Learn More Topic: Definitions of Key Terms
The following terms are important for understanding the scope of the NPDES permit program:
- Point source. This term is defined very broadly in the CWA. It means any discernible, confined, and discrete conveyance, such as a pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, or rolling stock. It also includes landfill leachate collection systems, concentrated animal feeding operations, and vessels or other floating craft from which pollutants are or may be discharged. Return flows from irrigated agriculture and agricultural stormwater runoff are not considered point sources. (Sec. 122.2)
- Pollutant. Pollutant means dredged spoil, solid waste, incinerator residue, filter backwash, 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 discharged into water. It does not mean sewage from vessels or injected wastes. (Sec. 122.2)
For regulatory purposes, pollutants have been divided into three categories:
— Conventional pollutants:
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Biochemical oxygen demand (BOD)
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Total suspended solids (nonfilterable) (TSS)
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pH
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Fecal coliform
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Oil and grease
— Toxic pollutants (“priority pollutants”):
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Heavy metals (e.g., Cu, Pb, Hg)
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Organic compounds (e.g., PCBs, dioxin)
— Non-conventional pollutants (e.g., chlorine, ammonia, nitrogen, phosphorus)
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Waters of the United States. The regulatory definition includes many types of surface waters:
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Rivers and streams
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Lakes and ponds
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Wetlands
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Sloughs
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Prairie potholes
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Intermittent streams
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Territorial seas
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Other
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(Sec. 122.2) Note also that EPA implements the CWA definition of “waters of the United States” in light of Supreme Court decisions handed down within the past decade (i.e., SWANCC in 2001 and Rapanos in 2006).