What is an impervious surface?
Impervious surfaces are anything that prevents water from soaking into the ground. This includes roofs, driveways, sidewalks, streets, and parking lots.
Why are they bad for a community?
One reason is that they can lead to flooding and erosion problems. Storm water runs immediately off of an impervious surface instead of soaking into the ground at a natural rate.
They also collect all the oil, fluids and grit that are a part of driving. During storms, water flows across these surfaces, sweeping all the pollutants into the groundwater and area streams.
Another thing they do is create heat islands. Impervious surfaces absorb heat during the day and release it at night. This causes the average daily temperature in the summer to be higher in areas where there are many impervious surfaces.
What can we do about it?
The fewer cars that are on the street, the less need there is for more roads and parking lots. There is also less need to widen existing streets to handle more traffic. When you use active transportation you are helping protect the area water systems and keep global warming in check.
