The desert Southwest: Oasis or mirage?

May 09, 2012 By Pete Zrioka
Lake Mead, located on the Arizona/Nevada border, in 2006. The layers of color on the rock show how much the water level dropped due to drought. Credit: ChrisMRichards/ Flickr/ CC-BY-NC-ND

(Phys.org) -- The American West has a drinking problem. On farms and in cities, we are guzzling water at an alarming rate.

Scientists say that to live sustainably, we should use no more than 40 percent of the from the . As it is now, we use 76 percent, nearly double the sustainable .

The water supports the populations of California, Arizona, Nevada, Utah, , Colorado and Wyoming, providing for and cities. With a and continued growth, increasing demand for water may make this vital resource increasingly scarce.

There are some in place against . The reservoir Lakes Mead and Powell can provide approximately five years of average annual at full capacity for insurance against low rainfall years.

But John Sabo, an associate professor in Arizona State University’s School of Life Sciences, believes that 50 years in the future – rather than five – should be the planning mark for water usage.

“My take on that is we’re already beyond the point where we have enough insurance against the bad years, which is why a year and a half ago we started talking about water rationing before it started raining in December,” says Sabo, who is also director of research development in ASU’s Global Institute of Sustainability.

After dipping to a record low in 2011, Lake Mead presently sits at below half capacity, and that’s with favorable rainfall and snowpack accumulating in the Rocky Mountains, which feed the Colorado.

Also, to our detriment, there is a culture dedicated to creating an oasis in the Southwest’s arid environment. Most of the West’s water falls in the mountains, where it slowly melts, We collect it and then spread it thin across the deserts. Moving water from wet areas to dry areas makes people feel safe, according to Sabo.

“We have lawns, palm trees and lush green parks because we store water from far away to offset the arid reality of the desert,” he says.

Regardless of how much our lawns guzzle, the largest use of water isn’t in urban areas but in agriculture. Farming uses 77 percent of the water allocated for human use in Arizona, according to the Morrison Institute for Public Policy’s publication “Watering the Sun Corridor.”

For example, Southwestern farms produce approximately 75,000 acres of lettuce annually. As much as 55,000 acres of that is grown in Arizona, according to University of Arizona publications. Of Arizona’s lettuce, 95 percent is grown in the southwestern corner, in Yuma county, which receives an average rainfall of about 3.6 inches.

“People might ask, why are we growing lettuce in Arizona?” questions Sabo. “Well, it’s because it’s warm here in the winter and people want salads in the winter. And if you want a salad in the winter and you don’t want to wait for natural salad season to come around, you’ve got a tradeoff, and that tradeoff is the water footprint.”

The water footprint of produce isn’t often taken into consideration, however.

“There’s this ‘eat local’ movement that has done a great job to educate people about how your decisions at the supermarket relate to your carbon footprint and climate change,” says Sabo. “But there’s nothing like that for water, and I think there needs to be.”

Since most water isn’t used for cities, urban lifestyle changes aren’t going to do much to solve the problem. Shorter showers and eco-friendly appliances aren’t enough to make a significant impact on our massive water use.

Sabo proposes that the Southwest cuts its water use to 60 percent. To get there, it comes down to policy and investment in infrastructure for the future.

“You would never know we had a water shortage here,” says Sabo. “We don’t pay a lot for it, we don’t expect pay a lot for it and we don’t expect to have to conserve it.”

David White, co-director of ASU’s Decision Center for a Desert City (DCDC), says that Arizona water policy has done a good job of providing adequate supplies for the growth of the region up to this point. But environmental and demographic factors will likely require changes in that system. The DCDC uses research to inform environmental policy in times of uncertainty.

“We’ve been able to deliver a consistent and reliable amount of water to residents even though the amount of water that comes into our system fluctuates wildly,” says White. “That system has been effective over the past 100 years under a set of conditions and assumptions that may be changing due to climate change, extended and prolonged droughts, and increased demand as a result of . It faces new challenges,” adds White.

