Vanishing Water
LAKE MEAD, Nev. – The biggest reservoir in the United States is dropping 1 foot each week. Lake Mead's rapidly sinking water level is set to reach an all-time low in July, driven down by a 14-year drought that scientists say is one of the most severe to hit the Colorado River in more than 1,200 years.
The water behind Hoover Dam supplies vast areas of farmland and about 25 million people in three states, and this critical reservoir stands just 40 percent full.
Droughts and even decades-long mega-droughts have long been part of the natural cycle of the Colorado River, but that ebb and flow is now occurring alongside global warming, which scientists say is influencing the weather and putting new pressures on water supplies that are already over-tapped and declining.
In many ways, climate change is starting to compound the problems of a water system in the Southwest that is fundamentally out of balance:
• The Colorado River would naturally flow through its delta to the Sea of Cortez. But so much water is taken from the river that it seldom reaches the sea, and federal officials say water use has begun to surpass the available supply, drawing down the river's reservoirs.
• Beneath desert cities and towns, in places from Palm Desert to Borrego Springs, groundwater levels have been dropping as more water is pumped from wells than flows back into aquifers.
• Scientists aren't sure to what degree climate change is influencing the natural cycle of droughts in the West, but they say it's clear that hotter temperatures worsen droughts, meaning that future dry spells will become more intense, more frequent and longer-lasting. And the current drought is taking an economic toll on agriculture in California's Central Valley, with UC Davis researchers estimating losses this year at $1.7 billion.
• Already, scientists say hotter temperatures across the West have led to less mountain snowpack and earlier melting of snow in the spring. More of the snow and rain that does fall is evaporating due to warmer temperatures, and that diminishes the flows of water into the Colorado River that sustain cities and farms across the Southwest.
Hoover Dam and Lake Mead on May 22, with the water level nearing a record low. The white ring left behind by minerals in the receding water shows where the water level stood more than 14 years ago.
(Photo: Richard Lui/The Desert Sun)
The white band left on the rocky banks of Lake Mead by minerals in the receding water illustrates the vulnerability of people across the Southwest to the risks of a changing climate — risks for which the region appears largely unprepared.
"Here's a reservoir that can hold two full years of the flow of the Colorado River, and it's now down to less than one year's worth of flow," said John Entsminger, general manager of the Southern Nevada Water Authority, which supplies water for Las Vegas. "That's the bank account for 25 million people from Santa Barbara to San Diego. It's the bank account for the 2 million people I'm responsible for. It's the bank account for all of central Arizona. With Lake Mead, a picture's worth a thousand words. You look at that lake and you say: This is a serious issue and we better start taking some proactive measures before things go from bad to worse."
The level of Lake Mead has been declining dramatically, and climate change is expected to put additional pressures on water supplies.
Richard Lui and Marilyn Chung/The Desert Sun
Climate change adds a new layer of complication for Entsminger and other water managers because they know hotter temperatures will mean less water, but they're unsure how much less.
"That's what climate change can mean for this basin, that you're going to see not only less precipitation but precipitation that doesn't get into the river and ultimately results in less water," Entsminger said. "All of us are going to have to come together and, in my opinion, in the 21st century figure out how to live with less water."
Some researchers say climate change in the Southwest is also essentially "water change" because the biggest, most difficult adjustments may be forced upon the region by worsening water scarcity.
Climate scientists have described the desert Southwest as a hotspot for climate change. Climate data show that much of the Southwest has been heating up more than other regions of the country, and scientists say the region's dryness appears to be contributing because in wetter areas, some of the sun's heat would be used up evaporating water vapor from the soil.
Sand and dust fill the air on a windy day in Cathedral City.
(Photo: Richard Lui/The Desert Sun)
Scientists also have found that recent droughts are worsening dust storms. Hotter temperatures and more frequent droughts are projected to worsen smog and air pollution in the future, posing health risks, particularly for those who are most vulnerable — the elderly, those with health problems and the poor.
A Desert Sun analysis of national climate data from more than 30 weather stations across the Southwest, in places from Palm Springs to Tucson, found that the average number of days each year with temperatures hotter than 90 degrees increased more than 25 percent during the past 20 years as compared to the average in the decades before 1960 — a time frame often used by scientists in studying climate change.
Average monthly temperatures have climbed 1.7 degrees Fahrenheit. In the winters, average lows have risen 3 degrees, and average summer highs have become 1.3 degrees hotter.
