Pelham Bay & City Island Flood Exposure · NYC DEP Separate Storm Sewer Area
Pelham Bay & City Island, Bronx - MS4 Area
Properties here drain through separate storm sewers: rain runs in its own pipes straight to Long Island Sound and Eastchester Bay, apart from the sewage. When a storm drops rain faster than the catch basins can take it in, the water collects on streets and low lots instead. Here’s what that looks like for Pelham Bay & City Island, Bronx specifically.
2,071 properties in Pelham Bay & City Island, Bronx drain through separate storm sewers to Long Island Sound and Eastchester Bay. Flood Form rates 33% of them Moderate or High for stormwater, 14% for sewer backup, 4% for groundwater, and 44% for coastal flooding. 81% of lots have yard area that legally qualifies for on-site infiltration. The ground is fairly level here, typically about 17 ft. The median building dates to 1935. 5% of parcels sit over a historic stream or pond. Their runoff reaches the water through 18 NYC DEP storm sewer outfalls. NYC DEP lists nitrogen as a pollutant of concern in these waters under its MS4 stormwater permit.
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Flood exposure in Pelham Bay & City Island (Long Island Sound & Eastchester Bay)
The share of properties Flood Form rates Moderate or High for each type of flooding, on the same Minimal to High scale as an individual report.
33%
Stormwater exposure: Moderate or High
14%
Sewer Backup exposure: Moderate or High
4%
Groundwater exposure: Moderate or High
44%
Coastal exposure: Moderate or High
What sets Pelham Bay & City Island (Long Island Sound & Eastchester Bay) apart
The three figures on which this area differs most from the rest of NYC’s separate storm sewer areas.
4%
Properties with Moderate or High groundwater exposure
Lower than 95% of NYC's separate storm sewer areas. Few lots show signs of a shallow water table.
1935
Median year built
Older than 90% of NYC's separate storm sewer areas. Buildings of this age tend to have aging drains and sewer connections.
62%
Average impervious cover per lot
Lower than 80% of NYC's separate storm sewer areas. More open ground to absorb rain.
Stats computed from Flood Form’s NYC parcel data as of October 28, 2026
Where Pelham Bay & City Island’s storm sewers drain
The waters NYC DEP maps this area’s storm sewer outfalls to, by number of properties.
738
Long Island Sound
483
Long Island Sound, Western Portion
346
Hutchinson River, Lower, and Tributaries
206
Westchester Creek
164
Eastchester Bay
85
New Rochelle Harbor
48
Westcchester Creek
1
Long Island Sound, Bronx
Common solutions for Pelham Bay & City Island properties
The measures that most often suit conditions here. An individual Flood Form picks the exact set for one lot. See all flood prevention solutions.
Downspout Diversion
Redirect roof downspouts away from the sewer system toward permeable yard areas, planters, or a rain barrel.
Complexity: Low · 1–4 weeks
Modular Drywell System
An NDS Flo-Well modular drywell system lets water soak into the ground on-site.
Complexity: Moderate · 1–3 weeks
Rain Garden
A shallow planted depression that collects runoff from roofs and paved areas and lets it soak into the ground over a day or two.
Complexity: Low · 1–3 weeks
Raised Threshold
Raising a doorway threshold with a concrete step or raised sill keeps shallow surface water from entering at ground-level and below-grade doors.
Complexity: Low · 1–2 weeks
Window Well
A lined enclosure around a below-grade basement window holds back soil and keeps surface water off the glass.
Complexity: Low · 1–2 weeks
Area Drain
A yard area drain — a surface inlet at the lowest point in the yard — provides a direct outlet for stormwater that pools on the site.
Complexity: Low · 1–4 weeks
Which of these fit your lot?
Your Flood Form rates your property’s exposure and recommends the measures suited to it.
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Questions about flooding in Pelham Bay & City Island (Long Island Sound & Eastchester Bay)
What does it mean that Pelham Bay & City Island has separate storm sewers?
This part of Pelham Bay & City Island, Bronx is served by a separate storm sewer system, which NYC DEP calls an MS4. Catch basins and roof drains carry rain in their own pipes straight to Long Island Sound and Eastchester Bay, while wastewater flows in another pipe to a treatment plant. Because rain doesn't share a pipe with sewage here, a storm is less likely to push sewage back into basements than in combined-sewer neighborhoods, though a blocked or undersized house sewer line can still back up. Flooding here mostly comes from runoff the storm drains can't take in fast enough, and from groundwater and tides.
How exposed to flooding is Pelham Bay & City Island (Long Island Sound & Eastchester Bay)?
The most widespread exposure in Pelham Bay & City Island is coastal flooding: Flood Form rates 44% of properties Moderate or High for it. The share is 33% for stormwater, 14% for sewer backup and 4% for groundwater. These figures describe the whole area, and exposure varies lot by lot within it.
Can properties in Pelham Bay & City Island (Long Island Sound & Eastchester Bay) manage stormwater on site?
81% of lots in Pelham Bay & City Island have yard area that legally qualifies for on-site infiltration, such as a drywell or rain garden. A lot without that room can still hold runoff with a detention tank or a blue roof.
Why does runoff from Pelham Bay & City Island matter for Long Island Sound and Eastchester Bay?
Storm sewers here discharge runoff without treatment, so what washes off streets, roofs and yards ends up in Long Island Sound and Eastchester Bay. NYC DEP lists nitrogen as a pollutant of concern in these waters under its MS4 stormwater permit. Holding roof runoff on site with a rain garden, drywell, or detention tank cuts flooding on the property and what reaches the water.
How do I check one property in Pelham Bay & City Island (Long Island Sound & Eastchester Bay)?
Enter the address on this page to get its free Flood Form. The report rates that property for stormwater, sewer backup, groundwater, and coastal flooding, and recommends measures suited to the lot.
Nearby separate storm sewer areas
- East River & Long Island SoundWhitestone & College Point4,510 properties · 25% with Moderate or High stormwater exposure
- Flushing Bay & CreekCollege Point & Flushing1,104 properties · 32% with Moderate or High stormwater exposure
- Little Neck BayBayside & Little Neck6,801 properties · 24% with Moderate or High stormwater exposure
- Bergen BasinSt. Albans & South Jamaica41,298 properties · 44% with Moderate or High stormwater exposure
- Newtown CreekMaspeth & East Williamsburg579 properties · 53% with Moderate or High stormwater exposure
- Shellbank & Hawtree BasinsHoward Beach5,067 properties · 52% with Moderate or High stormwater exposure