Illicit Discharge



Illicit Discharge Detection and Elimination (IDDE)

What is an Illicit Discharge?

Any activity which results in a discharge to the Georgetown County Storm Water System or receiving waters that is not composed entirely of storm water except (a) discharge pursuant to an NPDES permit and (b) other allowable discharges as noted in the table below.

Allowable DischargeExamples of Illicit Discharges
  • Water Line Flushing
  • Landscape irrigation
  • Diverted stream flows
  • Uncontaminated ground water
  • Discharges from potable water sources
  • Springs
  • Air conditioning condensation
  • Lawn watering
  • Flows from wetlands
  • Dechlorinated swimming pool discharges
  • Residential car washing
  • Sanitary Wastewater
  • Effluent from Septic Tanks
  • Car wash wastewaters
  • Improper oil disposal
  • Radiator flushing disposal
  • Laundry wastewaters
  • Spills from roadway accidents
  • Improper disposal of auto and household toxics

What to do if you witness an Illicit Discharge?

Note: * All reports will remain anonymous unless otherwise requested *


Why Are IDDE Efforts Necessary?

Illicit discharges enter the system through either direct connections (e.g. wastewater piping either mistakenly or deliberately connected to the storm drains) or indirect connections (e.g., infiltration into the MS4 from cracked sanitary systems, spills collected by drain outlets, or paint or used oil dumped directly into a drain or drainage swale). The result is untreated discharges that contribute high levels of pollutants, including heavy metals, toxics, oil and grease, solvents, nutrients, viruses, and bacteria to receiving waterbodies. Pollutant levels from these illicit discharges have been shown in EPA studies to be high enough to significantly degrade receiving water quality and threaten aquatic, wildlife, and human health.

Outfall Inventory

An outfall is any point where a conveyance of the stormwater system discharges into streams, lakes, wetlands and marshes.

Outfall inventory is a requirement of Georgetown County's "MS4" Stormwater Permit, which focuses on discharges of stormwater to surface waters in regulated urbanized areas across the state.

The inventory involves identifying and mapping stormwater outfalls, specific attributes (pipe shape, condition, landuse, etc) were collected for each outfall. It was noted whether flow is present in dry weather, which may lead to a pollution source upstream.

Stormwater Division has gone above and beyond the requirements of the MS4 Permit and is doing a complete system inventory. This includes not just the outfalls, but all pipes, ditches, catch basins, ponds and creeks throughout the MS4 area. One of the ultimate goals of our division is to improve water quality in all of Georgetown County and knowing where every ditch and pipe drains is the first step.

As of October 1st 2010, 99% of Murrells Inlet has been inventoried. If you have a question where your water travels, give us a call!

Outfall Inventory Map

Old County Courthouse, Room 274 · 129 Screven Street, Georgetown, South Carolina 29440
Phone: (843) 545-3524 · Fax: (843) 545-3005 ·