenix’s Sorensen said. “And I can see it.”

 

Read Next: Running Dry: New Strategies for Conserving Water on the Colorado

 

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As the Southwest faces rapid growth and unrelenting drought, the Colorado River is in crisis, with too many demands on its diminishing flow. Now those who depend on the river must confront the hard reality that their supply of Colorado water may be cut off.

First in a series republished from Yale Environment 360.

The Colorado River below Dead Horse Point in southeastern Utah. (Ted Wood)

By Jim Robbins for Yale Environment 360
Photography by Ted Wood
Originally published January 14, 2019

The beginnings of the mighty Colorado River on the west slope of Rocky Mountain National Park are humble. A large marsh creates a small trickle of a stream at La Poudre Pass, and thus begins the long, labyrinthine 1,450-mile journey of one of America’s great waterways.

Several miles later, in Rocky Mountain National Park’s Kawuneeche Valley, the Colorado River Trail allows hikers to walk along its course and, during low water, even jump across it. This valley is where the nascent river falls prey to its first diversion — 30 percent of its water is taken before it reaches the stream to irrigate distant fields.

The Never Summer Mountains tower over the the valley to the west. Cut across the face of these glacier-etched peaks is the Grand Ditch, an incision visible just above the timber line. The ditch collects water as the snow melts and, because it is higher in elevation than La Poudre Pass, funnels it 14 miles back across the Continental Divide, where it empties it into the headwaters of the Cache La Poudre River, which flows on to alfalfa and row crop farmers in eastern Colorado. Hand dug in the late 19th century with shovels and picks by Japanese crews, it was the first trans-basin diversion of the Colorado.

The Colorado River gathers momentum in western Colorado, sea-green and picking up a good deal of steam in its confluence with the Fraser, Eagle, and Gunnison rivers. As it leaves Colorado and flows through Utah, it joins forces with the Green River, a major tributary, which has its origins in the dwindling glaciers atop Wyoming’s Wind River Mountains, the second largest glacier field in the lower 48 states.

The now sediment-laden Colorado (“too thick to drink, too thin to plow” was the adage about such rivers) gets reddish here, and earns its name – Colorado means “reddish.” It heads in a southwestern direction through the slick rock of Utah and northern Arizona, including its spectacular run through the nearly 280-mile-long Grand Canyon, and then on to Las Vegas where it makes a sharp turn south, first forming the border of Nevada and Arizona and then the border of California and Arizona until it reaches the Mexican border. There the Morelos Dam — half of it in Mexico and half in the United States — captures the last drops of the Colorado’s flow, and sends it off to Mexican farmers to irrigate alfalfa, cotton, and asparagus, and to supply Mexicali, Tecate, and other cities and towns with water.

While there are verdant farm fields south of the border here, it comes at a cost. The expansive Colorado River Delta — once a bird- and wildlife-rich oasis nourished by the river that Aldo Leopold described as a land of “a hundred green lagoons” — goes begging for water. And there is not a drop left to flow to the historic finish line at the Gulf of California, into which, long ago, the Colorado used to empty.

Nature, in fact, has been given short shrift all along the 1,450-mile-long Colorado. In order to support human life in the desert and near-desert through which it runs, the river is one of the most heavily engineered waterways in the world. Along its route, water is stored and siphoned, routed and piped, with a multi-billion dollar plumbing system — a “Cadillac Desert,” as Marc Reisner put it in the title of his landmark 1986 book. There are 15 large dams on the main stem of the river, and hundreds more on the tributaries.

The era of tapping the Colorado River, though, is coming to a close. This muddy river is one of the most contentious in the country — and growing more so by the day. It serves some 40 million people, and far more of its water is promised to users than flows between its banks — even in the best water years. And millions more people are projected to be added to the population served by the Colorado by 2050.

The hard lesson being learned is that even with the Colorado’s elaborate plumbing system, nature cannot be defied. If the over-allocation of the river weren’t problem enough, its best flow years appear to be behind it. The Colorado River Basin has been locked in the grip of a nearly unrelenting drought since 2000, and the two great water savings accounts on the river — Lake Mead and Lake Powell — are at all-time lows. An officially announced crisis could be at hand in the coming months.

Some scientists believe a long-term aridification driven by climate change may be taking place, a permanent drying of the West.

Meanwhile the Lower Basin states — Arizona, California, and Nevada — have, despite much debate, been unable to come up with a Drought Contingency Plan to keep water in Lake Mead below levels that would trigger a crisis and lead to mandatory cuts in water. And if the states do not agree on a plan by the end of this month, U.S. Bureau of Reclamation Commissioner Brenda Burman says she will step in and force hard decisions.

There are large, existential questions facing the 40 million people who depend on the river — there simply is not enough water for all who depend on it, and there will likely soon be even less.

Most of the water in the Colorado comes from snow that falls in the Rockies and is slowly released, a natural reservoir that disperses its bounty gradually, over months. But since 2000, the Colorado River Basin has been locked in what experts say is a long-term drought exacerbated by climate change, the most severe drought in the last 1,250 years, tree ring data shows. Snowfall since 2000 has been sketchy — last year it was just two-thirds of normal, tied for its record low. With warmer temperatures, more of the precipitation arrives as rain, which quickly runs off rather than being stored as mountain snow. Many water experts are deeply worried about the growing shortage of water from this combination of over-allocation and diminishing supply.

There is tree ring data to show that multi-decadal mega-droughts have occurred before, one that lasted, during Roman Empire times, for more than half a century. The term drought, though, implies that someday the water shortage will be over. Some scientists believe a long-term, climate change-driven aridification may be taking place, a permanent drying of the West. That renders the uncertainty of water flow in the Colorado off the charts. While not ruling out all hope, experts have abandoned terms like “concerned” and “worrisome” and routinely use words like “dire” and “scary.”

