Sewershed WI-056 · NYC DEP Combined Sewer Overflow Tributary Area
WI-056 - Riverdale, Bronx
Properties in this area share the WI-056 combined sewer — during moderate-to-heavy rain, runoff can exceed pipe capacity faster than it drains, which is what drives sewer backup exposure block by block. Here’s what that looks like for Riverdale, Bronx specifically.
WI-056 is a combined sewer area covering 3,548 properties in Riverdale, Bronx. Flood Form rates 34% of them Moderate or High for stormwater exposure, and 24% for groundwater. 83% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 112 ft. The median building dates to 1930. 22% of parcels sit over a historic stream or pond.
3,548
Properties in sewershed
83.1%
Legally eligible for on-site infiltration
34%
Stormwater exposure: Moderate or High
24%
Groundwater exposure: Moderate or High
What sets WI-056 apart
112 ft
Median ground elevation
68%
Average impervious cover per lot
1930
Median year built
22%
Properties over a historic stream or pond
Stats computed from Flood Form’s NYC parcel data as of October 9, 2026
Common solutions for Riverdale properties
Downspout Diversion
Redirects roof runoff away from the combined sewer and into landscaped or permeable areas on the lot.
Infiltration System
Drywells or infiltration chambers that let stormwater soak into the ground on-site instead of entering the sewer.
Detention System
Holds stormwater temporarily and releases it slowly, reducing peak flow into the combined sewer during a storm.
Drain Improvement
Upgrades yard, area, or foundation drains so water is carried away from the building instead of pooling.
Foundation Waterproofing
Protects the foundation from groundwater intrusion, relevant where groundwater exposure runs high.
Nearby sewersheds
- WI-054Riverdale251 properties · 22% with Moderate or High stormwater exposure
- WI-077Spuyten Duyvil646 properties · 56% with Moderate or High stormwater exposure
- WI-053Riverdale171 properties · 35% with Moderate or High stormwater exposure
- WI-076Spuyten Duyvil130 properties · 35% with Moderate or High stormwater exposure
- WI-078Kingsbridge214 properties · 24% with Moderate or High stormwater exposure
- WI-057Fordham855 properties · 29% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form