Which action directly protects water quality by slowing runoff and absorbing pollutants?

• A. Buffer zone.
• B. Clearing vegetation.
• C. Paving soil to direct water flow.
• D. Removing wetlands.

Answer: (A)

Buffer zones along land-water interfaces act as living filters that both slow runoff and capture pollutants before they reach streams or groundwater. When vegetation, leaf litter, and mulch are present, rainfall can infiltrate the soil rather than rushing over the surface. The slowing of overland flow reduces erosion and sediment transport, while plant roots and soil structure help trap sediment and allow pollutants like nutrients, pesticides, and heavy metals to be absorbed, sorbed, or degraded by microbes. Plants also take up some nutrients directly, reducing their concentration in water bodies. The overall effect is cleaner water and reduced flood peaks.

Clearing vegetation removes that protective filter, increasing runoff and erosion and delivering more pollutants to waterways. Paving soils to direct water flow concentrates flow, speeds it up, and often carries more sediment and pollutants into water bodies. Removing wetlands eliminates a natural filtration and storage system that would otherwise reduce pollutant loads and moderate flows, making water quality worse.