“These conditions could mean a hell of a lot less water in the river,” said Jonathan Overpeck, an interdisciplinary climate scientist at the University of Michigan who has extensively studied the impacts of climate on the flow of the Colorado. “We’ve seen declines in flow of 20 percent, but it could get up to 50 percent or worse later in this century.”

Even in rock-ribbed conservative areas, those who use the water of the Colorado say they are already seeing things they have never seen before — this year state officials in Colorado cut off lower-priority irrigators on the Yampa River, a tributary of the Green, and recreation had to be halted, for example — and have grudgingly come to believe “there is something going on with the climate.”

If water cuts are mandated, some states will be required to send others their allotted water, whether they have it to spare or not.

As the authors of a 2015 study on the region’s climate future put it: “Our results point to a remarkably drier future that falls far outside the contemporary experience of natural and human systems in Western North America, conditions that may present a substantial challenge to adaptation.”

So there are conventions and meetings and papers being written throughout the Colorado Basin, seeking an agreeable adaptive future for a river in crisis. One of the big rubs in an incredibly complex debate is this: In 1922, California was booming and helping itself to an increasing share of the water, while other states were growing far more slowly. The other basin states wanted to assure their share before California could suck it up and, with guidance from then-Secretary of Commerce Herbert Hoover, created a Colorado River Compact that divvied up 15 million acre-feet of water — 7.5 million to the Upper Basin States and the same amount to Lower Basin States.

It’s well known now that this Law of the River was a product of irrational Manifest Destiny exuberance, a false premise based on unrealistic projections, because it was signed in one of the wettest periods on the river in centuries. Yet the actual amount apportioned among the states is more than 16 million acre-feet, 1.2 million acre-feet over the too-optimistic apportionment. These extravagant numbers are baked into the system, something known officially as a “structural deficit.”

This winter is make or break for the short term. A crisis is underway — record low flows were seen throughout last summer and fall. Another low- snow winter could light the fuse of a major crisis — an escalating crescendo of emergencies ending in a “compact call” when the lower basin states call on the upper basin states to send them their legally mandated allotment of water — whether they have it to spare or not. All of the players along the river are jockeying for “water security,” an oft-heard term in the region these days.

Cities from Tucson, Arizona, to St. George, Utah, to Denver are booming and need more water to keep growing. Municipal officials across the basin are apprehensive about the future of their growth economy in a time of an increasing likelihood of limits.

Another friction point is the fact that the Upper Basin States — Wyoming, Colorado, New Mexico, and Utah — still have “paper water,” meaning water owed to them by the 1922 compact, which they have not yet taken out of the river. And while many experts say no new straws should be dipped into the river to suck more water out, even if a state is entitled, there are plans afoot to do just that, setting up even more contention and wranglings.

Speculators are quietly buying up farms with water rights and holding them for the day that the price of water soars.

The future of farms and ranches that depend on Colorado River water is most uncertain. Agriculture uses about 80 percent of the Colorado’s flow to irrigate 6 million acres of crops, the largest share of which is alfalfa grown to feed cattle; cities use just 10 percent. While agriculture’s rights are senior — it staked the first claims and so, by law, is the last to lose its water in a crunch — if the going gets tough and cities start running out of water, political and economic clout would favor the millions of people who live there. In that case, agriculture would start losing some of its allotment, either willingly or unwillingly.

“You don’t have to be a rocket scientist to see that there is going to be pressure on your water,” says Mark Harris, general manager of the Grand Valley Water Users Association, a group of irrigators in western Colorado trying to adapt to a new era. “We have a target on our back.” Dewatering agriculture could lead not only to the buying and drying of farms, but the collapse of many small towns whose raison d’être is growing food.

And then there is the recreation industry, a $26 billion part of the Colorado River economy. Last year, raft companies had to reduce their season and cut back the number of trips on the river because of diminished flows.

Meanwhile, speculators and investors have waded into this complex “Chinatown”-like scenario, and are playing a quiet, though growing, role. Hedge funds and other interests, a breed of vulture capitalists, are quietly buying up farms with water rights, and holding them for the day things become more dire and the price of an acre-foot of water soars.

Lastly are the natural attributes of the Colorado River. The needs of fish, wildlife, and native flora have always been at the bottom of the priority list, lost to the needs of booming cities and thirsty crops. That’s changing, as a growing number of people and organizations are working to carve out a future for a more natural river — from the sandy beaches of the Grand Canyon, to the endangered fish along the river’s length, to the birds and jaguars of the Colorado River Delta in Mexico.

The bill for a century of over-optimism about what the river can provide is coming due. How the states will live within their shrinking water budget will depend on how severe the drought and drying of the West gets, of course. But however the climate scenario plays out, there is a good deal of pain and radical adaptation in store, from conservation, to large-scale water re-use, to the retirement of farms and ranches, and perhaps an end to some ways of life. Worst case, if the reservoirs ever hit “dead pool” — when levels drop too low for water to be piped out — many people in the region could become climate refugees.

“I hate to use the word dire, because it doesn’t do justice to the good-thinking people and problem solvers that exist in the basin, but I would say it is very serious,” said Brad Udall, a senior scientist at the Colorado Water Institute. “Climate change is unquantifiable and puts life- and economy-threatening risks on the table that need to be dealt with. It’s a really thorny problem.”

 

Read Next: On the Water-Starved Colorado River, Drought Is the New Normal

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