Scientists have determined that the decade from 2001 to 2010 was hotter than all other decades in the Southwest since 1900. Heat waves have also increased in a region that is the hottest and driest in the nation.
Firefighters attempt to stave off flames during the July 2013 Mountain Fire in the San Jacinto Mountains.
(Photo: Crystal Chatham/The Desert Sun)
And as temperatures have climbed, the numbers of big wildfires have also risen.
Scientists said in a 2013 report that it's highly likely heat waves in the Southwest will increase in frequency, intensity and duration. The report was authored by a list of climate scientists from universities and other institutions such as the National Oceanic and Atmospheric Administration and Scripps Institution of Oceanography.
The researchers also concluded it's highly probable that droughts leading to diminished flows of the Colorado River will worsen and result in deficits of water unlike any seen before in recorded history.
The water level in Lake Mead today stands at an elevation of 1,085 feet above sea level, and in July it is set to sink below the all-time low of 1,081.8 feet, a record set in November 2010.
If the water level drops 31 feet beyond that, to 1,050 feet, the Southern Nevada Water Authority would no longer be able to pump water from one of the two intake pipes that supply Las Vegas. Anticipating that possibility, the water agency began several years ago building a third intake in the bottom of the lake. The 20-foot-wide tunnel is being drilled underneath the lake at a cost of $817 million, and is scheduled to be finished next year.
While the deeper intake will solve an immediate problem for Las Vegas, Entsminger said much more needs to be done to save water on a bigger scale across the region.
John Entsminger, general manager of the Southern Nevada Water Authority, speaks during an interview at his Las Vegas office. Entsminger said he expects the region will need to learn “how to live with less water.”
(Photo: Richard Lui/The Desert Sun)
Devastating droughts have hit the Southwest before. Scientists have reconstructed stream flows in the region going back more than 1,200 years using tree rings, and the U.S. Bureau of Reclamation says that research shows the Colorado River Basin is now in its fifth worst 14-year drought period in that time frame.
And as the drought persists, Entsminger acknowledges wondering about the unknowns.
"What if we're seeing a compounding of a historic drought with now the effects of human-caused climate change? That's what's most worrisome for me, because that would mean we're seeing something that even in the last 1,200 years we've never seen before," he said. "If things could be this bad just with the natural cycle, and then humans are making it worse, what's worse than a prolonged 50-year drought?"
Risks and vulnerability
The ruins of cliff dwellings and other archeological sites in parts of the Southwest show how indigenous societies such as the Ancestral Pueblo, Hohokam and Sinagua peoples once flourished and expanded, and then collapsed.
Those civilizations disappeared between the 13th and 15th centuries during periods of repeated mega-droughts that scientists have identified using tree rings and other methods. Analyzing the demise of those societies in the book "The West without Water," UC Berkeley paleoclimatologist B. Lynn Ingram and environmental planner Frances Malamud-Roam write that "the greatest societal catastrophes occurred after populations expanded during years of plenty and were then struck by disastrous droughts — an unnerving parallel to modern times."
The 20th century was a relatively wet period in the West compared with prior centuries. By planning the water system in a time of relative abundance, Ingram said, "we kind of built up our whole modern civilization based on an unrealistic expectation."
The modern laws that govern allocations of water from the Colorado River also were laid out during much wetter times, starting with the 1922 Colorado River Compact. Those laws have since evolved, with various legal battles over water along the way.
In 2007, when the Colorado River was in an eighth year of drought, the federal government adopted new guidelines for releasing flows from Lake Powell and Lake Mead. Those rules specify that if the water level of Lake Mead is below 1,075 feet as of Jan. 1 in a given year, the Interior Secretary can declare a shortage condition, which would trigger cuts in water deliveries to Arizona and Nevada.
Water levels in Lake Mead are projected to rise later this year, boosted by flows released from Lake Powell after a year with normal snowpack. But that's just one year in a larger drought, and the Bureau of Reclamation has estimated that by 2017, there will be a 50-50 chance of low water levels prompting the declaration of a shortage. Starting in 2018, the estimated likelihood of reaching that threshold — and cutbacks in water deliveries — rises to 60 percent.
California holds the most senior rights to water from the Colorado River, and given that first-priority position, Southern California would be the last in line to feel the pain of any cutbacks.
But scientists and water managers have increasingly promoted the idea of states working together to address water shortages, and some have said all parties along the river need to be engaged in discussions about how to use less water and keep looming shortages from harming economies.
