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A peek inside the $1.4-billion revitalization that will provide new homes, new jobs, wildlife habitat, and, yes, flood protection.
I’m standing in the hot sun on the top deck of a three-metre-high observation tower made of metal scaffolding looking out over a sprawling construction site. With me is Ken Dion, who works with Waterfront Toronto, the agency that oversees development on the city’s waterfront. In front of us, to the south and east, dump trucks and concrete trucks rumble past on dusty Commissioners Avenue and turn onto Cherry Street. Here and there, behind what must be kilometres of safety fencing, are huge mounds of earth, stacks of pipes, and all manner of heavy machinery. Construction workers move about, wearing, like us, white hardhats and orange safety vests. In the middle distance, a sleek white metal bridge spans a river, and, just to the east, is the red-and-white, 124-metre-long Sunnanvik, a cement carrier ship moored in front of a Lafarge Canada Inc. plant.
From our modest perch, Dion and I are getting a bird’s eye view of one of North America’s biggest infrastructure undertakings: the Port Lands Flood Protection Project. It’s an ambitious multi-year $1.4-billion redevelopment scheme — rooted in citizen activism in the 1980s and an award-winning design by American landscape architect Michael Van Valkenburgh Associates — that will forever reshape a key chunk of Toronto’s waterfront by rerouting the mouth of the Don River. Dion, who’s Waterfront Toronto’s director for Port Lands integration — among other duties, he makes sure all the project elements are designed and coordinated with each other and conform to environmental standards — says the project is remarkable not only for its massive scale but also because it has encountered scant public opposition.
“The river portion has been extremely well received,” says Dion, recalling a public meeting held just before the project’s initial environmental assessment was submitted for approval. “We had about 500 people show up. And usually, when you're in a public meeting, it's a lynching. But every time someone presented some aspect of the project and took a breath, people got up and started giving a standing ovation. It was just so much support.”
The folks at the meeting had good reason to be pleased. Over the next decade or so, Villiers Island — one of two new islands created as part of the project — will include almost 5,000 new homes, including up to 2,700 units of affordable housing, employment for some 2,900 people in retail and cultural spaces, and 25 hectares (62 acres) of new parkland for active outdoor recreation for thousands of residents and visitors. The project’s centerpiece is a newly built 1.3-km naturalized river valley that will serve as the new outlet to Lake Ontario for the Don River, provide extensive wetland habitat, and, most importantly, protect approximately 240 low-lying hectares of Toronto’s downtown — roughly encompassing the land bordering the southernmost section of the Don and the Port Lands between there and Ashbridges Bay — from catastrophic flooding.
“If you're going to develop in an area like this, you have to eliminate the risk of flooding from a river,” says Dion, gesturing to everything around us. “All of our flood protection design criteria are aimed at making the Port Lands able to withstand a massive hurricane, which is well beyond a one-in-1000-year flood event.”
Reducing Flood Impacts
Toronto has seen only one hurricane: Hurricane Hazel in 1954, which was the most destructive storm in the city’s history and remains the Ontario benchmark for catastrophic flooding. On July 16, 2024, Toronto suffered its most recent bout of severe flooding when 100 millimetres of rain drenched the city in a matter of hours and quickly overwhelmed the city’s stormwater infrastructure. Storm sewers overflowed and swamped roads and basements. About 100,000 Torontonians lost power. In the central part of the city, the swollen Don River tumbled downstream to Lake Ontario, swamping the Evergreen Brickworks site, parts of the Don Valley Parkway, and sections of railroad tracks that parallel the Gardiner Expressway.
The troubles near the mouth of the Don occur because, for roughly a century, the 38-km river hasn’t emptied into Lake Ontario like a normal river. Instead, it runs into the Keating Channel, constructed in the 1890s to connect the Don to Toronto Harbour so nearby industries could ship and receive goods. Unfortunately, the Keating was built at a right angle to the Don’s mouth to avoid a huge wetland — the Ashbridge’s Bay Marsh — that existed at the time and was seen as both a health hazard and barrier to development. Today, during a major storm event, fast-flowing water (or ice, during the spring thaw) can spill over the Keating’s concrete channel wall and flood the low-lying 290-hectare industrial and residential area — the former marsh, which was infilled — to the south and east. The new Port Lands river channel will solve this problem by allowing the Don to follow a more natural, meandering course before it empties into Toronto Harbour.
