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What is Runoff?

Storm DrainRunoff is the water that flows over the surface of the land, 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. That water either fed grass, plants, and trees, replenished ground water sources, or was discharged to lakes, wetlands and streams. As we farmed the land and built our cities, we re-routed the runoff by creating ditches, stormwater pipes and culverts. As a result, the runoff drains directly into our local lakes, wetlands and streams, therefore, 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 to prevent new sources of pollution and runoff to our waters
  • Constructing pollution control measures like raingardens, pervious pavements, and tree trenches to capture rain where it falls
  • Using plants and the soil to filter and reduce/control 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 use-- have a direct impact on clean water