Ville de Laval

    Spring Flooding, Ice and Floods

    Laval is an island surrounded by water. The Division sécurité civile of the Service de police de Laval steps up its monitoring of water levels at certain times of the year in order to prevent flooding.

    ​Spring Flooding Monitoring

    Updated: May 15, 2020 at 3 p.m.

    Present status: Recovery

    From March 15 to May 15 of each year, the Division sécurité civile (emergency preparedness division) of the Service de police de Laval carries out its seasonal spring flood watch. This period is more prone to flooding due to warming temperatures, melting snow and the break-up of ice cover.

    Update on the situation

    Weather: Check the local forecast​​

    • Decrease in water levels on the Mille Îles and des Prairies rivers, as well as the flow of the Outaouais river at the Carillon dam.
    • Little precipitation expected over the next week.
    • Reservoirs north of the bassin des Outaouais will store runoff produced from melting snow cover.

    To come

    Rest assured that specialists are closely monitoring the situation to detect any potential problems. Flood watch with on-site crews is now set up. Ville de Laval will inform you if the situation deteriorates.

    On this page

    > Status of the situation
    > Floods and COVID-19> Interventions and Recovery> Press releases
    > Floods: documentation and general information
    > Spring flooding> Frazil ice and safety on the rivers in winter> Watercourse monitoring> Response strategies> What to do in case of a flood?> For more tips
    > Spring flooding 2019

    Status of the situation

    Floods and COVID-19

    Despite the situation related to the COVID-19 pandemic, Ville de Laval continues to be mobilized in order to support its riverfront residents and has been preparing for the spring flood season for the past several months. 

    It should be noted that in case of flooding, Ville de Laval—faced  with the spread of a pandemic virus and in order to protect its employees and maintain its services—will not be able to provide assistance similar to 2019. However, it is working to ensure that emergency vehicles always have access to risk areas, provide essential services to the residents concerned, protect municipal infrastructure and support vulnerable populations.

    Ville de Laval strongly recommends that in order to be quickly informed, Laval residents subscribe to the City's communications in order to receive important notices or notices of emergency situations.

    What you can do during the COVID-19 situation

    Although Ville de Laval workers are deployed to install protective measures in various exposed areas, you have an important role to play to ensure your safety, that of your family and to safeguard your property. 
    Get ready now :
    • Find a solution for your own shelter in the event of an evacuation.
    • Inform your loved ones and the City of where you plan to take shelter.
    • Follow hygiene and physical distancing orders in all your actions related to the spring flooding, especially when filling sand bags and building dikes.
    In this regard, the Organisation de la sécurité civile du Québec (OSCQ) recommends specific work techniques (in French)​​ for building dikes.

    Health recommendations on COVID-19issued by the Ministère de la Santé et des Services sociaux will also apply in the event of flooding. 

    Interventions and Recovery

    Maps of planning zones for spring flooding-related operations

    To find out in which zone your home is located, consult the interactive map or call 311.

    Find out the planning zones

    Measures in place

    • Proactive distribution of sandbags: 
      • Zone A on the Des Prairies river and Zone A on the Mille Îles river
      • Zone B on the Des Prairies river

    Note that a sandbag and pallet collection will be carried out (in French)​​ will be carried out starting May 25 and will take place over several weeks. Residents who had built dikes to protect their homes can safely remove them. In order to recover the sandbags, they must be placed at the entrance of the residence or on the property, by the roadside. Pallets can be placed with the bags.

    • Installation of temporary protection measures: 
      • Zone A on the Des Prairies river and Zone A on the Mille Îles river
      • Zone B on the Des Prairies river 

    Note that the City will begin the dismantling of the temporary protection measures deployed (in French)​​ from May 18.

    Note that other operations planning zones (OPZs) could be activated depending on the developments of the situation.

    Sand depot

    Depending on how the situation develops, the City may open self-serve sand depot sites for residents at strategic locations. If necessary, bulk or bagged sand will be spaced out and physical distancing and hygiene measures will have to be followed by everyone present.

    Services for flood victims

    In order to avoid the risk of contamination, no accommodation center will be opened by the City to house flood victims. Services for riverfront residents and flood victims will be managed off-site as much as possible.

    Please note that the City invites flood victims to call 311 to help them find temporary accommodation if they become affected and are unable to find alternative accommodation.

    Press releases

    Floods: documentation and general information

    Floods can be caused by one of the following elements, all of which have a direct impact on water levels and flow rates: 

    • Increase in the flow of a watercourse by heavy rainfall, snowmelt or dam failure
    • Reduction of water flow space through the formation of frazil ice or ice jams 
    • Local increase in water level at locations exposed to high winds

    Floods bring many consequences :

    • Damage to objects and buildings
    • Food and drinking water contamination
    • Damaged or closed roads and bridges
    • Power outages
    • Evacuation from home or workplace
    • Accidents and drowning

    Flood-prone areas

    Land and buildings in the 0-20-year floodplain (high-velocity zone) have a greater than 5% chance of being flooded every year, while those in the 20-100-year floodplain (or low-velocity zone) have between 1% and 5% chance of being flooded annually. Beyond this area, the annual risk of flooding is less than 1%. 

