A form of diffuse pollution originating from a wide land area, not from one specific location. Typical forms of NPS pollution result from sediment, nutrients, organic and toxic substances originating from land-use activities, which are carried to lakes and streams by surface runoff. NPS contamination can occur when rainwater, snowmelt, or irrigation washes off fields, paved streets, roofs and suburban yards and picks up soil and dust particles, street dirt or chemicals and pollutants, such as nutrients and pesticides.