Reliez Valley, CA— fire, flood & earthquake hazard information
Reliez Valley is a unincorporated community in Contra Costa County in the San Francisco Bay Area, covering about 2.4 square miles. This page summarizes what official government maps show for Reliez Valley: CAL FIRE fire hazard severity zones, FEMA flood zones, state seismic hazard zones, dam inundation areas, airport noise contours, and air-quality indicators. Figures are the share of Reliez Valley’s area that falls inside each mapped zone.
View Reliez Valley on the interactive map → to check any specific address, free.
Wildfire hazard severity zones
Per CAL FIRE's Fire Hazard Severity Zone maps, 12% of Reliez Valley is in a Very High fire hazard severity zone, 65% is in a High zone, 1% is in a Moderate zone. The remainder of its area is outside currently designated zones.
| Very High severity zone | 12% |
| High severity zone | 65% |
| Moderate severity zone | 1% |
FEMA flood zones
less than 1% of Reliez Valley lies within a FEMA Special Flood Hazard Area (1% annual chance, zones A/AE/AH/AO). Federally backed mortgages in a Special Flood Hazard Area generally require flood insurance.
| Special Flood Hazard Area (100-yr) | less than 1% |
Earthquake faults & seismic zones
The nearest mapped fault, the Franklin fault, is about 0.4 mi (0.6 km) from the center of Reliez Valley. 1 named fault trace in the USGS Quaternary fault database cross its boundary. 31% of its area is in a state-designated liquefaction zone of required investigation. 40% is in an earthquake-induced landslide zone.
| Nearest mapped fault | Franklin fault — 0.4 mi (0.6 km) |
| Named fault traces crossing boundary | 1 |
| Liquefaction zone | 31% |
| Earthquake-induced landslide zone | 40% |
Dam inundation, aircraft noise & air quality
annual average fine-particle (PM2.5) concentration across its census tracts is 8.7 μg/m³, and its composite pollution burden ranks around the 3th percentile statewide.
| Annual PM2.5 (tract average) | 8.7 μg/m³ |
| Pollution burden percentile (statewide) | ~3 |
Frequently asked questions
- Is Reliez Valley in a wildfire hazard severity zone?
- Per CAL FIRE's Fire Hazard Severity Zone maps, 12% of Reliez Valley is in a Very High fire hazard severity zone, 65% is in a High zone, 1% is in a Moderate zone. The remainder of its area is outside currently designated zones.
- Is Reliez Valley in a FEMA flood zone?
- less than 1% of Reliez Valley lies within a FEMA Special Flood Hazard Area (1% annual chance, zones A/AE/AH/AO). Federally backed mortgages in a Special Flood Hazard Area generally require flood insurance.
- What earthquake faults and seismic zones affect Reliez Valley?
- The nearest mapped fault, the Franklin fault, is about 0.4 mi (0.6 km) from the center of Reliez Valley. 1 named fault trace in the USGS Quaternary fault database cross its boundary. 31% of its area is in a state-designated liquefaction zone of required investigation. 40% is in an earthquake-induced landslide zone.
- How do I check a specific address in Reliez Valley?
- Use the free sitelume interactive map at https://sitelume.com — search any Reliez Valley address to see which mapped zones it falls in, layer by layer.
Nearby in Contra Costa County
Sources: CAL FIRE Fire Hazard Severity Zones; FEMA National Flood Hazard Layer; USGS Quaternary Faults; CGS Seismic Hazard Zones & Alquist-Priolo zones; Cal OES dam inundation maps; county ALUC noise contours; CalEnviroScreen 4.0. Area shares are computed against each place’s Census TIGER boundary (last computed 2026-07-24). Boundaries and zone designations change; always verify with the issuing agency.