March-April 2011

Water Sustainability

Water is essential for life and is central to human civilization. It is a finite natural resource. Across the globe, a natural, disproportionate amount of precipitation falls on some regions. While arid regions sometimes receive the majority of their annual precipitation in only a few events, humid regions typically have an abundance of precipitation.

The American Southwest is a semi-arid to arid region that is home to tens of millions of people and one of the most productive agricultural areas in the country. It is because of our ability to move massive amounts of water that this desert region has been able to grow large amounts of food and sustain such a population. But how long can this last? How much more of a population can be sustained in a naturally water-stressed region?

In ancient times, water was the guiding path for our nomadic ancestors. As time progressed and nomads began settling down to form more permanent residences, they settled near a stream, river, or lake, some source of water to provide for their needs. Civilizations sprung up near sources of water out of the need for survival and for the sake of convenience. However, for civilizations in arid regions where water sources are scarce, unpredictable, and seasonal, it was, and still is, necessary for water to be diverted and transported from a reliable source to where it was needed. 

As time progressed further and civilizations advanced and spread out, water sources were not always close by, reliable, or adequate to sustain growing populations. This led to the construction of water conveyance systems. In some cases, these were simple irrigation ditches, and, in other cases, elaborate aqueduct systems were built in order to deliver water to where it was needed. 

The Hohokam, who lived in south-central Arizona from roughly 200 B.C. to 1450 A.D., are recognized as the “desert irrigation specialists” in the American Southwest. They built extensive irrigation canal systems totaling over 350 miles, primarily along the Salt River in the present-day Phoenix, AZ, metropolitan area, that diverted water to irrigate an area of about 100,000 acres in the Salt River Valley. At the height of the Hohokam civilization, there were 20 villages with separate canal systems, sustaining a total population of around 4,000. Some of the same canal routes built by the Hohokam were used to build the present-day water conveyance system for the Phoenix metropolitan area known as the Salt River Project, which is one of the state’s largest water providers. Today, Phoenix is the 5^th largest city in the United States with a metropolitan population of close to 4 million people.

Moving into recent times, there is not much difference in the basic concepts of managing water resources. It largely remains the same: getting adequate supplies to sustain a growing population. Except now, instead of 4,000 or even one million people, we must support and sustain a much larger population. Because of the advancement of technology, we have been able to build large complex water conveyance systems in order to divert water. As the global population continues to rise, so does the demand: More and more water is needed to sustain an increasing population. In fact, global water consumption has almost doubled since the 1950s and is expected to continue to escalate. 

One of the luxuries of the modern American society is that we have a choice of where we want to live. And on a whole, more and more Americans have chosen to live in the warm regions of the US—also the most water-stressed—and have seen explosive growth in the past two decades. So not only does a disproportionately low amount of precipitation fall on these regions, but a disproportionate amount of people live in those same water-stressed regions, setting the stage for a water crisis.

Water Management in the 20^th Century: Supply and Demand
In order to compensate for the disproportionate distribution of precipitation and to facilitate growth and development, water policy in the 20^th century centered on the construction of large water infrastructure projects—especially in the western US—in order to control rivers, store water, and distribute water when needed, as well as for hydroelectricity generation, recreation, and navigation.  

At the dawn of the 20^th century, the National Reclamation Act of 1902 was created to encourage settlement and facilitate growth in western states by funding the construction of irrigation projects. This act created the Reclamation Service, known today as the Bureau of Reclamation, the government agency that is responsible for water management west of the 100^th meridian. This act also spawned the long, litigious process (that continues today) of allocating and managing the Colorado River, known as the Law of the River. 

The surface water law that governs water rights in the western US is the doctrine of prior appropriation, or the western water law of prior appropriation. What this law decrees is that the first entity to put surface water to “beneficial use” holds the senior rights (referred to as the senior appropriator) to that water and can use as much as is needed for the declared beneficial use. Beneficial use basically means any water that is used for a purpose, e.g., irrigation, mining, or providing wholesale water. Any entity gaining water rights after the senior appropriator holds junior rights to that water (referred to as the junior appropriator), meaning that in times of decreased water availability, the junior appropriator is the first to receive supply reductions, while the senior appropriator receives full allocations of his/her water rights. The primary concept of this law is simply described as “first in time, first in right.” 

