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.​​​​

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.​