Response Undertaken on Seton River to Address Freshet Flood Risk on Anderson Lake

Apr 28, 2016
Affected Communities: 
All Areas


With assistance from CN Rail, the Squamish-Lillooet Regional District’s (SLRD’s) Emergency Program extracted several large boulders from the mouth of the Seton River at Seton Portage yesterday morning, in order to improve water flows out of Anderson Lake, and decrease the risk of freshet flooding to the communities around the lake.

The boulders were a consequence of the September 2015 debris flow that impounded Anderson Lake for several days and reduced the channel capacity of the Seton River by approximately fifty percent. The Lake level rose by approximately one metre as a result of this debris flow, compromising its ability to absorb the typical spring run-off.

Following the unseasonably high temperatures of 18-22 April, the SLRD, supported by BC Water Stewardship and Emergency Management BC, initiated a response plan to the freshet flood risk on Anderson Lake.

This morning, a CN rail-mobile excavator was able to extract the boulders from the river and they were then removed from the riparian corridor. Water flow from Anderson Lake through the Seton River improved immediately.

On-site technical assistance was provided by the Ministry of Forests, Lands and Natural Resources Operations (MFLNRO) Regional Flood Safety Engineer, and environmental oversight was provided by an environmental technician from Triton Environmental Services.

Sand bags are being coordinated for a few properties in Seton Portage, and the SLRD is working with the Seton Volunteer Fire Department to ensure that those residents wishing to protect their properties have access to sand bags from a central location. N’Quatqua Fire Department has coordinated a sandbagging effort to protect the N’Quatqua pump house facility, which supplies the communities of N’Quatqua and D’Arcy with drinking water. Sandbag supplies are expected to arrive within two days.

The SLRD will continue to monitor the situation closely. The SLRD thanks all those partners and stakeholders, including CN Rail, the Ministry of Forests, Lands and Natural Resources Operations’ Regional Flood Safety, the Department of Fisheries and Oceans (DFO), Emergency Management BC, N’Quatqua, and Tsal’alh for their collaborative efforts.

Residents with questions or concerns should contact Ryan Wainwright, SLRD Emergency Program Manager at 604-698-6442 or



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