Water and sediment pollution can come from point sources or non-point sources (NPS). Point-source pollution is defined as any discernible, confined, and discrete conveyance, such as sewage outfalls or industrial discharges (U.S. Environmental Protection Agency 2001). Sewer outfalls in particular are known to discharge a variety of heavy metals, toxic compounds, organic nutrients, and solids. Industrial discharges generally involve the direct discharge of chemical pollutants from industrial operations. Non-point source pollution differs from industrial and sewage treatment plant pollution because it originates from many diffuse sources. NPS pollution may be caused by overland runoff that carries natural and human-made contaminants (e.g., nitrates, phosphates, pesticides, petroleum, sediment from cleared soil, and fecal coliform bacteria) into receiving water bodies, such as rivers, lakes, groundwater, and nearshore habitats (U.S. Environmental Protection Agency 1997; Masterson and Bannerman 1994). Sources include construction, agriculture, and stormwater runoff (Newton et al. 1997). Residential NPS pollution is associated with everyday activities, such as operating motor vehicles, washing equipment and structures, fertilizing home gardens, and controlling pests. Leaking septic tanks also allow contaminants to enter groundwater that can eventually enter nearshore waters. Of the two, point-source pollution is most identifiable and can be remediated with a higher level of certainty.
