Illicit Discharges

Municipal Separate Storm Sewer Systems (MS4s and SMS4s) are not designed to accept, process and treat discharges containing high levels of pollutants. EPA studies indicate that these discharges degrade water quality and can threaten aquatic, wildlife and human health.

Coconino County is required to regulate any discharges that are not composed entirely of stormwater. These discharges are referred to as illicit discharges because they can contain heavy metals, toxics, oil and grease, solvents, nutrients viruses and bacteria.

Eighteen categories of non-stormwater discharges are exempt from regulation by the County as long as these are determined to not be significant contributors of pollutants to their SMS4s. The categories are:
  • Air conditioning condensation
  • De-chlorinated swimming pool discharges
  • Diverted stream flows
  • Emergency fire fighting activity discharges
  • Flows from riparian habitats and wetlands
  • Foundation and footing drains
  • Irrigation water
  • Landscape irrigation
  • Lawn watering
  • Non-commercial charity and individual residential car washing
  • Potable water source discharges
  • Rising groundwater
  • Springs
  • Street wash water
  • Uncontaminated groundwater infiltration
  • Uncontaminated pumped groundwater
  • Water from crawl space pumps
  • Water line flushing

Examples of Illicit Discharges


  • Intentional or unintentional sewer discharging into storm drains
  • Industrial wastewater piping discharging into storm drains
  • Effluent from cracked or improperly functioning sanitary systems
  • Car wash wastewater
  • Oil, hydraulic fluid and radiator fluid spills, and improper disposal of each
  • Improper disposal and spills of paint, paint thinners, lab chemicals and wastes
  • Laundry wastewaters
  • Spills from roadway accidents
  • Improper disposal of household toxics including cleaners, herbicides, insecticides and pesticides

Report illegal dumping or discharges

Reporting Environmental Violations

What Can You Do About Illegal Dumping or Discharges?

Never dump anything into the streets or down the storm drains. Pesticides, herbicides, pet wastes, leaking fluids from a vehicle, or household chemicals could all end up in our washes, streams and retention basins if proper care is not taken.

To report illegal dumping or discharges into streets, storm drains or washes, please call (928) 679-8886, then press 1 at any time to record your message. You may remain anonymous.