are affected, whether they are growing crops or fishing 

 for sport. Those changes can also severely alter or destroy 

 the habitats of other species. More than half the wetlands 

 in parts of Australia, Europe, New Zealand, and North 

 America were destroyed during the twentieth century. 

 When people divert water into desert regions to maintain 

 thirsty crops, luxurious green lawns, and golf courses — 

 instead of growing drought-adapted crops and native and 

 ornamental plants — water resources are decimated. Even 

 high-volume rivers such as the Colorado, the Ganges, 

 and the Nile have been reduced, in some places, to pol- 

 luted trickles. 



In water-rich regions, people may wonder how their 

 actions could have any effect on how people use water 

 in water-deprived areas. But consumer choices obviously 

 help drive what agriculture and industry produce and how 

 they produce it. If agriculture and industry account for 

 more than 90 percent of water usage, our closets, cup- 

 boards, desks, and refrigerators are filled with what has 

 been termed "virtual water": products that require water 

 for their growth, manufacture, and packaging. Those 

 products now come from all over the world, including 

 from places with limited water resources. 



More than 700 gallons of water are needed to grow enough 

 cotton to make a T-shirt. Your choice to buy the shirt could 

 lead farmers in arid Central Asia to divert water to irrigate a 

 cotton crop. Although poor farmers may welcome the cash, 

 such diversions have led, for instance, to a 75 percent loss 

 of volume in the Aral Sea. Once the fourth-largest inland 

 body of water by area, the Aral has now shrunk so much 

 that its former lakebed is littered with rusty ships, rimmed 

 with abandoned fishing villages miles from the water's 

 edge, and scoured by storms of toxic dust. 



Conserving water helps not only to preserve irreplace- 

 able natural resources such as the Aral, but also to 

 reduce the strain on urban wastewater management 

 systems. Wastewater is costly to treat, and requires continu- 

 ous investment to ensure that the water we return to our 

 waterways is as clean as possible. During storms, rainwater 

 runs off the pavement, collecting pollutants as it goes. 

 Where storm sewers and sanitary sewers are connected, 

 the influx of storm water can overwhelm sewage treat- 

 ment facilities, leading to the release of untreated sewage 

 and polluted storm water directly into local waterways. 

 Forty billion gallons of such a toxic cocktail flow into the 

 Hudson River and its estuary each year. Several towns and 

 cities around the world are installing innovative solutions 

 to such problems that also benefit surrounding ecosystems. 

 Rainwater overflow, for instance, can be channeled into 

 wetland systems instead of into storm sewers. 



Human activities affect water quality in other ways as 



well. Particularly in large cities, once water has disappeared 

 down the drain or into a storm sewer, it is rarely thought 

 of again. But what becomes of the household chemicals 

 poured daily into the water supply — cleansers, antibacterial 

 soaps, medicines? Ecologists are just now learning about 

 their downstream effects. One that is well documented 

 is the disruption of growth and reproduction in trogs 

 and fish. Cities with sophisticated treatment systems can 

 filter out many chemicals, but antibiotics, hormones, and 

 antibacterial compounds remain hard to handle. 



The UN estimates that by 2025, forty-eight nations, 

 with a combined population of 2.8 billion, will face 

 freshwater "stress" or "scarcity." Water shortages already 

 impede development, perpetuate poverty, and damage 

 health in low- and middle-income countries. As popula- 

 tions grow and the demand for water increases, problems 

 will intensify and will not be contained within national 

 borders. Population displacements and conflict over shared 

 surface and groundwater resources are bound to exacerbate 

 international turmoil. It is no coincidence that the word 

 "rival" derives from the Latin word for "one living on an 

 opposite bank of a stream from another." 



The world also faces the uncertain effects of global 

 warming. The loss of mountain ice caps and glaciers, for 

 instance, may alter the quantity and reliability of water for 

 drinking, agriculture, and power generation. California's 

 Central Valley, which produces a quarter of the food sold 

 in the U.S., depends on timely seasonal snowmelt from 

 surrounding mountains; farmers could face tailing or 

 lower-yielding crops as the climate warms and less water 

 is available in the growing season. 



Water policy makers have focused on technological solu- 

 tions to increase water supplies — diverting surface water, 

 pumping up groundwater, extracting the salt from seawater. 

 Such solutions often have high costs, both monetary and 

 environmental. And so the focus has shifted to reducing 

 demand. Hydrologists estimate that as much as 60 percent 

 of the water extracted from aquatic systems for human use 

 is simply wasted — lost to leakage, evaporation, inefficient 

 appliances, and human carelessness. Changes in various 

 technologies and in everyday behavior could slash that 

 number in half. Saving water in the home calls for install- 

 ing water-efficient appliances and fixtures, fixing leaks, 

 refilling water bottles from the tap, landscaping with native 

 plants, and generally being more conscious about water 

 use. Municipalities could construct wetlands or, better yet, 

 refrain from destroying existing ones. Towns and businesses 

 could pave with a permeable material that enables water 

 to seep back into aquifers. Industries and municipalities 

 can reuse water that has been treated but does not reach 

 drinking-water standards. A bounty of choices is available, 

 once we decide to stop taking water for granted. 



To find Web links related to this article, visit 

 www.naturaihistorymag.com and click "Online Extras," then "Web Links," and finally "November 2007." 



November 2007 n aturai his i oio 



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