Flood mapping for the Chemainus River watershed is imperative after last year’s historic flooding event, according to North Cowichan Mayor Al Siebring.
Speaking at the Cowichan Valley Regional District’s regional services committee meeting on Jan. 27, Siebring endorsed a recommendation from CVRD staff that the district submit an application to the National Disaster Mitigation Program for a $473,000 grant to update flood mapping of the Chemainus River.
“Flood season is coming and we urgently need to deal with this now,” he said.
“We really want to move forward on this before we get to the next flood season.”
A Category 4 atmospheric river passed over the Cowichan Valley over two days on Jan. 31 and Feb. 1, 2020, bringing torrential rains that flooded the region and its rivers, including the Chemainus River, causing numerous evacuations and a state of emergency to be declared by the CVRD.
The region all around Westholme experienced extreme flooding during the event, as well as the Island Highway in the area, Russell Farm Market and the Halalt First Nation’s reserve.
In a letter to the CVRD written by Siebring on behalf of North Cowichan council, he said last year’s flood is only one example of the need by all levels of government to manage the flows related to the Chemainus River watershed, which covers a number of local government jurisdictions.
“Our staff, CVRD staff, Halalt and other senior staff from the province have been in ongoing discussions regarding this matter since the summer, and the creation of a long-term flood management plan was an outcome of those discussions,” Siebring said.
“Our staff have been collaborating with CVRD environmental services thus far to move the project along, led by the CVRD environmental services division. Further, the municipality has a Bonsall Creek watershed plan in which an early priority has been modelling of the watershed. The river and creek affect one another at high flood stage as evidenced in January 2020, warranting a combined study.”
Siebring said North Cowichan has already committed $100,000 toward a combined mapping study.
A staff report by Jeff Moore, the CVRD’s senior environmental analyst, said flood mapping in B.C. has been the responsibility of local governments since 2004.
He said most provincial floodplain mapping is now several decades old and may not incorporate recent changes to river channels, nor the increased intensity of rainfall projected due to climate change.
“The (CVRD’s) environmental services division has recently completed updates to the flood mapping for several floodplains within the region, including Shawnigan Lake and portions of the Cowichan and Koksilah Rivers,” Moore said.
“A 2018 risk assessment suggested that the existing provincial flood mapping for Cowichan Lake was still reasonably accurate, given climate projections. The remaining floodplain in the region, the Chemainus River, was last mapped in 1991. As illustrated by the devastating flooding on the Chemainus River in February 2020, updated flood mapping to inform flood mitigation is urgently needed in this floodplain.”
The regional services committee voted to recommend to the board that it submit the grant application for the flood mapping on the Chemainus River to the NDMP.
Alison Nicholson, the CVRD’s director for Cowichan Station-Sahtlam-Glenora, suggested that the board hold workshops on the CVRD’s overall regional floodplain management and strategies moving forward.
“Flooding will only get worse in the future,” she said. “I’m feeling out of the loop at this point.”