Like most older sewage systems, New York City’s sewage system is what’s known as a “combined sewer system.” This means that the system was never built to accommodate clean rainwater and dirty wastewater separately and therefore, when it rains, the clean rainwater is dumped into the sewer outfalls together with our dirty wastewater.

In the image above you can see a perfect example of how NYC’s older sewer system (top)  differs from newer, “separate sewer systems” (bottom). As you see, during dry weather, all that happens in both cases is that wastewater goes to the publicly owned treatment works (POTW). But when it rains, new systems keep the wastewater and rainwater separate and send only the wastewater to the POTW while the clean rainwater goes to the river.

In NYC, when it rains, a mix of rainwater and wastewater goes to both the POTW and to the river. As a result, after heavy rains our sewer outfalls often experience what is called a “combined sewer overflow” or CSO. During a CSO it is dangerous to boat, swim, fish or conduct countless other activities around the heavily polluted water.

The existence of CSOs is in itself a problem that the DEP has to deal with. But it is a problem that will take years and years and billions and billions of dollars. What can we do to mitigate the dangers of CSOs right now?

The answer is better CSO notification procedures. NYC currently has about 500 CSO outfalls according to the New York Water Environmental Association. In 1999, the city began putting signs up at their CSO sites like this one at Wallabout Bay. The signs say “IF YOU SEE A DISCHARGE DURING DRY WEATHER PLEASE CALL! 311.” Now, I ask you: if you hadn’t read the first three paragraphs of this post, would you know what this means? I wrote the first three paragraphs of this post and I’m still not sure what this means!

Here’s another problem: If it just rained last night and this afternoon your son or daughter wants to go swimming in, say, Paedergat Basin, how are you supposed to know whether or not they are about to climb into a toxic cesspool?

Thanks to pressure from our friends over at SWIM (Storm Water Infrastructure Matters), the DEP (with a little help from HydroQual Environmental Engineers) recently created a web page where you can check on the status of CSO sites around the city. I include a link here so that you can take a look yourself and decide if this is sufficient for a system that has 500 CSO outfalls that your child can be swimming in, that your husband can be fishing in or that the entire family can be taking a boat ride in.

We live in an age obsessed with notifications. The federal government requires notifications on every single pack of cigarettes and bottle of alcohol. The mayor requires calorie counts to be posted in every donut shop in NYC. Why are we more concerned with what we put inside our bodies than with what we put our bodies into? A large, easy to read sign near every single CSO outfall into New York that says something to the effect of “IF YOU SEE WATER COMING OUT OF THIS PIPE, DO NOT SWIM HERE. ALL WATER COMING FROM THIS PIPE IS TOXIC AND DANGEROUS TO YOUR HEALTH” is the best way to keep us safe from the unfortunate, unavoidable effects of CSO.