Snow sublimates rapidly in a hot, dry atmosphere ~ The Conversation


Creeks, rivers and lakes that are fed by melting snow across the U.S. West are already running low as of mid-July 2021, much to the worry of farmers, biologists and snow hydrologists like me. This is not surprising in California, where snow levels over the previous winter were well below normal. But it is also true across Colorado and the Rocky Mountains, which in general received a normal amount of snow. You’d think if there was normal amount of snow you’d have plenty of water downstream, right?

Over a century ago, snow scientist James Church at the University of Nevada, Reno, began examining how the amount of snow on mountains related to the amount of water in riversfed by the melting snow. But as hydrologists have learned over the many decades since, the correlations between snows and river flows are not perfect. Surprisingly, there is a lot researchers don’t know about how the snowpack is connected to rivers

Of course, a dry winter will result in meager flows in spring and summer. But there are other reasons snow from the mountains won’t reach a river below. One growing area of research is exploring how droughts can lead to chronically dry soil that sucks up more water than normal. This water also refills the groundwater below. 

But another less studied way moisture can be lost is by evaporating straight into the atmosphere. Just as the amount of snow varies each year, so too does the loss of water to the air. Under the right conditions, more snow can disappear into the air than melts into rivers. But how snowfall and loss of moisture into the air itself relate to water levels in rivers and lakes is an important and not well understood part of the water cycle, particularly in drought years.

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Losing moisture to the air

There are two ways moisture can be lost to the atmosphere before it reaches a creek or river. 

The first is through evaporation. When water absorbs enough energy from the Sun, the water molecules will change into a gas called water vapor. This floating water vapor is then stored in the air. Most of this evaporation happens from the surface of lakes, from water in the soil or as snow melts and the water flows over rocks or other surfaces.

Another way moisture can be lost to the atmosphere is one you might be less familiar with: sublimation. Sublimation is when a solid turns directly into a gas – think of dry ice. The same can happen to water when snow or ice turns directly into water vapor. When the air is colder than freezing, sublimation happens when molecules of ice and snow absorb so much energy that they skip the liquid form and jump straight to a gas.

A number of atmospheric conditions can lead to increased evaporation and sublimation and eventually, less water making it to creeks and streams. Dry air can absorb more moisture than moist air and pull more moisture from the ground into the atmosphere. High winds can also blow moisture into the air and away from the area where it initially fell. And finally, the warmer air is and more Sun that shines, the more energy is available for snow or water to change to vapor. When you get combinations of these factors – like warm, dry winds in the Rockies called Chinook winds – evaporation and sublimation can happen quite fast. On a dry, windy day, up to around two inches of snow can sublimate into the atmosphere. That translates to about one swimming pool of water for each football field-sized area of snow.

A small green metal tower and green wooden box in a snowy mountain forest.
Snow survey sites, like the one seen here in Montana, can help scientists measure snowpack, but most sublimation happens above the treeline, a zone for which there is little data. USDA NRCS Montana/WikimediaCommons

Sublimation is mysterious

It is relatively easy to measure how much water is flowing through a river or in a lake. And using satellites and snow surveys, hydrologists can get decent estimates of how much snow is on a mountain range. Measuring evaporation, and especially sublimation, is much harder to do.

Today researchers usually estimate sublimation indirectly using physics equations and wind and weather models. But there are lots of uncertainties and unknowns in these calculations. Additionally, researchers know that the most moisture loss from sublimation occurs in alpine terrain above the treeline – but snow scientists rarely measure snow depths there. This further adds to the uncertainty around sublimation because if you don’t know how much moisture a system started out with, it is hard to know how much was lost.

Finally, weather and snowpack depths vary a lot from year to year. All of this makes measuring the amount of snow that falls and then is lost to the atmosphere incredibly difficult

When scientists have been able to measure and estimate sublimation, they have measured moisture losses that range from a few percent to more than half of the total snowfall, depending on the climate and where you are. And even in one spot, sublimation can vary a lot year to year depending on snow and weather.

When moisture is lost into the atmosphere, it will fall to the surface as rain or snow eventually. But that could be on the other side of the Earth and is not helpful to drought-stricken areas.

It is hard to say how important loss of moisture to the atmosphere is to the total water cycle in any given mountain range. Automated snow monitoring systems – especially at high elevations above the treeline – can help researchers better understand what is happening to the snow and the conditions that cause losses to the atmosphere.

The amount of water in rivers – and when that water appears – influences agriculture, ecosystems and how people live. When there is a water shortage, problems occur. With climate change leading to more droughts and variable weather, filling a knowledge gap of the water cycle like the one around sublimation is important


Science & Tech

The composite image offers a startling look into a violent event.

Sarah Cascone, June 4, 2021

Composite image of the Galactic Center. Courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT./CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.
Composite image of the Galactic Center. Courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT./CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.

NASA’s latest image of the Milky Way is two decades in the making.

The dramatic view of the heart of the galaxy combines 370 observations taken over a period of 20 years and features billions of stars.

“What we see in the picture is a violent or energetic ecosystem in our galaxy’s downtown,” astronomer Daniel Wang of the University of Massachusetts Amherst told the Associated Press.

