Should Toronto Islands get ready for another flood?
Scientists expect average water levels in Lake Ontario to decrease slightly with climate change, but stronger storms mean Toronto Islands could face flooding.
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Packed sandbags, some faded and frayed, still stand guard on Ward’s Island. While they are unnecessary for the moment as the receded lake laps gently at the shore, not so long ago they were an integral part of the island’s defence against flood waters.
Scientists say they could be needed again. As climate change progresses Environment Canada expects Lake Ontario’s average water level to decline slightly, but a changing climate also causes stronger storms and that means the Toronto Islands could face more flooding like the kind faced this spring and summer.
Michael Page, who has called the islands home since 1983, isn’t going anywhere, though. “I will be on the island until I die,” he said, sitting on his second-floor deck in the early October sun. “I really love living here, it’s a fabulous place.”
He wants an engineering solution that will protect the islands and their tight-knit community from future threats. And after the dramatic flooding this year, public bodies are mobilizing to figure out what those threats are and what can be done about them.
Environment Canada and other agencies that monitor the great lakes are planning further research to determine just how likely it is we’ll see Lake Ontario rise to similar levels again. Meanwhile, the Toronto Region and Conservation Authority has applied for funding to pay for a flood risk assessment on the islands, building on the lessons they learned this summer.
The task before them is not an easy one.
It was the “rain, rain, and more rain” in the spring that caused Lake Ontario to reach unprecedented levels this year — 75.9 metres above sea level — the highest the islands had seen since at least 1918, when the first reliable measurements of the lake were taken, said Frank Seglenieks, a water resources engineer with Environment and Climate Change Canada.
“We just got hit by storm after storm,” he said.
As Lake Ontario was rising, flooding in Ottawa and Montreal was at its peak, compounding the situation facing the islands.
The flooding to the east restricted how much water a dam in Cornwall, Ont. could release from Lake Ontario into the St. Lawrence River, which was already inundated with high waters from the Ottawa River. Lowering the lake by 10 cm would have raised the water in Montreal, where thousands of people had already been evacuated, by one metre, Seglenieks said.
So the water continued to rise in Lake Ontario. Later, its recession was hampered by higher-than-normal inflow from the other great lakes, prolonging the flooding.
“It was something that certainly caught us all by surprise,” said Rehana Rajabali, a senior engineer with the Toronto and Region Conservation Authority flood risk team.
This spring was the first time this generation of TRCA flood duty officers, who are on call 24/7 to monitor weather and watershed conditions, faced lake-based flooding. Before, they focused on Toronto’s “flashy” network of rivers and creeks, receiving a bulletin about the lake levels from Environment Canada just once a month.
But the flood risk team adapted quickly to their new reality. They began monitoring the lake daily and used high-resolution elevation data to map the vulnerability of the islands to flooding.
While riverine flooding in the Toronto area happens quickly, as water runs swiftly along hard, impervious surfaces into rivers and creeks. Lake flooding is a “slower burn,” which means there was more time to put protective measures — like sandbags and sump pumps — in place, Rajabali said.
Islanders and staff from both the city and the TRCA spent hours filling sandbags and stacking them to protect homes and other infrastructure. Pumps were spread across the island. It was a community effort, Page said.
Despite those measures, the water kept coming.
At times the water levels were so high that standard emergency vehicles couldn’t reach parts of the islands, said Nancy Gaffney, who leads the TRCA’s watershed programs.
Some days, the waves crashed over the first line of sandbags on Ward’s Island and water seeped up from below, soaked up through the “great big sandy sponge,” Page said.'
At the height of it, his front yard was a “duck pond” and 15 inches of water pooled below his house almost as fast as he could pump it out, warping the wood floors on the first level. It still smells musty and damp.
Climate models suggest the Toronto region will see more precipitation in the future, but that doesn’t tell us much about what will happen on Lake Ontario. To know that, you have to consider what’s going to happen on Lake Superior and Lake Huron, then Lake Michigan, Lake Erie, and finally Lake Ontario.
“It’s one big system, you really have to study the whole thing,” Seglenieks said.
According to an international climate study of the upper great lakes, which Seglenieks was part of, the average water levels in Lake Ontario are expected to decline by up to 20 cm between 2035 and 2065 as evaporation outpace precipitation.
“There’s nothing that says it’s going to be hurricanes coming up to southern Ontario and deluging Lake Ontario with a big tsunami or anything like that, we definitely don’t see things like that, but in general we do see some stronger storms,” Seglenieks said.
He added that we should be prepared for the highest highs and the lowest lows, plus a “safety factor.”
The TRCA’s risk assessment, which is expected to kick off in March, is a first critical step, Rajabali said.
It will consider the range of possible lake levels and what areas are most at risk, ultimately, helping determine what permanent changes are needed to make the islands more resilient.
“You can’t stop the lake from going up or down there isn’t control over that but what you can do is understand how to… protect the islands,” Rajabali said.
In the short term, the city will raise the roads to ensure emergency vehicles can access all parts of the island during storms. They’re also planning to establish some long-term pump systems and protective berms, Gaffney said. Even before the flooding this year, they were considering offshore protection at Gilbraltar Point where storms have repeatedly pulled away at the sand, she added.
“Toronto Islands is actually pretty resilient in that it’s been suffering from this kind of abuse from wave action for years and years and really has held its ground,” Gaffney said.
The islanders have stood their ground too. If Page is the measure it will take more than an increased risk of flooding to chase them off. Worst comes to worst, he could raise his house further off the ground, he said.