Description: Urban development is associated with an increase in impervious surfaces, that is, surfaces such as rooftops, sidewalks, and streets that prevent precipitation from infiltrating into the groundwater.  Impervious surfaces increase the volume and energy of stormwater that reaches streams and can lead to adverse physical and water quality impacts, including erosions and increased nutrient runoff.   In this video USGS scientist Tom Cuffney and Tom Schueler, director of the Chesapeake Stormwater Network, discuss the effects of impervious surfaces on stream health.