Flood mitigation study recommends diverting river around Harriston

·3 min read

MINTO – The Town of Minto will be contemplating future flood mitigation plans as a lengthy study makes its way to council.

The report by Triton Engineering has shortlisted some suggested actions and projects to do over a period of 20-years to mitigate issues from flooding.

Minto Mayor George Bridge said the urban area of Harriston can be prone to flooding because Harriston is settled at one of the lowest points in the watershed.

“There’s a 300 foot drop from where the water starts 20 km up north of us … we’re in the bottom end at Harriston,” Bridge said. “It’s like the bottom end of a tub, everything's gonna come at you.”

The report noted there have been 15 documented floods since it was first settled over 100 years ago.

Bridge said he can somewhat recall the damage flooding from Hurricane Hazel caused in Harriston when he was a young boy but a more recent event on June 23, 2017, made clear further action was necessary.

On that day, a 170 mm rainfall caused a storm sewer surcharge and river flooding that damaged over 160 properties, closed roads and damaged infrastructure.

This was referred to as a 100-year storm–meaning a storm that has a one per cent chance of occurring in any given year.

“That particular event was unbelievable, it basically was a thunderstorm that just sat over us for four or five hours it never moved,” Bridge said. “It just kept dropping rain on us.”

The study was prepared as a result of the historic flooding in Harriston with some recommendations to reduce the number of properties that could be affected by flooding.

Actions include removing vegetation, spoils, regrading the floodplain, improvements to the river channel and eventually a new watercourse connecting upstream Maitland River flow to Dredge Creek. that effectively diverts the river around Harriston’s urban area.

This would remove nearly all properties from the floodplain.

Bridge noted these would be implemented slowly, likely over the course of 20 years, with each step slowly working away at the number of affected properties.

Some steps won’t help too much for major events that are the scale of the 100-year storm but Bridge said they can ease the effects of smaller more common flooding.

A cost breakdown estimates this work to cost upwards of $38 million, but again this would be over a long period of time.

Bridge said federal and provincial funding will be necessary for this.

The federal government does provide some flood protection insurance for homeowners in flood prone areas but Bridge said he thinks the feds should look into flood mitigation to save money in the long run.

“They’ll do some marginal stuff for you, like, you lose a furnace … but that costs us millions and millions of dollars,” Bridge said. “We’re getting more (major storms) every year now, they’re not taking 100 years. The federal government might want to get out of the business of just putting the patch on.”

Minto council is holding a special meeting on Tuesday evening to discuss this report.

“There’s been a lot of background work to get to this point,” Bridge said. “Now we have to take all this information and try to get an engineer to put actual final costs.”

Keegan Kozolanka, Local Journalism Initiative Reporter, GuelphToday.com