What is the potential risk of using pesticides near waterways?

Using pesticides near waterways poses a significant risk of water contamination. When pesticides are applied in close proximity to water sources, they can easily runoff during rainfall or irrigation events, leaching into streams, rivers, lakes, and other bodies of water. This contamination can have detrimental effects on aquatic ecosystems, including harm to fish and other wildlife, disruption of food chains, and potential hazards to human health through drinking water sources.

In contrast, the other options do not represent the immediate risks associated with pesticide use near waterways. For example, increased pest population may occur from inappropriate pesticide use but is not a direct consequence of application near water. Enhanced crop yield refers to the positive outcomes of effective pesticide use, and while it might be a motivation for application, it does not directly relate to the risks posed by proximity to waterways. Similarly, reduced application efficiency relates to the effectiveness of pesticide use but does not encapsulate the environmental risks involved.

Overall, the potential for water contamination with harmful pesticides highlights the critical need for careful and responsible pesticide application practices around any water bodies to protect environmental and public health.