An illicit discharge is the release of non-stormwater materials to the stormwater system. The result is untreated discharges that contribute pollutants (heavy metals, toxins, oil and grease, solvents, nutrients, and bacteria) to receiving waters.

Not all liquids or solids may be allowable discharges into the stormwater conveyance systems.Here are some of the following activities that are allowed provided that they do not significantly impact water quality:

• Filter backwash and draining associated with swimming pools;

• Filter backwash and draining associated with raw water intake screening and filtering devices;

• Condensate from residential or commercial air conditioning;

• Residential vehicle washing;

• Flushing and hydrostatic testing water associated with utility distribution systems;

• Discharges associated with emergency removal and treatment activities, for hazardous materials, authorized by the federal, state or local government on scene coordinator;

• Uncontaminated ground water (including the collection or pumping of springs, wells, or rising ground water and ground water generated by well construction or other construction activities);

• Collected infiltrated stormwater from foundation or footing drains;

• Collected ground water and infiltrated stormwater from basement or crawl space pumps;

• Irrigation water;

• Street wash water;

• Flows from fire fighting;

• Discharges for the pumping or draining of natural watercourse or waterbodies;

• Flushing and cleaning of stormwater conveyances with unmodified potable water;

• Wash water from the cleaning of the exterior of buildings, including gutters, provided that the discharge does nor pose an environmental or health threat; and

• Other non-stormwater discharges for which a valid NPDES discharge permit has been approved and issued by DEQ, and provided that any such discharges to the municipal separate storm sewer system shall also be authorized by the city.

No person shall discharge or cause to be discharged into the municipal storm drain system or watercourses any materials, pollutants, waters, or other substance containing any pollutants that cause or contribute to a violation of applicable water quality standards, other than storm water. Examples of illegal discharges include, but shall not be limited to:

• Dumping of oil, anti-freeze, paint or cleaning fluids;

• Commercial car wash washwater;

• Industrial discharges;

• Contaminated fountain drains;

• Cooling waters, unless no chemicals added and has valid NPDES permit;

• Wash waters from commercial and industrial activities;

• Chlorinated backwash and drainage associated with swimming pools;

• Domestic wastewater;

• Septic system effluent;

• Washing machine discharges; and

• Sanitary sewer discharges.