Non-point source pollution is caused by many people over a large area. Non-point source pollution refers to pollution that comes from many diffuse sources, such as agricultural fields, urban areas, and suburban lawns. It is difficult to control non-point source pollution because it comes from many different sources and is often carried by rainwater or melting snow into nearby water bodies. Some examples of non-point source pollution include runoff from streets and parking lots, agricultural chemicals and fertilizers, and soil erosion from construction sites..