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Illicit discharge or illegal dumping is against the law!

Only Rain Down the Drain; Illicit Discharges are Against the Law!


Illicit Discharges, more commonly known as illegal dumping, are a significant cause of stormwater pollution. Pollutants like trash, fertilizer, antifreeze, paint, pet and lawn waste, if improperly handled or disposed of, can pose a serious risk to water quality.

Recognizing Illicit Discharges

Here are some common indicators to look for at storm drains and around outfalls:

  • Unusual color or cloudiness
  • Algae
  • Strong pungent or musty odor
  • Dead vegetation or inhibited growth
  • Floating debris
  • Pipe corrosion
  • Surface scum or foam
  • Stains on channel bottom or sides
  • Oil sheen
  • Dead animals

What Should You Do if You See an Illicit Discharge?

Public witness complaints provide the most common source of information. For questions about illicit discharges, please call 720-977-6256. To report Illicit Discharges during business hours, please complete the Code Violation Form at the City Development Department (9500 Civic Center Dr., Thornton, CO). You may also send an email to or call 303-538-7517. To report Illicit Discharges on the weekends or after regular business hours, call 720-977-5150. When a complaint is received, Code Compliance investigates the claim and assembles evidence for prosecution when possible. The case is then released to the appropriate city, county, or federal authorities.

Federal, state, and local laws prohibit certain non-stormwater discharges to the storm drain system. These regulations aim to protect the quality of the nation's surface water resources by minimizing contamination associated with urban activities.