Remarkable Drop in Colorado River Water Use a Sign of Climate Adaptation
By Brett Walton
Use of Colorado River water in the three states of the river's lower basin fell to a 33-year low in 2019, amid growing awareness of the precarity of the region's water supply in a drying and warming climate.
Arizona, California, and Nevada combined to consume just over 6.5 million acre-feet last year, according to an annual audit from the Bureau of Reclamation, the federal agency that oversees the lower basin. That is about 1 million acre-feet less than the three states are entitled to use under a legal compact that divides the Colorado River's waters.
The last time water consumption from the river was that low was in 1986, the year after an enormous canal in Arizona opened that allowed the state to lay claim to its full Colorado River entitlement.
States have grappled in the last two decades with declining water levels in the basin's main reservoirs — Mead and Powell — while reckoning with clear scientific evidence that climate change is already constricting the iconic river and will do further damage as temperatures rise.
For water managers, the steady drop in water consumption in recent years is a signal that conservation efforts are working and that they are not helpless in the face of daunting environmental changes.
"It's quite a turnaround from where we were a decade ago and really, I think, optimistic for dealing with chronic shortages on the river in the future, knowing that we can turn the dial back and reduce demand significantly, all three states combined," said Bill Hasencamp, the manager of Colorado River resources for the Metropolitan Water District of Southern California, a regional wholesaler and one of the river's largest users.
Observers of the basin's intricate politics are also impressed with the trend lines for a watershed that irrigates about 5 million acres of farmland and provides 40 million people in two countries and 29 tribal nations with a portion of their water.
"It is an incredibly important demonstration of the fact that we can use less water in this incredibly important water-use region," John Fleck told Circle of Blue. Fleck is the director of the University of New Mexico water resources program.
Projections for 2020 indicate that conservation will continue, though not quite at last year's pace. Halfway through the year, the Bureau of Reclamation forecasts water consumption to be roughly 6.8 million acre-feet. An acre-foot is the amount of water that will flood an acre of land to a depth of one foot, or 325,851 gallons.
"I have to give them credit," Jennifer Gimbel, a senior water policy scholar at Colorado State University, told Circle of Blue about the lower basin states. "They're working hard to get these numbers."
Raising Lake Mead
Just five years ago, in 2015, the three states were making use of their entire 7.5-million-acre-foot allotment. By statute and tradition, the basin is divided into a lower basin, where use is higher, and an upper basin, which includes Colorado, New Mexico, Utah, and Wyoming. The basins have different water allocation systems and rules governing its use.
In the lower basin, Arizona's annual allocation is 2.8 million acre-feet, but last year it used just 2.5 million. Nevada used 233,000 of its 300,000 acre-feet. The big savings were in California, which used only 3.8 million of its 4.4 million acre-feet. California hasn't used that little water from the Colorado since the 1950s, Fleck said.
The drop in California last year is due in large part to Metropolitan Water District, which consumed only 537,000 acre-feet. Five years ago, the district's tally was around 1 million acre-feet per year. Urban conservation and development of local water sources have played a large role in the decline, but the district's Colorado River water use is also influenced by snow levels in the Sierra Nevada mountains. When more water is available to be imported from the northern part of the state, as it was last year, the district leans less heavily on the Colorado River.
Total Lower Colorado Basin Consumptive Use
Reclamation's annual audit measures the amount of water consumed by humans, plants, and animals in the lower basin. Consumptive use equals total withdrawals minus any water that is returned to the river system, from irrigation runoff or wastewater treatment plants.
As meticulous as it is, the audit neglects a significant piece of the basin's water budget: evaporation from reservoirs and system losses, which is water consumed by riverside vegetation and absorbed by the ground. Together, these add up to about 1 million acre-feet per year, Jeremy Dodds, water accounting and verification group manager for Reclamation, told Circle of Blue.
This factor is part of the lower basin's "structural deficit," which means that total demand in the lower basin — use by Arizona, California, and Nevada, plus evaporation and required deliveries to Mexico — exceeds the amount of water that flows into Lake Mead, the lower basin's supply source.
Gimbel, who was the principal deputy assistant secretary for water and science for the U.S. Department of Interior from 2014 to 2016, said that despite the conservation efforts reflected in the audit, the lower basin still has much work to do. "They're closing the deficit, but they're not there yet," she said.
The goal of the lower basin's conservation is to keep Lake Mead from a precipitous decline into "dead pool" territory, where the reservoir is too low to send water downstream. The dead-pool threshold is at elevation 895 feet. Not using 1 million acre-feet last year most certainly helped the reservoir. Dodds said that at the current elevation of 1,089 feet, each block of 85,000 acre-feet equals 1 foot of elevation. So last year's conservation added 12 feet to Mead, compared to a scenario in which the three states use their full entitlement.
