Flood Zones: Altadena vs Pasadena
How do flood zones rules compare between Altadena, CA and Pasadena, CA?
Altadena has fewer restrictions than Pasadena.
Altadena, CA
Los Angeles County
Most of Altadena is in FEMA Flood Zone X (minimal hazard), but the area along Eaton Wash, the Arroyo Seco tributaries, and post-Eaton Fire burn-scar areas have heightened flood and debris-flow risk. LA County Code Ch. 22.142 (Floodplain Management) applies in mapped Special Flood Hazard Areas.
View full Altadena rules →Pasadena, CA
Los Angeles County
Pasadena has flood-prone areas along the Arroyo Seco and other waterways. The city participates in FEMA's NFIP. Construction in flood zones must meet FEMA elevation requirements and city floodplain management standards.
View full Pasadena rules →Key Facts Comparison
| Fact | Altadena | Pasadena |
|---|---|---|
| Most of Altadena | Zone X (minimal hazard) | - |
| Eaton Wash Adjacent | Zone A / AE possible | - |
| Code Section | LA County Code Ch. 22.142 | - |
| BFE+1 Required | In SFHA | - |
| Post-Eaton Fire | Elevated debris-flow risk | - |
| NFIP | - | Participating community |
| Freeboard | - | 1 foot above base flood elevation |
| Key Areas | - | Arroyo Seco, Eaton Wash |
| Hillside | - | Additional drainage requirements |
Highlighted rows indicate differences between cities.
Altadena FAQ
Is Altadena in a flood zone?
Most of Altadena is in FEMA Zone X (minimal hazard), but areas along Eaton Wash and the foothill channels can be in Zone A/AE. Check the FEMA Map Service Center for your specific parcel.
Did the Eaton Fire affect flood risk?
Yes — post-fire burn scar areas above Altadena have elevated debris-flow and flash-flood risk during winter storms. USGS and NWS issue post-fire debris-flow advisories.
Pasadena FAQ
Is Pasadena in a flood zone?
Parts of Pasadena have FEMA flood zones along the Arroyo Seco and other waterways. Check FEMA flood maps for your property.
Can I build in a flood zone?
Yes, with proper permits. Construction must meet elevation requirements and the city's floodplain management standards.
Compare other topics
See how Altadena and Pasadena compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool