What considerations should be made when applying pesticides near water sources?

When applying pesticides near water sources, ensuring no runoff and maintaining buffer zones is critical for several reasons. This practice helps protect aquatic ecosystems, as pesticides can have harmful effects on fish, insects, and other wildlife residing in or near the water. Runoff occurs when rain or irrigation causes pesticides to wash away from the application site, potentially contaminating nearby water bodies. Establishing buffer zones—areas where no pesticide application occurs—provides a safety margin that can help filter out contaminants through vegetation and reduce the likelihood of runoff entering the water source.

The other options do not align with best practices for pesticide application near water. Applying as close to the water source as possible increases the risk of pesticide contamination. Using a heavier concentration of pesticides can lead to greater toxicity and an elevated chance of runoff, while covering the water source with tarps may not be a practical or effective method for preventing contamination and could lead to other environmental concerns. Hence, option A reflects a responsible and environmentally-conscious approach to pesticide application near water.