Toronto’s human-made river is about to cross its biggest milestone to date

The Don River’s course into Lake Ontario will soon be redirected through a new human-made river mouth, marking perhaps the most significant milestone to date in what will prove the defining feature of Toronto’s monumental $1.3 billion Port Lands Flood Protection Project (PLFP).

Crews have begun removing an underground wall that connects the river with the new artificial waterway carved through the Port Lands, meaning the long-industrialized Don River will soon once again terminate in a meandering wetland for the first time in over 100 years.

A new video shared by Waterfront Toronto offers an update on the new valley’s forthcoming reconnection with the Don River, a long-awaited step in the unprecedented renaturalization project.

Don Forbes, project director at Waterfront Toronto, calls the river “one of the biggest civil works projects in North America,” boasting, “there’s never been anything like this. It’s massive.”

Forbes notes that it’s more than just the project scale that makes it “truly unprecedented.”

He acknowledges that there are “lots of other flood protection projects around the world,  some even involving rivers. But never has anyone engineered an entirely new river,  creating an island for a new community, designed to protect that community from flooding, all doing it through contaminated lands.”

“To make this happen, we built a new river and wetlands, as well as cleaning up contaminated soil and raising the grades in the surrounding area,” says Forbes.

He goes on to explain that the entire river valley was divided by underground walls referred to as plugs, saying that these retaining structures “kept the excavation area dry and stable while we dug the new river.”

“When we filled the river, we left a cutoff wall at either end, which allowed us to fill it in a controlled way. We call these walls the ‘plugs’: the north plug, where the Don River will eventually flow into the new river valley, the west plug, where the new river will meet Lake Ontario, and the south plug, which will connect one of the wetlands to the ship channel.”

The river valley was filled back in February 2024, and once the water level was equal with the lake, crews began removing the west plug this past July to finally connect the flooded trench with Toronto Harbour.

Work has since begun to remove the north plug dividing the river valley from the main course of the Don River.

The north plug takes the form of a one-metre-wide reinforced concrete wall that extends from the bedrock below the riverbed to a couple of metres above the waterline.

These structures are engineered to withstand a beating, so removing them is no simple task and requires heavy equipment and plenty of time.

Forbes explains that crews are using an excavator equipped with a grinder attachment to chew away at the concrete, leaving behind just the steel beams. These reinforcing beams will then be cut off by divers and pulled out of the river using an excavator.

You can witness the removal unfold from the new Commissioners Street Bridge, though it’s a process that might require some patience from onlookers, as Forbes says, “removing the north plug will take a little while.”