Which of the following best illustrates a nonpoint source pollution scenario?

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Nonpoint source pollution comes from many diffuse sources across the landscape, not from a single, identifiable outlet. It often happens when rain or snowmelt washes pollutants from soils, fields, streets, and rooftops into streams and rivers, so the impact accumulates from numerous locations rather than one discrete discharge.

The scenario with diffuse agricultural runoff from multiple fields across a watershed fits this idea perfectly. Pollutants like fertilizers and pesticides are carried by runoff from many farms, and no single pipe or outlet is responsible. In contrast, discharges from a single factory pipe or a municipal sewer outfall are classic point sources—clear, identifiable origins where pollutants enter the water. A spill from a tanker into a river is also tied to a specific source, albeit a one-time or irregular event, and thus aligns more with point-source characteristics than with widespread, diffuse runoff.