The goal of SEMSWA’s Illicit Discharge Detection and Elimination (IDDE) Program is to reduce the frequency and environmental impact of illegal discharges that are accidentally or intentionally put into the storm sewer system.

With few exceptions listed below, an illicit discharge is any discharge to the storm sewer system not composed entirely of stormwater. Since only stormwater is allowed in the storm sewer system, all fluids that are not stormwater can be considered harmful when discharged to the storm sewer system. 

• IDDE Fact Sheet

Allowable Discharges to the Stormsewer System:

• Irrigation return flow / lawn watering
• Diverted stream flows
• Rising groundwater or uncontaminated pumped groundwater 
• Discharges from potable water sources
• Discharges from foundation drains, air conditioning condensation, water from crawl space pumps, footing drains
• Individual residential car washing activities
• Flows from riparian habitats and wetlands
• Swimming Pools (if dechlorinated, less than 0.05 ppm)

Regulatory Mechanism

SEMSWA utilizes regulatory mechanisms that include enforcement actions, procedures for tracing and removing the source, and training staff to detect illicit discharges. SEMSWA also relies on citizens to report unauthorized discharges. 

• Arapahoe County IDDE Manual
• City of Centennial IDDE Manual

Household Hazardous Waste Pick-up

In an effort to keep hazardous materials out of the storm sewer system, SEMSWA offers door-to-door waste pick-up for citizens within our service area. The program accepts most household hazardous materials including motor oil, paint, pesticides/herbicides, and household chemicals.

• At Your Door Flyer

How to Report an Illicit Discharge or Spill: 

For emergency spills or hazardous spills call 911.

Reports for illicit discharges in the City of Centennial during business hours:

• SEMSWA (303) 858-8844
• City of Centennial (303) 325-8000

Reports for illicit discharges in Arapahoe County during business hours:

• SEMSWA (303) 858-8844
• Arapahoe County (720) 874-6500

Reports for illicit discharges after-hours (City of Centennial and Arapahoe County):

• Sheriff’s office: (303) 795-4711
• Spill hotline: 1-877-518-5608