From which locations should samples typically be taken?

The correct choice identifies critical points at which water quality samples should be collected to ensure comprehensive data for pollution assessments and compliance with environmental regulations.

Sampling from the source acknowledges the importance of understanding the quality of water directly from its origin, which is essential for establishing baseline data. Clean water sampling serves to verify the effectiveness of water treatment processes or conservation efforts by providing a reference point for comparison. Lastly, sampling from spill sites is vital for assessing contamination levels and determining necessary remediation actions.

Together, these sampling locations provide a holistic view of water quality across varying conditions and sources, which is crucial for effective environmental management and response strategies.