terrifying jmage

by Cyrene Oraya Reyes--Fri 19 Dec 2025

The Toronto wetland restoration project, which cost approximately 1.25 billion Canadian dollars from multiple government levels, proved that nature has remarkable staying power. When workers brought soil from Lake Ontario’s bottom to create new wetlands, seeds that had been buried for over a century began sprouting. Tiny water fleas and other organisms emerged from their long dormancy to populate the restored habitat.

The project, which began in December 2017 and completed by the end of 2024, transformed 250 hectares of industrial land at the Port Lands into a functioning wetland system. Workers excavated contaminated soil and replaced it with sediment dredged from the lake bottom. That sediment contained seeds and dormant life forms that had been waiting underground since before Toronto became a major industrial city.

The unexpected revival of different wetland fauna and floral species was documented. Plants that hadn’t grown in the area for generations appeared without being planted. Water fleas called Daphnia emerged from the sediment and began filtering algae from the water. These tiny crustaceans had survived in a dormant state called diapause for decades.

The restoration reconnected the Don River to Lake Ontario through a naturalized mouth. For more than a century, the river had been channeled through a concrete straightjacket that prevented it from forming wetlands. Industrial activities had contaminated the surrounding land with heavy metals and other pollutants.

The project required removing contaminated material accumulated during decades of industrial use. Lead, mercury, and petroleum products had saturated the soil. Workers transported this hazardous material to approved disposal sites before bringing in clean sediment.

Engineers moved six million cubic meters of soil during construction. They created marshes, channels, and flood plains that mimic natural wetland functions. The new landscape allows the river to meander and flood safely, protecting downtown Toronto from storm surges while creating wildlife habitat.

Engineers created proper hydrology and  designed water flow patterns that prevent stagnation while maintaining moisture levels wetland plants need. Gates and weirs control water movement during different seasons and weather conditions.

Native plants began appearing within months of completing the earthwork. Cattails, bulrushes, and sedges sprouted from seeds that had remained viable in the lake sediment. These plants established root systems that stabilized shorelines and filtered pollutants from water flowing into the lake.

The Toronto wetland restoration demonstrates seed longevity in aquatic environments. Seeds can remain dormant in oxygen-poor sediment for extraordinarily long periods. When exposed to light, water, and air again, they germinate as if only a few seasons had passed.

Water quality measurements showed rapid improvement after wetland plants established themselves. The vegetation absorbed excess nutrients and trapped sediment. Fish species that had abandoned the polluted river mouth began returning to spawn in the restored marshes.

Daphnia populations played an unexpected role in making the water clear. These water fleas consume algae and bacteria, acting as natural filters. Their emergence from century-old sediment meant the wetland gained this cleaning function immediately, rather than waiting for populations to colonize from elsewhere.

Bird populations increased dramatically as the wetlands matured. Waterfowl found nesting sites in the marsh grasses. Herons and egrets arrived to hunt in the shallow waters. Songbirds used the wetland edges as migration stopovers.

Fish surveys documented 40 species using the restored wetlands. Some come from Lake Ontario to spawn in protected marshes. Others live permanently in the channels and pools. This diversity indicates water quality has reached levels that support sensitive species.

The flood protection aspect addresses urgent climate concerns. Increased storm intensity threatens low-lying urban areas. The wetlands absorb storm surge and heavy rainfall that would otherwise flood streets and buildings. This dual-purpose design maximizes the value of restored land.

Monitoring continues as the ecosystem matures. Scientists track which plant species thrive and how animal populations develop. This data informs future urban wetland restoration efforts in other cities facing similar challenges with degraded waterfronts.

Maintenance requirements remain minimal compared to engineered alternatives. Natural wetlands largely manage themselves once established. Occasional invasive species removal and water level monitoring comprise most ongoing work. This makes wetland restoration cost-effective over the long term.

The Toronto wetland restoration shows that cities can reverse environmental damage even in heavily industrialized areas. The key involves removing contamination, restoring natural water flow, and allowing native species to reestablish themselves. Patient observation reveals that nature retains the capacity to heal when given the opportunity.

The project transformed a liability into an asset. The Port Lands had been contaminated, flood-prone, and largely unused. The restored wetlands provide recreation, education, flood control, and wildlife habitat while improving water quality entering Lake Ontario.