The rush to lay claim to water rights in the West is what has defined its water management paradigm. The “use it or lose it” concept has caused appropriators to use as much water as they can in order to keep their rights to it—that is, if they do not put the water to beneficial use, they can lose their rights to the water. This goes against the notion that water should be treated as a valuable resource in a desert region where water is naturally scarce.

In the Southwest, water is diverted hundreds of miles to expansive farms and thirsty cities. The Colorado River is the largest river in the Southwest and fifth largest in the nation. Many dams, including two of the world’s largest, the Hoover and Glen Canyon, are built on the Colorado River to create monstrous reservoirs, divert massive amounts of water, and produce hydroelectricity. Large, extensive open canal systems cut across hundreds and hundreds of miles of desert landscape moving water up and down mountains to urban centers and agricultural lands. These dams and canals are the sole reason that upwards of 25 million people can thrive in the desert and one-quarter of the nation’s food can be produced on arid lands. And with current projections, this population will jump to 38 million by 2020.

When the Colorado River was allocated in the 1920s, it was divvied up using data from extremely wet years that are essentially anomalous to its hydrologic history. Bottom line is that it has been over-allocated, and now over 25 million people depend on it, not to mention the rest of the country that depends on the food that is produced in this region. There is mounting evidence that the Colorado River Basin is prone to massive droughts that can last for several decades. According to the Bureau of Reclamation, the Colorado River Basin is currently experiencing a protracted multi-year drought that began in October 1999, causing Lake Powell to experience an all-time low in 2002 and the level of Lake Mead to continue to drop to this day.

The Southwest relies on the Colorado. What if there is a drought that is worse than the current one? What will happen if this one continues for another decade? 

Water Management in the 21^st Century: Uncertainty
Today water managers are faced with the impacts of climate change. The Southwest has experienced an increase in temperature over the last decade. Increasing temperatures have a direct impact on water resources and cause a decline in water supply availability and reliability due to higher drought risk; changes in precipitation; decreased snowpack, runoff, and streamflow; and increased evapotranspiration. Warmer temperatures also increase water demand. An increase in water demand due to warmer temperatures and population growth coupled with the aforementioned impacts, adequate water supplies for future generations remain uncertain.

In fact, studies have shown that current demands on water resources in the Southwest will not be able to be met under the projections of reasonable climate models. In particular, climate change impacts will result in a degradation of the Colorado River reservoir system performance and an increased likelihood of system failure. Lake Mead, which is formed by the Hoover Dam and functions as the storage facility for California, Arizona, and Nevada, has been declining and is currently at its lowest level since it began filling in the 1930s. If current population growth rates were to continue, this would exacerbate water shortages on the Colorado River. Therefore, the water management challenge of the Southwest now becomes how to meet demands with a less secure water supply.

Water and economic growth are what have made the Southwest what it is today. Since the growth is going to continue, there will have to be a more sustainable approach to water use. There needs to be a paradigm shift to water sustainability. This is going to be a tough challenge since, as mentioned before, the paradigm of water resource management in the Southwest has been to use as much water as possible or risk losing your water rights. 

This notion has to be overcome. There is going to be growth whether local people want it or not; the global population is growing exponentially. What we need to be is practical and smart about how the growth happens. We need to learn how to work together to make the world a better place for our children and our children’s children. We need to take responsibility for our own consumption and our own actions, or our problems will be inherited.

The Southwest has the highest per capita water consumption rates in the country and, arguably, in the world. Per capita consumption in the Southwest averages around 230 gallons per capita per day (gpcd), with some cities having a per capita consumption upwards of 300 gpcd. To put this in perspective, the national average in the US is 101 gpcd, in Canada it is 86 gpcd, 39 gpcd in France, and 20 gpcd in Jordan. The reason the Southwest in general has such an astronomical daily consumption rate is because most, that is 60 to 80%, of that water is used primarily for turf and landscape irrigation, and because it is a semi-arid to arid region, most of that water is lost through evapotranspiration. 

One of the biggest questions is: Why is water wasted keeping lawns green in a desert? This has been able to happen because of the technology we have developed to move massive amounts of water from where it is to where it is needed. However, this began when the population was a lot smaller than it is today. Moving this water has created expansive oases and an allusion of an abundance of water, when in fact there is not. Now add natural climate variability and climate change, and you have a recipe for disaster. 

