Illegal Discharges

Did you know that only rain should enter the storm system? Learn more about what illegal discharges are, why only rain and snow melt should enter the storm sewer system, and what to do if you see a weird color in a stream.

Page updated on Oct 19, 2016 at 4:37 PM

What is an Illegal Discharge?

An illegal (also called illicit) discharge is what happens when pollutants are poured directly into a storm drain, stream, or waterbody, as well as when pollutants are left out on the ground and can be carried by rain to a storm drain, stream, or waterbody.  Because the storm drain system (also called a storm sewer) is not treated, everything that enters the system goes directly to our local streams. 

The following should never go onto the ground, into storm drains, or in streams:

  • Paint, cleaners, or chemicals
  • Washing machine, dishwater, sink, or mop water
  • Oil, gas, or other car fluids
  • Cooking oil or grease
  • Pet waste
  • Litter or other illegal dumping
  • Dumpster juice

What is Not an Illegal Discharge?

There are a few exceptions to what can enter the storm drain system.  These exceptions are:

  • Uncontaminated groundwater
  • Air conditioning condensation
  • Water from fire-fighting activities
  • Individual residential car washing
  • Dechlorinated pool water with no chemicals in the water
  • Water line flushing
  • Landscape irrigation

What is That Stuff in the Stream?

The Water is a Weird Color

  • Cloudy/MilkyIllegal Discharge image
    If the water in the stream is a cloudy or milky color it is likely that something has been dumped either in the stream or in a storm drain. 



  • BrownStream with Sediment
    If the water in the stream is brown and hard to see through, there is too much sediment in the water.  This could be caused by a large amount of water entering the stream, like during a water main break, or it could be because a construction site is not controlling sediment leaving the site. 
     
  • Orange SlimeStream with Orange Bottom
    There are some streams in the City that have orange slime along the bottom.  While this orange slime can look out of place it is actually completely natural and is caused by iron bacteria that are naturally occurring in the groundwater in the City.  The most common place to see this orange slime is in Hooff’s Run, but any stream in the City that is fed by groundwater can have it. 

Is That Rainbow Sheen Natural or Oil?

Did you know that sometimes rainbow sheen on water can be naturally occurring?  Natural sheen is caused by the same iron bacteria that cause the orange slime above.  This bacteria is naturally occurring in groundwater. 

So how do you tell the difference between a natural or oil rainbow sheen?  The easiest way is to use a stick to poke into the sheen to try and break it apart.  If the rainbow sheen stays broken up in pieces, then it is most likely natural sheen.  If the rainbow sheen swirls back together then it may be caused by oil or petroleum.  An oil or petroleum sheen will also usually smell like oil or gas.  If you believe that there is an oil/petroleum spill, please call the Alexandria Fire Department at 911. 

Always remember you can call the Stormwater Management Division at 703.746.4014 if you see anything unusual in the streams or have any questions. 

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