Point Source Pollution
Point source water pollution comes from discrete conveyances and alters the chemical, biological, and physical characteristics of water. Point source pollution is largely regulated by the Clean Water Act (CWA) of 1972. These sources of water pollution are described by the CWA as "any discernible, confined, and discrete conveyance from which pollutants are or may be discharged." These include pipes or man-made ditches from stationary locations such as sewage treatment plants, factories, industrial wastewater treatment facilities, septic systems, ships, and other sources that are clearly discharging pollutants into water sources.
Among other things, the Clean Water Act requires dischargers to obtain a NPDES permit to legally discharge pollutants into a waterbody. Before the CWA was enacted, companies indiscriminately discharged their effluents into water bodies.
There are a variety of water quality parameters that may be affected by point source water pollution. They include: dissolved oxygen and biochemical oxygen demand (BOD), temperature, pH, turbidity, phosphorus, nitrates, total suspended solids, conductivity, alkalinity, and fecal coliform. Given that much of the point source water pollution in the United States comes from municipal wastewater treatment plants.
Point source water pollution is largely regulated through the Clean Water Act, which gives the EPA the authority to set limits on the acceptable amount of pollutants that can be discharged into waters of the United States. The Clean Water Act broadly defines a pollutant as any type of industrial, municipal, and agricultural waste discharged into water, such as: dredged soil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal, and agricultural waste. Point source water pollution is discharged into waters through both direct and indirect methods.
Direct discharges are pollutants that are discharged directly into the water. To legally discharge pollutants directly into a waterbody, a National Pollution Discharge Elimination System (NPDES) permit must be obtained.