Nonpoint source (NPS)

a source of water pollution that is not a “point source” as defined by section 502(14) of the Clean Water Act as any discernible, confined and discrete conveyance.  NPS pollution comes from many diffuse sources and is caused by rainfall or snowmelt moving over and through the ground. As this water, or runoff, moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters and ground waters (U.S. EPA, 2010c).