Nonpoint source pollution occurs when rainfall or snowmelt runs over land or through the ground, picks up pollutants, and deposits them into rivers, lakes, wetlands, and coastal waters or introduces them into groundwater. Some of the primary activities that generate nonpoint source pollution include farming and grazing activities, timber harvesting, new development, construction, and recreational boating. Manure, pesticides, fertilizers, dirt, oil, and gas produced by these activities are examples of nonpoint source pollutants. Even individual households contribute to nonpoint source pollution through improper chemical and pesticide use, landscaping, and other household practices.

After Congress passed the Clean Water Act in 1972, the water-quality community within the United States placed a primary emphasis on addressing and controlling point source pollution (pollution coming from discrete conveyances or locations, such as industrial and municipal waste discharge pipes). Not only were these sources the primary contributors to the degradation...