Life in the Southwest may not be able to continue its lush, artificial existence, and the need to return the desert to its original state is mounting. Not to say that people cannot live in the desert—we have proven that completely possible—but we need to grasp that our water use needs to change. It needs to become more practical and mimic the natural environment; it needs to become more sustainable. 

The Paradigm Shift to Water Sustainability
As population increases so does water demand. As a result, water managers have adapted ways to ensure that there is enough water to facilitate growth, and, in many cases, this involves seeking out different water sources, or supply augmentation. As mentioned, in the 20^th century, the focus has been on large infrastructure projects of dams and canal systems. Building new dams in most cases is cost-prohibitive (not to mention that we have essentially run out of potential dam sites), and there is a growing awareness of the environmental impacts dams have on stream hydrology and aquatic species. Because of the limited opportunities and high costs associated with developing new water supplies, water managers have turned to other supply augmentation strategies in recent years. Some of the strategies used by Southwest water managers include water reuse, groundwater banking, agricultural-to-municipal water transfers, water marketing, desalination, and weather modification. 

Population growth coupled with the prediction of climate-induced water shortages and the increased risk for drought make it prudent for water conservation and water use efficiency to become a common practice in the Southwest. Using water efficient technologies, adapting water efficient practices, reusing water, and using alternative water supplies whenever possible will be the most beneficial to decrease demand on potable water across all sectors. And of course, because of the water-energy nexus, conserving energy also conserves water and vice versa. This is because it takes water to produce energy, and it takes energy to pump and distribute water. 

In the urban sector, taking a holistic approach is best when it comes to using water sustainably. There are many ways to conserve, harvest, and reuse water, indoors and out, in order to decrease the demand on potable water. A water audit can be helpful to facilitate customer education and to identify where efficiencies can be made from large office complexes to a single family home.

For indoor water use, demand reductions are commonly achieved water efficient devices and technologies. Faucet aerators, high-efficiency toilets, waterless urinals, water efficient showerheads, and pre-rinse spray valves can be installed, as well as high-efficiency appliances such as dishwashers and clothes washers. Of equal importance, being cognizant of how water is used and when it is wasted can lead to more water efficient practices.

For outdoor water use, demand reductions occur through water efficient landscaping. Xeriscape principles—water efficient landscape design and maintenance practices that are optimal for semi-arid and arid regions—can be implemented. Rainwater—an alternative water source that is harvested off roofs and stored in tanks—is commonly used for outdoor irrigation and/or for non-potable uses indoors, e.g., toilet flushing. Greywater (no food or human waste) can be redirected and used for non-potable uses and outdoor irrigation. Reclaimed water can be distributed via “purple pipes” and used for outdoor irrigation. These are just a few of the water conservation measures that can be taken to reach water sustainability.

Utilities can implement aggressive water conservation programs whereby customers are incentivized to conserve water and make changes in the way they use water. A thorough water conservation campaign would use all three types of incentives: educational (e.g., pamphlets, bill inserts, TV ads, informational signs, workshops), financial (e.g., rebates, water pricing, water rate structures), and/or regulatory (e.g., outdoor watering ordinances, mandatory installation of water efficient landscaping for new construction). Of course, the extent of the water conservation program would depend on the budget of the utility. 

It is also best for municipal buildings to implement these practices so citizens can see that the government practices what it preaches, especially if water restrictions and conservation programs are in place. What I mentioned here are just a handful of the options that can be utilized to decrease the demand on potable water, and as technologies advance and people start making wiser choices about their water consumption, more water will be saved and water sustainability will be achievable.

In a region with characteristics of naturally limited water resources, semi-arid to arid climate, and large population, water efficient practices should be inherently second nature. Not only that, but the uncertainties of climate change place a question mark over the future water supplies, especially for those who are dependent on the Colorado River. People need to become more conscious of their water use, especially if they desire to live in the desert region of the American Southwest. Water conservation and efficiency strategies can act as the impetus for a behavioral change in the way people use water and help to foster a collective sustainability ethic that can ensure adequate water supplies for future generations.