What quantity of flammable liquid spill is considered reportable?

The correct answer identifies any visible sheen on water as a reportable quantity of a flammable liquid spill. This is based on regulations that prioritize environmental protection and public safety. A sheen on water is indicative of chemical contamination and can represent a significant risk to aquatic ecosystems as well as public health. The presence of a sheen can often signal that harmful substances may be entering waterways, leading to broader ecological and regulatory concerns.

While other quantities mentioned may have specific contexts for reporting, the visibility of a sheen represents an immediate indicator that action must be taken to address potential contamination. In fact, regulations often require that any sheening is reported regardless of the volume of the spill, as it can signify larger, underlying issues that pose environmental risks.