Indeed, even though a small temporary dam at Lakeshore Boulevard still prevents most of the Don from flowing into the new river valley, the July 16 storm proved that the new Port Lands design is working the way it’s supposed to. “The increased waters travelling down the Don River moved through the Keating Channel,” recalls Dion about this summer’s rain event. “There is a small notch that was installed in the [dam] earlier to facilitate bank protection works where it meets the wall, and some of the flood water and debris flowed around that notch. As a result, the water level in the new river was a little higher than usual, but otherwise, the storm did not impact the construction site.”
“Though July 16 was a large flood, it was still a much smaller flood than the project is designed for,” notes Dion. “However, given that there were no impacts, even with most of the north plug in place and the SDMA [sediment and debris management area] in an incomplete condition, suggests that the project would function as designed under much larger flood conditions.”
The Big Clean Up
Because the objectives of the Port Lands project go beyond flood protection to include housing, wildlife habitat, and cultural amenities, creating the new valley involved much more than simply carving out a giant trench south of the Keating Channel.
For starters, the soil the crews had to dig out of the Port Lands was contaminated. Lakefill was dumped into the area between 1912 and 1922 to fill in Ashbridge's Bay Marsh and create new industrial land south and east of the Keating Channel. (Today we know what’s left of the erstwhile marsh as Ashbridge’s Bay.) But before that, the marsh had been compromised by sewage and other waste flowing into it via the Don River. In subsequent decades, the infilled soil was further contaminated by oil refining, coal tar manufacturing, waste disposal, and other activities.
To deal with the toxic soil, Port Lands work crews dug it up, piled it up on-site, and, over months, treated it with specialized bacteria that fed on hydrocarbons and broke them down into their relatively benign constituents. Any soil too polluted to be treated was trucked away and remediated elsewhere. As the project moves forward, the remaining mini-mountains of soil — some trucked in from elsewhere, some remediated soil from the site, some untreated but deemed clean and safe enough to be reused on the site — will be spread around to raise the level of the new Port Lands district between three and six metres above the level of the river to provide an extra element of flood protection for the homes and businesses that will eventually occupy the site.
However, soil remediation was only one part of the work. Before any soil could be dug out, workers installed three “plugs” — basically, small reinforced concrete dams — at either end of the future river valley and another along its course to keep water from the Don and the harbour out of the new valley as the excavation proceeded. Still, as the soil was being removed, polluted groundwater kept seeping in. To address the issue, engineers built a fully functioning water treatment plant next to the river valley. Every day for 1,412 days, 967,000 litres of polluted water was pumped out of the trench, treated, and pumped into Lake Ontario. The treated water was cleaner than the water in the lake.
Since it was impossible to remove all the contaminated soil in the area, the project engineers had to ensure no polluted groundwater would infiltrate into the new section of river, either during its construction or in the future. The solution was to cap the bottom of the channel with multiple layers of clay and impermeable matting, the same technologies used in landfills to prevent pollutants from leaching out. Here, the technique was used to stop pollutants from leaching in. The riverbanks were then lined with large flat boulders (or “stone armour”) and old tree trunks (“anchored wood”), to protect the riverbank from erosion during a significant flood event.
Bringing The River Back to Life
Yet another step in the creation of the river valley was to plant — individually, by hand — its banks with thousands of native plants, trees, and shrubs, and carefully nurture them so they’d be fully established for birds and other wildlife once the new watercourse was linked to the Don River. Interestingly, some of the wetland plants were grown from seeds that were buried during the infilling of the Port Lands in the late 1800s and early 1900s.
“During the excavation, we dug down to the original peat layer of the old marsh,” says Dion. “Then we had to dig in another area for the summer, but at the end of the summer, we got a phone call from the construction crew saying, ‘I think someone should come down here. Something's growing.’ So we got down here. There was a large area of the peat layer that had been left untouched by construction, and seeds from the original wetland that had lain dormant for over 120 years underneath a heavily industrialized area had germinated. So we had a big swath of river bulrush established.”