The conservation tool box that the states have employed has a range of instruments. Cities have provided incentives to remove grass lawns and replace inefficient toilets, showerheads, and washing machines. In Imperial Irrigation District, farmers have lined earthen canals with concrete to prevent seepage and they have agreed to fallow land to save water. Those measures, in both town and country, have helped to reduce demand. Supplies, on the other hand, have been bolstered by more investment in recycling and reuse, groundwater treatment, and desalination. As a whole, the seven states in the watershed came together in 2019 to modify rules for mandatory water-use restrictions that kick in as Lake Mead drops.
The decline in Colorado River water consumption mirrors regional and national trends. In Metropolitan Water District's service area in Southern California, water use per person fell from about 181 gallons per person per day in the mid-1990s to 131 gallons in 2018, a drop of 27 percent. Colorado River consumption on the Colorado River Indian Tribes reservation, in Arizona, is down about 20 percent since 2016.
According to Tom Ley, a water consultant to the tribes, the decline is due to changes in farming practices and participation in a land fallowing program that will see 10,000 acres taken out of production in the next three years. The tribes' decrease in consumptive water use "may look even more dramatic once the 2020 report comes out," Ley told Circle of Blue.
All of these actions amount to a shift in the perception of what's possible, Fleck said.
"It shows that the expectation that a growing population and a robust agricultural economy require more water is wrong," explained Fleck, who is optimistic about the basin's capacity to wield the tools of conservation effectively. Environmental doom is not the inevitable outcome, he says. "We're seeing success in the transition away from the tragedy narrative," he added.
Still, there are minefields to navigate. There are dozens of proposals in the upper basin states to withdraw more water from the river, which, if they were built, would further stress supplies. Some of the water conserved in Lake Mead is stored as a credit that participating agencies can theoretically draw upon in the future. How agencies handle those withdrawals, especially if large requests are made as lake levels plummet, is an uncertainty. On top of that, a warming climate will suck more moisture from the basin, even before rain and snow reach the river.
A hot, dry spring this year in the upper basin is evidence of what aridity can do. Snowpack in the basin's headwaters was roughly average on April 1 and runoff into Lake Powell, a key water supply indicator, was expected to be 78 percent of normal. But then dry conditions arrived in April and May. Combined with dehydrated soils, which took their share of water, the runoff forecast by June 1 had diminished to just 57 percent of normal.
Those climate signals are the counterbalance to the conservation success so far. Water managers, now wary, know the risk.
"Just hopefully we don't get a string of dry years coming back," Hasencamp said.
This story originally appeared in Circle of Blue and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.
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By Tara Lohan
Warming temperatures on land and in the water are already forcing many species to seek out more hospitable environments. Atlantic mackerel are swimming farther north; mountain-dwelling pikas are moving upslope; some migratory birds are altering the timing of their flights.
Numerous studies have tracked these shifting ranges, looked at the importance of wildlife corridors to protect these migrations, and identified climate refugia where some species may find a safer climatic haven.
"There's a huge amount of scientific literature about where species will have to move as the climate warms," says U.C. Berkeley biogeographer Matthew Kling. "But there hasn't been much work in terms of actually thinking about how they're going to get there — at least not when it comes to wind-dispersed plants."
Kling and David Ackerly, professor and dean of the College of Natural Resources at U.C. Berkeley, have taken a stab at filling this knowledge gap. Their recent study, published in Nature Climate Change, looks at the vulnerability of wind-dispersed species to climate change.
It's an important field of research, because while a fish can more easily swim toward colder waters, a tree may find its wind-blown seeds landing in places and conditions where they're not adapted to grow.
Kling is careful to point out that the researchers weren't asking how climate change was going to change wind; other research suggests there likely won't be big shifts in global wind patterns.
Instead the study involved exploring those wind patterns — including direction, speed and variability — across the globe. The wind data was then integrated with data on climate variation to build models trying to predict vulnerability patterns showing where wind may either help or hinder biodiversity from responding to climate change.
One of the study's findings was that wind-dispersed or wind-pollinated trees in the tropics and on the windward sides of mountain ranges are more likely to be vulnerable, since the wind isn't likely to move those dispersers in the right direction for a climate-friendly environment.
The researchers also looked specifically at lodgepole pines, a species that's both wind-dispersed and wind-pollinated.
They found that populations of lodgepole pines that already grow along the warmer and drier edges of the species' current range could very well be under threat due to rising temperatures and related climate alterations.
"As temperature increases, we need to think about how the genes that are evolved to tolerate drought and heat are going to get to the portions of the species' range that are going to be getting drier and hotter," says Kling. "So that's what we were able to take a stab at predicting and estimating with these wind models — which populations are mostly likely to receive those beneficial genes in the future."
