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 Measure 3:  Illicit Discharge Detection and Elimination

An illicit discharge from a storm drain is a dry weather flow that contains pollutants and/or pathogens. (dry weather flow that does not contain pollutants is considered simply a discharge). The most significant sources of illicit discharges are:

  • Cross-connections with a wastewater system,
  • Infiltration of wastewater to the stormwater sewer system from cracked sanitary sewer systems or malfunctioning septic systems,
  • Inappropriate discharges from industrial and commercial areas,
  • Paint, used oil or other pollutants dumped directly into storm drains.

Illicit discharges can cause high levels of pollutants such as heavy metals, toxics, oil and grease, solvents, nutrients, viruses and bacteria to local waterbodies.  Finding and removing illicit discharges will help to improve local water quality. 

Measure 3 requires Phase II communities to detect and remove illicit discharges from their storm sewer system. In the Phase II stormwater general permit, you will find the following table under Illicit Discharge Detection and Elimination. Your individual permit may vary slightly.  Click on the links to find specific guidance for each of the BMPs.

Measurable Goals
a) Develop/Implement Illicit Discharge Detection and Elimination Program Develop and implement and Illicit Discharge Detection and Elimination Program.  Include provisions for program assessment and evaluation.
b) Establish and maintain appropriate legal authorities Establish and maintain adequate legal authorities to prohibit illicit discharges and enforce the approved Illicit Discharge Detection and Elimination Program.
c) Develop a Storm Sewer System Base Map Complete identifications, locations of and mapping of stormwater drainage system components.  At a minimum, mapping components includes outfalls, drainage areas and receiving streams.
d) Implement illicit discharge detection procedures Implement an inspection program to detect dry weather flows at system outfalls.  Establish procedures for tracing the sources of illicit discharges and for removing the sources.  Develop procedures for identifying priority areas likely to have illicit discharges.  Continue to identify, locate and update map of drainage system components of a priority basis per approved Illicit Discharge Program.
e) Conduct employee cross-training Conduct training for municipal/county staff on detecting and reporting illicit discharges.
f) Provide public education Inform public employees, businesses and the general public of hazards associated with illegal discharges and improper disposal of waste.
g) Establish a public reporting mechanism Establish and publicize a reporting mechanism for the public to report illicit discharges.

Note: You can view a copy of your own local government's stormwater permit on the NC Division of Water Quality Stormwater Unit web site.