Toronto's artificial peninsula set to keep growing for decades

Toronto's man-made peninsula, the Leslie Street Spit, is still growing, and will be for the next few decades to come as dredged material from the city's harbour continues to be deposited along its shoreline.

Created in 1959 by the Toronto Harbour Commissioners (THC), now PortsToronto, for "port-related facilities," the Leslie Street Spit's expected use as an outer harbour port never panned out, yet the landform has expanded significantly through millions of cubic metres of concrete, earth fill, and dredged sand, and today supports Tommy Thompson Park.

The artificial peninsula extends five kilometres into Lake Ontario and is over 500 hectares in size. The park is home to some of the largest existing natural habitats on the Toronto waterfront, and includes wildflower meadows, cottonwood forests, cobble beaches, and coastal marshes.

Aerial view of the Leslie Street Spit in 1975. Photo: Toronto and Region Conservation Authority (TRCA).

It's also become one of the best nature watching areas in the city thanks to its diverse population of birds, and the site of other recreational activities like hiking, cycling, rollerblading, and fishing.

Between 1974 and 1983, the land base increased dramatically, as 6.5 million cubic meters of sand and silt were dredged from the Outer Harbour and placed at the spit, which resulted in the formation of lagoons and sand peninsulas, which now represent a significant portion of what now constitutes Tommy Thompson Park.

The peninsula in 1980. Photo: Toronto and Region Conservation Authority (TRCA).

Each year, PortsToronto continues to remove roughly  30,0000 to 40,000 cubic metres of dredged material from the mouth of the Don River in an effort to prevent future flooding. Once removed from the channel bed, the mix of debris and sediment is transported to the Leslie Street Spit for "proper containment" in a "cell" or Confined Disposal Facility (CDF).

Aerial view of Tommy Thompson Park in 1985. Photo: Toronto and Region Conservation Authority (TRCA).

The cells, which are located at the Spit, were designed to properly contain natural material dredged from the Keating Channel. Back in 2007, PortsToronto and the Toronto and Region Conservation Authority (TRCA) finished the Cell 1 Wetland Creation Project, which converted the CDF into a seven-hectare coastal wetland, and is now home to marsh birds, turtles, amphibians, small mammals, and native fish.

"Cell 1 has been very successful to date with reports of significantly increased fish populations and the return of pike and muskie to the harbour," PortsToronto notes on its website.

Aerial view of Tommy Thompson Park in 1998. Photo: Toronto and Region Conservation Authority (TRCA).

In December 2014, PortsToronto began sealing Cell 2 with a layer of clean fill, and in September 2016, work on the cell was completed, with the result being a second nine-hectare habitat that benefited fish, migratory birds, and other wildlife species. With the completion of Cell 2 capping, the TRCA notes that it is no longer accepting fill (including concrete, bricks, or blocks) at the Leslie Street Spit.

Cell 3, which is the final cell, continues to be used for dredged materials, with roughly 30 to 40 years of capacity remaining, according to PortsToronto.

Photo: Toronto and Region Conservation Authority (TRCA).

If you're interested in seeing how the area has changed over the past few decades, you can use the Google Earth Timelapse by typing "Tommy Thompson Park" into the search bar and clicking the play button to watch its transformation from 1984 to 2022.