What does the term 'agricultural runoff' refer to?

The term 'agricultural runoff' specifically refers to water that carries fertilizers, pesticides, and other chemicals used in farming as it flows from agricultural land into nearby waterways. This runoff occurs when rain or irrigation causes excess water to move over the surface of the field, picking up these substances along the way. This is significant because agricultural runoff can lead to water pollution, affecting ecosystems and human health, as it may carry harmful chemicals into lakes, rivers, and streams.

The other choices represent different concepts but do not accurately define agricultural runoff. Water evaporating from fields refers to the loss of moisture through evaporation, which is a natural process not involved in runoff. Rainwater collected for irrigation describes a method of water usage rather than a byproduct of agricultural practices. Water used for livestock pertains to water consumed by animals rather than the movement of water across land. Thus, the focus on the chemicals transported in the runoff is what makes the second choice the correct description of this term.