Debris Flow

Debris flows are very fast-moving, liquefied landslides that carry soil and other debris including boulders, and vegetation. Debris flows are most often triggered during periods of intensive rainfall resulting in high soil saturation levels but can also be triggered by rock fall or avalanche on unstable slopes. Known debris flow hazards within Squamish include the Cheekye Fan and Stawamus River.

If you live near or visit areas prone to debris flows, you should become familiar with the terrain between your property and the creek channel and fan apex. During a major flood event, creeks may suddenly change course and flow along a new or abandoned flood channel, and debris flow material may run out onto the fan area. Terrain features to be aware of include: abandoned creek channels; levees; scarred trees; and local deposit features.

If you have further concerns regarding how your property may be affected, you may wish to consult a qualified professional for assistance. It is possible to design elements on your property to mitigate debris flow and landslide risks. If concerns exist on public property, please contact the District of Squamish immediately.

Debris Flow Hazard Map website2Debris Flow Hazard Areas

What to do in the event of Debris Flow

Debris flows can happen quickly and with limited warning. It is best to be vigilant during heavy rainfalls or immediately after hearing unusual sounds. It is best practice to immediately evacuate yourself and your family if you notice any of the following around your area:

  • Sounds of intense cracking or falling trees, particularly in the absence of strong winds, or sounds of boulders knocking together;
  • Rapid water or slurry flow, where it has not been observed before;
  • If you are near a stream or channel, be alert for irregularities or any sudden increase or decrease in water flow and notice whether the water changes from clear to muddy. Such changes may mean there is debris flow activity upstream so be prepared to move quickly.

If no escape is possible:

  • Find cover in the section of the building that is furthest away from the approaching debris flow;
  • Take shelter under a strong table or bench;
  • Curl into a tight ball and protect your head.

If you have not observed any of the above debris flow warning signs but an official warning has been issued in your area, the best way to stay safe is to evacuate the premises regardless of imminence level.

Be sure to visit our Preparedness page to learn how you and your family can help stay safe in an evacuation. Please also consult the Community Evacuation Map to plan your route safely away from the current emergency.

If the debris flow has already occurred be aware of the possibility of a secondary debris flow and new hazards as a result of the event. If you are currently safe it may be best to not evacuate the area but wait for emergency responders to come to your aid.