What is an example of non-point source pollution?

Non-point source pollution refers to contaminants that do not originate from a single identifiable source; rather, they come from diffuse sources that can be challenging to pinpoint. Runoff from agricultural fields perfectly exemplifies this type of pollution.

When it rains, water can wash over farms and agricultural lands, carrying with it fertilizers, pesticides, and sediment into nearby waterways. This runoff can vary in amount and composition based on various factors, including weather conditions and farming practices, making it difficult to trace back to a specific source.

In contrast, the other options represent point sources of pollution, where the contaminants are discharged from a specific location, such as a leaking sewer line, wastewater from factories, or discharges from a wastewater treatment plant. These sources have identifiable points of origin, which fundamentally distinguishes them from non-point source pollution.