“There are a lot of supernova remnants, black holes, and neutron stars there. Each X-ray dot or feature represents an energetic source, most of which are in the center.”

Wang created the composite photograph while working from home over the past year, according to CNN, combining data from the orbiting Chandra X-ray Observatory and the MeerKAT radio telescope in South Africa.

He published the resulting image and his associated findings in the Monthly Notices of the Royal Astronomical Society journal.

The stunning photograph shows hot gas streaming out of regions near Sagittarius A*, a supermassive black hole at the center of the galaxy some 26,000 light years away.

Wang believes this is evidence of a magnetic field reconnection event, when two opposing magnetic fields collide and combine, expelling large amounts of energy. It’s believed to be the same phenomena that triggers solar flares and the Northern Lights.X-ray & Radio Image of G0.17-0.41. Image courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.

X-ray & Radio Image of G0.17-0.41. Image courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.

The Milky Way, a spiral galaxy, formed about 13.51 billion years ago. Observing the galactic center is difficult because it is surrounded by a thick fog of dust and gas, but the new photo reveals a interstellar tapestry of gas and magnetic fields.

“The galaxy is like an ecosystem,” Wang explained. “We know the centers of galaxies are where the action is and play an enormous role in their evolution.”

See more views of the galactic center below.Composite image of the Galactic Center made with X-ray imagery from the Chandra X-ray Observatory. Courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.

Composite image of the Galactic Center made with radio data from MeerKAT. Courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.Composite image of the Galactic Center made with radio data from MeerKAT. Courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.

Composite image of the Galactic Center made with radio data from MeerKAT. Courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.Composite image of the Galactic Center with labeled features. Courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT./CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.

Composite image of the Galactic Center with labeled features. Courtesy of NASA/CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT./CXC/UMass/Q.D. Wang; Radio: NRF/SARAO/MeerKAT.

Rearrangement of World’s Plant Life Looms ~ YaleEnvironment 360


Previous periods of rapid warming millions of years ago drastically altered plants and forests on Earth. Now, scientists see the beginnings of a more sudden, disruptive rearrangement of the world’s flora — a trend that will intensify if greenhouse gas emissions are not reined in.

Some 56 million years ago, just after the Paleocene epoch gave way to the Eocene, the world suddenly warmed. Scientists continue to debate the ultimate cause of the warming, but they agree on its proximate cause: A huge burst of carbon dioxide entered the atmosphere, raising Earth’s average temperature by 7 to 14 degrees Fahrenheit. The Paleocene-Eocene Thermal Maximum (PETM), as this event is known, is “the best geologic analog” for modern anthropogenic climate change, said University of Wyoming paleobotanist Ellen Currano.

She studies how the PETM’s sudden warmth affected plants. Darwin famously compared the fossil record to a tattered book missing most of its pages and with all but a few lines obscured. The PETM, which lasted roughly 200,000 years, bears out the analogy. Wyoming’s Bighorn Basin is the only place on Earth where scientists have found plant macrofossils (visible to the naked eye, that is) that date to the PETM. The fossil leaves that Currano and her colleagues have found there paint a vivid portrait.

Before the PETM, she said, there lived a forest of cypress, sycamores, alders, dogwoods, walnuts and other species, all of them suggestive of a temperate climate — a bit swampy, perhaps not unlike that of the southeastern United States. Then, with the onset of the PETM, that forest disappeared, its trees vanishing from the fossil record. “During the climate event you have a nearly complete turnover of plants,” Currano said. A new forest appeared, this one consisting of palms, heat-tolerant members of the bean family, and other plants evocative of the semi-arid tropics.

It is a story repeated throughout the fossil record: When the climate changes, so does the arrangement of the world’s plants. Species move back and forth toward the poles, up and downslope. Some species grow more common, others rarer. Species arrange themselves together in new combinations. The fossil record reveals plants for what they are, as mobile beings. For plant species, migrating in response to climate change is often a matter of survival.

Warmth-loving plants are growing more common, from the middle of the Amazon to the middle of Nebraska.

As human-generated greenhouse gas emissions cause the world to rapidly warm, this movement is once again under way. Scientists have observed plants shifting toward the poles and upslope. They’ve noted old ecosystems suddenly replaced by new ones, often in the wake of fire, insect outbreaks, drought or other disturbances. They’ve observed an increase in the number of trees dying and watched as a growing number of the world’s biggest and oldest plants, including the baobabs of Africa and the cedars of Lebanon, have succumbed. Just this month, scientists announced that the Castle Fire, which burned through California’s Sierra Nevada last year, singlehandedly killed off more than 10 percent of the world’s mature giant sequoias. 

So far, many of these changes are subtle, seemingly unrelated to one another, but they are all facets of the same global phenomenon — one that scientists say is likely to grow far more apparent in the decades to come. 

The climate is currently warming at least 10 times faster than it did at the onset of the PETM. Under its worst-case scenario, the Intergovernmental Panel on Climate Change projects that, over the next 100 to 150 years, Earth’s average temperature could rise by roughly the same amount as it did during the PETM. Dramatic vegetational shifts could arrive not in a matter of centuries or millennia, but decades; a 2019 study, for example, projected that Alaska’s vast interior forests will shift from being dominated by conifers to being dominated by broadleaf trees as soon as the middle of this century.

