Which of the following is an example of nonpoint source pollution?

• A. Factory wastewater discharge.
• B. Sewage treatment plant effluent.
• C. Agricultural runoff or urban stormwater.
• D. Direct oil spill.

Answer: (C)

Nonpoint source pollution happens when many diffuse sources contribute pollutants to a water body, carried by rainfall or snowmelt over broad areas rather than from a single discharge point. This makes it different from pollution released through a specific outlet or pipe.

Agricultural runoff or urban stormwater fits this idea best because rainwater picks up fertilizers, pesticides, sediments, oils, and other contaminants from fields, sidewalks, and roads across large areas and transports them into streams and rivers. There isn’t one identifiable outlet; the pollution comes from widespread land use.

In contrast, factory wastewater discharge, sewage treatment plant effluent, and a direct oil spill all originate from a defined source with a recognizable discharge point, so they are point sources rather than nonpoint sources.