Definitions for "Nonpoint source"
Any conveyance not meeting the definition of point source.
Diffuse discharges of waste throughout the natural environment which are a major cause of water pollution. Difficult to pinpoint physically, but can be classified by type: urban runoff, agriculture, mining, septic tank leach fields and silviculture.
Nonpoint source pollution does not have a single point or origin, but rather comes from diffuse sources. Examples are lawn chemicals, agricultural pesticides, or oil residues on streets and parking lots that rainwater washes away, thus polluting rivers and streams. (See also "Point Source").