Summer Safety Message
Be Aware of Urban Flooding Due to Thunderstorms
Conservation Halton is reminding residents of the dangers that exist near rivers, streams, ponds and lakes due to high intensity thunderstorms. Thunderstorms can develop suddenly during the warmer months and are often accompanied by strong winds, hail, lightning and heavy rain. Residents should be aware that flooding can occur very quickly with passing thunderstorms.
River flooding occurs when rivers and streams rise over their banks and spill into the surrounding land. With high intensity summer thunderstorms, watercourses within Conservation Halton’s jurisdiction can receive large amounts of precipitation over a short period of time, causing water levels to rise with little warning. This type of flooding is more common in urban areas.
Summer Safety Tips – River Flooding
- Stay away from riverbanks and avoid recreational activities in watercourses during storm events, especially thunderstorms.
- Do not drive through, stand, or walk in any moving water. Avoid low-lying areas such as road underpasses and walkways.
- Stay informed on storm events such as thunderstorms through local radio, television, mobile, or other public alerting systems.
- If you are instructed by emergency officials to evacuate due to flooding, do so immediately.
- If you are in danger, call 911 immediately.
Flood Forecasting and Operations Program
Conservation Halton provides a flood forecasting and operations program to reduce the risk of property damage and loss of life due to flooding. When flooding is possible or about to occur, Conservation Halton issues flood messages to municipal officials, emergency medical services, police, school boards and media. It is the responsibility of municipal officials to warn local residents.
Conservation Halton is responsible for the maintenance and operation of four major flood control dams (Kelso, Hilton Falls, Scotch Block and Mountsberg) and more than 12 kilometers of flood conveyance channels (Sixteen Mile Creek through Milton, Morrison-Wedgewood diversion in Oakville and the Hager-Rambo diversion in Burlington).
The following is the flood and water safety terminology that is used by Conservation Halton, as well as other conservation authorities throughout Ontario, and Ontario Ministry of Natural Resources and Forestry. The terms were developed by a committee of representatives of conservation authorities, Conservation Ontario, the Ministry of Natural Resources and Forestry and Environment Canada, to ensure alignment with terminology used by other agencies such as the Weather Network.
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/or cause ice jams.
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.
Shoreline Hazard Watch: High water levels and waves along the Lake Ontario Shoreline (within Conservation Halton jurisdiction) that could lead to flooding and erosion caused by a combined water level of above 75.1 m (IGLD 1985) and forecast offshore waves of greater than 2.0m (related to public safety and erosion risks) or a static water level between 75.5m – 75.9m (IGLD 1985).
Shoreline Hazard Warning: High water levels and waves along the Lake Ontario Shoreline (within Conservation Halton jurisdiction) that could lead to flooding and erosion caused by a static water level > 75.9m (IGLD 1985).