What is a bioswale?

• A. A lined drainage ditch that channels stormwater away from the site.
• B. A stormwater detention basin that stores runoff without treatment.
• C. A perforated pipe system designed to convey rainwater under driveways.
• D. A vegetated drainage swale that captures and treats stormwater runoff.

Answer: (D)

A bioswale uses plants and soil to manage stormwater by slowing runoff, filtering pollutants, and encouraging infiltration rather than just routing water away. It’s a shallow, vegetated channel designed to capture runoff from impervious surfaces, letting roots and the soil media remove sediments, nutrients, and other contaminants while some water infiltrates or evaporates. That’s why describing it as a vegetated drainage swale that captures and treats stormwater runoff fits best: it emphasizes both the physical channel and the treatment process provided by the vegetation and soil. The other descriptions describe methods that focus on conveying water, storing it without treatment, or moving it underground, none of which incorporate the treatment and ecological aspects that define a bioswale.