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Information Bulletin – April 20, 2023
Regional Direction of Civil Security and Fire Safety of the Outaouais

Flood expertise table

During spring flooding, the Ministère de la Sécurité publique (MSP) coordinates a flood expertise table to allow authorities to monitor the situation and anticipate any issues that may arise. This table, which meets weekly, is made up of experts from various departments of the Quebec and Canadian governments, as well as organizations such as Hydro-Québec (HQ) and Hydro-Météo.

Following the meeting of Thursday, April 23, 2023, here is the important information that the experts had to transmit to us for the greater Outaouais region.

Weather conditions

The rainfall received last Monday and Tuesday (April 17-18) left between 10 and 20 mm over the entire region. As for future rainfall, two separate events are expected over the next few days in Western Quebec. The first event, expected between Friday and Sunday, will bring 30 to 50 mm of rain to Abitibi-Témiscamingue. Since this rain will fall north of the Outaouais, in the regulated section of the Ottawa River watershed, the large reservoirs will be able to capture most of the rainfall.

The second weather event is expected to affect the Outaouais (southern and central Quebec) on Sunday and Monday (April 23-24). This system will bring 20 to 40 mm of precipitation and should be the only rain event observed for the next 5 to 7 days. On the other hand, it will be accompanied by a thaw, which should accentuate the effect on snowmelt.

In general, precipitation is expected to remain below normal until mid-May.

Impacts on watercourses and reservoir management

Reservoirs

Currently, the managers of the large reservoirs inform us that they are carrying out the maximum storage possible in order to allow the water from the first flood to flow into the southern part of the Ottawa River watershed and avoid accentuating its consequences. However, this strategy has the effect of filling the reservoirs much more quickly than expected.

Ottawa River

Forecasts issued by the Ottawa River Regulation Planning Board (ORRPB) show that a levelling off should be observed around Friday. These levels and flows are expected to remain stable for a period of one to two weeks and are subject to minor changes depending on actual temperatures and precipitation.

Forecast issued by the ORRPB as of 19 April 2023 / 17:00

Gatineau River

Hydro-Québec confirms that the strategy at the Baskatong remains the same as in the last few days, i.e. to keep the level at 164.9m at Maniwaki in order to let the maximum amount of water through, without any consequences for the downstream municipalities. It is specified that the withdrawal will be adjusted according to the precipitation to be received so that the level determined remains stable. No risk of flooding is anticipated.

IN SUMMARY

Two significant rainfall events are expected in the next few days. One will be captured by the reservoirs, the other will flow into the Ottawa River watershed via the various tributaries. The levels and flows observed tomorrow (Friday) will remain stable for a period of 1 to 2 weeks. Since the reservoirs are filling up quickly, it is recommended to remain cautious and to ensure increased monitoring of the hydrometeorological conditions to come in the next few weeks.

Other relevant information

The MSP would also like to remind you that a wide range of relevant information on spring flooding is available on the Government of Quebec’s web portal in the “Safety and Emergency” section.

You will also find an information and awareness kit designed to help municipalities prepare for the next spring flood. This kit contains information, awareness, preparation and steps to follow in the event of a disaster.

You are also invited to consult the various tools of our partners, which are made available to you to enable you to be aware of changes in the water level of rivers and reservoirs, the flow of watercourses, the state of the snow cover, future weather conditions, etc.

Finally, don’t forget that the Government Operations Centre receives, processes and transfers to the appropriate responders calls from government and municipal emergency lines to report a civil security emergency, 24 hours a day, 7 days a week. If you have noticed a natural disaster such as a flood, a landslide or any other event that could compromise the safety of people or essential infrastructures in your municipality, do not hesitate to contact the GOC.

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