Scientists debate what this floral rearrangement will look like. In some places, it may take place quietly and be easily ignored. In others, though, it could be one of the changing climate’s most consequential and disruptive effects. “There’s a whole lot more of this we can expect over the next decades,” said University of Wisconsin-Madison paleoecologist Jack Williams. “When people talk about wildfires out West, about species moving upslope — to me, this is just the beginning.”

These baobab trees, near Morondava, Madagascar, are up to 2,800 years old. Scientist attribute the sudden deaths of ancient baobabs in recent years to climate change.
These baobab trees, near Morondava, Madagascar, are up to 2,800 years old. Scientist attribute the sudden deaths of ancient baobabs in recent years to climate change. ATLANTIDE PHOTOTRAVEL / GETTY IMAGES

Williams is a senior co-author on a study published this month in Science that provides context on floral change in the present and recent geological past. Led by University of Bergen ecologists Ondřej Mottl and Suzette Flantua, the team of researchers used more than 1,000 fossil pollen records collected from around the world to compare rates of floral change over the last 18,000 years. It is the largest such study of its type, Williams said, representing many thousands of hours of combined scientific effort. 

The researchers found that the rate of change peaked first as the world warmed at the end of the last ice age. Then, the rate of change began climbing even faster beginning between 2,000 and 4,000 years ago. This was a period when the global climate was relatively stable, so the changes were likely due to human activities. The study suggests that people, who have spent thousands of years rearranging the world’s plants for agriculture and other reasons, currently remain the strongest driver of change in the shifts of the world’s plants. But it also affirms how powerfully climate has driven change and suggests how it might again. “There’s likely a human legacy from quite some time ago,” Flantua said. “On top of that we’re adding a quite massive change in temperature. It is a dangerous combination.”

Native species or invasive? The distinction blurs as the world warms. Read more.

How will floral change look and feel to those living through it? While the fossil record offers a useful sense of the big picture, it is often fuzzy on the specifics, particularly at the scales of years and decades. Scientists trying to track the comings and goings of plant species in the present face a similar problem. Plants are constantly casting off seeds and spores, little genetic fingers that will grab hold wherever they are able. When physical or biological conditions change, so do the places where various plant species can find purchase; over time, the range and abundance of the whole species shifts. That’s how it works in theory, anyway. Catching it happening is another matter. To do so, scientists need long-term records for comparison. Such records are unevenly distributed around the world, and all are of either limited geographic or temporal scope; global satellite imagery, for instance, dates only to the 1970s.

Still, in the places where scientists do have long-term historical records, they’ve tended to find plants on the move in recent decades. Shrubs are popping up across the Arctic. New species of plants are colonizing mountain summits. In one of the most wide-ranging studies of floral range shifts, a group of researchers led by University of Miami ecologist Kenneth Feeley used herbarium data to track how plant communities across the Western Hemisphere had changed from 1970 to 2011. Comprising 20,000 species and 20 million individual observations, the data shows that warmth-loving plants were growing more common nearly everywhere the researchers looked, “from the middle of the Amazon to the middle of Nebraska,” Feeley said.

Some species can migrate remarkably fast, perhaps as much as a mile a year.

This type of floral change will likely often go unnoticed by people, said Yale School of the Environment geographer Jennifer Marlon, who studies the public’s perception of climate change. People, she said, are attuned to the wild variation between days and weeks and seasons, not the long-term shifts wrought by the changing climate. People also tend to have a short memory of their surroundings, a phenomenon known as the “shifting baseline.” “We just forget very quickly what the baseline was,” she said. “We tend to normalize change around us.”

The species whose migration we’ll likely notice first are those of agricultural, commercial or cultural importance. University of Maine paleoecologist Jacquelyn Gill points to sugar maple, whose range scientists project will shift far to the north in the coming decades. “As an ecologist, I’m happy that sugar maple is tracking the climate,” Gill said — it is a sign of resilience. On the other hand, she said, “As a person who lives in Maine and loves maple syrup, I am extremely concerned for the impact of sugar maple’s movements on a food I care about, on my neighbors’ livelihoods, and on the tourist industry.”

These shifts in species’ ranges also have serious implications for conservationists. Experts say the changing climate means that Sequoia National Park will eventually be left without its sequoias, Joshua Tree National Park without its Joshua trees. As with Gill’s sugar maples, this is distressing from a human perspective, though potentially of little importance from the plants’ perspective. The question is whether sequoias, Joshua trees, and countless other plants will be able to reach newly suitable habitats. For decades, scientists have debated whether plants would be able to track the rate of climate change, and whether people should intervene to help rare, isolated species reach more suitable habitat.

On the one hand, fossil evidence from the late Pleistocene and early Holocene suggests that some species can migrate quickly, perhaps more than a mile per year. On the other hand, studies in Europe and North America suggest that many tree species did not keep up with the climate as it warmed at the end of the Pleistocene.

