Click on image for larger view. The U.S. Environmental Protection Agency (EPA) defines point source pollution as âany single identifiable source of pollution from which pollutants are discharged, such as a pipe, ditch, ship or factory smokestackâ (Hill, 1997).Factories and sewage treatment plants are two common types of point sources.lick on image for larger view. The U.S. Environmental Protection Agency (EPA) defines point source pollution as âany single identifiable source of pollution from which pollutants are discharged, such as a pipe, ditch, ship or factory smokestackâ (Hill, 1997).