Mapping New York City’s Sewage System and CSO Outfalls

New York City has a combined sewer system that collects both stormwater runoff and wastewater into a single pipe system. When it rains or snows, the sewage treatment facilities cannot process all of this combined sewage and the untreated portion is dumped into our waterways via combined sewer overflow (CSO) outfalls that dot our waterfront.

In this post, I’ve included maps that offer different ways to see the locations of CSO outfalls in New York City.

NYC Green Infrastructure Plan

The NYC Green Infrastructure Plan, released in September 2010, outlines the city’s new approach to improving water quality by cleaning up the city’s rivers, creeks and coastal waters. An important component of this plan is investment in stormwater controls that will help reduce the amount of untreated sewage released through CSO outfalls. On page 16 of this plan, you can view the location of CSOs. The Tier 1 CSOs, marked in red, release the highest amount of untreated sewage into NYC’s waterways:

NYC Green Infrustructure Plan - CSO Outfalls

NYC Green Infrustructure Plan - CSO Outfalls

NYC OASIS Map

The Open Accessible Space Information System (OASIS) is an interactive map that displays data about New York City’s transportation, environment, parks, land use and population. The CUNY Mapping Service at the Center for Urban Research manages this large-scale mapping project, now in its tenth year, with the support of its many data partners.

In the right-hand legend of the OASIS map, you can activate the “Combined Sewer Outfalls” option within the “Environmental Impact/Cleanup” layer. The location of all CSO outfalls are displayed as on the following screen shot (direct link to OASIS map displaying outfalls):

OASIS Map - Combined Sewer Overflow Outfalls in New York City

OASIS Map - Combined Sewer Overflow Outfalls in New York City

Then you can zoom-in to a specific CSO outfall and click the map to view a satellite image of the surrounding area. You can click the “N”, “E”, “S” and “W” letters at the top left of the resulting image to rotate your point of view so you can see the outfall:

OASIS - Aerial Photo of Combined Sewer Overflow in the Bronx

OASIS - Aerial Photo of Combined Sewer Overflow in the Bronx

In a 2009 post on Urban Omnibus, Steven Romalewski, director of CUNY Mapping Service, shares the history of OASIS and includes information about the combined sewer overflow layer.

HabitatMap and Stormwater Infrastructure Matters

HabitatMap is a community-based, map-making initiative designed to show the impact of the built environment on human health. Anybody can create a map, place markers to highlight sites of interest and add multimedia content to each location.

Michael Heimbinder, founder of HabitatMap, collaborated with the S.W.I.M coalition (Stormwater Infrastructure Matters) to create the Where Does My Toilet Flush To? map. This map focuses on the location of the Tier 1 CSO outfalls and the disproportionate amount of sewage they release. In the following screen shot of this map, the green flags represent the location of Tier 1 outfalls and the orange flags represent the location of sewage treatment plants. When you visit this map, click on the green flags for detailed information about the amount of sewage released at each location:

HabitatMap and S.W.I.M Coalition: Location Tier 1 CSO Outfalls in NYC

HabitatMap and S.W.I.M Coalition: Location Tier 1 CSO Outfalls in NYC

You can learn more about the “Where Does My Toilet Flush To?” map on the S.W.I.M. site.

On HabitatMap, you can view additional maps that highlight environmental and sustainability issues including: Barge NYC’s Garbage and Newton Creek Green Infrastructure (scroll down page for map).

About Doug Fox

Doug Fox is a New York City tour guide, urban explorer and waterfront enthusiast. Email Doug at: nyctransported [at] gmail [.] com