A wildfire in Australia's Blue Mountains National Park in 2018. More and hotter fires are accelerating changes in flora globally.
A wildfire in Australia’s Blue Mountains National Park in 2018. More and hotter fires are accelerating changes in flora globally. ANDREW MERRY / GETTY IMAGES

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Lake Powell hits a record-low amid mega-monsoon ~ the Land Desk

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Jonathan P. Thompson
Jul 26

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We’ve got good news and bad news to report regarding the big aridification of the West this week. Let’s start with the good: After a two-year hiatus, the monsoon has returned to much of the Southwest, bringing huge rains with it. Tucson’s arroyos are running full and the Sonoran desert is getting positively lush. Multiple highways in Western Colorado were closed due to debris flows and flash floods. And a lot of farmers, especially those who lost ditch water early, are breathing a huge sigh of relief as, we suspect, are their crops. 

The monsoon days are the best time of year in the desert Southwest. They always start out clear and hot and the mercury can shoot up into the triple digits before the cobalt clouds arrive, piled miles high in the sky. The first big raindrops bring the petrichor—the scent of blood and iron—followed by the deluge, followed by muddy water crashing through arroyos that were bone-dry just a moment earlier. Then the rain subsides, always just before sunset it seems, leaving the air crisp and clean. And the sun bursts through the clouds, setting the sky ablaze. 


J. C y r @AllophileSabino Canyon is flowing again after last night’s storm; closed beyond the 1.5mi point… #azwx #getintotheoutthere July 24th 20218 LikesTomas Dawson @myfjcruiserWhen you realize the flooding is massive. #gatewaycolorado #flashflood #flood July 25th 2021

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But all of that moisture falling from the sky isn’t enough to bust the drought, yet, nor can it save Lake Powell, which dropped this weekend to its lowest level since 1969 (when it was still filling up). Lake Powell’s growing bathtub ring is a visual indicator not only of the lake’s level, but also of the aridity of much of the West. 

Powell’s downward slide began in 1999, falling 140 feet in just six years and bottomed out—for the time being—during the spring of 2005, before a substantial runoff that year bounced levels back up. But even the huge water year of 2011 was not enough for a full recovery. In the decade since, the level has crashed by 100 feet, in spite of healthy snowfall in 2019, bringing the lake to where it is now: The dam’s hydropower generating capacity is diminished, boat-ramps are rendered unusable, and the Bureau of Reclamation is desperately trying to shore up levels by releasing extra water from upstream reservoirs. 

But the worst part of it all is what the shrinkage says about the health of the Upper Colorado River Watershed: it isn’t so good. And it will take more than one good monsoon to bring it back. 

Bureau of Reclamation @usbrIn the next few days, Lake Powell’s elevation will drop below the record low of 3,555.10 feet reached in April 2005. These record low numbers stress the need for actions started last week under the Upper Basin Drought Response Operations Agreement.



By Haley Brink and Hannah Gard, CNN Meteorologists

Sat July 24, 2021 

(CNN)A surge of monsoonal moisture is bringing rounds of heavy rain and strong thunderstorms to areas of the Southwest that are currently suffering from extreme to exceptional drought conditions. 

Nearly 10 million people are under flash flood watches across Arizona, Colorado, New Mexico and Utah.

While expansive rain and thunderstorms will affect much of the Southwest this weekend, the highest rainfall totals are expected across the state of Arizona where some locations could tally upwards of 6 inches. This amount of rain in such a short period of time have prompted significant flash flooding concerns.

Tucson, Arizona, was under a flood warning for much of the day on Friday where 1 to 4 inches of rain fell across the region, most of it accumulating in the overnight and early morning hours. The city has seen nearly 3 inches of rain so far this month which is more than an inch above the city’s normal rainfall for the month.

The heavy rain Thursday night into Friday morning even submerged highway ramps north of Phoenix, and more rain is expected through the weekend.

Just outside of Tucson, the Vail School District alerted families on its Facebook page that due to the flooding, road closures could impact bus routes Friday. “If you live in an area that is prone to road closures due to flooding, you can assume that bus routes will be delayed or unavailable this morning”.”

What we’re expecting to see here is a widespread rain event across the majority of the state of Arizona,” said National Weather Service Tucson meteorologist Rob Howlett. “Looking at just southeast Arizona a lot of the valleys are going to see rainfall amounts most likely between 1 to 2 inches, maybe higher in other spots.”

The mountains and foothills across the Southwest could see the most rain with five or more inches possible, but even the metropolitan areas, including Flagstaff and Tucson, could see 3 or more inches of rainfall through the weekend. When heavy rain falls in a brief period during the stronger thunderstorms, flash flooding can occur extremely quickly. 

“Normally dry stream beds can instantaneously turn into torrents of fast-moving water, especially below burn scars,” CNN meteorologist Chad Myers said. 

The weather service office in Tucson is likening the weather pattern setup this weekend to that of the 2006 rain event that caused widespread flooding and damage to areas of Tucson. Similarities include large burn scars in the area and already saturate soils from previous flood events earlier this month

“Numerous burn scars scattered throughout the area will be a significant cause of concern for widespread flash flooding events,” according to the Weather Prediction Center. “As such, the Weather Prediction Center has issued a Moderate Risk for Excessive Rainfall for portions of Arizona and New Mexico that will be carried through Sunday morning.” 