Pressures on the Colorado River have been driven partly by the increasing populations of cities in the Southwest, which have grown faster than other parts of the country.
"Climate change interacts with and exacerbates the existing vulnerabilities of a given region," said Katharine Hayhoe, an atmospheric scientist and director of the Climate Science Center at Texas Tech University. "We're already in a situation where we don't have enough water to go around, and then climate change is coming along and climate change is exacerbating the problem that we have already created ourselves."
As water becomes less reliable, she said, that increases the risks of new conflicts over water, whether between states or between cities and farming regions.
In many parts of the world, climate change is projected to make wet regions wetter and dry regions drier.
"The Southwest is generally expected to get somewhat less precipitation in the future, not drastically less, but somewhat," said Kelly Redmond, a climatologist and deputy director of the Desert Research Institute's Western Regional Climate Center in Reno.
Redmond explained that because temperatures are hotter, water evaporates more quickly from soils and reservoirs. "So, temperature alone has some consequences on drought, even if precipitation doesn't change at all."
A view of Las Vegas from the Lake Las Vegas development. Reclaimed wastewater accounts for about 40 percent of the water used in southern Nevada.
(Photo: Richard Lui/The Desert Sun)
One important aspect of climate change, he said, is that its effects are layered on top of a host of other environmental stresses, including urban sprawl and intense demands for water.
"In conjunction, it's sort of a stress multiplier, of stresses that maybe we could normally get through, but because it's there, it takes us over a threshold that we might not have crossed," Redmond said.
Among other climatic changes, storm tracks have shifted over the western U.S. in recent decades, and more of the region's precipitation has fallen as rain rather than snow.
"We've seen changes in river flow timing because of losses of snowpack in the western U.S., in California and the Rocky Mountains as snow disappears faster and faster because of higher temperatures," said Peter Gleick, a water researcher and president of the Pacific Institute in Oakland. "Those are all examples of some of the impacts we thought we would see and are now seeing from climate change."
Gleick said, however, that even without climate change, the region's water system faces enormous stresses.
"We're past the point of 'peak water' in the western U.S.," he said. "We overdraft our groundwater, we take too much from our rivers and streams, and so, even without climate change, part of the answer is changing the way we manage the system, improving especially the efficiency of our water use."
A pleasure boat cruising near the steep canyon walls of Lake Mead on May 23. The boat is dwarfed by the "bathtub ring" that shows the reservoir’s high-water mark.
(Photo: Richard Lui/The Desert Sun)
Along with the risks posed by growing water scarcity, Gleick said, changes in the timing of river flows also will be hard to manage because reservoirs and other infrastructure were designed for a different climate.
"Adding climate change on top of a system that's already out of balance makes all of our problems more difficult," Gleick said. "We have to realize that there are limits, especially in the dry Southwest. We can't just pretend that we can grow our cities forever and somehow find new resources for them, new water for them. We have to change the way we do planning. We have to change the way we manage water. And if we don't, changes are going to be forced on us."
Planning for uncertainties
Some of the water that pours out of Lake Mead through Hoover Dam eventually makes its way to the Coachella Valley, flowing through the Coachella branch of the All-American Canal or through the Colorado River Aqueduct. The valley's water agencies obtain some of that water by exchanging their allotments from the State Water Project for equivalent amounts from the Colorado River.
The Coachella branch of the All-American Canal in Mecca.
(Photo: Richard Lui/The Desert Sun)
The water that flows in through the Coachella branch of the All-American Canal is used to irrigate crops such as grapes and peppers, and to water some of the valley's 124 golf courses.
A portion of the imported water fills replenishment ponds in La Quinta and Palm Springs, where it sinks into the soil to replenish the underground aquifer. Despite those inflows, groundwater levels have been declining for decades in much of the Coachella Valley.
Climate change could add to that problem in the long term and make it more difficult for local water agencies to prevent declines in groundwater levels.
The Desert Water Agency, which provides water to Palm Springs and surrounding areas, is raising water rates and boosting spending on programs to encourage conservation, including cash incentives for lawn removal and free irrigation controllers. The water agency also has joined other Southern California water districts in supporting the state's $25 billion plan to build water tunnels beneath the Sacramento-San Joaquin River Delta, saying the project would make water deliveries more reliable and guard against rising sea levels.
