What is an example of non-point-source contamination of groundwater?

Non-point-source contamination of groundwater occurs when pollutants are transported over a large area rather than from a single identifiable source. An example of this is runoff from an agricultural field. When it rains, water can flow over the land surface and carry with it various contaminants, including pesticides, fertilizers, and sediments, into nearby water bodies or percolating down through soil layers to groundwater.

In contrast, other choices point to more direct or identifiable sources of contamination. Industrial discharge represents a specific facility emitting pollutants into a water body. A leak from a storage tank is similarly a point-source issue, as it originates from a specific tank that has failed. These examples illustrate single, identifiable sources of contamination, which distinguishes them from the broader, dispersed nature of non-point-source contamination represented by runoff from an agricultural field. Hence, understanding non-point-source contamination is crucial in developing comprehensive environmental management strategies and implementing effective agricultural practices to protect water quality.