Numerous fires have ravaged the state in 2021, with two of the largest fires in Arizona history scorching thousands of acres outside of Phoenix. The record 2020 wildfire season left its mark with a 119,978-acre scar on the Tucson foothills. 

“The Bighorn Fire near Tucson, we are going to be watching that very closely for any heavy rainfall there as we have concerns downstream from that. There is the potential for some flash flooding along those washes and rivers,” Howlett said. 

Heavy rainfall runs off burn scars easily because the soil, once burned, becomes hydrophobic — unable to absorb water — and the vegetation that typically holds soil in place is destroyed. 

Rain to put a dent in the drought

In the short term, this torrential rainfall will lead to dangerous flash flooding. But in the long run these types of rain events bring very beneficial rain that could break the ongoing drought across the region.

Massive heat dome brings yet another heat wave, this time covering most of the USNearly the entire state of Arizona — 99% — is under some level of drought, with more 80% of the state in either extreme or exceptional drought. 

The extent of the drought improved across the Southwest over the last week due to monsoon rains that impacted the region last week. The highest level of drought fell from 58% to 36% and marked improvements are expected again next week, with this current burst of monsoon moisture. 

The heaviest rain is concentrated in the worst drought regions in Arizona along the border of New Mexico up the eastern side to the Utah border.

 “Usually, to make a really good dent in drought conditions you want to have that steadier rain that can infiltrate the soils more deeply, but this time of year that’s just not the kind of scenarios that we see,” said Howlett. “We get thunderstorms and a lot of that is runoff, but every drop counts.” 

The sporadic, intense nature of monsoon thunderstorms frequently leads to runoff instead of moisture soaking into the soils efficiently and reliving the drought-stricken earth. Nonetheless, any rainfall is welcomed during the hottest part of the year.

“It’s going to make a difference, and we really count of rain this time of year to help us out with our drought conditions because for the entire year, half of our rainfall occurs during the monsoon season.” 

CNN’s Allison Chinchar contributed to this report.

Visualizing water inequality–from space ~ The Land Desk



Plus: Housing crisis creates labor crisis; other news from around the West

Jonathan P. ThompsonJul 23

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You know that water inequality—and drought—have gotten out of hand when you can see them from space. And this year, satellite imagery that highlights vegetation tells a harrowing story of fallowed fields a stone’s throw from emerald-green ones, of empty ditches next to ones with at least some water in them. And it shows how, during dry years, the abyss between the water-rich and the water-poor widens, a phenomenon most apparent this year in Montezuma County, Colorado. 

Exhibit one includes two views of a section of Montezuma County in the far Southwestern corner of the state, one from July 2019 (top) and the other from a few days ago.

Montezuma County in July 2019 and July 2021. Red is an indicator of leafy vegetation. Source:

The Montezuma Valley north of Cortez looks about the same in both images—a big swath of red, which is an indicator of leafy vegetation (piñon, juniper, and sage don’t seem to register). But the area northwest of there, heading towards Dove Creek, is clearly a lot drier now than it was two years ago. Meanwhile, McPhee Reservoir has not only shrunk considerably—by about 10 billion gallons—but its shape also changed dramatically as a result. 

So what gives? Seniority, that’s what. 

Western water law is based on a simple foundation: First in time, first in court, first in right. Which is to say, whoever files for a portion of the water in a stream first gets priority. When the stream starts shrinking, the junior water rights holders must shut off their ditches so that the senior rights holders can continue to get their share of water. 

That’s what happened in Montezuma County. When the flow of the area’s main source of water—the Dolores River—waned after a string of dry winters, and McPhee Reservoir began shrinking, it became clear that there wouldn’t be enough water to go around to all the users. 

The river, itself—and the fish and other aquatic life that depend on it—were the first to get cut off, as the McPhee Dam operators decreased downstream releases to about 10 cubic feet per second or less, a mere trickle that does not make it as far as Slickrock, where the riverbed is dry. Next to go were the Towoac Canal (which I’ll get to in a moment) and the Dove Creek Canal, which carries water from McPhee west to the town of Dove Creek. The canal serves Dolores Water Conservation District irrigators from Yellowjacket up to Dove Creek and provides drinking water to the town. During the first part of the irrigating season, flows in the Dove Creek Canal 50 to 75 percent below normal. Then, in early July, they stopped altogether. 

The meagre flows in the Dove Creek Canal are manifested in the image above. In 2019, the fields west of McPhee Reservoir were mostly bright red—which is to say the alfalfa, corn, sunflowers and other crops were well-watered and healthy. In 2021, however, many of those same fields show no vegetation at all, indicating that they were fallowed or simply shriveled up due to lack of water. The few fields that did get a little water produced far less. Some Montezuma County alfalfa farmers told the Cortez Journal they expected a 95% decrease in yield this year—which amounts to an equivalent decrease in revenue, more or less (with some help from rising hay prices—up to $300/ton—resulting from scarcity). 

