The latest El Niño/Southern Oscillation (#ENSO) diagnostic discussion is hot off the presses from the Climate Prediction Center

Click here to read the discussion:

ENSO Alert System Status: La Niña Watch

Synopsis: ENSO-neutral is favored through the Northern Hemisphere summer and into the fall (51% chance for the August-October season), with La Niña potentially emerging during the September-November season and lasting through the 2021-22 winter (66% chance during November-January).

Near-average sea surface temperatures, consistent with ENSO-neutral conditions, were observed across most of the equatorial Pacific Ocean during June. In the last week, most Niño indices were near zero except for the Niño-1+2 index, which was +0.3oC. Subsurface temperature anomalies were slightly positive (averaged from 180-100oW) and remained steady during the month. However, in parts of the eastern Pacific, below-average subsurface temperature anomalies returned near the thermocline. For the month, the low-level and upper-level winds were near average across most of the equatorial Pacific Ocean. Tropical convection was suppressed near the Date Line, while remaining mostly near average elsewhere. Overall, the ocean and atmosphere system reflected ENSO-neutral conditions.

A majority of the models in the IRI/CPC plume predict ENSO-neutral to continue through the fall and winter 2021-22. However, the latest forecast model runs from the NCEPCFSv2, many of the models from the North American Multi-Model Ensemble, and some models from our international partners indicate the onset of La Niña during the Northern Hemisphere fall, continuing into winter 2021- 22. The forecaster consensus favors the semodel ensembles, while also noting the historical tendency for a second winter of La Niña to follow the first. In summary, ENSO-neutral is favored through the Northern Hemisphere summer and into the fall (51% chance for the August-October season), with La Niña potentially emerging during the September-November season and lasting through the 2021-22 winter (66% chance during November-January; click CPC/IRI consensus forecast for the chances in each 3-month period).

Another #Heatwave is Scorching the West. More Are Likely On Horizon — #Wyoming Public Media #ActOnClimate

Photo credit: Elisa Stone via the World Weather Attribution

From Wyoming Public Media (Robyn Vincent):

Just weeks into the summer season, a heatwave is once again suffocating parts of the Mountain West including areas already grappling with historic drought conditions.

Blistering temperatures in Nevada, Utah and Idaho come on the heels of an analysis by the World Weather Attribution linking extreme heat in the Pacific Northwest to human-caused climate change.

“An event such as the Pacific Northwest 2021 heatwave is still rare or extremely rare in today’s climate, yet would be virtually impossible without human-caused climate change,” the study reads. “As warming continues, it will become a lot less rare.”

Bryan Shuman, a climate scientist at University of Wyoming, was not surprised by the analysis.

“There’s no doubt that as the atmosphere and the ocean absorb more heat, we’re going to have more warm days,” he said. “The Earth is currently absorbing far more heat from the sun than it releases back to space. And so we feel that — it’s like putting on a warm coat around the whole planet.”

Across the Mountain West, Shuman says this summer’s heat is “really unusual, in terms of how incredibly hot it’s been, but it’s also really surprising, I think to many people, how early the heat has come.”

The reality right now, Shuman says, is that extreme warm events, like heatwaves, are becoming the norm. “In fact, we basically have lost our extreme cold events. What would seem like cold events now are actually just normal events — middle of the road, cool weather.”

That is a concern in the Mountain West for multiple reasons. For one, many homes lack air conditioning…

Easing the impacts of the climate crisis hinges on small behavioral shifts, such as flying less, Shuman said. “That’s probably the biggest single way I personally add carbon in the atmosphere and help make things warm.”

But he was careful to point out that large systematic shifts are significantly more impactful. To spur that kind of change, he suggests tapping into economic forces, such as enacting a tax on carbon emissions.

#ColoradoRiver’s voluntary fishing closure could be first of many in Grand due to low flows, high temps — The Sky-Hi Daily News #COriver #aridification

From The Sky-Hi News (Amy Golden):

Colorado Parks and Wildlife has asked anglers to voluntarily avoid fishing on the Colorado River between Kremmling and Rifle — and more voluntary closures could be coming.

The closure is in effect until further notice with a possibility of a mandatory emergency closure to all fishing if conditions worsen…

Heat, drought and low water levels are contributing to elevated water temperatures in much of Colorado, depleting oxygen levels and leaving trout vulnerable. Trout are cold-water fish that function best in 50-60 degree waters. When temperatures exceed 70 degrees, they often stop feeding and become more susceptible to disease.

