Petaluma has flooded many times. A Petaluma Wetlands Alliance summary of the city's floodplain plan says the largest flood of record, January 3 to 5, 1982, caused an estimated $28 million in damage; El Niño storms in February 1998 caused nearly $6 million; and on December 31, 2005, flooding damaged about 53 structures, not counting mobile home parks (Petaluma Wetlands Alliance).
What the City has done
The City of Petaluma lists flood projects including the Payran Reach (river widening and floodwalls), Denman Reach along Industrial Avenue, and Capri Creek east of North McDowell Boulevard, and updated its flood modeling in 2023 to account for sea-level rise (City of Petaluma). Check your address on the City's maps and FEMA's Flood Map Service Center.
Why mold follows Petaluma floods
- Crawlspaces under many older homes hold water and mud.
- Creek water is contaminated, so the EPA recommends experienced professionals (EPA).
- Cool, damp winters slow natural drying.
First steps
- Make sure it's safe to enter and document damage.
- Remove standing water and soaked porous materials. CDPH says porous materials wet more than a day or two may need removal (CDPH).
- Dry the structure and crawlspace; aim for indoor humidity below 60 percent (EPA).
- Have remaining mold remediated before rebuilding.
Want a local pro to take a look?It's free for homeowners and there's no obligation.
Related
- Petaluma River flood cleanup on Sonoma County Water Damage
- Roof repair in Petaluma on Sonoma Roof Repair
- Crawlspace moisture in Sonoma County
Sources
- Petaluma Wetlands Alliance: Flooding
- City of Petaluma: Flood management
- FEMA Flood Map Service Center
- EPA: Mold cleanup in your home
- EPA: A Brief Guide to Mold, Moisture and Your Home
- CDPH: Frequently asked questions about mold
Sources checked October 18, 2026.
Frequently asked questions
Is my Petaluma home in a flood zone?
Check FEMA's Flood Map Service Center and the City of Petaluma's updated flood maps. Being outside a mapped zone lowers, but doesn't eliminate, risk.
Can crawlspace mold affect the house above?
Yes. Air and moisture move up into living spaces, and ongoing dampness damages framing.