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Post-Bond Fire Debris Flow Information

Locations downhill and downstream from burned areas like the recent 2020 Bond Fire are very susceptible to flash flooding and debris flows, especially near steep terrain. Post-fire debris flows are particularly hazardous because they can occur with little warning, can exert great impulsive loads on objects in their paths, and can strip vegetation, block drainage ways, damage structures, and endanger human life. The powerful force of rushing water, soil, and rock, both within the burned area and downstream, can destroy culverts, bridges, roadways, and structures, and can cause injury or death if care is not taken.

Storms can quickly develop and can cause flash flooding and debris flows with little or no warning. Officials may only be able to alert the public with just a few minutes notice, or none at all. It is imperative that you understand the seriousness of the situation and are always prepared.

Please utilize the interactive mapping above to familiarize yourself with potential evacuations areas and the resources below to learn more on how you can prepare.

***December 2022 Update***

Local public safety officials, in consultation with subject matter experts from the California Geological Survey (CGS) and the state's Watershed Emergency Response Team (WERT), evaluate the Bond Fire burn scar's recovery progress on an annual basis to assess the current risk to the community and to make any needed changes to planned protective actions.  This year's review reached the following conclusions:

  • Due to the ongoing drought and lack of significant rainfall, vegetation recovery continues to be slow.
  • Flash Flood Warning rain intensity thresholds have been raised to reflect limited vegetation recovery. These changes reflect an increase in the intensity of rain expected to trigger mud and debris flows.  They also increase the intensity of rain necessary for the issuance of evacuations and other protective measures.
  • Modjeska Canyon will be removed from the Evacuation Plan due to vegetation recovery in high-risk locations identified in the WERT Report. However, the threat of minor to moderate debris or mud flows remains and residents should remain vigilant.
  • Evacuation planning for future Flash Flood Watches and Warnings will continue to include Silverado and Williams Canyons as vegetation recovery in these areas remains poor. The potential for debris flows to impact homes and multiple points of travel along Silverado Canyon Road still presents a significant life safety risk.

The decision to issue evacuations is never taken lightly and is considered only in situations where lives may be in extreme peril. Orange County public safety officials will always put the safety of the public and first responders first.

For emergency information during an active event, click here.

Debris Flowchart3

What to do before the storm

1. Prepare your home

If you know you are in known flood area or your home is identified as value at risk in the Watershed Emergency Response Team report you should act now to protect your home. Review OC Public Works Post-Burn Preparedness webpage for suggested methods on how you protect your home. Many of us are used to protecting our properties with sandbags, culverts, k-rails, or retaining walls. These can help redirect mud and water, but not debris flows. If you stay at home, that will not protect your property but will endanger you. If you are told to evacuate, leave. The only sure way to protect your life from a debris flow is to avoid being in one.

2. Make a Plan

Make a personal or family evacuation plan so know what to do should evacuations be issued. To learn about how to make a plan visit

3. Stay Informed

Follow official government agency webpages/social media and sign up for to receive detailed alert messages should evacuations be issued. Stay informed monitor local weather forecasts and be aware when heavy rain is predicated.

4. Be ready to go

When evacuations warnings or orders are issued act immediately. Don’t wait.


Resource Links and Documents

Post Bond Fire Debris Flow & Evacuation Fact Sheet (PDF below)

Bond Fire Watershed Emergency Response Team (WERT) Report

Homeowners’ Guide for Post-Fire Flood, Debris, and Erosion Control

Emergency Work in Creeks and Rivers Information (PDF below)

Large Animal Evacuation Planning

Virtual Local Assistance Center


Official Sources of Information

For emergency information during an active event, click here