As the aquatic biologist for CPW’s Hot Sulphur Springs office, Jon Ewert has seen already seen the local impact to the fishery firsthand. After a number of public reports of fish mortality along the Colorado River, he recently floated from Radium to Rancho del Rio to verify the issue. On that float, he counted 15 fish carcasses…

River flows have been exceptionally low this year.

The USGS gauge on the Colorado River at Catamount Bridge has been measuring 600-700 cfs, less than half what is historically expected there. The USGS gauge on the Colorado River near Dotsero is running at 1,250 cfs, down from an expected 3,000-4,000 cfs.

Mixed with high temperatures, these conditions spell disaster for the fishery. And it’s not just the Colorado River downstream from Kremmling.

According to Ewert, temperatures for other river sections in Grand are also edging toward dangerous levels for fish…

Ewert explained that these types of voluntary closures on rivers are not unheard of, but the extent of the closures might be…

Around 60% of Grand County’s water is diverted, mostly to the Front Range, with the Denver metro area receiving about 20% of its water from Grand.

In early June, temperatures were already spiking to 70 degrees on the Colorado River near Kremmling. Grand County coordinated with the Colorado River District, Denver Water, Northern Water and other partners to boost water levels where possible…

Denver Water estimated that by early July it will have voluntarily foregone collecting around 11,000 acre-feet of water from Grand County…

Northern Water said it has bypassed more than 6,000 acre-feet or about 2 billion gallons of water this year that has been sent downstream in the Colorado River…

Representatives of the Grand County Learning By Doing Cooperative Effort, the partnership of Front Range and West Slope water stakeholders, said that coordination is underway to release additional flows to mitigate temperatures.

While these voluntary efforts by those with water rights in Grand are helping, the sharp contrast in water use is hard to ignore for those invested in the health of the county’s rivers.

“Here’s what really breaks my heart: The Front Range water diverters filled their reservoirs … they continued to divert as much water as they did in a wet year,” [Kirk] Klanke said. “They don’t seem to feel they have any more wiggle room to leave a little more water in the river …

“Now we’re at the mercy of senior water right calls downstream. As I watch my guide friends become unemployed, I watch Kentucky bluegrass be watered on the Front Range. It’s hard to swallow.”

Kremmling bird count studies how birds use irrigated agriculture — @AspenJournalism

Wildlife biologist Bill Vetter watches and listens for birds in irrigated fields outside of Kremmling. Vetter is part of an avian monitoring program run by Audubon Rockies that aims to learn more about how birds use irrigated agriculture.

From Aspen Journalism (Heather Sackett):

In the gray light of dawn, hundreds of swallows darted over a pool of standing water in an irrigated field along the Colorado River. The birds were attracted to the early-morning mosquitos swarming the saturated landscape. Bill Vetter, a wildlife biologist with Wyoming-based Precision Wildlife Resources, methodically counted the birds. For six minutes, he marked down every bird he saw or heard at eight different locations across the ranch, 250 meters apart.

Vetter is part of an avian-monitoring program, headed up by Audubon Rockies, which aims to learn more about how birds use irrigated agricultural lands. In 2020, the fields near Kremmling where Vetter counted purposely did not irrigate as part of a state-grant-funded study on water use in high-elevation pastures. This year, irrigators are back to watering their usual amount and Vetter is tracking the trends in bird species and numbers.

This year, Vetter counted four or five additional species, including the yellow-headed blackbird, white-faced ibis and sora.

“I can say that for sure we got additional species this year that we didn’t have last year, and those species are largely associated with water habitat,” he said.

Across the Western Slope, birds and other wildlife have come to depend on these artificially created wetlands, a result of flood irrigation. But as the state of Colorado grapples with whether to implement a demand-management program, which would pay irrigators to temporarily dry up fields in an effort to send more water downstream, there could be unintended consequences for the animals that use irrigated agriculture for their habitat.

Learning more about how birds use these landscapes is a key first step, according to Abby Burk, Western rivers regional program manager with Audubon Rockies.

“Wetlands are the unsung hero for all the ecological services and functions they provide for wildlife,” she said. “Those low-field wetlands are good habitat for birds, for breeding, for migratory stopovers.”