Even worse off are the irrigators on the Towaoc Canal, most significantly the Ute Mountain Ute Tribe’s extensive agricultural operations located south of Ute Mountain. Most years, the canal’s flow ranges from 60 to 70 cfs throughout the summer, enough water for multiple alfalfa cuttings and a strong corn crop to feed the operation’s mill. This year flows ranged from 10 to 20 cfs until June, when they plummeted to the single digits, forcing the operation to fallow most of its fields. The results are apparent below.

The Ute Mountain Ute Tribe Farm and Ranch Enterprise in July 2019—following a wet winter—and in July 2021 (right). The operations received about 10 percent of their usual water allocation this year. Source:

Now, keeping that image in your brain, go back up to the first image and notice all the red north of Cortez. The Montezuma Valley Irrigation Company was able to keep its ditches about half full this summer, and have yet to be cut off entirely, which should allow them to get more than one cutting of hay and a relatively decent yield from their other crops, assuming the grasshopper plague (of Biblical proportions, I’ve been told) doesn’t devour them. They got more water than other users because they have the most senior rights on the Dolores River, having filed for them back in 1885, a century before construction of McPhee Dam was completed. 

If you’re having trouble wrapping your mind around the concept of the Ute Tribe’s farms getting cut off from water before the Montezuma Valley irrigators, you’re not alone. The Ute people were here, relying on the water in the Dolores River, for centuries prior to the arrival of the white settlers who built a tunnel from the Dolores River to a network of canals in the Montezuma Valley. And under the Winters Doctrine, the tribe is entitled to all of the water they need and then some, with an appropriation date of 1868, meaning the tribe should get all the water. 

But when negotiating to get their water delivered to them, the Ute Tribe made some concessions. They didn’t give up their 1868 priority date, but they did accept a later priority date for the delivery of that water—at least that’s how I understand this language from the Colorado Ute Indian Water Rights Settlement of 1986:

(Dear Land Desk water expert readers: Please feel free to correct my understanding of Dolores River water rights or to further elucidate the issue in the comments section or via email to me.)

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To be sure, all farmers are having a tougher time of it this year, even the ones whose ditches are running full. If they aren’t suffering from lack of water, they’re dealing with grasshoppers, which are more prevalent this year due to the lack of precipitation and the relatively warm winter. If they’re lucky enough to be outside the grasshopper zone, then they’re grappling with heat, which damages the health of crops and the people who tend to them. And if they’re wannabe farmers trying to help supply the burgeoning, pandemic-induced demand for local produce, they’re running into skyrocketing land prices. And guess which land is most expensive and most out of reach of folks on a farmer income? The land with the good water. 

And so, wealth inequality leads to water inequality—and round and round we go. 

The “Dryside” of La Plata County in July 2019 and 2021. Source:


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Robbing Peter to save Powell ~ The Land Desk

The Bureau of Reclamation is draining reservoirs to fill reservoirs 

Jonathan P. ThompsonJul 21

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Throw a few pesos to Thompson. He’s not some entitled white guy, but a creative and hard working journalist that loves his home in the South West. rŌbert

The Horseshoe Bend overlook, which affords some 50,000 selfie-snappers per month a gander of the Colorado River as it bends back on itself, is surely one of the most popular viewpoints in the Southwest. I’ve passed by it many a time, but have never been tempted to stop. Instead, I rev the engine on the ol’ Silver Bullet, drive into the western fringe of Page, past the McDonalds and the most-out-of-place golf course on the planet, and then take a left turn to get to my favorite viewpoint: The one that offers a stunning, explicit, full frontal look at Glen Canyon Dam. 

It gets me every time—an almost physical blow to the gut coupled with the insta-vertigo inflicted by confrontation with the sublime. 

I’m not sure what it is about the dam that invokes such a strong reaction. Perhaps it’s just the sheer size—700-feet high, 1,500 feet long at the crest, 300 feet thick at its base—or the ungodly amount of water it holds back. Maybe I’m mourning the hundreds of miles of Edenic canyons that were inundated. Maybe it’s a combination of terror and anticipation of the power that would be released if the dam finally cracked and crumbled. 

Or maybe it’s the hubris that the dam represents, the belief that, with enough concrete and engineering ingenuity, we humans could control that wild, tumultuous creature known as the Colorado River and harness it to turn thousands of miles of desert into lawns and alfalfa fields and golf courses and housing developments. Sure, it worked. Until it didn’t. And now Lake Powell’s water levels have taken a great fall, and all of Bureau of Rec’s engineering, and all of Bureau of Rec’s plumbing, can’t put Powell back again. 

Still, they’re trying. Last week the Bureau of Reclamation announced that they would crank open a few valves on the massive plumbing system known as the Upper Colorado River, releasing extra water from Flaming Gorge, Blue Mesa, and Navajo reservoirs in order to shore up the rapidly declining water levels in Lake Powell. 

The point of this exercise is not to keep houseboats from scraping bottom—which is already happening—but to preserve what remains of Glen Canyon Dam’s hydropower generating capacity. Already the dam has become less potent in this respect, because as water levels drop, so does the pressure the water exerts, meaning that the same amount of water run through the turbines generates less power. More worrisome is what happens when the level falls below 3,490 feet, or the minimum power pool: Generation stops altogether. 

