Environmental Problems, Their Causes, and Sustainability 1

Running Short of Waterin Las Vegas, NevadaLas Vegas, located in the MojaveDesert, is an artificial aquaticwonderland of large trees, greenSPOTLIGHT lawns and golf courses, waterfalls,and swimming pools. Accordingto water experts, Las Vegas uses more water per personthan any other city in the world. It is also one of thefastest-growing cities in the United States.Tucson, Arizona, in the Sonoran Desert, is amodel of water conservation. It began a strict waterconservation program in 1976 that includedraising water rates 500% for some residents. As aresult, low-flush toilets, low-flow showerheads,Xeriscaping, and use of drip irrigation have becomethe norm.In contrast, Las Vegas, which gets one-third lessrainfall than Tucson, only recently started to encouragewater conservation. It has raised waterrates, but they are still less than half those inTucson and have not gone up. Las Vegas is almostwholly dependent on water from the ColoradoRiver stored in Lake Mead. Since 1999, a droughthas reduced its water level to 59% of capacity, andit could drop to 42% by 2008.Water experts project that even if these recentwater conservation efforts are successful, Las Vegasmay begin running short of water by 2007.Critical ThinkingIf you were an elected official in charge of Las Vegas,what three actions would you take to improvewater conservation? What might be the politicalimplications of doing these things?domestic water. It accounts for about 38% of domesticwater use, followed by bathing (32%), and washingclothes and dishes (20%). New models of low-flushtoilets can remove the equivalent of two dozen golfballs in one flush without clogging and use fewer than6.1 liters (1.6 gallons) of water—less than half theamount required by EPA standards.About 50–75% of the water from bathtubs, showers,bathroom sinks, and clothes washers in a typicalhouse could be stored and reused as gray water for irrigatinglawns and nonedible plants. About two-thirdsof the wastewater in Israel is reused this way. All ofSingapore’s sewage is treated at reclamation plants forreuse by industry.Another problem is leakage and other losses fromsystems that supply water to homes, businesses, andindustries. According to UN studies, 15–40% of thewater supplied in urban areas is lost mostly throughleakage of water mains, pipes, pumps, and valves, andillegal water hook-ups. In some parts of Africa suchlosses can reach 50–70% of the water extracted fromsurface waters and aquifers. Even in an advanced industrializedcountry such as the United States suchlosses average 10–30%. However, such losses havebeen reduced to about 3% in Copenhagen andDenmark and 5% in Fukuoka, Japan.How Can We Reduce the Use of Waterin Removing Industrial and HouseholdWastes? Changing the Way We Deal withWastesWe can mimic the way nature deals with wastesinstead of using large amounts of high-quality waterto wash away and dilute our industrial and animalwastes.Industrialized countries use large amounts of watergood enough to drink to dilute and wash or flush awayindustrial, animal, and household wastes. Sewagetreatment plants remove valuable plant nutrients anddump most of them into rivers, lakes, and oceans. Thisoverloads aquatic systems with plant nutrients thatshould be recycled to the soil, as nature does.We also use high-quality water to flush toxic industrialwastes into sewers and send them to treatmentplants that do not remove most of the harmfulchemicals. The FAO estimates that if current trendscontinue, within 40 years we will need the world’s entirereliable flow of river water just to dilute and transportthe wastes we produce.We can use five principles to redesign the way wemanage sewage and industrial wastes while savingenormous amounts of water.■ Use pollution prevention and waste reduction tosharply decrease the amount of industrial wastes weproduce.■ Ban discharge of industrial toxic wastes into municipalsewer systems.■ Rely more on waterless composting toilets thatconvert human fecal matter to a small amount of dryand odorless soil-like humus material that can beremoved from a composting chamber every yearor so and returned to the soil as fertilizer. They work.I used one for almost two decades without anyproblems.■ Return the nutrient-rich sludge produced by conventionalwaste treatment plants to the soil as a fertilizer.Banning the input of toxic industrial chemicalsinto sewage treatment plants will make thisfeasible.■ Shift to new ways to treat sewage that mimic theway nature breaks down and recycles the nutrientsin organic waste material. Examples include solarpoweredwaste treatment systems and using wetlandsto treat sewage, as discussed in Chapter 22.326 CHAPTER 15 Water Resources