Flood Forecasting

Flood Forecasting and Warning

The responsibility for dealing with flood emergencies in Ontario is shared by municipalities, conservation authorities, and the Ontario Ministry of Natural Resources and Forestry. As with all emergencies, municipalities have the primary responsibility for the welfare of residents and are required to incorporate flood emergency response into municipal emergency planning. Conservation Authorities are primarily responsible for operating a forecasting and warning system and for monitoring and advising municipalities on flood conditions. The Ministry of Natural Resources and Forestry coordinates the provincial response in support of municipal action and supports the Conservation Authority’s flood forecasting programs.

Conservation Authorities have several areas of responsibility for flood emergencies:

  1. Monitor watershed and weather conditions and operate a flood forecasting system to provide a warning of anticipated or actual flood conditions.
  2. Issue flood alert and flood warning bulletins to municipalities and other appropriate agencies to advise of the potential for flooding.
  3. Operate conservation authority dams and flood control structures to reduce the effects of flooding.
  4. Provide advice to municipalities for preventing or reducing the effects of flooding.
  5. Maintain communications with municipalities and the Ontario Ministry of Natural Resources and Forestry during a flood event.

Conservation Halton monitors, on an ongoing basis, weather forecasts and watershed conditions and uses this information to assess the potential for flooding. When spring melt or severe storms are anticipated Conservation Halton estimates the severity, location and timing of possible flooding and provides these forecasts to local agencies.

Conservation Halton Flood Terminology 

The current terminology was adopted by Conservation Halton, other Conservation Authorities across Ontario and the Ontario Ministry of Natural Resources  and Forestry (MNRF) in February, 2012. The change is to ensure flood messages are consistent and in line with severe weather terminology used by other agencies such as Environment Canada and the Weather Network. The terms were developed by a committee of representatives of Conservation Authorities, Conservation Ontario, the Ministry of Natural Resources and Forestry, Environment Canada, and other agencies

The following is the flood and water safety message terminology  used by Conservation Halton:

Normal: Conditions are within normal limits. No flooding is expected;
  Watershed Conditions Statement: a general notice of weather conditions that could pose a risk to personal safety or which have the potential to lead to flooding. There are two variations of these:
Watershed Conditions Statement - Water Safety: High flows, unsafe banks, melting ice, or other factors could be dangerous for recreational users such as anglers, canoeists, hikers, children, pets, and others. Flooding is not expected
Watershed Conditions Statement - Flood Outlook: Early notice of the potential for flooding based on weather forecasts calling for heavy rain, snow melt, high wind, or other conditions that could lead to high runoff and cause ice jams, lakeshore flooding, or erosion.
Flood Watch: Flooding is possible in specific watercourses or municipalities. Municipalities, emergency services, and individual landowners in flood-prone areas should prepare;
Flood Warning: Flooding is imminent or already occurring in specific watercourses or municipalities. Municipalities and individuals should take action to deal with flood conditions. This may include road closures and evacuations.


Flood Forecasting and Warning Links:

Floods and You

If a flood message is issued in your area, take heed and follow the advice and instructions of the emergency response authorities. As a precaution, consider what you can do in advance to be prepared for flood emergencies.


The following information can help get you started in thinking about emergency preparedness and developing an emergency plan for you and your family:

  • Halton Region has compiled information on what you can do before, during, and after a flood to safeguard yourself and your family;
  • Ontario Ministry of Natural Resources has compiled some emergency management facts on floods;
  • Environment Canada also has information on what you can do before, during, and after a flood to safeguard yourself and your family.

More Information