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Wetlands of the United States are defined by the United States Army Corps of Engineers and the United States Environmental Protection Agency as "those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetations typically adapted for life in saturated soils. Wetlands generally include swamps, marshes, bogs, and similar areas."〔Definition from Corps of Engineers, Wetlands Delineation Manual, by Environmental Laboratory, U.S. Army Corps of Engineers, Waterways Experiment Station, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199〕〔42 Federal Register 37125-26, 37128-29. 1977-07-19. via 〕〔http://water.epa.gov/type/wetlands/types_index.cfm〕 Wetlands can be valued in terms of their contributions to ecological, economic and social systems. Wetlands service these systems through multiple processes including water filtration, water storage and biological productivity.〔http://www.epa.gov/owow/wetlands/facts/fun_val.pdf〕 They also contribute the functions of flood control, providing a nutrient sink, groundwater recharge and habitat.〔http://web.mit.edu/ckolstad/www/Salzman.pdf〕 The United States is a signatory to the Ramsar Convention, an international treaty for the conservation and sustainable utilization of wetlands. Under the Swampbuster provisions of the Food Securities Act of 1985, farmers who modify existing wetlands may lose their benefits under the USDA farm program. Additionally, every Presidential administration since George H.W. Bush has operated under a "no net loss" of wetlands federal policy goal. In the United States, some wetlands are regulated by the federal government under the Clean Water Act. Determining the boundary between regulated wetlands and non-regulated lands therefore can be contentious. In reality, there is no natural boundary between the classes that humans define on these gradients (wetland/upland), and this issue is highlighted by the U.S. Fish and Wildlife Service's definition from Classification of Wetlands and Deepwater Habitats of the United States, which defines wetlands as "lands transitional between terrestrial and aquatic systems." Regulations to protect water quality and highway safety require that we create arbitrary boundaries within those gradients, but these boundaries are scientifically definable, and consist of areas where three criterion of the presence of hydric soils, the presence of wetland vegetation, and the presence of appropriate hydrology. Such regulations must be predictable, reproducible, and enforced otherwise there will be a sacrifice of clean water for development in the case of wetlands regulation (or vice versa), or sacrifice safe travel for quick travel (or vice versa) in the case of speed limits. Determining which wetlands are regulated under section 404 of the Clean Water Act or Section 10 of the Rivers and Harbors Act is termed "jurisdictional determination". Determining the boundary of wetland, whether jurisdictional under sections 404 or 10, or not jurisdictional but still meeting the technical definition of a wetland, that is having the soils, vegetation and hydrology criterion met is called a "wetland delineation", and generally is performed by college graduates with natural science or biology degrees working for engineering firms or environmental consulting firms who are familiar with the 1987 U.S. Army Corps of Engineers Wetland delineation manual. Defining a boundary depends upon the ground and vegetation characteristics; it is easier to do where the slope of the land is steeper. Deciding if a wetland is a regulated wetland depends on classifying the water in it as "water of the United States" or not. Classifying water as "of the U.S." or "not of the U.S." for purposes of enforcing the Clean Water Act suggests a natural boundary that probably does not exist in nature, and one that was not created regarding air for purposes of enforcing the Clean Air Act. Indiana Wetlands are the focus of the U.S. National Wetlands Coalition, which in turn has become the focus of some controversy over "false fronts," a form of political camouflage. == Wetlands loss in the United States == Since the 16th century, more than half of the estimated original 220,000,000+ acres of U.S. wetlands have been degraded or destroyed.〔http://water.epa.gov/type/wetlands/vital_status.cfm〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Wetlands of the United States」の詳細全文を読む スポンサード リンク
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