In 2020, the bird count turned up 1,285 birds, comprising 39 different species, including great blue herons, meadowlarks, red-winged blackbirds, an osprey, a peregrine falcon, and several types of swallows, warblers and sparrows. The numbers are not yet tallied for this year, but the general expectation is that more water means more birds.

“Birds have adapted to how we have created these different habitat types,” Burk said. “We’ve really got to look at the larger effects of how we use water can impact birds and other wildlife. Where there’s water, birds also do thrive.”

This pool of standing water in a field near the Colorado River is a result of flood irrigation. It’s also great habitat for mosquito-loving swallows.

Water-use study

The seven ranches where the avian monitoring is taking place are part of a larger water study that is evaluating conserved consumptive use in the upper Colorado River basin. Consumptive use is a measure of how much water is consumed by thirsty plants. Conserved consumptive use is the amount by which consumptive use is reduced as a result of changing irrigation practices.

Researchers from Colorado State University are studying the impacts of using less water on the high-elevation fields in Grand County and how long it takes them to recover once water returns. Researchers hope to fill in a data gap about the impacts of reducing irrigation water on high-elevation pastures.

In 2020, some participating landowners did not irrigate at all and some only irrigated until June 15. This year, landowners reverted to their historical irrigation practices. Remote sensors and ground-based instruments are monitoring the difference in plant and soil conditions, and will continue to do so through 2023. Early results found that the plants used about 45% less water in 2020 compared with the previous four years.

The first phase of the project received a $500,000 grant from the Colorado Water Conservation Board (CWCB) under its Alternative Agriculture Water Transfer Method program, which aims to find alternatives to “buy and dry” water transfers. The CWCB in September will consider another $60,000 grant request for Trout Unlimited to continue to do monitoring with a field technician.

This monitoring station is part of a research project by Colorado State University to track soil and plant conditions in irrigated pastures. The study aims to learn more about how using less water affects high-elevation fields.

Demand management

Although the project is not directly related to the state’s demand-management feasibility investigation, the results could have implications for any potential program that the state eventually comes up with.

“We are hoping all this information and research is going to be used down the road if a program does develop,” said Mely Whiting, Colorado water project legal counsel with Trout Unlimited. Trout Unlimited is helping to fund and implement the research project.

At the heart of a demand-management program is paying irrigators on a voluntary and temporary basis to not irrigate and to leave more water in the river in an effort to bolster levels in Lake Powell and help Colorado meet its downstream obligations.

Under the Colorado River Compact, the Upper Basin (Colorado, Wyoming, Utah and New Mexico) must send 7.5 million acre-feet each year to the Lower Basin (California, Arizona and Nevada). Failure to meet this obligation could trigger a “compact call” where junior water users in the Upper Basin would have their water cut off. (An acre-foot is enough water to cover one acre of land one foot deep.)

As rising temperatures due to climate change continue to rob the Colorado River and its tributaries of flows and increase the risk of a compact call, finding solutions to water shortages is becoming more urgent. Lake Powell, the river’s biggest reservoir, is just under 34% full and projected to decline further. Demand management would let the Upper Basin set aside up to 500,000 acre-feet in a special pool in Powell to help avoid a compact call.

Some still-unanswered questions remain: How much of the conserved consumptive water from high-elevation pastures would actually make it downstream to Lake Powell? And how much would local streams benefit from the added flows?

“One critical part of what we’re doing is looking at the stream and saying: Do we see any changes from one year to the next? How much water would actually make it to the stream?” Whiting said. “We are measuring to see if there’s any distinction between the year the conservation practices were applied and the following year.”

Wildlife biologist Bill Vetter and Western Rivers Regional Program Manager with Audubon Rockies Abby Burk walk along an irrigation ditch in Grand County. An avian monitoring program aims to learn more about how birds use irrigated agriculture.


The unintended consequences of different irrigation patterns under a demand-management program could be many and far-reaching. In 2018, the CWCB formed nine workgroups to examine some of these issues, including one that looked at environmental considerations.

In notes submitted to the CWCB last July, the environmental workgroup acknowledged there could be trade-offs, sometimes among species. For example, reducing irrigation and leaving more water in rivers would benefit fish and riparian habitats, but might negatively impact birds or other species that use wetlands created by flood irrigation. And with full irrigation, birds may thrive, but to the detriment of river ecosystems.

