The discharge of untreated sanitary wastewater (including industrial and commercial wastewater) or other polluting materials into a river, stream or other water body from:
Improper sewage connections such as sources of sanitary sewage which should be connected to the sanitary sewer but are inappropriately connected to the storm sewer
Effluent from improperly designed and/or operated septic systems
Sanitary sewer overflows
Improper disposal of waste products such as emptying a mobile home holding tank into a catch basin or pouring used motor oil into a catch basin
Other discharges not composed entirely of storm water
Improper physical connection of illicit discharges to the stormwater drainage system, or other connections not authorized by the local authority (where required) to the storm water drainage system. Examples of illicit connections are:
A floor drain in an automobile repair shop that is connected to the storm sewer rather than the sanitary sewer
A septic tank discharge line that has been connected to the storm sewer
An improper connection of a source of stormwater to the sanitary sewer would also be considered an illicit connection, for example, a parking lot catch basin that is tapped into the sanitary sewer
Sump pumps connected to the sanitary sewers would also be an illicit connection.
The IDEP identifies both short-term and long-term efforts to eliminate illicit discharges and connections. When the majority of known illicit discharges and connections have been eliminated, a less intensive on-going program will be implemented to prevent future problems.