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Image: Open Sewer Atlas / SWIM Coalition


Visualize it


Mapping helps us to visualize data, track changes and progress, and communicate issues and solutions to the public and elected officials. Maps are often the best means of understanding key points of SWIM's mission.

Browse our library of maps and see how stormwater and sewage infrastructure form the circulatory system of our City. 

Open Sewer Atlas NYC

Founded by Josh Eichen of Pratt Center for Community Development and Korin Tangtrakul of Pratt Institute, Open Sewer Atlas NYC compiles publicly available sewer system data into easy-to-use visualizations, such as interactive and foldout maps and downloadable shapefiles. Their work continues under the NYC Soil & Water Conservation District, with support from SWIM and Riverkeeper. 

Where does my Toilet Flush to?

In other words, what is your "sewershed?" Every day, New Yorkers discharge 1.5 billion gallons of liquid waste into the sewer system, which navigates 6,000 miles of pipe towards two possible futures: decontamination at a waste water treatment plant (WWTP) or directly into our waterways as combined sewer overflow (CSO). This HabitatMap shows the drainage areas of the City’s 14 WWTPs. 

Where Does My Toilet Flush to When It's Raining?

When it rains, sewers become inundated by stormwater runoff and the combined wastewater is discharged into New York Harbor via a CSO outfall. CSO pollution can be triggered by a fraction of an inch of rain. This map from allows you to navigate NYC’s CSO outfalls.

Are All CSO Outfalls Created Equal?

No way. Some CSO outfalls discharge pollution very infrequently or in small amounts.  Others overflow practically every time it rains, dumping polluted wastewater entering the estuary. These 15 (out of 434) CSO outfalls in the five boroughs are responsible for 50% of the total volume of CSO pollution that is released each year.

Is all of NYC connected to CSO outfalls?

No. Nearly a third of the City has either a separate storm sewer system (rain off the street goes into its own pipes) or some other system (like the Staten Island Bluebelt). NYC is developing a Stormwater Management Plan as part of a state-mandated MS4 Permit. 

Is there Green Infrastructure in My Neighorhood?

Green infrastructure (GI) is an important part of stormwater management. Learn more about GI in our work and on the NYC DEP website. Check out this map to see if GI is in, or coming to, your community.

Where can I find citizen-science data?

SWIM member Riverkeeper, Inc. coordinates citizen science water-testing data throughout the warmer months, as does NYC Water Trail Association. There's also an app for that! SwimGuide is a smartphone app managed by Lake Ontario Waterkeeper.

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