Which statement best describes point source versus nonpoint source pollution?

• A. Point source originates from diffuse, non-identifiable sources.
• B. Point source from a single discharge; nonpoint from diffuse sources.
• C. Point source is natural; nonpoint is man-made.
• D. Point source only affects air; nonpoint only affects water.

Answer: (B)

Pollution is categorized by how it enters the environment: point sources come from a single, identifiable discharge, while nonpoint sources come from many diffuse inputs spread across the landscape. This distinction is why the statement describing a single discharge as point source and diffuse sources as nonpoint is the best description.

Examples help: a pipe from a factory releasing wastewater into a river is a point source because the outlet is identifiable and traceable. In contrast, runoff from rain carrying soil, fertilizer, oil, and litter from many different surfaces across large areas is nonpoint because it comes from numerous small, widely dispersed sources rather than one outlet.

The other options mischaracterize the concept. Point sources aren’t defined as diffuse or non-identifiable, and natural versus man-made is not what distinguishes them. Also, the idea that point sources affect only air and nonpoint only affects water isn’t accurate—both types can impact air and water depending on the context, though the water-quality focus is typical for point-source regulation.