Flooded stormdrain

Urban areas are dominated by hard surfaces such as streets, roofs, and parking lots. These surfaces allow very little rain and snow to penetrate into the ground underneath, and are therefore called impervious surfaces. Whereas natural land cover absorbs about 90% of precipitation, suburban neighborhoods may only soak up about 70% and downtowns are even worse at 45%. What is not absorbed by the ground flows downhill and becomes stormwater runoff.

For more information on how you can help, visit our Stormwater Runoff page.