The Third wave of the ‘atmospheric weather’ is upon us and Environment Canada is maintaining the Rainfall Warning for the region. Rainfall is expected to continue through to Wednesday evening. The forecast calls for rainfall totals ranging from 60 to 80 mm in low lying areas of the Fraser Valley and as much as 120 mm in the mountain areas.
BC Hydro continues a controlled release from the Alouette Reservoir and the rainfall forecast in the next 48 hours will likely result in the dam reaching ‘freecrest’ level resulting in an uncontrolled release into the South Alouette River on Wednesday afternoon or evening depending on rainfall amounts in the watershed. As this occurs, river levels and flow rates have the potential to increase significantly. BC Hydro are monitoring flows into the reservoir and will have a revised model on Wednesday which we will share in our daily update. The higher flows could potentially result in flood impacts for properties in the Alouette Basin as noted in the attached map.
The North Alouette levels and flow rate will rise as this third wave of rain continues. This will likely result in additional flooding and road closures on 224 Street north of 132 Avenue and along 132 Avenue between 216 and 232 Street.
The Kanaka water system is expected to have high waterflows and volumes throughout the next rain event lasting into Thursday.
On Monday City staff delivered letters to properties throughout the Alouette Basin with the greatest risk of impacts from flooding due to an uncontrolled release from the Alouette Reservoir into the South Alouette.
The City is preparing for the worst potential impacts from this third wave of rain. The potential freecrest water release from the Alouette Reservoir may result in flooding of the 232 Street access into the Silver Valley and Rockridge neighbourhoods, Golden Ears Park and the UBC Research Forest. Combined with flood related closures of 224 Street along the North Alouette, this would result in a complete road closure for these areas until the waters recede. Therefore, citizens in these neighbourhoods are being advised to prepare to ‘shelter in place’ for up to 72 hours until safe access is available.
The attached map reflects the properties that are currently estimated to be at risk of flood impacts. The City will develop new mapping when BC Hydro updates their forecast for the Reservoir inflows related to this weather system.
As a precaution, the people who are boarding horses or livestock in the hatched area of the attached map should consider moving their animals out of the area until the rainfall event ends.
It is important to be prepared for the conditions at the high end of the forecast rain amounts. The information available at this time indicates the peak flows on the South Alouette may happen on Wednesday evening into Thursday morning.
Sand and sandbags are available at the 232 Street parking lot at Maple Ridge Park adjacent to the South Alouette Bridge. Sand and sandbags have also been dropped off at the north parking lot of Maple Ridge Park off fern Crescent. There is also sand and sandbags at the parking lot adjacent to the Hammond outdoor pool at 20601 Westfield Avenue.
Citizens are encouraged to sign up for notifications through the City’s Alert Centre at mapleridge.ca/list.aspx. You can subscribe to Emergency Alerts or any other notification you choose. With the option to receive email or text notifications. Please share this information with your friends and family. Stay safe.
Updates will be posted as a spotlight on the City’s website at mapleridge.ca.
Updates are also posted on the City’s Facebook page @yourmapleridge. We encourage you to follow our posts there for road closures and other updates.
You can get the latest information on regional road impacts online at DriveBC.
A new update will be posted on Wednesday as weather forecasts and projected flows into the Alouette Reservoir are updated by other agencies. Thank you for your patience, for your preparation and for sharing this information with your friends and neighbours.