That would mean that Glen Canyon Dam’s electricity output would plummet from 10,000 megawatt-hours or so of juice each day—enough to power some 350,000 homes—to near zero. That would be very bad for the Southwestern electricity grid, which is already strained by heat-induced soaring demand coupled with diminished hydropower generation across the West. Grid operators would have little choice but to turn to natural gas generation to fill the gap, increasing greenhouse gas emissions and electricity costs. 

In one month, from mid-June to mid-July, Lake Powell lost 416,000 acre feet of water—or 135 billion gallons (which translates to about five and a half feet of surface-level elevation). About 36,000 of those acre feet vanished via evaporation. The rest was sent through Glen Canyon Dam’s turbines, destined for the Grand Canyon and then shrinking Lake Mead. If levels continue to drop at that rate, the Lake will reach minimum power pool in a year from now (The Bureau of Reclamation is projecting a slower rate of decline, even in its worst case scenarios. See accompanying graph).

The feds know they can’t stop the drop with this scheme. But via the planned releases—totaling an additional 181,000 acre feet over the next six months—they can slow it down, theoretically. Instead of falling another 28 feet by the end of the year, the surface level should only drop by, wait for it, 25 feet, assuming a continuation of current rates of decline. Basically, the Bureau is draining down three reservoirs in order to offset evaporation from Lake Powell. 

It just might succeed, in delaying the inevitable. But without a lot of help from Mother Nature in the form of massive winter snowfall across the entire Upper Colorado River watershed, there is little chance that the planned plumbing adjustments will amount to much. And if the snows don’t come, what happens to the depleted upper basin reservoirs and the people who rely on them? 

The plan seems even crazier in light of a proposal to build a pipeline that would siphon yet more hydropower-generating water from Lake Powell and ship it to southwestern Utah, or plans to divert yet more water from the Colorado River Basin toward the urban centers of Colorado’s Front Range. But then, none of it is any crazier than building the dam in the first place with the belief that doing so would turn a desert into an oasis.

Lake Powell is just six inches away from hitting it’s lowest level since it was filled. The previous low record was set in 2005. 

Colorado River Basin Reservoirs Begin Emergency Releases To Prop Up A Troubled Lake Powell ~KUNC


KUNC | By Luke Runyon

Published July 15, 2021

Anchored houseboats hang out at Hall’s Crossing Marina at Lake Powell in southern Utah.

Emergency water releases from reservoirs upstream of Lake Powell are underway to preserve the nation’s second-largest reservoir’s ability to generate hydroelectric power.

The Bureau of Reclamation started releasing additional water Thursday from Flaming Gorge reservoir in Wyoming. Additional water releases from Blue Mesa reservoir in Colorado and Navajo reservoir in New Mexico are planned to commence later this year. Emergency releases could last until at least December, and could extend into 2022.

Lake Powell is projected to hit a record low in July. It’s situated on the Colorado River, a drinking and irrigation water source for more than 40 million people in the Southwest. Spring and early summer inflows to the massive reservoir were the third lowest on record in 2021. That followed a meager runoff in 2020.

The releases are meant to maintain some level of hydroelectric power at Lake Powell’s dam, which is under increasing threat due its low level. Glen Canyon Dam’s minimum hydropower level is at 3,490 feet above sea level. It’s currently at 3,557 feet, and is forecast to drop to 3,515 feet by the end of April 2022.

Even above its minimum power elevation, production might become unfeasible due to turbine cavitation, when small air bubbles form and cause damage to the machine’s inner workings. 

Releases from Flaming Gorge Dam will increase by 50 cubic feet per second (cfs) every day until July 23. Daily releases from Flaming Gorge will rise from 860 cfs to 1310 cfs, “in response to basin-wide drought and storage concerns at Lake Powell,” Reclamation staff told stakeholders this week.

The Colorado River basin states of Colorado, Wyoming, New Mexico and Utah agreed to possible federal intervention, under emergency circumstances, to boost Lake Powell’s levels in the 2019 Drought Contingency Plan. This is the first time this portion of the plan has been put into action.

“We are facing unprecedented dry conditions in the Colorado River Basin. More details about conditions as well as planning efforts are forthcoming,” said Rebecca Mitchell, Upper Colorado River Commissioner for the state of Colorado. “What we do know is that the Upper Basin Drought Contingency Plan calls for increased coordination and planning in situations like this. And those agreements call for the Bureau of Reclamation to closely consult with the Upper Basin States, including Colorado. It has never been more critical to work together.”

A federal shortage declaration in the river’s lower basin is expected next month due to record low levels at Lake Powell’s downstream sister reservoir, Lake Mead. The two are managed jointly by guidelines agreed to in 2007.

This story is part of ongoing coverage of the Colorado River, produced by KUNC and supported by the Walton Family Foundation.



By Hannah Gard and Judson Jones, CNN

Sat July 17, 2021 

(CNN)Monsoon rains brought extreme flash flooding to the Southwest this week, causing at least one death and scenes of vehicles bobbing down roads like rafts on rapids.More flash flooding may occur this weekend.A flash flood in Grand Canyon National Park killed Rebecca Copeland, 29, of Ann Arbor, Michigan, in the Tatahatso Camp on the Colorado River, the National Park Service said in a press release. The flood injured four others who were hospitalized and in stable condition.

