A long-awaited study on flooding in the Alouette Valley suggests digging out the riverbed of the North Alouette at 224th Street and creating a policy to ensure flooding won’t worsen if farmland elevation is raised or dikes are built.
But both of those steps have already been taken, says local farmer Ken Knechtel.
“There’s already those requirements, you can’t hurt your neighbour,” by increasing the flooding risk when working the land, he said Tuesday.
“We’ll have to wait see where it goes from here.”
And Maple Ridge has already decided to excavate the North Alouette at the 224th Street crossing, to remove silt and deepen the channel and reduce flooding risk.
That’s confirmed in a staff report introducing the summary of the North Alouette and South Alouette Rivers Assessment and Flood Plain Analysis.
The study concludes the river is doing what it’s done for the past century, flooding periodically and causing damage to properties nearby.
It also concludes, the river flows aren’t worsening, despite an historic high-water flow in March 2007, when an estimated 245 cubic metres rushed down the North Alouette River. That may have been caused by a blockage in the stream nearby suddenly giving way, a footnote adds.
The report also notes that other high flows, ranging from 118 cubic metres per second to 162 m3/s, took place on 10 occasions over the past 30 years.
Northwest engineer Tamsin Lyle told council that there are four ways in which the Alouette system can flood: through heavy rainfall, by backflow from a flooding Fraser River, through erosion or sedimentation of the river channel, and from log jams or blockages.
Coun. Craig Speirs said it’s obvious, “the stream bed is rising.
“We need to know what we can do and what we can’t do.”
Coun. Linda King questioned why any development is even allowed in the flood plain, saying the cost is too much for taxpayers.
“We should not be building there at all because we’re just going to create problems for people and ourselves.”
But Coun. Cheryl Ashlie said most people in the Alouette Valley are worried about the effect of raising farmland elevations and how that affects others in the floodplain and wanted that as a priority. That’s been one of the most commonly raised issues during her first term on council, she added.
Council has been waiting a long time for the report, added Coun. Mike Morden. “We need to get the ball rolling a little bit.” Funding for the study was approved in 2007.
He asked if staff can address the role of the Agricultural Land Commission in managing the floodplain.
The study points out that the North Alouette is more unstable than the South Alouette, whose flow is regulated by the Alouette dam.
It also suggests that connecting the two rivers by building a channel could also help reduce flood risk, but that could be expensive and have some environmental costs.
It suggests that the district only allow any new flood protection measures provided they don’t increase the overall flooding risk in the area.
“A no-net adverse impact flood level policy should be implemented for future developments on the flood plain.”
Any solutions will also require a multi-disciplinary approach, says the staff’s covering report. Those would be implemented over several years.
“That’s been flooding down there for centuries,” said Mayor Ernie Daykin.
“We haven’t issued any fill permits in that area in the last couple of years.”
Maple Ridge engineer Andrew Wood said staff will review the report and meet with the Alouette River task force.