Knox County Tennessee

Illicit Discharge Detection and Elimination (IDDE) Program

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Report an Illicit Discharge In Knox County

Click Here to Report An Illicit Discharge in Knox County

The goal of the Knox County Illicit Discharge Detection and Elimination Program is to comply with the NPDES MS4 Permit for the detection, identification, and elimination of all non-stormwater discharges into the Knox County-owned municipal separate storm sewer system (MS4) in the unincorporated areas of Knox County. The storm sewer system includes storm drains, pipes, ditches, drainageways, spillways, creeks, and streams. The MS4 is also called the stormwater drainage system. When it rains, the water flows across driveways and roads and rushes into grates and inlets. These grates and inlets are part of the stormwater drainage system and they connect to a series of pipes and ditches that carry the stormwater to a low point. That low point is usually a creek or river.

What is Knox County doing to meet this goal of detecting, identifying, and eliminating discharges to the storm sewer or stormwater drainage system that should not be there?

  • Updating and maintaining a storm drainage system infrastructure map
  • Prohibiting illicit discharges
  • Conducting field inspections during dry weather to identify prohibited discharges (dry weather screening), stream monitoring and visual stream assessments.
  • Requiring special pollutant abatement permits (SPAP) for “hot spot” businesses.
  • Emergency spill response
  • Complaint response investigation and enforcement
  • General Public, Business, and Municipal education, outreach, and training

What Is an illicit discharge?

An illicit discharge is any discharge to the storm sewer system that is not composed entirely of stormwater. This video will explain in further detail.

Why only rain down the storm drain?

Storm drains and the storm sewer system do not drain to wastewater treatment facilities. In Knox County, there is a separate set of pipes that carries sanitary waste from our homes and businesses to the wastewater treatment facilities.  The storm sewer system carries stormwater runoff and discharges directly to the nearest stream or water body without any treatment. Any pollution running into or placed in the storm sewer system will cause water quality problems, harm aquatic life, cause flooding, and can lead to excessive and costly maintenance and clean-up.


Here are examples of illicit discharges that are prohibited from Knox County storm sewers and creeks.

grey water into a creek

Discharge from a utility sink (grey water) into a creek.

Chemical dumping into a storm

Chemical dumping into a storm drainpipe.

Bacteria and nutrients in to a stream

Bacteria and nutrients from failed septic system going into a stream.

photo about paint discarded into storm drain

Paint discarded into storm drain.

photo about branches and debris dumped in a drainage ditch

Branches and debris dumped in a drainage ditch.

photo about grease dumping

Cooking grease dumped into a storm drain grate.

photo about trash dumping

Trash from a renovation project dump on streambank.

phone about petroleum leak in a creek

Petroleum leak from above ground tank into creek.