David Graf, water-resource specialist with Colorado Parks and Wildlife, participated in the environmental-considerations workgroup. He said irrigated agriculture provides a lot of diversity in forbes, grasses and insects — good sources of protein for birds. But fish need water too. And in the summer and fall, the more, the better. There is an environmental value in irrigated agriculture, but only if the streams aren’t suffering at its expense, Graf said.

“There is a whole bunch of wildlife that is dependent on irrigated agriculture,” he said. “I think we all recognize the value that irrigated agriculture brings to wildlife, but it’s at the expense of fisheries in a lot of cases. There’s a little bit of a trade-off on a local level. I think we get the balance wrong sometimes.”

This pool of standing water in a field near the Colorado River is a result of flood irrigation. It’s also great habitat for mosquito-loving swallows.

Birds as indicator

Burk acknowledged that the usefulness of the bird count is limited by the absence of baseline data, because there was no bird monitoring on the fields before 2020. But trends are still important and, like the proverbial canary in the coal mine, birds can be an indicator of what’s happening on a landscape. Burk said she would like to do a bird-monitoring program on a larger scale at different locations around the Western Slope.

“As we learn more about how birds respond to water on the landscape, whether that’s in the river, in the fields, in the wetlands and adjacent habitats, it’s going to help give us a better picture of how the entire landscape and our natural systems are responding,” Burk said.

Colorado River water issues sometimes make for seemingly strange bedfellows. Nonprofit environmental groups such as Audubon are usually focused on keeping more water in the rivers, while irrigators traditionally take it out. In this case, interests align with keeping water on the landscape, with birds as the beneficiaries. Burk said those “us-versus-them” distinctions among water users are evaporating as people realize they are not facing the water crisis alone.

“When we drop the silos, drop the fences and walls between water users, we can see that this is one water — people, wildlife, the environment, the recreation industry — we all depend upon it,” Burk said. “So, how do we keep these natural systems so they can keep doing their job for everyone with reduced water? Water has to go further because there’s less of it.”

This story ran in The Aspen Times and the Craig Press on July 10.

Governor Polis declares #drought emergency for western #Colorado — The #PagosaSprings Sun #SanJuanRiver #ColoradoRiver #COriver #aridification

West Drought Monitor map July 6, 2021.

From The Pagosa Springs Sun (Clayton Chaney):

On Wednesday, June 30, Gov. Jared Polis formally declared a drought emergency for 21 counties in the western portion of the state by proclamation.

The proclamation states that Colorado is now in phase 3 activa- tion of the State Drought Plan for 21 counties, including Archuleta, Hinsdale and La Plata counties.
Mineral County was not in- cluded in the governor’s proclamation.

However, a press release from the Colorado Water Conservation Board (CWCB) explains that counties along the Continental Divide in abnormally dry conditions or a moderate drought “will continue to be closely monitored and added to the drought emergency proclama- tion as appropriate.”

The CWCB press release explains that phase 3 is the highest level of activation under the State Drought Plan.

The CWCB press release notes that on June 22, 2020, phase 2 of the State Drought Plan was activated for 40 counties and expanded to all 64 counties by September 2020…

Colorado Drought Monitor map July 6, 2021.

Drought report
According to the National Integrated Drought Information System (NIDIS), as of 10 a.m. on June 29, 100 percent of Archuleta County remains in a moderate drought stage, with more than half of the county in extreme drought.

The NIDIS website notes that under a moderate drought stage, dry-land crops may suffer, rangeland growth is stunted, very little hay is available and risk of wildfires may increase.

The NIDIS website also notes that 71.17 percent of the county is in a severe drought stage.

According to the NIDIS, under a severe drought stage, fire season is extended.

Additionally, the NIDIS website notes that 51.04 percent of the county is in an extreme drought, mostly in the western portion of the county.

The NIDIS website notes that under an extreme drought stage, large fires may develop and pasture conditions worsen.

According to the NIDIS, 6.24 percent of the county, in the southwestern portion, is in an exceptional drought stage…

River report

According to the U.S. Geological Survey (USGS), the San Juan River was flowing at a rate of 149 cfs in Pagosa Springs as of 10 a.m. on Wednesday, July 7.

Based on 85 years of water re- cords at this site, the average flow rate for this date is 482 cfs.

The highest recorded rate for this date was in 1995 at 2,080 cfs. The lowest recorded rate was 17.5 cfs, recorded in 2002.

