The National Pollutant Discharge Elimination (NPDES) Program was initiated as part of the 1987 amendments to the Clean Water Act to address pollution associated with storm water runoff.  The NPDES Program required implementation of on-site erosion and sediment controls necessary to minimize discharge of pollutants from storm water runoff.  The NPDES permit regulates storm water discharges into Waters of the United States and sets limitations for off-site discharges of sediment and other pollutants.  

The program was introduced in two phases. Phase I of the NPDES Storm Water Program began in 1990 and applied to large and medium municipal separate storm sewer systems (MS4, see below) and 11 industrial categories including construction sites disturbing five acres of land or more. Phase II of the NPDES Storm Water Program began in March 2003 and applies to additional MS4s and construction sites disturbing equal to or greater than one acre of land.  The Illinois Environmental Protection Agency (IEPA) is in charge of implementing both phases of the NPDES Storm Water Program in Illinois.

Construction Sites

Phase II of the storm water program requires all construction activities disturbing one or more acres of land to obtain an NPDES permit, prepare a Storm Water Pollution Prevention Plan (SWPPP), submit a Notice of Intent (NOI), complete at a minimum weekly inspections and submit a Notice of Termination (NOT).  

The SWPPP should be developed prior to the start of construction and must be present on-site and accessible to everyone during construction activities.  Best Management Practices (BMPs) must be implemented according to the SWPPP.  All sites are subject to inspection by government officials.      

An SWPPP Must Include the Following:

• Site description identifying potential sources of pollution that may affect the quality of storm water discharges.
• Appropriate best management practices (BMPs), including erosion, sediment, and storm water management controls to minimize the discharge of pollutants from the site.
• Description of steps taken to prevent and control pollutants in storm water discharge from the site, including inspection of all disturbed, unstabilized areas and maintenance of all controls to ensure their effective operation.

A Notice of Termination (NOT) must be submitted to IEPA when land disturbing activities are complete and the site has been finally stabilized or when the permittee is no longer an operator of the site.  The USEPA considers that a site has been finally stabilized when all land disturbing activities are complete and a uniform perennial vegetative cover with a density of 70 percent of the cover for unpaved areas and areas not covered by permanent structures has been established or equivalent permanent stabilization measures have been used.

General Storm Water Permit for Small Municipal Separate Storm Sewer Systems (MS4)

Phase I of the NPDES Storm Water program began in 1990 and required medium and large municipal separate storm sewer systems (MS4s) to obtain NPDES coverage. The expanded Phase II program begins March 2003 and requires small MS4s in urbanized areas to obtain NPDES permits and implement six (6) minimum control measures. An urbanized area as delineated by the Bureau of Census is defined as a central place or places and the adjacent densely settled surrounding area that together have a residential population of at least 50,000 people and an overall population density of at least 500 people per square miles. (See IEPA Website for a list of MS4s.)

MS4 Permit Requirements:

1. Develop a storm water management program comprised of best management practices (BMPs) and measurable goals for each of the following six minimum control measures:

• Public education and outreach on storm water impacts
• Public involvement and participation
• Illicit discharge detection and elimination
• Construction site storm water runoff control
• Post construction storm water management in new development and redevelopment
• Pollution prevention/good housekeeping for municipal operations

2. Submit a completed Notice of Intent. Operators can choose to share responsibilities for meeting the Phase II program requirements. Those entities choosing to do so may submit jointly with other municipalities or governmental entities (i.e. Lake County SMC covers 4 out of the 6 minimum control measures).

3. Submit an annual report to IEPA in June of each year starting in 2004. The reports must include:

• The status of compliance with the permit conditions, including an assessment of the BMPs and progress toward the measurable goals;
• Results of any information collected and analyzed, including monitoring data;
• A summary of the storm water activities planned for the next reporting cycle;
• A change in any identified best management practices or measurable goals; and
• If applicable, notice of relying on another governmental entity to satisfy some of the permit obligations.