How is the effectiveness of stormwater treatment typically measured?

The effectiveness of stormwater treatment is primarily measured by the reduction of specific pollutants. This approach focuses on evaluating how well a stormwater management system removes or mitigates contaminants from runoff before it enters natural water bodies. Pollutant reduction is essential for maintaining water quality standards and ensuring that the treated stormwater does not negatively impact the environment.

Quantifying the decrease in pollutants such as sediments, nutrients, heavy metals, and pathogens allows for a clear assessment of the treatment measures' performance. By employing standardized methods to sample and analyze these pollutants, inspectors and engineers can determine if a stormwater management system is functioning as intended and meeting regulatory requirements.

While the other options involve important aspects of stormwater management, they do not directly reflect treatment effectiveness. For instance, the volume of water stored can indicate system capacity but does not inherently measure how well the system treats pollutants. User satisfaction is subjective and not a scientifically measurable parameter of effectiveness. Monitoring land usage changes may provide insights into broader environmental impacts but does not assess the direct performance of stormwater treatment.