Erosion and Sediment Control
IDOT ensures that highway construction projects and highway separate storm sewer systems in urbanized areas comply with the National Pollutant Discharge Elimination System (NPDES). This is a permitting program, under the federal Clean Water Act, which regulates construction, industrial activities and both large and small metropolitan separate storm sewer systems to reduce the discharge of pollutants into waters of the United States. Whenever an acre or more of ground is disturbed for roadwork, it is IDOT's responsibility to implement measures to control the discharge of sediment and other pollutants into nearby rivers, streams and wetlands. This is done through the use of an Erosion and Sediment Control Plan, which implements a variety of temporary and permanent measures (e.g. perimeter silt fence, ditch checks, temporary and permanent seeding) to prevent soil and other pollutants from leaving the construction site.