As of 10 a.m. on Wednesday, July 7, the Piedra River near Arboles was flowing at a rate of 119 cfs.

Based on 58 years of water records at this site, the average flow rate for this date is 372 cfs.

The highest recorded rate for this date was 1,920 cfs in 1975. The lowest recorded rate was 8.05 cfs in 2002.

Low water levels in #LakePowell could affect #NavajoLake — The #PagosaSprings Sun #SanJuanRiver #ColoradoRiver #COriver #aridification

Graphic credit: Brad Udall via InkStain

From The Pagosa Springs Sun (Joe Napolitan):

During a meeting on June 21, members of the San Juan Water Conservation District (SJWCD) board discussed local implications of historically low water levels in Lake Powell.

“The article that came out today just said that there’s a threshold that Lake Powell has to reach for the CWCB (Colorado Water Conservation Board) to enact some legal movements,” said board member Joe Tedder. “Apparently we’re going to hit that, probably by the end of June.”

The threshold Tedder referred to is outlined in the Colorado River Drought Contingency Management and Operations Plan (DCP).

The plan states that if Lake Powell reaches a surface elevation of 3,525 the upper-basin states and the U.S. Bureau of Reclamation (USBR) shall take action to send more water to Lake Powell from reservoirs upstream.

According to the USBR, the surface elevation of Lake Powell was 3,559 feet on July 4. Aside from the drought in 2005, such low water levels have not been seen since the 1960s, when Lake Powell was still filling after the construction of the Glen Canyon Dam was completed in 1963.

Low water levels in Lake Powell have implications for the Colorado River Basin, which includes the San Juan River and Pagosa Springs.

According to a report by the Pacific Institute in 2013, roughly 70 percent of the Colorado River Basin’s water is used to irrigate nearly 5.7 million acres of land for agriculture. The USBR estimates that more than 40 million people depend on the river to support their lives.

Another report prepared by Southwick Associates in 2012 esti- mated that 5.6 million people over the age of 18 use the Colorado River for recreational purposes each year.

The same report totals the value of all spending resulting from such recreational expenditures to be $25.6 billion, generating $1.6 billion in federal tax dollars…

SJWCD board member Doug Secrist outlined provisions in the DCP, stating that in an effort to stabilize Lake Powell, water would be reallocated from reservoirs up- stream, otherwise referred to as initial units…

“I can tell you that PAWSD is senior to all those reservoirs, so PAWSD water is pretty well protected,” SJWCD Board of Directors President Al Pfister said of the Pagosa Area Wa- ter and Sanitation District. “But it is a very intricate and interwoven issue.”


The National Integrated Drought Information System reports that Archuleta County is experiencing its driest year in over a century, and that the initial units from which water is planned to be supplied to Lake Powell are already low in volume and inflow…

The USBR predicts that the preliminary unregulated flow which supplies the Navajo Reservoir, which presently has a pool elevation 27 feet below the 1981-2010 average, will be 36 percent of the average for the month of July.
For Blue Mesa, which presently rests 43 feet below the 1981-2010 av- erage, is projected to have an inflow volume 40 percent of average.
Flaming Gorge, which rests only 3 feet below its average pool eleva- tion, is projected to have an unregu- lated inflow volume of 42 percent of average.

Once a Rich Desert River, the #GilaRiver Struggles to Keep Flowing — Yale 360 #ColoradoRiver #COriver #aridification

Gila River. Photo credit: Dennis O’Keefe via American Rivers

From Yale 360 (Jim Robbins). Click through for Ted Wood’s photo gallery:

The Gila was once a vibrant desert river, providing a lifeline for the riparian habitat and wildlife that depended on it in the U.S. Southwest. But population growth, agricultural withdrawals, and, increasingly, climate change have badly diminished the river and threaten its future.

The confluence of the tiny San Pedro River and the much larger Gila was once one of the richest locales in one of the most productive river ecosystems in the American Southwest, an incomparable oasis of biodiversity.

The rivers frequently flooded their banks, a life-giving pulse that created sprawling riverside cienegas, or fertile wetlands; braided and beaver-dammed channels; meandering oxbows; and bosques — riparian habitats with towering cottonwoods, mesquite and willows. This lush, wet Arizona landscape, combined with the searing heat of the Sonoran Desert, gave rise to a vast array of insects, fish and wildlife, including apex predators such as Mexican wolves, grizzly bears, jaguars and cougars, which prowled the river corridors.

