Nonpoint source (NPS) pollution, unlike pollution from industrial and sewage treatment plants, comes from many diffuse sources. NPS pollution is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters, and even our underground sources of drinking water.These pollutants include: excess fertilizers, herbicides, and insecticides from agricultural lands and residential areas; oil, grease, and toxic chemicals from urban runoff and energy production; sediment from improperly managed construction sites, crop and forest lands, and eroding streambanks; salt from irrigation practices and acid drainage from abandoned mines; bacteria and nutrients from livestock, pet wastes, and faulty septic systems; and atmospheric deposition and hydromodification are also sources of nonpoint source. This article is a review of 2002 literature on several aspects of NPS pollution including policy, economics, water quality characterization, management practices, watershed modeling, and pollutant load allocation rule. GENERAL, POLICY, ECONOMICSMarsalek and Chocat (2002) discussed the findings of an international survey of urban stormwater management practices from 18 countries. The survey results underscored the emphasis on source control, transition from traditional "hard" -2 -infrastructure (drain pipes) to green infrastructures, needs for infrastructure maintenance and rehabilitation, formation of stormwater agencies with both public and private sectors, and sustainable funding through drainage fee rather than general taxes. Yetman (2002) reported results of a stream corridor survey developed by the Maryland Department of Natural Resources as a watershed management tool to identify environmental problems and to help prioritize restoration opportunities on a watershed basis. The survey proved to be a cost-effective starting point for many watershed restoration efforts. Woodward et al. (2002) reviewed the current status of water quality trading (WQT) nationally and discussed the structures of the markets that have been formed. The development of effective solutions for addressing nonpoint source pollution on a watershed basis often involves watershed stakeholders. Smutko et al. (2002) examined attributes of the issues confronted by stakeholders to engage in a collaborative decision making process. Booth et al. (2002) cited the case of King County, Washington which had implemented progressively more demanding structural and nonstructural strategies in an attempt to protect aquatic resources. The experience demonstrated the difficulty of meeting urban and suburban water-quality and aquatic resources protection goals in the face of competing social priorities and variable political resolve on environmental issues that require sustained, long-term strategies to achieve progress. The author concluded that new management goals are needed for those watersheds whose existing development ...