What best management practices can reduce runoff from parking lots?

The selection of permeable pavement and vegetated swales as the best management practices for reducing runoff from parking lots is based on their effective design to enhance water infiltration and management of stormwater. Permeable pavement allows rainwater to percolate through its surface and into the ground below, thereby reducing the volume of runoff that can carry pollutants into nearby waterways. This type of paving material helps to recharge groundwater supplies and minimize surface pooling.

Similarly, vegetated swales—shallow, landscaped channels designed to convey and treat stormwater runoff—play a crucial role in filtering pollutants while also promoting infiltration. They utilize plants and soil to naturally treat runoff, allowing for the removal of sediments and other contaminants before the water enters the drainage system or local waterways.

This approach contrasts with options that might divert or block water but do not facilitate natural infiltration or effective treatment. Practices like concrete barriers and metal grates, retention ponds and plastic sheeting, or sandbags and earth berms may have limited effectiveness in managing runoff in terms of allowing water to soak into the ground or filtering out pollutants. Instead, they tend to focus on containment rather than the ecological processing of stormwater, underscoring why the first choice is the most suitable practice for reducing runoff from parking