Experts say the historic Western drought is to blame.

The drought has ravaged the region for decades, leaving the soil less like a sponge and more like pavement. 

“The moisture isn’t absorbed into the soil as much and all of that water is running off and that is what leads to the roadways and flooding of people’s properties,” National Weather Service Flagstaff meteorologist Tim Steffen said.Urban areas with plentiful concrete and little drainage can easily experience flash flooding events when heavy rain falls in a brief period of time. Videos of cars floating down brown floodwater rapids surfaced Wednesday after the extreme flooding in Flagstaff. 

“We had widespread heavy rainfall across the Flagstaff area on Wednesday that led to flash flooding and some closures of area roadways. That is our big concern every monsoon season,” Steffen said. “These types of intense, local rain events happen each summer, but often in unpopulated areas,” said Michael Crimmins, climate science extension specialist for Arizona Cooperative Extension. “The impacts are quite large when they occur in populated areas like Flagstaff.”Flagstaff been preparing for flash flooding events since the Museum fire north of the city in 2019 left a large burn scar. In the following monsoon seasons, there was little rainfall, creating flash flooding problems in the area. 

Arizona saw two massive wildfires devour the hillsides outside of Phoenix earlier this year, and eight large fires burning over 60,000 acres are currently active in the state.Wildfire burn scars can create a flash flood runway that can last for years. “You can think of it as concrete where the water is not being absorbed into the soils; it’s all just running off,” Steffen said. “Downstream of those fire scars all that water is running off, some debris as well from the fire, and that can clog culverts. Those areas are susceptible to flash flooding more so than those areas that haven’t been burned.” Fires burn off plant matter that normally would hold soils in place during flooding events. Drought underlies the whole problem because there’s not much chance for vegetation to grow back and “keep things in place,” said Daniel Ferguson, director of the Climate Assessment for the Southwest (CLIMAS).The West’s historic drought in 3 mapsCLIMAS says climate change is affecting monsoon season. “Warmer temperatures have expanded and intensified the North American monsoon ridge, resulting in fewer storms across Arizona during the peak of the monsoon season (late-July to mid-August),” according to theclimate report for Coconino County, where Flagstaff is located. Gov. Doug Ducey on Friday issued a declaration of emergency for Coconino County, making up to $200,000 available for response efforts.Although storms will be less frequent, they may be more forceful. As the air heats up, it is able to hold more water, leading to heavier downpours and more flash flooding potential than typical monsoon thunderstorms in the past. Each year more people are killed by flash flooding than lightning, with the average being 88 deaths according to the NWS. “Most people fail to realize the power of water. For example, 6 inches of fast-moving flood water can knock you off your feet,” the NWS warns

As the 26th year of historic drought leaves most of Arizona in extreme to exceptional drought conditions, rainfall is a welcome addition to the weekly weather forecast. The rain reduces soaring temperatures and provides brief relief from the relentless sun. But previous years of scant rainfall and recent record-breaking heat have proven detrimental to the Southwest. “What has contributed to the current drought, especially here in Northern Arizona, is two of the driest monsoons on record in 2019 and 2020. That created a problem,” Steffen said. Moisture in any form can help the drought by relieving strained greenery and soils. The bulk of Arizona’s yearly rainfall occurs during the monsoon season. “This is typically when we receive a lot of our precipitation during the year, and winter, so it’s very important that we have a good monsoon season because it does help quell some of the drought problems,” Steffen said. The 2021 monsoon season has already given some areas of Arizona more rainfall than during the entire 2020 season, according to the NWS. Flagstaff has seen over an inch more rain than it did all last year’s season. However, the rain is not doing much to replenish reservoirs that are faltering because of the winter season snow drought and record heat waves.”All rainfall helps improve our water situation although runoff from summer monsoon rain rarely produces a significant improvement in reservoir levels,” said said Shauna Evans, spokesperson for the Arizona Department of Water Resources (ADWR). “Monsoon rain however can help rehydrate our soils, which helps get snowmelt runoff into the reservoirs. Also, some portion infiltrates into the ground and replenishes the aquifers.”But monsoons rains can simply be a short-term fix to a long-term problem. In terms of hydrological drought, we really do need to have widespread cool season precipitation, particularly snowfall,” said NWS Phoenix meteorologist Larry Hopper.”The snow melts into the reservoir which helps improves the water supply, which is a major component of hydrological drought. Monsoon, you don’t usually capture as much rainfall because it’s not as widespread.”Monsoon season rainfall is typically sporadic in nature, with bursts of downpours in some areas while other areas remain dry. Widespread drought alleviation is difficult unless an active monsoon season drenches the region. The Southwest will see more monsoonal moisture this weekend bringing heavy rainfall.

“Instances of flash flooding will remain a concern throughout parts of Arizona and New Mexico into the weekend. Additional isolated rainfall totals up to 1 inch are possible today across central and southeastern Arizona, where Flash Flood Watches have been issued to highlight the potential hazard,” according to the Weather Prediction Center.