What type of pollution is caused by precipitation runoff from land into watersheds?

The correct answer is nonpoint source pollution, which is characterized by runoff that carries various pollutants from diffuse sources into watersheds. This type of pollution occurs when rain or melting snow washes contaminants off surfaces such as agricultural fields, urban areas, and forests, which are not easily identifiable as singular points of origin.

Unlike point source pollution, which stems from a specific, identifiable source, nonpoint source reflects a more widespread issue where it’s difficult to trace the exact origins of the pollutants. This can include everything from fertilizers and pesticides to oil and heavy metals, all being transported by rainfall into bodies of water. Nonpoint source pollution contributes significantly to degradation of water quality in streams, rivers, lakes, and coastal areas, posing a risk to aquatic ecosystems and human health.

Recognizing the nature of this pollution is critical for effective water quality management and the implementation of appropriate policies to mitigate its effects. Solutions often include best management practices (BMPs) that aim to reduce runoff and improve the quality of water entering waterways.