The confluence now is a very different place, its richness long diminished. A massive mountain of orange- and dun-colored smelter tailings, left from the days of copper and lead processing and riddled with arsenic, towers where the two rivers meet. Water rarely flows there, with an occasional summer downpour delivering an ephemeral trickle.

On a recent visit, only a few brown, stagnant pools remained. In one, hundreds of small fish gasped for oxygen. An egret that had been feeding on the fish flew off. The plop of a bull frog, an invasive species, echoed in the hot, still air.

Gila River watershed. Graphic credit: Wikimedia

The Gila River, which was listed by the advocacy group American Rivers in 2019 as the nation’s most endangered river, drains an enormous watershed of 60,000 square miles. Stretches have long been depleted, largely because of crop irrigation and the water demands of large cities. Now, a warmer and drier climate is bearing down on ecosystems that have been deprived of water, fragmented, and otherwise altered, their natural resilience undone by human activities.

Other desert rivers around the globe — from the Nile to the Tigris and Euphrates to the Amu Darya in Central Asia — face similar threats. Efforts are underway to restore some integrity to these natural systems, but it is an uphill battle, in part because desert rivers are more fragile than rivers in cooler, wetter places.

Last year was the second-hottest and second-driest on record in Arizona, where heat records are frequently broken. The last two years have seen fewer desert downpours, known locally as monsoons, an important source of summer river flow.

“We’re dealing with a rapidly changing climate that is becoming, overall, more dry and varied and warmer,” said Scott Wilbor, an ecologist in Tucson who studies desert river ecosystems, including the San Pedro. “We are in uncharted territory.”

Born of snowmelt and springs in the mountains of southern New Mexico, the Gila is the southernmost snow-fed river in the United States. It was once perennial, running 649 miles until it emptied into the Colorado River. As the climate warms, scientists predict that by 2050 snow will no longer fall in the Black and Mogollon ranges that form the Gila’s headwaters, depriving the river of its major source of water.

“We’re seeing a combination of long-term climate change and really bad drought,” said David Gutzler, a professor emeritus of climatology at the University of New Mexico. If the drought is prolonged, he said, “that’s when we’ll see the river dry up.”

The Gila River as it nears the Florence Diversion Dam in Arizona was almost dry by May this year. Photo credit: TED WOOD via Yale 360.

The same scenario is playing out on the once-mighty Colorado, the Rio Grande, and many smaller Southwest rivers, all facing what is often called a megadrought. Some research indicates that a southwestern U.S. megadrought may last decades, while other scientists fear the region is threatened by a permanent aridification because of rising temperatures.

Worldwide, said Ian Harrison, a freshwater expert with Conservation International, “pretty much where there are rivers in arid areas, they are suffering through a combination of climate change and development.”

Like the Gila, many of these rivers have high degrees of endemism. “Life is often highly specialized to those particular conditions and only lives on that one river, so the impacts of loss are catastrophic,” he said.

Rivers everywhere are important for biodiversity, but especially so in the desert, where 90 percent of life is found within a mile of the river. Nearly half of North America’s 900 or so bird species use the Gila and its tributaries, including some that live nowhere else in the U.S., such as the common blackhawk and northern beardless tyrannulet. Two endangered birds, the southwestern willow flycatcher and yellow-billed cuckoo, live along the Gila and its tributaries, including the San Pedro and the Salt.

Desert rivers, of course, make life in the desert possible for people, too. Growing crops in the perpetual heat of the desert can be highly lucrative, especially if the water is free or nearly so thanks to subsidies from the federal government. Agriculture is where most of the water in the Gila goes.

A vermillion flycatcher perched near the Gila River in Safford, Arizona. Photo credit: TED WOOD via Yale 360

This spring, photographer Ted Wood and I made a journey along the length of the Gila, from the headwaters in New Mexico to west of Phoenix. In most of Arizona, the Gila is dry. Where it still flows, I was impressed by how such a relatively small river, under the right conditions, can be so life-giving. The trip brought home what desert rivers are up against as the climate changes, and also how much restoration, and what types, can be expected to protect the biodiversity that remains.

