Illicit Discharge Detection & Elimination

An illicit discharge is defined as any release into the Municipal Separate Storm Sewer System (MS4) of contaminated water, or any non-stormwater discharge that contributes pollutants to receiving waters. 

Examples of Illicit Discharges

  • Sanitary wastewater from crushed or collapsed pipes or surcharges
  • Direct septic connections into the storm drain system
  • Overflow from septic tanks, car wash wastewater
  • Laundry wastewater
  • Improper disposal of automobile and household products

Exceptions Not Considered Illicit Discharges

  • Water line flushing
  • Landscape irrigation
  • Diverted stream flows
  • Rising or out breaking groundwater
  • Uncontaminated pumped groundwater (includes clean sump pump discharges)
  • Potable water source discharges  
  • Foundation drains
  • De chlorinated swimming pool discharges 
  • Stormwater runoff from streets and sidewalks


CPW will be conducting inspections of stormwater outfalls throughout town as part of our ongoing compliance to our Phase II Stormwater Management Plan. If pollutants or irregular flows are detected, the system will be traced back to find the source of the illicit discharge. Please note that regulations are currently being proposed within the town to develop an enforcement and fining procedure for illicit discharges found within the Town's MS4. Any discharge deemed a threat to public safety or public health is automatically in violation of the health code and is thus subject to a removal order and/or fines by the Health Department. For more information on illicit discharges, view the New England Interstate IDDE Manual website.

For Additional Information

For more information regarding the Phase II Stormwater Management Program, contact Concord Public Works at 978-318-3210.