What is Runoff?

Storm DrainRunoff is the water that flows over the surface of the land or a building or road downstream to a lake, wetland or stream.

Before the land was altered, much of the water that fell on it soaked directly into the ground. Water was then used by vegetation, recharged stores of ground water, or was discharged to lakes, wetlands and streams. As we farmed the land and built our cities we re-routed runoff via ditches, stormwater pipes and culverts directly to local lakes, wetlands and streams. As a result, we are overwhelming many of our water bodies today.

Runoff carries pollutants. To help control this developers began to include stormwater ponds years ago. Today there are additional methods to limit the amount of pollutants reaching our waters. This includes:

  • Regulating land use and development to prevent new sources of pollution and runoff to our waters
  • Implementing pollution control investments like raingardens, pervious pavements, and tree trenches to manage rain where it falls
  • Using plants and the soil to filter and manage runoff (which also provide habitat for wildlife and improve air and water quality)
  • Educating the public about how the choices we make -– particularly with land development -- have a direct impact on clean water