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Unformatted text preview: 1, Overview: Status of Inland Waters Freshwater systems-lakes, wetlands, rivers, and streams-have been critical to the establishment of civilizations throughout human history. From ancient times, civilizations have been built based on their proximity to water: ancient Mesopotamia thrived because of the ample water pro- vided by the Tigris and Euphrates rivers; ancient Egypt grew up along the Nile; the Romans expended vast resources in building elaborate net- works of aqueducts to supply water to their cities. Water bodies are essential to humans not only for drinking but also for transportation, agriculture, energy production, industry, and waste disposal. Despite the reliance of societies on freshwater systems, only in this century has the importance of protecting the quality of these systems become widely recognized. In the United States, the passage of the Clean Water Act in 7972 reflected widespread awakening to the deteriorating status of the nation's surface waters. The Clean Water Act set a goal of restoring all U.S. lakes and rivers to a "fishable and swimmable" condition by ]uly 1, 1983. A court decision in 1975 ruled that under the act, the federal government also was obliged to protect wetlands (Mitsch and Gosselink, 1993). The Clean Water Act focused on reducing municipal and industrial wastewater discharges to water bodies, and the results have been signifi cant. In the decade following the act's passage, sewage discharges to U.S surface waters dropped by 46 percent and industrial discharges by 7 percent, even though the population grew by 11 percent (Frederick, 1991 Two decades iater, 85 percent of sewage plants and 87 percent of industri; plants discharging to water bodies were in compliance with the act (Keal et al., 7993). Nevertheless, according to the Environmental Protectic Agency (EP A,7994),40 percent of U.S. surface waters remain too degradt 10 ovERvtEw 11 for fishing and swimming. Contaminated runoff from expanding urban and agricultural areas, airborne pollutants, and hydrologic modifications such as drainage of wetlands are just a few of the many factors that continue to degrade U.S. surface waters despite reductions in sewage and industrial waste discharges. Determining which of these factors has the most significant influence on the quality of a water body requires knowl- edge about how the water body interacts with its watershed and airshed and how the various inputs affect its physical, chemical, and biologicai characteristics. One of the critical sciences required to understand these freshwater interactions is called limnology (from the Greek limne, llreaning pool or marshy lake). As defined in this report and other recent reports on the fie1d, limnology includes the study of iakes, reservoirs, rivers, and fresh- water wetlands (Edmondson, 1994; Lewis, 1995; Lewis et a1., 1995). It is a multidisciplinary science that draws from all the basic sciences relevant to understanding the physical, chemical, and biological behavior of fresh-...
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This note was uploaded on 01/23/2012 for the course BIOL/EVPP 350 taught by Professor Kimdemutsert during the Fall '11 term at George Mason.
- Fall '11