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

• A. Rooftop solar array.
• B. Pervious pavement.
• C. Wind turbine.
• D. Stormwater bioswale.

Answer: (D)

A vegetated water-management channel that filters pollutants and slows runoff is a bioswale. Bioswales are designed as shallow, planted channels that capture stormwater from impervious surfaces like roofs and parking lots and guide it through vegetation and soil. The plants, soil media, and mulch act as a natural filter, trapping sediments and absorbing nutrients and contaminants. The slowed flow increases contact time, allowing microbes in the soil to break down pollutants and giving water a chance to infiltrate or drain more gradually, which reduces erosion and manages flood risks downstream. This concept is distinct from rooftop solar arrays or wind turbines, which are energy-generation features, and from pervious pavement, which is a permeable surface designed to let water infiltrate but does not provide a vegetated filtration channel.