Pemberton, BC – The Squamish-Lillooet Regional District (SLRD) will share the latest findings regarding the Upper Squamish River flood hazard and risk at a community meeting planned for later this month.
Flood hazard mapping and risk assessment of the Upper Squamish River was undertaken in 2018 and the findings from that project will be shared on Saturday, January 12, 2019 from 2:30 – 4:30 p.m. at Queen of Peace Monastery (1021 Cloudburst Crescent) in Squamish (First right turn after the Pilchuck Bridge, Squamish Valley Road).
The floodplain mapping and risk assessment project was funded by a grant from Emergency Management BC. The project was commissioned by the SLRD with the work conducted by Northwest Hydraulic Consultants (NHC) Ltd., which has recently performed similar work in the Pemberton Valley, on behalf of the Pemberton Valley Dyking District.
NHC representatives will present the report findings at the community meeting and a question and answer session will follow. SLRD Electoral Area D Director / Board Chair, Tony Rainbow and SLRD Emergency Management staff will also be in attendance.
The Upper Squamish Valley is prone to recurrent flooding, while also subject to increased development. The report findings will help inform emergency management plans and future development criteria.
“This information gives us a more accurate and current picture of the flood hazard of the Upper Squamish River. We know that the area is prone to flooding and now we have the information we need to better understand the hazard so we can plan accordingly," said Tony Rainbow, SLRD Board Chair and Electoral Area D Director. This vital information provided in the report will allow for better and more accurate emergency response planning while also enabling us to best prepare for future development.”
With the Upper Squamish Valley report, NHC conducted hydrologic analysis to estimate Squamish River design flows corresponding to the 20- through 500-year flood events, including projected climate change effects.
The report shows that almost all of the valley is subject to flooding and that a potential flood caused by a landslide-blocked river could reach populated areas within a few hours and raise the water surface by several metres. The flood modeling shows that at the 50-year flood event and above, most of the valley floor is flooded with typical depths of one to two metres.
The report makes a number of recommendations including sharing the findings with key authorities, stakeholders and the public, planning new development away from high hazard areas, implementing new Flood Construction Levels (FCLs) in order to create more flood-resilient development, identifying access and egress routes which need improvements, as well as identifying the location of temporary evacuation areas. The report also recommends that consideration be given to relocating or flood-proofing existing housing and other development in extreme flood hazard areas as well as continued monitoring and surveying of the Squamish River channel.
This project completes the assessment of the Squamish River system floodplain in the Upper Squamish Valley to the District of Squamish (DOS) Boundary. The information derived from this study, in combination with an earlier DOS study, gives a complete flood risk profile to the entire Squamish River system.
The Upper Squamish River Flood Hazard Mapping and Risk Assessment report is available on the SLRD website at www.slrd.bc.ca/UpperSquamishRiverFloodHazard.
Squamish-Lillooet Regional District
Phone: 604.894.6371 x239