When the Russian River comes up, it doesn't just wet homes; it leaves contaminated water and silt in walls, floors and crawlspaces. In February 2019 the river crested at 45.38 feet at Guerneville, and the NWS counted roughly 2,000 properties with some damage in the Guerneville and Monte Rio area (NWS). The County estimated about 1,900 homes damaged countywide, 1,760 with major damage (County of Sonoma).
Know your number
The CNRFC's Guerneville gauge impact list ties river levels to streets (CNRFC): Lower Mill Street and Old Bohemian Highway at 32 feet; riverside resorts and Riverside Park starting at 34 to 35 feet; River Road in Hacienda and Canyon 7 Road in Rio Nido at 39 feet; and much of downtown Guerneville at 44 to 46 feet. If your home took water, mold prevention starts the day you get back in.
What's different about river homes
- Contamination. Floodwater carries sewage and chemicals. The EPA recommends professionals experienced with contaminated water (EPA).
- Access delays. Highway 116 and River Road closures can keep owners out for days. CDPH says porous materials wet more than a day or two may need removal even if they don't look moldy (CDPH).
- Raised homes and crawlspaces full of mud and wet insulation.
- Slow drying under redwoods in winter. Plan on mechanical drying.
The cleanup sequence
- Re-enter only when officials allow and it's safe.
- Photograph everything.
- Muck out silt; remove carpet, pad, soaked drywall and insulation.
- Clean hard surfaces with detergent and water; dry completely (EPA).
- Dry framing and the crawlspace; verify before rebuilding.
- Hire licensed contractors for rebuild work (CSLB).
Want a local pro to take a look?It's free for homeowners and there's no obligation.
Related
- Mold after a Russian River flood (full guide)
- Russian River flood cleanup on Sonoma County Water Damage
- Storm roof repair on the lower river on Sonoma Roof Repair
Sources
- NWS: Historic flooding across the North Bay, Feb 2019
- County of Sonoma: flood damage estimate, Mar 2019
- CNRFC: Russian River at Guerneville
- EPA: Mold cleanup in your home
- CDPH: Frequently asked questions about mold
- CSLB: license check
Sources checked October 18, 2026.
Frequently asked questions
How long before mold grows after a flood?
The EPA's benchmark is 24 to 48 hours for drying. After a river flood, assume porous materials that were underwater need to come out.
Will my flood insurance cover mold?
Flood policies have specific rules about mold, often tied to whether you took reasonable steps to dry the home. Check your policy and document everything.