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Stormwater is the rain and melting snow that falls on our rooftops, streets, and sidewalks. Rather than being absorbed naturally into the ground, much of the stormwater in New York City flows into roof drains or catch basins in the streets, and from there into the sewers. Stormwater can pose challenges to the City by triggering combined sewer overflows, washing pollutants into our waters through the separate storm sewer system, and causing flooding. This section describes how stormwater is conveyed through the City, the challenges it creates, and what the City is doing to overcome them.

Homeowner’s Guide to Rain Event Preparedness
Tips to help you protect your home from sewer backups and flooding due to rainfall events.
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NYC Green Infrastructure Program
New York City’s Green Infrastructure Program is a multiagency effort to design, construct and maintain sustainable stormwater management practices throughout New York City.
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Types of Sewer Drainage Areas in New York City
In New York City, stormwater is conveyed through combined sewers or separate sewer systems. In unsewered areas, water flows directly over the ground into waterways.
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Combined Sewer Overflows
Sometimes, during heavy rain and snow storms, combined sewers receive higher than normal flows. Treatment plants are unable to handle flows that are more than twice design capacity and when this occurs, a mix of excess stormwater and untreated wastewater discharges directly into the City’s waterways at certain outfalls. This is called a combined sewer overflow (CSO). We are concerned about CSOs because of their effect on water quality and recreational uses.
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Municipal Separate Storm Sewer System (MS4) Discharges
As stormwater flows over streets and other impervious surfaces, it sweeps up pollutants such as oils, chemicals, pathogens and sediment. In separate sewer areas, this pollution is carried by stormwater runoff and discharged directly into the City’s waterways. This can have a negative impact on water quality and recreational uses.
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Southeast Queens Project Map

This map highlights projects that are in construction or have been completed as part of the City’s $1.9 billion effort to reduce flooding and upgrade infrastructure throughout Southeast Queens.

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Local Law 56 (PDF)
City Council Reporting Requirements 2017 (PDF)
Local Law Report Table (PDF)


Flooding in New York City
A look at the areas prone to flooding, the causes of flooding in New York City, and what residents can do to help protect our City from flooding.
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Rain Barrel Giveaway Program
As part of its citywide effort to reduce stormwater runoff and create a more livable, sustainable city, DEP initiated the Rain Barrel Giveaway Program. Rain barrels capture stormwater from your roof and store it for future use such as watering your lawn or garden.
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The Bluebelt Program
The Bluebelts are an award winning, ecologically sound and cost-effective storm water management system for approximately one third of Staten Island’s land area. The program preserves natural drainage corridors, called Bluebelts, including streams, ponds, and other wetland areas.
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Guidelines for the Design and Construction of Stormwater Management Systems
DEP has published Guidelines for the Design and Construction of Stormwater Management Systems.
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Green Infrastructure