Reporting an Illicit Discharge

An “illicit discharge” is any unpermitted discharge to waters of the state and or the Town of Greenwich that does not consist entirely of stormwater or uncontaminated groundwater; except: (1) certain allowable non-stormwater discharges that are not significant contributors of pollution as identified by the Municipal Separate Storm Sewer System (MS4), and (2) discharges authorized under a separate National Pollutant Discharge Elimination System (NPDES) permit that authorize a discharge to the MS4.

Illicit discharges may take a variety of forms and may enter the drainage system through direct or indirect connections. Some illicit discharges are intentional such as purposely dumping used oil (or other pollutant) into catch basins, a resident or contractor illegally tapping a new sewer lateral into a storm drain pipe to avoid the costs of a sewer connection fee and service, illegal dumping of yard waste into surface waters, connected floor drains in old buildings, as well as sanitary sewer overflows that enter the drainage system. Sump pumps legally connected to the storm drain system may be used inappropriately, such as for the disposal of floor washwater, washing machine connections, or old household products; in many cases these connections are done due to a lack of understanding on the part of the homeowner.

The following categories of non-stormwater discharges are allowed under the MS4 Permit provided: (1) the permittee controls such non-stormwater discharges to the Maximum Extent Practicable (MEP), as required by the MS4 Permit, (2) such non-stormwater discharges do not contribute to a violation of water quality standards, and (3) such non-stormwater discharges are documented in the Stormwater Management Plan and are not significant contributors of pollutants to any identified MS4:

  • Uncontaminated groundwater discharges including, but not limited to, pumped groundwater, foundation drains, water from crawl space pumps and footing drains;
  • Irrigation water including, but not limited to, landscape irrigation and lawn watering runoff;
  • Residual street washwater associated with sweeping (typically done by the Town);
  • Discharges or flows from firefighting activities (except training);
  • Air-conditioning condensation;
  • Individual residential car washing;
  • Dechlorinated swimming pool discharges;
  • Naturally-occurring discharges such as rising groundwater’s, uncontaminated groundwater infiltration (as defined at 40 CFR 35.2005(20)), springs, diverted stream-flows and flows from riparian habitats and wetlands.

If these discharges are identified as significant contributors to the MS4, they will be considered an “illicit discharge” and will need to be addressed by the IDDE program (i.e., control these sources so they are no longer significant contributors of pollutants, and/or eliminate them entirely).

To report an Illicit Discharge please complete the Illicit Discharge Investigation Form.