Runoff destination: Natural condition In the natural landscape, very little water runs off directly into streams and other water resources. Most water either goes back into the atmosphere through evaporation and transpiration or through the ground into the aquifer where it slowly makes its way to the stream as clean water.

Runoff after conventional development After conventional development, site clearing and impervious surfaces cause most rainfall to speed to the water resource as runoff that is both the wrong temperature and polluted with non-point source pollutants such as fertilizers and car exhaust particulates.

Runoff after low impact development: Small-lot residential Direct run-off of polluted water into streams and water bodies is minimized by protecting trees and pervious surfaces and by proper grading.