EPA-美国农业面源污染治理措施

EPA-美国农业面源污染治理措施 The nation’s aquatic resources are among its most valuable assets. While environmental protection programs in the United States have successfully improved water quality during the past 25 years, many challenges still remain. Although significant strides have been made in reducing the impacts of discrete pollutant sources, aquatic ecosystems remain impaired, primarily due to com-plex pollution problems caused by nonpoint source (NPS) pollution. The most recent national water quality inventory shows that, as of 2000, 39% of assessed stream miles, 45% of assessed lake acres, and 51% of assessed estuary acres are impaired. The leading causes of impairment are nutrients, siltation, metals, and pathogens. State inventories indicate that agriculture, including crop production, animal operations, pastures, and rangeland, impacts 18% of the total river and stream miles assessed, or 48% of the river and streams identified as impaired (EPA, 2002). The Purpose and Scope of this Guidance This guidance document is intended to provide technical information to state program managers and others on the best available, economically achievable means of reducing NPS pollution of surface and ground water from agriculture. The guidance provides background information about agricultural NPS pollu-tion, where it comes from and how it enters the nation’s waters, discusses the broad concept of assessing and addressing water quality problems on a water-shed level, and presents up-to-date technical information about how to reduce agricultural NPS pollution. This document is not intended to be a “how to” technical guide for natural resource assessment, planning, design, and imple-mentation. The causes of agricultural NPS pollution, specific pollutants of concern, and general approaches to reducing the impact of such pollutants on aquatic re-sources are discussed in the Overview (Chapter 2). A general discussion of best management practices (BMPs) and the use of combinations of individual practices (BMP systems) to protect surface and ground water is given in Chapter 3. Management measures for nutrient management; pesticide management;