Water flows into one of the percolation ponds that refills the aquifer in Palm Springs.
(Photo: Jay Calderon/The Desert Sun)
"If climate change teaches us anything, it is that the need to conserve water will not come and go with the condition of the snowpack in the Sierras from year to year," said Craig Ewing, president of the DWA board. "As average temperatures rise and new uncertainty is raised about future sources of supply, climate change should cause everyone to pay even greater attention to creating a more robust storage and delivery system, and to reducing our use of water."
The Coachella Valley has long had some of the lowest water rates in California, and some of the highest per-capita rates of water usage. For decades, subdivisions and resorts have been built around lush expanses of grass and artificial lakes. That is starting to change as more homeowners and new developments have adopted desert landscaping, and as more water agencies have adopted tiered rates that penalize heavy water users.
The Coachella Valley Water District has included a section on the potential impacts of climate change in its water management plan, which lays out a long-term strategy for preventing future declines in the aquifer. The document says in a chapter titled "Emerging Issues" that climate change could affect sources of imported water and could also increase demands for water by boosting evaporation. It notes there are no precise estimates of how global warming will affect river flows, but says "the aggregate change for the basin could be significant."
A lake, golf course, and thousands of homes as seen from the air above La Quinta.
(Photo: Jay Calderon/The Desert Sun)
Some argue that water districts and local governments need to be preparing for climate change with a greater sense of urgency.
Eric Corey Freed, a Palm Desert architect who leads the Coachella Valley branch of the U.S. Green Building Council, points to San Luis Obispo County as an example. After some wells began to go dry near the wine-growing areas of Paso Robles, San Luis Obispo County responded with an ordinance last year establishing a moratorium on new groundwater pumping for farms or developments unless that pumping can be offset with reductions elsewhere.
"I think things are getting severe enough with the water supply that maybe it's a good time to force people to have a little long-term thinking for a change," Freed said. "What I'd like to see is, declare a state of emergency over water valley-wide and in doing so take control of our water system and find a way to better manage it — mandatory water budgets for everybody."
Freed argued that efforts reminiscent of the mobilization of civilians during World War II are needed to address climate change and bring about changes in how water is used.
"In World War II, at a time of crisis, we asked everybody to make sacrifices and to do it in a long-term view in the name of victory. We rationed everything, precious materials, rubber, steel, aluminum," Freed said. "And we did it all in the greater good, for the bigger picture, in the name of victory. That's what we need to do again. We need to redefine victory, a Coachella Valley that will still be here in a hundred years."
Resilience
As levels of carbon dioxide in the atmosphere continue to increase, ideas for combating climate change are being promoted and debated by activists, scientists, politicians and citizens. Proposals range from weaning the world from coal-fired power plants to stemming deforestation, expanding rooftop solar systems, and reinventing transportation systems.
At the same time, many experts and policymakers are emphasizing a need for adaptation. President Barack Obama has proposed a $1 billion fund to help communities prepare for the effects of climate change and to promote more resilient infrastructure.
Farms in the Coachella Valley are irrigated with water from the Colorado River.
(Photo: Richard Lui/The Desert Sun)
Gov. Jerry Brown's administration has promoted adaptation strategies in California that include studies of vulnerabilities as well as research into how agriculture can optimize crop yields in the face of decreasing water supplies. Brown said recently that "humanity is on a collision course with nature, and we're just going to have to adapt to it in the best way we can."
In the deserts of the Southwest, adaptation will likely involve learning to live with more extreme heat. Scientists predict in the newly released National Climate Assessment report that annual average temperatures in the Southwest could rise by 5.5-9.5 degrees by the end of the century if emissions of greenhouse gases continue to grow.
That would make the climate of cooler high-elevation deserts more like the region's hottest low-elevation deserts.
Palm Springs, Indio and El Centro, among other places, could be scorched by average temperatures hotter than those seen today in Death Valley, which holds the record for the hottest temperature ever recorded: 134 degrees.
Some desert cities have already experienced dramatic warming. The Desert Sun's analysis of climate data found that Palm Springs had average temperatures 3.4 degrees hotter during the past two decades as compared to the decades prior to 1960.
Phoenix saw its average temperatures rise 5 degrees, a change attributed in part to the urban "heat island" effect, in which asphalt and concrete capture heat during the day and then radiate heat at night, pushing up nighttime lows.
Read more at:
http://www.desertsun.com/longform/ne...ught/10418637/
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