Which feature is a vegetated water-management channel that filters pollutants and slows runoff?

• A. Paved drainage trench with grates.
• B. Vegetated channel that filters and slows runoff.
• C. Concrete canal designed for rapid runoff.
• D. Stormwater retention pond.

Answer: (B)

A vegetated channel uses plants and soil to remove pollutants as water flows through, while the vegetation and rough channel surface slow the water down. This combination reduces runoff speed and allows sediment and contaminants to be filtered out, delivering cleaner water downstream and helping to prevent erosion. A paved drainage trench with grates moves water quickly with little opportunity for filtration. A concrete canal designed for rapid runoff similarly channels water fast without vegetation. A stormwater retention pond stores water, primarily relying on settling and storage rather than a continual vegetated conveyance. The vegetated channel uniquely provides both filtration and slowed runoff along the flow path, so it’s the best fit.