It was monsoon season in Squamish, so the record rainfall of October 2003 did not even seem out of the ordinary. At least, not until the water came within a foot of overtopping some of our dikes and many homes were flooded. The damage estimate from this flood event was approximately $40 million and about 800 people in the corridor were directly affected. More troubling than this was the thought of what could have happened if the water had been slightly higher. Experts now tell us that this was a one-in-150-year flood event. The recommended provincial standard is to have a flood protection systems that can withstand a one-in-200-year event.
On Jan. 11, 2011, Council received the results of a consultant's report titled the "Squamish River and Mamquam River Survey and Flood Assessment." This two-phase report first collected topographical and bathymetric survey data to assess the current river hydraulics. The second phase developed a hydraulic model and assessed potential future flood profiles. In summary, it concluded that considerable additional flood hazard mitigation is required to meet the provincial standard. In particular, kilometers of dike upgrading in the Lower Judd Slough, Eagle Run and North Yards areas is recommended. The cost estimate for this work ranged from $1.4 million to $2.8 million. In addition, the study indicated that approximately 115,000 cubic meters of sand and gravel should be removed from the rivers annually to maintain flood water capacity. A report by another engineering firm assessing concerns associated with water seeping through or under the dike in the Eagle Run area ("piping") will be brought forward to Council in the near future. The upgrading required to resolve this concern will also be expensive.
There has been significant work done to our flood protection system in the years since 2003. However, much of this work was to repair damage from that flood. The recent consultants' reports make it crystal clear that the community should focus on upgrading our flood protection systems. It is easy to forget about flood protection until there is an emergency situation, so it is important that we give this issue the priority it deserves. The District of Squamish engineering staff will be bringing forward information on work programs, cost estimates and funding sources this spring. Let's ensure that our community supports completing this work on a timely basis. It is not a question of if, but simply when, the next major flood event occurs.
For more details, our staff report and the Kerr Wood Leidal Flood Assessment Report can be accessed at www.squamish.ca by opening the January 11, 2011 Committee of the Whole Agenda. Thank you for your attention to this is fundamental community protection issue.
