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Mud Slides and Debris Flows

Mud slides and debris flows: What are they? 

  • Mud Slide: A river of liquid and flowing mud on the surface of normally dry land areas, as when earth is carried by a current of water 
  • Debris Flow: rapid movements of rock, earth, and other debris saturated with water, carried by gravity

Rain over burned areas presents a very high risk of mud slides and debris flows. Wildfires destabilize the soil and duff layers, making them available to join rainwater runoff. As water saturates the ground of a burned area, runoff pulls sediment and debris into a liquid state (the slide or flow). Heavy rains over burned areas easily generate flows. High severity burn scars may initiate flows with only small amounts of rain. Flows build velocity as they move downslope, picking up larger boulders, trees and debris. These events are extremely destructive and require planning to maintain firefighter safety.

How can you protect yourself from a mudslide/debris flow? 

Some ways that firefighters can avoid these natural disasters:

  • Keep informed on fire weather conditions and forecasts (IAP forecast or Climate Prediction Center Hazard Outlook, link in references)
  • Communicate changing conditions up and down your chain of command
  • Stay out of creeks, canyons, and chimneys in or below the burned area during precipitation
    • Designate low-lying areas as high-risk and communicate them to personnel
  • Identify all drainage crossings and bridges where access/egress may be cut off by flows
  • Be alert for signs of a mudslide/debris flow (loud wind-like noises, trees falling down, rolling materials)
  • Maintain awareness of locations where ingress and egress may be impacted
  • Set trigger points to leave the burned area (rain observed in the burned area, radar indicated storms)
  • Identify safety zones and staging areas where resources can safely wait until the risk has passed
  • Never attempt to cross a flow or flash flood – “Turn around, don’t drown.”
Anatomy of a mudslide showing the activity during heavy rain.
(Source: USA Today)

Discussion Questions:

  • What time of year and in what geographic areas can you expect heavy rain over wildfires?
  • Have you ever been in a mudslide/near one? Explain what it looks like and sounds like to others in your group.
  • Think back to an experience when rain caused or posed a threat of debris flows on a fire.Did you consider the above bullet points? What course of action did you take and what protocol did you follow?How was this information communicated?

References:

Category
Miscellaneous Fireline Hazards, Operational Engagement, Weather - Fire Behavior

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NWCG Latest Announcements

LMC Equipment Bulletin 26-001: Aquatic Invasive Species – Seasonal Reminder for Mussels

Date:  July 30, 2026
Questions? 
Please contact: Equipment and Technology Subcommittee

The Logistics and Equipment Management Committee (LMC) issued Equipment Bulletin 26-001: Aquatic Invasive Species - Seasonal Reminder for Mussels, reminding the wildland fire community that aquatic mussels continue to be a problem. Mussels rapidly colonize hard and soft surfaces, including aquatic plants and fire equipment, clogging pipes, fouling motors, disrupting water systems, and impacting native species.

To help prevent their spread, fire personnel must follow the decontamination procedures outlined in the NWCG Guide to Preventing Aquatic Invasive Species Transport by Wildland Fire Operations, PMS 444. Additionally, report any sightings immediately to your Lead Resource Advisor and include clear, close-up photos (with a pen or your hand for size reference) and location details.”

Read the complete LMC Equipment Bulletin 26-001, to learn more. 

References:

NWCG Alerts

LMC Equipment Bulletin 26-001: Aquatic Invasive Species - Seasonal Reminder for Mussels

NWCG Guide to Preventing Aquatic Invasive Species Transport by Wildland Fire Operations, PMS 444

Intermediate Faller (FAL2) Position Task Book Update

Date:  July 24, 2026
Questions? 
Please contact: Tree Felling Subcommittee

NWCG Operations Management Committee (OMC) has issued an update to the NWCG Position Task Book for Intermediate Faller (FAL2), PMS 311-91. To ensure clarity for both trainees and evaluators, the updated FAL2 Position Task Book (PTB) explicitly states who is authorized to sign off on your tasks:

“Evaluators must be qualified as a FAL2, or an Advanced Faller (FAL1).”

If you are currently working out of a previously published version of the FAL2 PTB, you do not need to restart. However, OMC highly encourages you to take the following step to prevent any confusion in the field:

  • Print and replace the updated evaluator information page (page 2) in your current physical PTB.

References:

Intermediate Faller (FAL2) Position Page

RMC Memo 26-01: Transition Plan for Implementing Updates to Intermediate Faller (FAL2) Position Qualifications

NWCG Position Task Book for Intermediate Faller (FAL2), PMS 311-91

Equipment Advisory 26-001: Potential Front Driveline Joint Failure on 2018 and Earlier Ram Pickups

Date:  July 10, 2026
Questions? 
Please contact: Equipment and Technology Subcommittee

The Logistics/Equipment Management Committee (LMC) has released Equipment Advisory 26-001: Potential Front Driveline Joint Failure on 2018 and Earlier Ram Pickups. This advisory highlights multiple U.S. Forest Service regions reporting front driveline joint failure incidents.

This advisory recommends firefighters and fire managers to: 

  • Follow all Ram-issued inspection, maintenance, and service guidance for front driveline joints. 
  • Consider installing a driveline loop. 
  • Coordinate with fleet managers and service providers to determine the most appropriate driveline loop kit for each pickup.

For further details, please refer to the complete advisory.

References:

Equipment Advisory 26-001: Potential Front Driveline Joint Failure on 2018 and Earlier Ram Pickups

Technical Service Bulletin: 03-002-21

NEW! NWCG Standard Operating Procedures, PMS 900

Date:  July 9, 2026
Questions? 
Please contact: NWCG Staff

NWCG is excited to announce the publication of the NWCG Standard Operating Procedures, PMS 900.

The new publication establishes general, consistent, and uniform standards for conducting business with the National Wildfire Coordinating Group.

References:

NWCG Standard Operating Procedures, PMS 900