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Spring Flooding and Floods

Spring flooding is the natural increase in water flow and levels in rivers due to snowmelt. A flood occurs when a watercourse overflows its banks.
Floods remain a risk on an island bordered by two major waterways. Here’s how to prepare for them.
Where and when is flooding a risk?
Certain areas, especially those near rivers, are more prone to flooding. These floods often occur during the spring freshet, typically between March 15 and May 15. Certain hydrometeorological phenomena can increase the risk of spring flooding (late thaw, heavy rainfall, significant runoff). Strong winds can also worsen the situation.
There are several ways to protect yourself or minimize flood damage :
- Contact your insurer to check coverage for sewer backups, groundwater infiltration, and river overflow.
- Ensure the maintenance and proper functioning of your sump pump and the watertight closure of your sewer backflow valve.
- If you live in a flood-prone area, store valuables on higher levels during the spring freshet.
- Secure objects that could be carried away by the current (patio chairs, docks, etc.).
- Prepare a family emergency plan and a go-bag for evacuation. Ensure you have supplies for at least 72 hours.
- Identify a shelter location in advance (family, friends, etc.).
- Protect building entrances (windows, doors, garage, etc.) with a sandbag barrier. Étapes de construction d’un muret (PDF guide, 558 ko). Check government financial assistance programs and grants available for temporary protective measures.
- Clear storm drains, gutters, and ditches of debris (ice, branches, leaves, etc.).
- Move furniture, electrical appliances, and important items to higher levels.
- Take detailed photos of your property and belongings before any disaster and store them in cloud storage or on a USB drive outside your home.
- Follow safety instructions from authorities.
- Use pumps to remove water, but never use gas-powered equipment indoors to avoid carbon monoxide poisoning.
- Call 911 to report situations where life, health, or safety is at risk.
- If conditions worsen, leave your home before roads become impassable to avoid driving through floodwaters.
- Turn off electricity if water starts rising near electrical systems.
- Stand on a dry surface and use a wooden stick to avoid contact with the electrical panel. Call an electrician if necessary.
- Shut off the main gas supply and secure propane or oil tanks if flooding is imminent.
- If electrical systems have been affected, they can cause electrocution or fires. Immediately notify Hydro-Québec to cut power.
- Stay away from fallen power lines, even during an outage.
- Block drains and sewer lines with a cloth if water backs up.
- Avoid walking in floodwaters without tall waterproof boots, as they may be contaminated.
When to Call 311?
- If your home is flooded (Call 911 if the water reaches electrical installations)
- When you evacuate your home
- When you return home
- For information requests
After a Flood
- Contact your insurance company.
- Do not drink tap water until the City gives the all-clear. Let water run for a few minutes when first reopening the tap. Check well water safety before drinking.
- Disinfect items ans discard any food and medications that came into contact with floodwater.
- Have an electrician inspect your electrical system and heating appliances before reconnecting them.
- Watch for mold and call a specialized company if needed.
- Document damages, take photos showing water levels, and inform your insurance company and the City of Laval.
- Quickly demolish and decontaminate flooded areas to prevent mold growth. Seek professional help if necessary.
- Keep records of all steps taken and receipts for cleaning and repair work for your insurance claim.
- Regularly update stored photos, especially after renovations or major purchases.
- Contact 211 for assistance from community organizations.
What to Do for Your Home After a Flood
Consult the reference document (In French) prepared by the Société d’habitation du Québec for guidance on post-flood home recovery.
How to assess the safety and sanitation of a building
After water infiltration, act quickly to prevent mold growth, which can cause health problems.
Look for :
- Musty, earthy, or alcohol-like odors.
- Green or black stains on walls, ceilings, cabinets, or behind unremoved materials.
Consult Quoi faire pour votre maison à la suite d’une inondation?
Learn how to identify and eliminate mold in the house.
Information on mold.
Restoring Your Home after a flood
- Property owners must secure the premises and prevent mold without delay.
- Removing damaged finishing materials (floating floors,Wall covering, door frames) does not require a permit.
- Some minor work, like painting or the replacement of the interior wall covering (gypsum), is considered maintenance and does not need a permit (In French).
- For major structural renovations, contact the Urban Planning Department for a renovation permit.(Interior residential renovation ou Exterior residential renovation (In French)).
How are waterways monitored?
Interested in how Laval monitors waterways? The City has installed 14 telemetry stations at strategic locations around Île Jésus. These stations track water levels and generate alerts.
A camera is also used for monitoring, but data is not available in real-time as it must be validated first. Laval also accesses government sensors for additional monitoring.
Several tools help track water flow :