Illicit Discharge Detection and Elimination

​​​​​​​​​​​​​​​​​​​​​​​​​The IDDE program consists of outfall inspections, field screening of dry-weather flows, and identifying and eliminating the source of illicit discharges.  SWM inspects outfalls to look for signs of illegal discharges to the storm drain system.  If dry-weather flow is observed, field screening is conducted to look for significant pollutants. Inspectors use visual observation (sometimes using CCTV video equipment) to track the flow up the storm drain line to attempt to identify the source.​​​​

 Outfall Inspections

  • City has identified over 800 outfalls.

  • Outfalls are inspected over the permit term.

  • Priority outfalls are inspected annually.

  • When an outfall has flow, the sampling crew conducts a field screening.


      Tracking the Source of Flow

      • If an outfall is observed to have a dry weather flow, an investigation is initiated.

      • Inspections use visual observations, open manholes and televise the storm drain to identify source of flows. 

      If you are interested in additional information, have questions, or see illegal dumping, contact the City of Phoenix's Stormwater Management Program.  

      Please call the Stormwater Hotline at 602-256-3190.

      Only stormwater belongs in the storm drain.  However, there is a short list of non-stormwater discharges that are also allowable, provided they are not a source of significant pollutants:

      1. Water line flushing

      2. Landscape irrigation

      3. Diverted stream flows

      4. Rising ground waters

      5. Uncontaminated groundwater infiltration

      6. Uncontaminated pumped groundwater

      7. Discharges from potable water sources

      8. Foundation drains

      9. Air conditioning condensation

      10. Irrigation water

      11. Springs

      12. Water from crawl space pumps

      13. Footing drains

      14. Lawn watering

      15. Individual residential car washing

      16. Flows from riparian habitats and wetlands

      17. Dechlorinated swimming pool discharges

      18. Street wash water

      19. Discharges or flows from emergency firefighting activities

      20. Discharges authorized by another NPDES or AZPDES permit.​


      Outfall sampling scene 
      Inspector collecting a water sample.​