Which statement best describes nonpoint-source pollution?

• A. It originates from diffuse sources across large areas, such as agricultural runoff or urban stormwater.
• B. It originates from a single pipe discharge.
• C. It is always municipal wastewater effluent.
• D. It refers to air pollution.

Answer: (A)

Nonpoint-source pollution comes from many diffuse sources spread over a large area, rather than from one identifiable outlet. Rain or irrigation runoff picks up pollutants like fertilizers, pesticides, sediment, oil, and urban debris as it moves across fields, roads, and construction sites, and deposits them into rivers, lakes, and groundwater. Because there isn’t a single discharge point, tracking and regulating the pollution is much more complex, which is why the diffuse, area-wide description fits nonpoint-source pollution best.

This contrasts with a single pipe discharge, which describes point-source pollution, where pollutants enter water through a known, identifiable outlet. Municipal wastewater effluent is typically released from designated pipes and thus is a common example of point-source pollution. Air pollution is about contaminants in the air, not water, so it doesn’t describe nonpoint-source pollution.