What does "water quality volume" refer to in stormwater management?

The term "water quality volume" in stormwater management specifically refers to the volume of stormwater runoff that must be managed to safeguard water quality. This concept is central to stormwater management practices, as it focuses on the amount of runoff that can carry pollutants and contribute to water quality degradation in nearby bodies of water.

Managing this volume is crucial for minimizing the impact of urban runoff on the environment, as it helps determine the size and design of Best Management Practices (BMPs) that treat stormwater before it is discharged.

The other options do not accurately define "water quality volume." The total amount of rainwater a site can hold relates more to site capacity rather than stormwater quality management. The volume required for landscape irrigation is an entirely different aspect of water use, focusing on water supply rather than runoff. Finally, while BMPs treat stormwater, the specific treatment capacity does not encompass the broader concept of water quality volume, which is more about the necessary volume of runoff to be managed for quality protection.