What is an example of a non-point source of water pollution?

Runoff from urban areas during rainfall is a prime example of a non-point source of water pollution because it originates from multiple sources over a broad area rather than a single identifiable point. When precipitation occurs, water flows over surfaces such as roads, rooftops, and lawns, collecting various pollutants like oil, heavy metals, litter, and chemicals along the way. This mixed pollution is discharged into nearby water bodies, complicating pollution control efforts since it is difficult to pinpoint specific sources.

In contrast, other choices represent point sources of pollution, where the discharge originates from a single, identifiable location, such as a pipe or a specific industrial facility. Industrial discharges and sewage from treatment plants are regulated due to their identifiable discharge points, making them easier to manage compared to the diffuse nature of urban runoff. Pesticide runoff from agricultural fields, while also non-point source pollution, doesn't encompass the broader urban-related context that is encapsulated in the correct answer.