Illicit Discharge

It sounds a little scary, doesn't it? Illicit discharge IS scary, making it the perfect topic to cover leading up to Halloween.  We're also working on illicit discharge sampling right now so I'm thinking about it pretty often.  Illicit discharges are discharges into the stormwater conveyance system that are not composed entirely of stormwater.  They often contain sediment, nutrients, bacteria and toxic pollutants.  In other words, illicit discharge is anything flowing through storm sewers that isn't rain.

So what makes up illicit discharges? A lot of different things can be illicit discharges. Sanitary wastewater (sewage) can end up in the storm sewer system through cross-connections: when a sanitary sewer is connected to the storm system.  Leaking oil and other fluids from vehicles parked outside can end up in storm drains.  When you wash your vehicle in the driveway, the wash water can go down the storm drain. Grease containers stored outside of restaurants can tip over and spill. Soil can be washed off of construction sites.  There is a list of potential illicit discharges on our website here.
We find illicit discharges in a few different ways.  The first is, as I mentioned previously, sampling.  We determine if there are illicit discharges in our storm sewers by sampling during dry weather.  When it's dry, nothing should be flowing through the storm sewers. We visit the stormwater outfalls (where the water leaves the sewers and enters streams, rivers, and the lake) when it's dry to see if there's anything coming out.  If there is, we take a sample and find out what's in it.  Once we know how much ammonia, potassium, fluoride, and detergent is in the sample, we can determine what kind of discharge it is.  Sometimes, it is tap water or a natural water source.  Other times, it is sanitary wastewater.  When we've figured that out, we try to figure out where it is coming from and eliminate the source.  We don't want illicit discharges because most storm drains in Superior don't lead to the wastewater treatment plant; they go out into the streams, rivers, and lakes without treatment.  We need to make sure the stormwater is as clean as possible so that we're not polluting our water bodies.
The other way that we find illicit discharges is with the help of everyone in Superior. We have an illicit discharge reporting form on our website at www.ci.superior.wi.us/idform. We also have a hotline that anyone can call at any time to let us know about potential stormwater pollution: 715-394-2761. If you see someone's car leaking, piles of pet waste concentrated in one area, litter covering a storm drain, or anything else you think could cause stormwater pollution, err on the side of caution.  Give us a call and we'll look into it! We need everyone to help us out to eliminate illicit discharge.

 For further information about illicit discharge, you can watch the webinar Wendy presented recently here.

-Written by Jillian Schubert Edwards