    The rules applicable to development, construction and renovation in these areas as well as the flood levels and maps defining their boundaries are defined by the following 3 legal instruments:

    Spring flood​​ing

    Spring flooding is caused by the rise in the water level of a river, well above normal levels. The spring flooding season is generally between March 15 and May 15 of each year.

    Various factors influence the flood risks associated with spring flooding:

    • Ice break-ups: Accumulation of large patches of ice following the melting of the river ice cover and increased water flow rate, which can cause very rapid local flooding. Ice break-ups are also possible in winter during major thaws. As the Mille Îles and Des Prairie rivers are quite wide, this risk is relatively low, however.
    • Snowmelt and rain: Creates an increase in the flow rate of the watercourses of the Ottawa River watershed and other rivers that flow into the Lac des Deux-Montagnes and the Mille Îles and Des Prairies rivers. A large amount of snow combined with rapid melting and heavy rains are increasing the risk of flooding.
    • Dam management: Dams make it possible to control part of the spring water inflows into the Ottawa River watershed, which impacts the rivers surrounding Laval. The reservoirs fill up with water in the fall and their level is lowered as much as possible during the winter to allow the maximum amount of water to be retained during the rise in water levels in the spring. However, this retention capacity is limited by the size of the reservoirs, the risk of flooding upstream and the many rivers not controlled by a dam. Near Laval, the Carillon and Rivière-des-Prairies hydroelectric dams have no retention capacity, while the Grand-Moulin dam regulates the amount of water entering the Mille-Îles river.

    Frazil ice and safety on the rivers in winter

    The frazil ice production period on the rivers is generally between December 15 and February 15 of each year.

    A winter flood may be caused by frazil ice—those ice crystals or fragments that look like slush and that are formed when water comes into contact with cold air. Frazil ice, swept by the current, tends to stick to objects, resulting in ice jams and potentially causing floods as well. Snow, ice and frazil ice accumulating on the water tend to impede water flow.

    Safety on the rivers in winter

    Prior to the formation of ice cover on rivers, the water can be very cold. Be sure to wear a life jacket at all times to ensure your safety.

    The mild temperatures and the snow accumulations may prevent the formation of an ice cover of a safe thickness on the rivers surrounding Laval. Keep in mind that it's always dangerous to venture out onto the ice. 

    • If possible, avoid any activities on bodies of water. 
    • Remain on marked trails, which are regularly checked by qualified people.
    • Stay far away from thin layers of ice and stay informed on ice thickness.
    • If someone unfortunately falls in the water, immediately phone 9-1-1 and toss a rope to the person in distress, taking care not to put your own life at risk.

    Firefighters of the Service de sécurité incendie de Laval are trained to effectively perform rescues in winter conditions. Do not hesitate to contact them if you witness an emergency situation. ​

    Watercourse monitoring

    14 telemetry stations are strategically located around Île Jésus and monitor the water levels of the Des Prairies and Mille-Îles rivers, making it possible to monitor the changes in levels and issue alerts in the event of a problem situation. A camera has also been installed to monitor specific situations in real time. However, this data is not available in real time, as it must be validated and interpreted in advance. Ville de Laval also has access to government probes that improve its system.

    During spring flooding season, flow rate forecasts are produced by the Ministère de l'Environnement et de la Lutte aux changements climatiques and by Hydro Météo to guide the City's actions. When the situation becomes more worrisome, the City can also deploy an on-site watch in more sensitive areas.

    Public tools for monitoring watercourses

    Response strategies

    What to do in case o​f a flood?

    Health ​r​​​​isks

    The Centre intégré de santé et de services sociaux (CISSS) de Laval can give you information if you are worried about your family's health or your own, with regard to mould, unsanitary conditions, etc. In case of doubt, you may consult the Laval en santé website or phone 811.​

    In case of a crisis or difficult situation: call 811 and select option 2.

    Qualified psycho-social counsellors are available 24 hours a day, 365 days a year, to answer your call. They can provide support, advice and information or refer you to the appropriate resources in the region. 

    For non-urgent health problems: call 811 and select option 1. 

    By calling 811, you can quickly reach a nurse in the event of a non-urgent health problem. The service is available 24 hours a day, 365 days a year. Info-Santé 811 nurses provide advice and can answer health-related questions.

    For more tips

    Corporation des maîtres électriciens du Québec - En cas de sinistre​​​​(in French)​​

    Ministère de la sécurité publique - Flooding​​​

    Urgence-Québec - Flooding​​​

    CISSS Laval - Inondations​​(in French)

    Public Safety Canada - Get prepared​​

    Canadian Red Cross - Floods​​​
    Évitez de vous retrouver... les pieds dans l'eau, 1 Mb (in French​)

    Insurance Bureau of Canada - All about insurance and water damage, 1 Mb

    Insurance Bureau of Canada - To better understand: flood insurance, 462 Kb

    Sécurité publique Québec - Preparing for ​Disasters​​

    Programme général d’indemnisation et d’aide financière lors de sinistres réels ou imminents​​ (in French)

    Spring flooding 2019