There are many types of pollutants. Common water pollutants include acid mine drainage, agricultural runoff, sewage, and dredging. Sources of pollution are classified according to the way they enter the environment. There are two major classes of pollutants: point-source and non-point-source. Point-source pollutants can be traced to their original source. Point-source pollutants are discharged directly from pipes or spills. Raw sewage draining from a pipe directly into a stream is an example of a point-source water pollutant. Non-point-source pollutants cannot be traced to a specific original source. These pollutants can only be traced to a general area. Non-point sources of pollution include runoff from backyards, parking lots, farms, mines, construction sites, etc.
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