Without major changes in Harriston, it seems flooding will continue to be a fact of life for residents.
Over 50 attended a recent meeting hosted by Minto with representation from Wellington County and the Maitland Valley Conservation Authority (MVCA) on hand to answer questions.
Minto Mayor David Anderson explained the meeting and emergency planning is a partnership of the three.
“We all know that Harriston has always been in the flood plain … flood fringe. We had the odd flood. It’s been part of our lives.”
That is why there is work to establish a program so that if there is a major disaster, officials would be able to react to it and keep people safe and minimize damages, Anderson said.
“We’re finding that our weather patterns are really changing. Mother Nature is just being a little … upset with us.”
He said there has been a ton of snow in Washington, “while we really haven’t had a winter here [this year].”
One of the issues is that there is no way to know for sure when major rainfall will happen. “All we can do is try to prepare for the worst … and hope it never comes.”
Anderson said, “We don’t want to lose lives.” Having a plan allows staff to react as soon as possible, he added.
MVCA water resources engineer Stephen Jackson spoke about the risk of flooding in Harriston, the impact of local climate trends on flooding and flood damage reduction strategies.
In reviewing records, Jackson said between 1910 and 1945 there were some very significant floods. From the 1940s to the 1970s there were almost none.
“But during the 1970s, those who lived in Harriston would have experienced extensive flooding,” Anderson said. Then, there were a number of years without floods again. From 2008 to 2009 there were floods.
“There is a cyclic nature to the flooding, and it’s always been there,” Jackson said.
The MVCA commissioned a study to look at climate trends within the watershed.
“What we have found is over that past 56 years, there have been some interesting trends in precipitation,” said Jackson. “Across the watershed, we’ve seen the amount of precipitation increase by the equivalent of a foot – about 30%.” That is combined with an increased intensity when rain does fall.
While the MVCA is always receiving anecdotal information from landowners about changing weather patterns, analysis of specific climate data, helped confirm that, Jackson said.
He added the area is seeing fewer winter days with temperatures below zero, which, in turn, increases the likelihood of flood events.
The first recorded flood in the area was in Listowel in the 1880s. “That was the first real summer thunderstorm” which created destructive damage in our watershed. In 1954’s Hurricane Hazel, there was about a day-and-a-half of steady rain – about 8 inches in that period.
“When we do our modeling, Hurricane Hazel is considered that regional storm.”
People might say Hurricane Hazel happened in Toronto not Harriston, but Jackson said it was only a minor event compared to a storm that recently just missed the Harriston area in 2005. “What we’re seeing are storms which may not deliver as much rain as Hurricane Hazel, but the storms are delivering the rain in a much shorter time.”
In a watershed like Harriston,that makes a big difference.
He explained with that amount of rain over two weeks, it is not a problem … but over a few hours, the flood risk increases significantly.
Jackson then spoke of an event in Molesworth in July 2005 where volunteer gauges recorded 10 inch of rain in 10 hours. As far as intensity is concerned, Jackson said that storm would exceed flows of Hurricane Hazel for Harriston.
He said the storm in Harriston in December 2008 was actually quite minor compared to events around Ontario and had only 4-inches of rain.
A similar storm in Hamilton dropped 4-feet of rain, but because it happened so quickly, it surpassed all their systems – even the ones designed to handle 100 year storms – the type that arrive once a century.
One of the issues with Harriston is because of where it is located in the watershed, “There is more of a chance of a surprise flood.”
Historically, flooding has been related to gradual snowmelt, he said. But with big storm events, flooding will happen much more quickly.
Jackson said the key message is not that the flood may not happen today, tomorrow, or two weeks from now. “The point is that the events happen so quickly, that when the firefighter knocks on your door and says that you need to pack and be out in two hours … believe me … you have two hours. Chances are in three hours, they are not going to be able to evacuate you.”
The key theme is understanding the flood risk, so people will be properly prepared.
In Harriston, there are over 200 houses in the flood plain.
He said, damage from such a flood could be $15-million.
“The unfortunate thing about that, is that according to the Insurance Bureau of Canada, there is no such thing as flood insurance in Canada.”
Jackson said residents are really covered only for sewage backup – but once water starts flowing through windows or doors the property is no longer covered. While the province does have programs that might pay for some damage, he said those are based on matching dollars raised in the community. He stressed the events of December 2008 were relatively minor compared to what could happen.
“Harriston is built on top of the river. The town just hasn’t given the river the space that it needs.”
Jackson explained three bridges in town act to slow the water and the river flows onto the flood plain through Harriston.
He said the MVCA’s role is small compared to the public perception. Jackson explained its primary role is getting information for flood forecasting.
“Environment Canada forecasts severe weather; we forecast floods. Then the municipality responds,” he said.
“And time is of the essence,” Jackson stressed.
Once the water reaches the height of the bridges, the water will start rising extremely quickly through the town.
“Once that happens, people are not going to have the opportunity to leave their homes and safely evacuate.”
Jackson said Minto made a significant investment in rain gauges upstream of Harriston, to help give people more time to evacuate. Previously, the only measurements were from a instruments downstream. Gauges upstream measure rainfall instead of waterflows.
To give an idea of the amount of water generated with 6-inch of rain from the 70 square kilometre watershed, Jackson said if all that water was on a hockey rink, the walls would have to be 6.4 kilometres high to contain it.
“That’s 12 times higher than the CN Tower.”
He said the information from rain gauges can give people an extra few hours warning, and residents have more time to prepare for the evacuation.
He said there are a number of reports dating back to the 1960s looking at how the flood risk can be minimized.
“A lot of measures … unfortunately come with a price tag of around $10- to $20-million for most of them.”
One proposal is encouraging storm water management on a smaller scale by creating numerous pockets of water to address the peak flows going through Harriston, rather than using a big flood control dam.
Many questions posed by residents focussed on what can be done to prevent floods, rather than how to deal with them when they arrive.
One said even if there is more warning, “There is still nothing in place to mitigate the flood.”
That person asked what is being done to stop floods, or at least to slow them down.
Anderson said Jackson has cited creation of small retention ponds.
But, Anderson pointed out “in all the levels of government, there is no extra funding available for a pond systems or floodway program.”
He suggested steps can be taken, but gradually. To do it properly, he estimated, would cost millions.
The resident asked if that means they are simply being asked to “put up” with the flooding.
When asked about specific plans, Anderson said the main issue is the municipality does not have the money. That it appeared, was not the answer residents were seeking.
Another resident asked what can be done to get the water out of the community faster.
Jackson explained engineering studies done on Harriston determined the community itself is the bottleneck.
“Even if Harriston was located at the top of Niagara Falls, the water still cannot get through Harriston because the bridges are so small and the water is so confined,” he said. “The fundamental fact is that the town is built on top of the river and the water has no place to go.”
Major options include d rerouting the river around the town and putting dikes through the town and improving the bridges.
“Ideally, I’d like to be able to say the MVCA?will get the funding to proceed with the options,” Jackson said.
He added, the MVCA is municipally owned and the costs would still end up coming from resident in the end. “We would like to be able to make these improvement, we just don’t have the money to do it.”
Jackson repeated that should not think about it as the water backing up into the community. “It is the river cannot get through the community in the first place.”
“The only way to [get water past the bridges] “is to either make the bridges significantly larger, or give the river back its flood plain. You can’t squeeze that volume of water under the bridges … that is the issue.”
The only low cost suggestion by residents, was to move the snow dump area from the community centre grounds to another part of the community.
The contention was the melting snow simply added to the existing problem.
Anderson assured residents that this is something that can be considered.
