Increased Risk of Flooding and Mud, Debris Flows after 2017 Wildfires

The City of Santa Rosa and the County of Sonoma encourage residents living in and around the areas burned by the October 2017 wildfires to prepare their property for the rainy season and remain alert for possible threats from intense winter storms. Many properties in the areas burned, and downstream of those areas, now have a higher risk for flash floods, rock falls, debris flows, and mud flows, and will remain so for the next few years.

The areas affected by the Nuns, Tubbs and Pocket Fires are seeing substantial improvement in watershed condition as vegetation grows, but the threat of natural hazards still exists. The highest danger occurs during heavy rainfall, but once soils are saturated, floods or mud and debris flows can occur hours or days after the rain has stopped. Property owners in burned areas, and downstream of burned areas, can prevent erosion and stay informed about winter storm warnings by following these steps:

1. Take Precautions for your Family
   • Check the Post-Fire Hazard Map for an estimate of the risk in your vicinity. Localized or changing conditions may result in a greater threat than displayed on the map.
   • Pack emergency supply bags and identify what you’d want to save in an emergency. Consider the 6 P’s: People and Pets, Important Papers, Prescriptions, Pictures, Personal Computers, and Plastic/Paper money.
   • Create an evacuation plan and include two possible evacuation routes.
2. Prepare your Property
   • Use erosion control techniques, such as installing straw wattles and rock bags, and remove debris near creeks, storm drains and drainageways on your property.
   • For additional erosion control resources, visit sonomacountyrecovers.org/rain-ready. For questions, if your property is in the City of Santa Rosa, call (707) 543-4649. In the unincorporated County, call (707) 565-6186.
3. Remain Alert
   Know how you’ll receive alerts:
   • Wireless Emergency Alerts: Always keep your phone on, with the ringer on, to receive alerts from the National Weather Service.
   • SoCoAlert: Sign up to receive emergency notifications at SoCoAlert.com. SoCoAlert will be used to send an emergency notification if there is an imminent threat to life or property.
   • In areas with limited cell service, or in areas that may experience power outages, have a battery powered weather emergency radio on hand to receive critical messages from the National Weather Service.

   The City and County are working in close coordination to prevent and monitor flooding. A series of rain and stream flow gauges were installed within and downstream of the burn areas by Sonoma Water as part of an early warning system for flooding. The gauges allow monitoring of streams and rainfall in real-time and offer a glimpse of conditions in the burn areas and downstream of areas that are vulnerable to flooding. Data from the gauges is used by the National Weather Service to develop their hazardous weather advisories, alerts, and warnings. This real-time rainfall and streamflow data is also available at sonoma.onerain.com.

   To assist property owners in the burn areas with managing storm water runoff, the City and the County have developed best management practices for the installation of erosion control measures at vacant lots and construction sites. These practices are designed to reduce erosion and the amount of sediment that washes off sites during rain storms - potentially causing pollution in creeks and blockage of drainageways. The City and County are conducting site visits at locations in the burn areas to ensure erosion control measures are properly installed and maintained.

For more information, visit sonomacountyrecovers.org/rain-ready.