Nonpoint Source Pollution

Nonpoint source pollution is the introduction of impurities into a surface-water body or groundwater from dispersed origins (e.g., fertilizer runoff from lawns) compared with point source pollution, which originates from a definitive location (e.g., wastewater treatment facility). Most nonpoint source inputs fall into six major categories: sediments, nutrients, road salts, heavy metals, toxic chemicals, and pathogens. The primary pollutant for any given city is largely determined by the location and development status of an urban area. For example, Atlanta, Georgia, receives less snowfall than cities in the northeastern United States, thus, road salts will be a minor pollutant in Atlanta compared with heavy metals and toxic chemicals. In addition, heavy metals and toxic chemicals from road and parking lot runoff will be more prevalent in downtown Atlanta compared with Atlanta's sprawling suburbs, where increased construction activity may cause sediments to be the primary nonpoint source pollutant.

In urban regions, nonpoint source pollution can pose a threat to aquatic life in rivers and lakes or encourage the growth of invasive species, thereby discouraging tourism and recreation. Polluting surface waters and groundwater also pose a health threat to those relying on drinking water, which receives nonpoint source inputs. Regulating and treating [Page 345]nonpoint source pollutants is challenging because of the dispersed nature of nonpoint source inputs and usually intermittent discharges, associated with a rainfall or snowmelt event, compared with point sources. Although point sources have been regulated through the National Pollutant Discharge Elimination System since the passing of the 1972 federal Clean Water Act, nonpoint source inputs were not regulated until the 1987 amendments were passed, referred to as the 1987 Water Quality Act. In these amendments, greater attention was focused on controlling nonpoint sources and required storm water regulation of municipal storm sewer systems, industrial activities, and construction activities. The 1987 Water Quality Act was instrumental in recognizing the threat of nonpoint source pollution to human health and aquatic life, thereby requiring cities in the United States to develop management plans to reduce nonpoint source inputs into rivers, lakes, and groundwater.