This discovery provided an ecological bonanza. Workers harvested seeds, the new plants, and a lot of the ancient peat. The bulrushes were replanted in wetlands in nearby Tommy Thompson Park and the Leslie Street Spit, and each of the new Port Lands wetlands has a 20-centimetre later of peat from the original marsh. University of Toronto researchers also took peat samples and germinated plants from the seeds it contained. These plants also found new homes in the new wetlands.
“We found some insane number of species of seed and pollen,” says Dion. “It really gives you an indication of the resilience of nature.”
“It was some insane number of species of seed and pollen that were found,” says Dion. “It really gives you an indication of the resilience of nature.”
To Dion’s delight, the new plantings are thriving and the engineered wetlands adjacent to the river are already attracting fish, beavers, ducks, and other wildlife, just as they were designed to do.
“Perhaps one of the more intriguing species that used the newly connected river channel was a male bowfin, which was guarding its nest of eggs and fry,” says Dion. “Bowfin are a native predator often referred to as a living fossil, going millions of years back into the fossil record, and they can even breathe air. Of course, we’re all very excited about how fast fish and other wildlife are being recruited to the newly constructed habitats.”
Connecting the Channel
Starting in February of this year, water was slowly pumped into the new river valley from Lake Ontario to a level that matches that of both the Don and the harbour. The west concrete plug at Cherry Street was removed in early July, finally connecting the channel with the harbour and Lake Ontario. The north plug will be removed this fall.
Once all the concrete plugs are gone, Dion says that during a major storm, roughly 60% of the Don’s water will flow through the Keating Channel, while the rest will flow through the new channel, which is about five metres shallower. To prepare for a worst-case stormwater scenario, Port Lands project engineers also built a two-hectare artificial wetland called the Don Greenway, at the southeast curve of the new river valley, to act as a relief valve during severe storms. If the Don overflows its banks, the excess flow will flow into the new wetland and then into the Shipping Channel to the south, which in normal (non-flood) conditions is the source of the wetland’s water. Fortunately, this didn’t happen on July 16.
Parks and Recreation for All
Public parks and nature trails are an important component of the project and will complement the Leslie Street Spit, Tommy Thompson Park, and Cherry Beach, which neighbour the Port Lands. In all, there will be two parks created, totaling 25 hectares of new green space, including 11 hectares of parkland. River Valley Park, as its name suggests, borders the riverbanks and will serve as a floodplain during a major flood event. Promontory Park, which has yet to be funded and is currently an expanse of packed and rutted earth, will take up the portion of Villiers Island west of Cherry Street. Both parks will include specially designed, nature-themed playgrounds — safely located above the projected high-water mark of a major storm — that allow kids to safely explore and challenge themselves.
Preparing for the eventual construction of new housing and business space on Villiers Island and connections to transit and utilities has required a lot of engineering. For instance, Cherry Street was rerouted, and two sleek steel bridges were built along its length: The Cherry Street North bridge across the Keating Channel, and another 425 metres further south, spanning the mouth of the new Don River outlet. A third bridge was installed where Commissioners Avenue crosses the new river valley. The bridges incorporate built-in conduits that can accommodate water and sewer lines since they can’t be laid across the river without tearing the cap and stirring up contaminants. The Cherry Street North bridge is actually two bridges: one for passenger vehicles and trucks, and another for an eventual LRT line that will connect Villiers Island with the rest of Toronto’s transit system. Of course, walking and bike paths will be everywhere — a total of 6 km of new trails — as a big part of the overall sustainability plan is to make the island as pedestrian- and bike-friendly as possible. And, of course, you’ll be able to canoe and kayak on the river.
The Future
It’s rare for a city to undertake a scheme as large, complex, and costly as the Port Lands project, but Toronto (supported by matched funding from the Ontario and federal governments) is pulling it off. Over the next few decades, as the climate changes in ways no one can exactly predict, it will be interesting to see whether the flood-protection elements built into the Port Lands will remain effective. If they do — and so far, there’s every indication that they will — the coming generation of Torontonians will have a new, world-class precinct where they can live, do business, and enjoy nature on the city’s waterfront. It just goes to show that a little citizen activism and hard work can go a long way.
Like what you’re reading? Check out our story about Toronto’s east-end microforest.
