Hazard information

A dam is a structure that holds back water in a river, lake, pond or stream. 

Dams are made of concrete, timber cribs filled with rocks or steel sheet piling. They can also be formed from a bank of earth or rock fill.

Dams are used to:

  • produce hydropower
  • support recreation and tourism
  • support navigation
  • mitigate high or low water levels
  • limit the spread of invasive species
  • support wetland habitat management

Extreme floods are one of the primary causes of dam failure. When lake and river levels rise due to heavy rain or fast-melting snow, water levels can exceed the capacity of the dam.

Safety tips

If you are an individual

Awareness is your best defence. 

If you notice warning or caution signs at the dam site, follow the instructions, stay back and leave the area.

If you live, work, or play near a dam, stay informed by following local flood warnings and emergency advisories issued by authorities, including any dam-specific notifications where applicable.

Contact local authorities immediately if you notice:

  • dam failure due to structural issue or extreme weather events
  • a washed out or unsafe bridge
  • stored water released in an uncontrolled manner
  • potential danger to people or watercrafts on, around or near dams
  • muddy water, ice jams, water over the dam deck or debris build up

If you are a dam owner

Practice your emergency preparedness plans annually to ensure you are ready to implement them during a dam failure emergency.

The Ministry of Natural Resources provides technical guidance and best management practices for design, construction, operation, maintenance and safety of dams. Private dam owners are responsible for the maintenance and safe operation of their structures.

This includes guidance on:

  • dam safety
  • how to identify public safety hazards associated with dams
  • how to eliminate or mitigate these hazards

Prepare now

Take the following steps so you and your family are prepared in the event of a dam failure:

  • Contact your local municipality to learn more about your community’s emergency response planning process.
  • Learn and practice evacuation routes, shelter plans and flash flood response.
  • Keep important documents in a waterproof container. Create password-protected digital copies.
  • Monitor for potential causes of dam failure, such as heavy rain, and regularly check for local flood messages and current conditions.