The Squamish-Lillooet Regional District has received the results of the Seton Portage Area Integrated Hydrogeomorphic Risk Assessment (“Assessment”) conducted by BGC Engineering Inc. (“BGC”) in 2017.
BGC was engaged to determine the hydrogeomorphic hazards and risks, including risk to life, buildings, critical facilities, business activities, culturally significant sites, and critical infrastructure like roads, bridges, railway, power, and communication lines. For the purposes of the Assessment, hydrogeomorphic hazards are defined as hazards stemming from Bear/Pete’s, Whitecap and Spider creeks and include floods, debris floods, debris flows and bank erosion on the Portage River (also known as the Seton River or Portage Creek). Additionally, hazards were assessed that could indirectly affect steep creek processes such as deep-seated landslides.
The Assessment was prompted by an increase in debris flowing down from steep creeks after heavy rainfall events 2015 and 2016, which raised concerns about the potential risk to the communities of Seton Portage and Tsal’alh.
The Assessment has confirmed the potential for land movement events that put 59 buildings below the Bear and Pete’s Creek drainages above the tolerable individual safety risk threshold and at a high priority for risk mitigation measures. Of these 59 buildings, 44 are on land within SLRD Electoral Area B and 15 are on Reserve Lands administered by Tsal’alh. According to the BGC analysis, debris flow risks from Bear and Pete’s creeks are much higher than risks from other creeks at Seton Portage. Safety risk from Whitecap Creek was assessed as tolerable (note that there is one building at higher risk but there are plans to move it), and safety risk on Spider Creek was assessed as acceptable. Further study of Portage River (also known as the Seton River or Portage Creek) was recommended.
The Assessment is available to download in the SLRD’s online Report Directory (filter for Emergency Management reports).
For additional background, please visit the Seton Portage Area Integrated Hydrogeomorphic Risk Assessment Project Page.
This notice is published in accordance with Section 25 of the British Columbia Freedom of Information and Protection of Privacy Act.