Definition - What does Non-Point Source mean?
Non-point source (NPS) pollution comes from a variety of sources diffused over an area. It is generally conveyed by runoff from precipitation, thereby moving over the ground to pollute surface water, or by means of infiltration through the ground where it can pollute underground water sources.
Safeopedia explains Non-Point Source
Examples of non-point source pollution include runoff containing agricultural fertilizers. If the amount of extra nutrients in the water increases, algal blooms deplete oxygen in the water effecting water quality to a point where it is no longer able to support a balanced ecosystem. There has also been concern about herbicides and pesticides entering ground water and the risks to human health that this might imply. Urban and industrial runoff may contain significant amounts of oil, grease and toxic chemicals.