Our journey began at the river’s source, where Cliff Dweller Creek spills out of a shady canyon lined with Gambel oak in Gila Cliff Dwellings National Monument. The creek is barely a trickle here. Above the creek, ancestral Puebloans, known as Mogollon, once lived in dwellings wedged into caves, making pottery and tending vegetable gardens. The Mogollon abandoned these canyons in the 15th century, perhaps done in by an extended drought.

From inside a Mogollon cave, I looked out at rolling hills, covered with ponderosa pine, pinyon and juniper trees. The green-hued water gains volume where three forks come together near here. Historically, the mountain snow melts slowly each spring, providing high steady flows through April and May. Flows slow to a trickle in June. In July and August, monsoons pass through and, along with frontal systems, cause flash flooding and a rise in water levels.

Flooding is a “disturbance regime,” not unlike a forest fire, that rejuvenates aging, static ecosystems. A healthy river in the mountains of the West is one that behaves like a fire hose, whipping back and forth in a broad channel over time, flash flooding and then receding, moving gravel, rocks, logs and other debris throughout the system. A flooding river constantly demolishes some sections of a river and builds others, creating new habitat — cleaning silt from gravel so fish can spawn, for instance, or flushing sediment from wetlands. A river that flows over its banks, recharges aquifers and moistens the soil so that the seedlings of cottonwoods, mesquite trees and other vegetation can reproduce. Along healthy stretches of the Gila, birds are everywhere; I spotted numerous bluebirds in the branches of emerald green cottonwoods.

Gila Cliff Dwellings National Monument New Mexico, an ancestral Puebloan ruin at the headwaters of the Gila River. Photo credit: TED WOOD via Yale 360

The riparian ecosystem that lines the 80 or so miles of the New Mexico portion is largely intact because of the protections afforded by federal wilderness areas, the lack of a dam, and the river’s flow not being completely siphoned off for farming. This is an anomaly in a state that has lost many of its riparian ecosystems. “This is the last free-flowing river in New Mexico,” said Allyson Siwik, executive director of the Gila Conservation Coalition.

The future of the New Mexico stretch of the river is uncertain because of the possibility of more water withdrawals and the loss of snowpack. “We’ve seen flows in the last 10 years lower than we’ve ever seen,” Siwik said. This year, she said, set an all-time low on the river, with flow less than 20 percent of normal.

Undammed, the Gila River through New Mexico still floods, refreshing the Cliff-Gila valley, which contains the largest intact bosque habitat in the Lower Colorado River Basin. The valley is home to the largest concentration of non-colonial breeding birds in North America. The river is also a stronghold for threatened and endangered species, such as nesting yellow-billed cuckoos, the Gila chub, Chiricahua leopard frogs and Mexican garter snakes all live there.

At odds with efforts to keep the Gila wild are plans by a group of roughly 200 long-time irrigators in southwestern New Mexico. Each summer they divert water from the Gila to flood-irrigate pastures, which de-waters stretches of the river. The irrigators have been trying to raise money to build impoundments to take even more of their share of water, but so far have been unsuccessful, in part because of opposition from conservation groups.

Severe drought this spring combined with water overuse resulted in the drying of the Gila River in eastern Arizona and the death of the fish population. Photo credit: TED WOOD via Yale 360

Cattle are another threat to the river’s biological integrity here — both unfenced domestic cattle and feral cows. Cattle break down riverbanks, widen the stream and raise water temperatures. They eat and trample riparian vegetation, causing mud and silt to choke the flow, and destroy habitat for endangered species. The Center for Biological Diversity recently sued the U.S. Forest Service to force the agency to take action.

“We’re in a cow apocalypse,” said Todd Schulke, a founder of the Center for Biological Diversity. “They are even in the recovered Gila River habitat. It’s just heartbreaking.”

As the river enters Arizona, the riparian ecology remains largely intact, especially in the 23 miles of the Gila Box National Riparian Area. Here, 23,000 acres of bosque habitat is in full expression, with thick stands of cottonwoods, velvet mesquite trees and sandy beaches. It is one of only two national riparian areas in the country set aside for its outstanding biodiversity; the other is on the San Pedro River.

As the river leaves the riparian area, it undergoes a striking change: massive cotton farms near the towns of Safford, Pima, and Thatcher, first planted in the 1930s, cover the landscape. The dried, brown stalks of harvested cotton plants stand in a field, bits of fluff on top. Growing cotton in the desert — which uses six times as much water as lettuce — has long been seen as folly by critics, made possible only by hefty federal subsidies.

