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Stormwater Illicit Discharge, Detection and Elimination


Nasty stuff (those things that professionals call Illicit Discharges) can lead to pollutants reaching creeks, streams, rivers, lakes and other bodies of water where we do our recreational activities or use it as drinking water. We are especially concerned about heavy metals (and we are not talking about the rock bands!), toxins, oil and grease, solvents, nutrients, pathogens, and bacteria.

There are types of discharges that are not considered illicit discharges to the MS4, and are exempt from regulation by the Douglas County Stormwater Ordinance.

View the lists of non-allowable illicit discharges and allowable discharges.

Stormwater Non-allowable Illicit Discharge

Following is a list of items that would be considered non-allowable illicit discharge (“nasty stuff”) that we do not want to have in the stormwater system:

  • Sanitary wastewater from improper sewerage connections exfiltration or leakage
  • Effluent from improperly operating or improperly designed septic tanks
  • Overflows of sanitary sewerage systems
  • Untreated commercial car wash wastewater
  • Untreated radiator flushing wastewater
  • Untreated engine degrease wastes
  • Improper oil, gasoline, and other automotive fluids disposal
  • Leaky underground storage tanks
  • Untreated leaking of oils, gasoline and other automotive fluids
  • Direct spraying of fertilizers, pesticides or herbicides onto areas where water runs off
  • Over-application of fertilizers, pesticides or herbicides onto landscaping
  • Laundry wastes
  • Non-contact cooling waters
  • Metal plating baths
  • Dewatering of construction sites
  • Washing of concrete ready-mix trucks
  • Contaminated sump pump discharges
  • Improper disposal of household toxic wastes
  • Spills from roadway and other accidents
  • Chemicals, hazardous materials, garbage, and sanitary sludge landfills and disposal sites
  • Commercial use of soaps and detergents; use in cleaning pavement, vehicles and equipment
  • Sediment from lack of or improper maintenance of erosion and sedimentation controls
  • Latex/oil-based paints and solvents
  • Trash and debris: littering and dumping, household or construction waste
  • Improper disposal of restaurant grease

Douglas County staff is in charge of ensuring unpermitted discharges are eliminated, cleaned up properly, and reported to the State Water Quality Control Division

Stormwater Allowable Discharge

The following types of discharges are not considered illicit discharges to the MS4, and are exempt from regulation by the Douglas County Stormwater Ordinance.

  • Landscape irrigation
  • Lawn watering
  • Diverted stream flows
  • Irrigation return flow
  • Rising groundwaters
  • Uncontaminated groundwater infiltration
  • Uncontaminated pumped groundwater

(Note: Discharges containing groundwater that comes into contact with construction activity is not considered “uncontaminated” due to the potential for sediment content.)

  • Springs
  • Flows from riparian habitats and wetlands
  • Waterline flushing in accordance with the division’s Low-Risk Policy Discharge

Guidance: Potable Water

  • Discharges from potable water sources in accordance with the Division’s Low-Risk Discharge Guidance: Potable Water

-The potable water shall not be used in any additional process. Processes include, but are not limited to, any type of washing, heat exchange, manufacturing, and hydrostatic testing of pipelines not associated with treated water distribution systems.

  • Foundation drains
  • Air conditioning condensation
  • Water from crawl space pumps
  • Footing drains
  • Individual residential car washing
  • Dechlorinated swimming pool discharges in accordance with the division’s Low-Risk Discharge Guidance: Swimming Pools.
  • Water incidental to street sweeping (including associated sidewalks and medians) and that is not associated with construction
  • Dye testing in accordance with the manufacturer’s recommendations
  • Stormwater runoff with incidental pollutants
  • Discharges resulting from emergency fire fighting activities
  • Discharges authorized by a CDPS or NPDES permit
  • Agricultural Stormwater Runoff
  • Discharges that are in accordance with the Division’s Low-Risk Policy guidance

documents or other Division policies and guidance documents where the Division has stated that it will not pursue permit coverage or enforcement for specified point source discharges.

Use the following link for more information regarding CDPHE Low Risk Discharge Guidance (WQP27)