Assessment and Management of Toxics in the Watershed



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United States Environmental Protection Agency


The demand for water is beginning to outstrip the available supply of water. The truly insidious insult to freshwater supplies comes from anthropogenic impacts that pollute freshwater supplies and the surrounding watersheds, making even less water available for use. Watersheds are impacted by a variety of toxic substances. Some of these toxic pollutants enter the watershed through direct introduction but by far the most serious problems of toxics found in the nation's water supplies are created through indirect means. Many toxics are introduced into the water supply through their movement through the biosphere. The more ubiquitous of these toxic substances are mercury and pesticides. Challenges to managing the numerous risks posed by mercury in the environment include: alternative treatment options for mercury contaminated wastes; in situ treatment of mercury in sediments; identification and control of diffusive sources of mercury; and the fate and transport of mercury in the watershed environment. Challenges to managing the numerous risks posed by pesticides in the environment include: pesticide degradate and mixture characterization and behavior; pesticide application and transport data; and reliability and effectiveness of pesticide occurrence modeling and pesticide management practices. This paper summarizes the current state of knowledge on toxic sources, their impact on ecosystem and human health, discusses challenges to the successful management of toxics, and presents an outline of suggested management-related research for watersheds.


24 pages; available for download at the link below.


water supply, water quality, water pollution, toxins