2021 Fraser River Freshet Information
May 11, 2021 Update:
The overall snow basin index for the entire Fraser River basin (e.g. upstream of the Lower Mainland) decreased to 109% from the April 1st index of 116%. As of May 1, 2021, the provincial River Forecast Centre has indicated the peak flow at Hope will likely be in the range of 7,500 to 10,500 m3/s. (9,000m3/s forecasted). This is a slight reduction from the April 1 forecast however weather is still a key factor for determining peak flows.
April 1, 2021 Update:
The overall snow basin index for the entire Fraser River basin (e.g. upstream of the Lower
Mainland) increased slightly to 116% from the March 1st index of 115%. By early April,
approximately 95% of the annual B.C. snowpack has typically accumulated.
As of April 1, 2021, the provincial River Forecast Centre has indicated the peak flow at Hope will likely be in the range of 8,000 to 11,500 m3/s. (9,500m3/s forecasted). As a comparison, the peak flow in 2012 was 11,700 m3/s, which equated to a peak water level at Mission Gauge of 6.4m (approximately a 1:20 year event). In 2012, some areas in the unprotected floodplain outside the dike system experienced flooding, but the water levels were well within the range that Chilliwack's dike system is designed to withstand.
The river levels in 2012 also caused the local groundwater table to rise, which resulted in some water getting into basements in parts of Fairfield Island. Residents in that area should review steps they can take to minimize possible damage in the event the water table rises to a similar level this year, such as having a sump pump and moving items off the basement floor.
Higher flows than 2012 are not predicted, however could occur this year depending on weather patterns in the coming weeks. The peak typically occurs between May and July, and the City will be closely monitoring conditions and forecasts.
Each year, regardless of snowpack conditions, the City undertakes spring flood preparedness measures including checking all flood protection infrastructure and reviewing and updating our Fraser River Flood Response Plan.
Information was provided in the presentation to Council on April 20, 2021.
Please also refer to these pages for more information:
For more information, please call our freshet information line at 604.793.2757.
|Fraser River Freshet Slides for Council - April 21, 2020||2020-04-21||843KB|