Sewershed BB-031 · NYC DEP Combined Sewer Overflow Tributary Area
BB-031 - Astoria, Queens
Properties in this area share the BB-031 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 Astoria, Queens specifically.
BB-031 is a combined sewer area covering 555 properties in Astoria, Queens. Flood Form rates 45% of them Moderate or High for stormwater exposure, and 28% for groundwater. 66% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 29 ft. The median building dates to 1930. 20% of parcels sit over a historic stream or pond. According to NYC DEP green infrastructure records, this sewershed drains to East River / Open Waters. NYC DEP has built 1 green infrastructure asset here.
555
Properties in sewershed
66.3%
Legally eligible for on-site infiltration
45%
Stormwater exposure: Moderate or High
28%
Groundwater exposure: Moderate or High
What sets BB-031 apart
29 ft
Median ground elevation
92%
Average impervious cover per lot
1930
Median year built
20%
Properties over a historic stream or pond
Stats computed from Flood Form’s NYC parcel data as of October 9, 2026
Common solutions for Astoria 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
- BB-030Hallets Point235 properties · 60% with Moderate or High stormwater exposure
- BB-032Hallets Point180 properties · 8% with Moderate or High stormwater exposure
- BB-029Astoria2,689 properties · 44% with Moderate or High stormwater exposure
- BB-034Ditmars5,122 properties · 39% with Moderate or High stormwater exposure
- BB-028Woodside5,778 properties · 37% with Moderate or High stormwater exposure
- BB-035Ditmars116 properties · 36% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form