Farmers in Safford, Arizona, pump groundwater near the Gila River to irrigate their fields. Photo credit: TED WOOD via Yale 360

Much of the flood pulse ecology is lost here, as the river is diverted or subject to groundwater pumping. Instead of flooding, the river cuts deeper into its channel, lowering the water table, which many plants can no longer reach. The cottonwood stands and other riparian habitats have disappeared. “You want the groundwater within five feet of the ground, but it’s mostly 8 to 12 feet,” said Melanie Tluczek, executive director of the Gila Watershed Partnership, which has been doing restoration here since 2014.

It is a harsh place for new planting. The river is dry in long stretches. Tamarisk, a pernicious invasive tree also known as salt cedar, needs to be cut down and its stumps poisoned to prevent regrowth. Small willows and Fremont cottonwoods have been planted on barren desert ground. Wire cages over infant trees keep elk, beaver and rabbits from gobbling them up.

Meanwhile, tamarisk grows prolifically, slurping up water, changing soil chemistry and the nature of flooding, robustly outcompeting natives, and increasing the risk of wildfire.

“If you can do restoration here, you can do it anywhere,” Tluczek said. She said the Gila Watershed Partnership has removed 216 acres of tamarisk along the river and planted 90 acres with new native trees. But the Gila here will never look like it did. “We can’t restore the past,” Tluczek said. “We’re going to see a floodplain that has more dryland species and fewer floodplain species.”

The Coolidge Dam in Arizona forms the San Carlos Reservoir, which is now at historic lows. Photo credit: TED WOOD via Yale 360

Downstream, the Coolidge Dam forms a giant concrete plug on the Gila. Built in the 1920s by the federal government, it was the result of irrational exuberance about the amount of water on the Gila and meant to supply farmers with water. Today, however, the reservoir is usually dry. Built to hold 19,500 acres of water, this year the water in the lake covered just 50 acres.

From here to Phoenix and on to the Colorado, water only occasionally flows in the Gila. Yet even the small amount of water that remains is vital to wildlife. “Where there has been water near the surface, animals smell it and will dig down in the sand in the riverbed to free it up,” Wilbor said. “You set up a camera and it’s like an African watering hole, with species after species taking turns to come use the water.”

Will the Gila River through most of Arizona to the Colorado ever be restored to a semblance of the biological jewel it once was? The chances are slim. But two pioneering efforts have brought back elements of the desiccated river.

In 2010, Phoenix completed a $100 million, eight-mile restoration of the long-dewatered Salt River where it joins the Gila and Agua Fria rivers at Tres Rios. Fed by water from the city’s sewage treatment plant across the road, this constructed complex includes 128 acres of wetlands, 38 acres of riparian corridor, and 134 acres of open water. It is thick with cattails and other vegetation, an island of green around a lake amid the sere surrounding desert.

Ramona and Terry Button run Ramona Farms on the Gila River Indian Community, where some water allocated to the tribe is being released into the Gila. Photo credit: TED WOOD via Yale 360

On the nearby Gila River Indian Community, meanwhile, home to the Pima — or the name they prefer, Akimel O’othham, the river people — is something called a managed area recharge. The Akimel O’othham, who share their community with the Maricopa, are believed to be the descendants of the Hohokam, an ancient agricultural civilization with a vast network of irrigation canals that was largely abandoned centuries ago. The Akimel O’othham continued to farm along the Gila in historic times until their water was stolen from them in the late 19th century by settlers who dug a canal in front of the reservation and drained it away.

After a century of the Akimel O’othham fighting for their water rights, in 2004 the Arizona Water Settlement Act provided the tribe with the largest share of Colorado River water from the Central Arizona Project, a share larger than the city of Phoenix’s allotment. The tribe is now water-rich, using much of that water to restore its tribal agricultural past, though with modern crops and methods.

Last year, some of the Colorado River water was released into the Gila to be stored in an underground aquifer and used to create a wetland.

Both of these projects, at Tres Rios and at the reservation, have created oases in a harsh desert landscape, bringing back an array of birds and wildlife, and — in the case of the Akimel O’othham — helping revitalize the cultural traditions of these river people.

“We’re not going to have rivers with native species in the Southwest unless we can protect and restore these systems,” especially with a changing climate, Siwik said. “Protecting the best, restoring the rest — or else we lose these systems that we need for our survival.”