Home to more than half of Arizona’s population, Maricopa County grew by 24 percent from 2000 to 2010, according to U.S. Census Bureau data. Additionally, “Watering the Sun Corridor,” projects the 2030 population of Phoenix and Tucson to exceed 7.8 million.

One way to reduce water use is through the addition of more sustainable infrastructure. According to Sabo, this would be most effective in areas of growth and expansion, such as Ahwatukee, Anthem and Sunrise.

“Retrofitting historical Phoenix would be a pain in the neck,” says Sabo. “The idea is to build sustainable infrastructure as we build out. Reclaimed water is cheaper to add in to unbuilt suburbs than to retrofit in older cities. When the time comes for refurbishing the old potable infrastructure in the central city, then we can consider retrofitting for dual distribution of potable water for drinking and reclaimed water for landscape irrigation at home.”

Such changes would help us follow White’s recommendation to stop siphoning our limited groundwater sources and live off of renewable surface water instead. Groundwater is water that is stored in underground aquifers. Although it is replenished by rainfall, we use it much faster than it can be replaced.

“Groundwater supplies a bank or a backup of water,” says White. “But by and large it’s a nonrenewable source and we should try to live within our means.”

It’s unlikely that the Southwest would run out of water. But as temperatures rise and population swells, how we value our water supply is going to change.

“You’re either going to have to pay more for it or you’re going to have to pay more for your winter salad,” says Sabo. “Either the farms or the luxury to use water the way we do in cities is going to go.”

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User comments : 8

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Lurker2358
1 / 5 (2) May 09, 2012
Shorter showers and eco-friendly appliances arent enough to make a significant impact on our massive water use.


First time I've ever seen anyone admit that.
kaasinees
2 / 5 (4) May 09, 2012
If we replace our agriculture with better practices like aquaponics we can slow water usage down though. We have to keep improving our tech and cut down on water usage in all areas, even if it helps by 5% it is worth it.
Terriva
1 / 5 (3) May 09, 2012
eco-friendly appliance
Actually the wind and solar plants could make droughts even worse, when they block the circulation of atmosphere and the atmospheric water. My only advice is, we should invest into cold fusion and into desalination technologies urgently. It would help to keep the carbon emissions low too.
Argiod
3.3 / 5 (6) May 09, 2012
Humans are stupid creatures who will deplete their environment of every exploitable resource; and then wonder why they're running out. Point of fact: a planet with finite resources cannot support infinite human growth. We are going to find that, in the next decade or two we will no longer have to worry about the cost of fuel; we will be warring over water; one of two most basic of resources. And we'll do it with our eyes wide open; and unable to stop the process due to the greed of the few who make billions on their exploitation. Sad ending to a creature with so much potential...
ROBTHEGOB
1 / 5 (2) May 09, 2012
Cadillac Desert. Read it.
Sanescience
3.7 / 5 (3) May 10, 2012
When something is cheap, it is misused. As water becomes more expensive, it will be used less. If water becomes expensive enough, it will be harvested into cisterns and pumped into water tanks on top of houses and buildings. In a way peak oil has encountered this effect, spreading out the expected sudden "shock" of running out of oil into a game of finding the harder to get oil, causing the price to rise but the availability to still be there.

That is not to say population growth, and especially uneven population growth, isn't going to eventually overwhelm large regions of the world.
Vendicar_Decarian
5 / 5 (1) May 10, 2012
How can that be when according to Libertarian Economist Julian Simon the earth's resources are infinite and the world could easily sustain a population of 100 billion people?

"Point of fact: a planet with finite resources cannot support infinite human growth." - ArgIod

Libertarian Simon wouldn't be a liar, would he? How could he be when he got so much support from the CATO group and similar thinking whacktard economists at Stanford University.
ryggesogn2
1 / 5 (2) May 10, 2012
When something is cheap, it is misused.

Tragedy of the commons.
Most of AZ is owned by the govt and like NV, its mineral resources were most important to the federal govt.