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Designing a wildlife refuge at the mouth of the Don

From Inner Harbour looking east towards the Don River.

Promontory Park looking west towards inner harbour

Looking west from Don Roadway over Commissioners Street.

Looking southwest over the Don River and Keating Channel

Snowy Owl at the Leslie Spit.

Snails rest on a wildflower at Tommy Thompson Park.

Earlier this month, Waterfront Toronto and its government partners announced $5 million in funding to complete due diligence work on a flood protection proposal for the mouth of the Don River. A reclamation of the concrete Keating Channel, the plan will see the development of an 88-acre urban island called Villiers Island, and increased naturalization of the 988-acre Port Lands area to include green space and wetlands. A mixed-purpose design that encompasses protection for up to Hurricane Hazel-level flooding in addition to creating a space that city dwellers can enjoy, the project is in equal part a reclamation of built space to allow for wildlife habitats. And, in nearby Tommy Thompson Park on the Leslie Street Spit, planners have the perfect local case study to draw from.

An internationally-recognized urban wildlife refuge

“Tommy Thompson Park, and the Leslie Spit, are one of the best examples of urban wildlife enhancement and very significant urban wildlife habitat within not only the GTA but also North America,” says Ralph Toninger, Senior Manager of Restoration Projects for the TRCA.

Though the Leslie Spit was constructed in the late-1950s and fortified throughout the 1960s and 1970s from the excess rubble of Toronto's construction boom, its reclamation as a wildlife habitat began through concerted efforts only as recently as the past two decades. Today, it is held up as an international model of urban habitat restoration. Home to a sizeable colony of double-crested cormorants, among some 300 other bird species, the spit is a designated IBA—that is, Important Bird Area—as well as a monarch critical staging area celebrated in an annual butterfly festival.

Historically, Toronto's lower shoreline was the Ashbridges Bay marsh, one of the largest coastal marshes on the Great Lakes. “Toronto's first settlers came here because marshes provided excellent fishing and waterfowl hunting,” Toninger says. Unfortunately, creation of the city's waterfront destroyed those original wildlife habitats.

Returning life to a man-made space

The move to restore wildlife populations on the spit happened in the 1990s, when reviving habitats from built environments became a broader priority among conservation biologists. Until then, conservation had largely meant preservation—in other words, building wildlife reserves rather than restoring former sites of wildlife habitat where human intervention had wiped them out.

The restoration process combined construction and engineering with biological replacement. “The goal of restoration is not to restore for any specific species, but to put ecological function back into land forms,” explains Toninger. Ultimately, restoration is considered a success if it provides habitat for the full life cycles of the species that use the area.

In practice, returning ecological function to the spit meant that the TRCA was tasked with levelling shorelines with quality soil to promote productive vegetation growth, in addition to setting up turtle nesting habitats, bank swallow cliffs, fish spawning shoals, and turtle basking logs—essential habitat features. "You can build a house that's full of empty rooms, but it's the furniture and amenities that attract people to house,” says Toninger. “The same is true of land forms."

Naturalizing the Don Mouth

In old days, flood protection usually meant erecting concrete channels. It was a space-efficient approach, but neither very pretty nor creature-friendly. The dual purpose for naturalization, on the other hand, means creating valleys that allow room for plenty of habitat.

According to Waterfront Toronto, the naturalization of the mouth of the Don River is projected to deliver four hectares of terrestrial habitat within the constructed valley system, and the creation and enhancement of 13 hectares of aquatic habitat. Three river channels will be completed—two of them new, and in addition to a modified Keating Channel—and there will be a series of levies with grasses, cattails and shrubs to the fore of 13 hectares of new coastal wetlands, which would provide habitat for fisheries, turtles. Meadows will be built for songbirds and small mammals.

“It will connect well with Tommy Thompson park and Cherry Beach,” says Ken Dion of the TRCA, who is overseeing the project's environmental assessment.

As Dion explains, flood protection systems were historically high-cost to implement and maintain, artficial, and when they failed, failed miserably. They were also barriers to wildlife. By incorporating the added purpose of naturalization, already existing habitats at the mouth of the Don River will be greatly enhanced. But there's another bonus, says Dion: “A piece of wilderness within the city, to remind people that the rivers are not sewers.”

The due diligence phase of the project is expected to continue for the next eight to 10 months. Construction is slated to begin in 2017. 

Correction: An earlier version of this article incorrectly stated that the plan would create 800 acres of parks and wetlands. In fact, the exact acreage of naturalized space has yet to be determined as the project's due diligence assessment continues. We regret the error.

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