That's important, he says, because wind-dispersed species like pines, willows and poplars are often keystone species whole ecosystems depend upon — especially in temperate and boreal forests.
And there are even more plants that rely on pollen dispersal by wind.
"That's going to be important for moving genes from the warmer parts of a species' range to the cooler parts of the species' range," he says. "This is not just about species' ranges shifting, but also genetic changes within species."
Kling says this line of research is just beginning, and much more needs to be done to test these models in the field. But there could be important conservation-related benefits to that work.
"All these species and genes need to migrate long distances and we can be thinking more about habitat connectivity and the vulnerability of these systems," he says.
The more we learn, the more we may be able to do to help species adapt.
"The idea is that there will be some landscapes where the wind is likely to help these systems naturally adapt to climate change without much intervention, and other places where land managers might really need to intervene," he says. "That could involve using assisted migration or assisted gene flow to actually get in there, moving seeds or planting trees to help them keep up with rapid climate change."
Tara Lohan is deputy editor of The Revelator and has worked for more than a decade as a digital editor and environmental journalist focused on the intersections of energy, water and climate. Her work has been published by The Nation, American Prospect, High Country News, Grist, Pacific Standard and others. She is the editor of two books on the global water crisis. http://twitter.com/TaraLohan
Reposted with permission from The Revelator.
The last Ice Age eliminated some giant mammals, like the woolly rhino. Conventional thinking initially attributed their extinction to hunting. While overhunting may have contributed, a new study pinpointed a different reason for the woolly rhinos' extinction: climate change.
The last of the woolly rhinos went extinct in Siberia nearly 14,000 years ago, just when the Earth's climate began changing from its frozen conditions to something warmer, wetter and less favorable to the large land mammal. DNA tests conducted by scientists on 14 well-preserved rhinos point to rapid warming as the culprit, CNN reported.
"Humans are well known to alter their environment and so the assumption is that if it was a large animal it would have been useful to people as food and that must have caused its demise," says Edana Lord, a graduate student at the Center for Paleogenetics in Stockholm, Sweden, and co-first author of the paper, Smithsonian Magazine reported. "But our findings highlight the role of rapid climate change in the woolly rhino's extinction."
The study, published in Current Biology, notes that the rhino population stayed fairly consistent for tens of thousands of years until 18,500 years ago. That means that people and rhinos lived together in Northern Siberia for roughly 13,000 years before rhinos went extinct, Science News reported.
The findings are an ominous harbinger for large species during the current climate crisis. As EcoWatch reported, nearly 1,000 species are expected to go extinct within the next 100 years due to their inability to adapt to a rapidly changing climate. Tigers, eagles and rhinos are especially vulnerable.
The difference between now and the phenomenon 14,000 years ago is that human activity is directly responsible for the current climate crisis.
To figure out the cause of the woolly rhinos' extinction, scientists examined DNA from different rhinos across Siberia. The tissue, bone and hair samples allowed them to deduce the population size and diversity for tens of thousands of years prior to extinction, CNN reported.
Researchers spent years exploring the Siberian permafrost to find enough samples. Then they had to look for pristine genetic material, Smithsonian Magazine reported.
It turns out the wooly rhinos actually thrived as they lived alongside humans.
"It was initially thought that humans appeared in northeastern Siberia fourteen or fifteen thousand years ago, around when the woolly rhinoceros went extinct. But recently, there have been several discoveries of much older human occupation sites, the most famous of which is around thirty thousand years old," senior author Love Dalén, a professor of evolutionary genetics at the Center for Paleogenetics, said in a press release.
"This paper shows that woolly rhino coexisted with people for millennia without any significant impact on their population," Grant Zazula, a paleontologist for Canada's Yukon territory and Simon Fraser University who was not involved in the research, told Smithsonian Magazine. "Then all of a sudden the climate changed and they went extinct."
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Transitioning to renewable energy can help reduce global warming, and Jennie Stephens of Northeastern University says it can also drive social change.
For example, she says that locally owned businesses can lead the local clean energy economy and create new jobs in underserved communities.
"We really need to think about … connecting climate and energy with other issues that people wake up every day really worried about," she says, "whether it be jobs, housing, transportation, health and well-being."
To maximize that potential, she says the energy sector must have more women and people of color in positions of influence. Research shows that leadership in the solar industry, for example, is currently dominated by white men.
"I think that a more inclusive, diverse leadership is essential to be able to effectively make these connections," Stephens says. "Diversity is not just about who people are and their identity, but the ideas and the priorities and the approaches and the lens that they bring to the world."
So she says by elevating diverse voices, organizations can better connect the climate benefits of clean energy with social and economic transformation.
Reposted with permission from Yale Climate Connections.
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