Environmental Problems, Their Causes, and Sustainability 1

Also, between 1972 and 2002, the percentage of U.S.stream lengths found to be fishable and swimmable increasedfrom 36% to 60% of those tested. And theamount of topsoil lost through agricultural runoff wascut by about 1.1 billion metric tons (1 billion tons) annually.In addition, between 1972 and 2002, the proportionof the U.S. population served by sewage treatmentplants increased from 32% to 74%. And between 1974and 2002, annual wetland losses decreased by 80%.These are impressive achievements given the increasesin the U.S. population and per capita consumptionsince 1972.Bad news. In 2000, the EPA found that 45% of thecountry’s lakes and 40% of the streams surveyed weretoo polluted for swimming or fishing. The number ofpolluted streams, lakes, and estuaries could be muchhigher because only 19% of the country’s streamlengths, 43% of its lake and reservoir area, and 36% ofits estuaries have been tested for water quality.Runoff of animal wastes from hog, poultry, andcattle feedlots and meat processing facilities pollutes 7of every 10 U.S. rivers. Most livestock wastes are nottreated and are stored in lagoons that sometimes leak.They can also overflow or rupture as a result of excessiverainfall and spill their contents into nearby streamsand rivers and sometimes into residential areas.Fish caught in more than 1,400 different waterwaysand more than a fourth of the nation’s lakes areunsafe to eat because of high levels of pesticides, mercury,and other toxic substances. A 2003 internal studyby the EPA found that at least half of the country’s6,600 largest industrial facilities and municipal wastewatertreatment plants have illegally discharged toxicor biological wastes into waterways for years withoutgovernment enforcement actions or fines.Should the U.S. Clean Water Act Be Strengthenedor Weakened? A Raging ControversySome want to strengthen the Clean Water Act whileothers want to weaken it.Some environmentalists and a 2001 report by theEPA’s inspector general call for the Clean Water Act tobe strengthened. Suggested improvements include increasedfunding and authority to control nonpointsources of pollution, upgrading the computer systemfor monitoring compliance with the law, and strengtheningprograms to prevent and control toxic waterpollution.Other suggestions include providing more fundingand authority for integrated watershed and airshedplanning to protect groundwater and surface waterfrom contamination, and expanding the rights ofcitizens to bring lawsuits to ensure that water pollutionlaws are enforced. The National Academy of Sciencesalso calls for halting the loss of wetlands, higher standardsfor wetland restoration, and creating new wetlandsbefore filling any natural wetlands.Many people oppose these proposals, contendingthat the Clean Water Act’s regulations and governmentwetlands regulations are already too restrictiveand costly. Farmers and developers see the law as acurb on their rights as property owners to fill in wetlands.They also believe they should be compensatedfor any property value losses resulting from federalregulations protecting wetlands.State and local officials want more discretion intesting for and meeting water quality standards. Theyargue that in many communities it is unnecessary andtoo expensive to test for all the water pollutants requiredby federal law.xHOW WOULD YOU VOTE? Should the U.S. Clean WaterAct be strengthened? Cast your vote online at http://biology.brookscole.com/miller14.22-7 DRINKING WATER QUALITYHow Is Urban Drinking Water Purified?The High-Tech Centralized ApproachCentralized water treatment plants that operatemuch like wastewater treatment plants can providesafe drinking water for city dwellers.Areas that depend on surface water for drinking usuallystore it in a reservoir for several days. This improvestaste and clarity by increasing dissolved oxygencontent and allowing suspended matter to settle. Nextthe water is pumped to a purification plant where it isfiltered as needed and chlorinated to meet governmentdrinking water standards. In areas with very puregroundwater sources, little treatment except disinfectionis necessary.How Can Modern Water-Purification SystemsBe Protected from Terrorist Acts? A DifficultProblemThe United States is upgrading security onwater purification and delivery systems, butit is difficult to protect such a vast and complexsystem.In the United States there is increased concern over terroristsadding harmful chemicals or biological agents toreservoirs and other parts of the nation’s vast networkof water purification systems. Reservoirs are so hugethat they are hard to poison with chemical or biologicalagents. Still, drinking water is hard to protect becauseof the large number of reservoirs, the vast network ofwater purification plants and water distribution systems,and accessibility of water systems on every streetthrough fire hydrants and service connections.514 CHAPTER 22 Water Pollution