Toronto’s harbor is a natural bay closed off by a long sandbar, and almost everything around it has been rebuilt. The sandbar became the Toronto Islands after a storm in April 1858 cut a permanent channel, the shoreline was pushed south by fill, and the federal Toronto Harbour Commissioners Act of 1911 created the body that carried out a major waterfront plan from 1912 to 1925. Since 2001 Waterfront Toronto has led the redevelopment of the eastern and central waterfront, and a new mouth for the Don River opened in 2025.
The geology of the shore, including the Scarborough Bluffs and the old lake shoreline, is covered in the article on Toronto’s elevation and topography and is not repeated here. This article follows the human changes to the harbor.
From sandbar to islands
Before 1858 the Toronto Islands were a peninsula. The Canadian Encyclopedia records that Quinn’s Hotel stood at its eastern narrows, that the first major breach of the narrows came in 1853, and that officials debated whether to protect the peninsula permanently or let nature take its course. On April 13, 1858, a severe storm cut a channel beside the hotel. The breach proved permanent, and steamers were passing through an eastern gap within a month. Other accounts give April 14 for the storm, and sources differ on how deep and wide the channel was, so those details are left out here. A history of the Toronto Islands, with park and ferry details, is in the article on the Toronto Islands.
The shoreline moves south
Downtown Toronto stands on land that was once lake. Thomas Young’s 1841 map marks the natural shoreline, which now runs roughly parallel to the south side of Front Street East between Yonge Street and Parliament Street. The curve of that shore gave Front Street its diagonal direction between Bay and George streets. After the survey, according to Spacing’s report on Heritage Toronto’s lost-shoreline project, the city filled the lake to create commercial land, and by the middle of the 1800s the shore was lined with warehouses and wharves. Heritage Toronto has announced a series of plaques on 10 streets in the St. Lawrence area to mark the old water’s edge.
The Toronto Port Authority’s history timeline records the Waterfront Esplanade as completed in 1865 and a breakwater built in 1882 to protect the Toronto Island. Railways ran along this filled strip, which is one reason the downtown core lost direct contact with the water.
The Harbour Commissioners
Control of the harbor was divided for decades. The Toronto Port Authority records that the Board of Trade began a campaign in 1844 for a harbor trust, that five Harbour Commissioners were appointed in 1850, and that ownership and control were still split among the commission, the City, the railways, and private owners. In 1911 the federal government passed the Toronto Harbour Commissioners Act, which created a single body to deal with the waterfront.
The commissioners’ plan, carried out between 1912 and 1925, cleared old piers, filled waterlots, expanded the Toronto Islands and the eastern Portlands, and developed new openings in the harbor. The timeline below lists dated items from the Port Authority’s own history page.
| Year | Event |
|---|---|
| 1865 | Waterfront Esplanade completed |
| 1911 | Toronto Harbour Commissioners Act passed by the federal government |
| 1918 | Commissioners complete their headquarters at 60 Harbour Street |
| 1922 | Sunnyside Park and its amusement park completed |
| 1929 | First civil air harbor and seaplane base; Ship Channel Bridge |
| 1939 | Island airport (now Billy Bishop Toronto City Airport) opened to the public |
| 1959 | St. Lawrence Seaway opens; Leslie Street Spit begun |
| 1975 | East gap becomes the new port entrance |
| 1991 to 1994 | 640 acres (259 hectares) of waterfront land ceded to the City and TEDCO |
The Port Authority’s page gives two dates for the end of the commission. Its introduction says the Canada Marine Act established the Toronto Port Authority on June 8, 1999, while its timeline says the Act came into effect on June 11, 1998. The organization has since carried the name PortsToronto and, according to the same page, was rebranded as the Toronto Port Authority in 2026.
Ashbridge’s Bay and the Don mouth
East of the old town lay Ashbridge’s Bay marsh. The Port Lands project history says pollution and sewage from the Town of York, and mills that blocked fish migration, had badly degraded the marsh by the end of the 19th century. In 1912 the Harbour Commission completed a plan to turn it into a large industrial district, and by 1922 the marsh had been filled to create more than 200 hectares (494 acres) of land, with 200 more planned. Later work in the 1950s added the Leslie Spit, the Hearn Generating Station, and the Commissioners Incinerator.
The Keating Channel, named for city engineer Edward Henry Keating, was built along the marsh’s northern edge, and the Don River’s mouth was redirected into its concrete lining. The Port Lands page places this in the late 1890s, while other references date Keating’s proposal to 1893 and the channel’s completion to the early 1920s, so no single year is given here. All sources agree on the result: the river turned sharply into the channel, which raised flood risk in the Port Lands. The Government of Ontario states that the layout was engineered mainly for transportation efficiency and to create port and urban land. For the other buried watercourses of the city, see the article on Toronto’s lost rivers.
The Gardiner Expressway
The Gardiner Expressway is named for Frederick G. Gardiner, the first chair of the former Metro Toronto Council, who championed it. The City of Toronto states that construction began in 1956 and that the expressway, 18 kilometers (11 miles) long, was built in segments and completed in 1965 at a cost of approximately $103 million CAD. Another City page says it was completed in 1966, so the finish year is shown as disputed. In June 2015 City Council adopted the Hybrid option for the eastern section, which keeps a continuous link to the Don Valley Parkway, and in April 2016 it approved the Hybrid 3 design of realignment.
Waterfront Toronto and the Port Lands
Waterfront Toronto came together in 2001 so that the federal, provincial, and municipal governments could work on waterfront issues jointly. It describes its designated area as 800 hectares (1,977 acres), from Dowling Avenue in the west to Coxwell Avenue in the east. The same year, the three governments named the Toronto and Region Conservation Authority as the eligible recipient of funding to naturalize the Don mouth, and the environmental assessment was approved on January 28, 2015.
On July 18, 2025, the City of Toronto announced that about 20 hectares (50 acres) of Biidaasige Park had opened on the new river mouth, with another four hectares (10 acres) to follow in 2026. The park lies beside Ookwemin Minising, a 39-hectare (98-acre) island where the Don meets the lake. The City describes the flood protection project as a $1.4 billion CAD investment by the three governments protecting 174 hectares (430 acres) of land in the Port Lands and eastern waterfront. Housing numbers for the island are projections by the City, not completed figures. Visitors and residents should consult the City and Waterfront Toronto for current access and construction details.
Frequently asked questions
When did the Toronto Islands become islands?
A storm on April 13, 1858 cut a permanent channel through the sandbar, according to the Canadian Encyclopedia. The first major breach had come in 1853.
Who ran Toronto’s harbor before 1911?
Control was divided. Five Harbour Commissioners were appointed in 1850, but the commission, the City, the railways, and private owners each held part of the waterfront until the 1911 Act.
Why does Front Street no longer touch the lake?
Front Street followed the natural shoreline shown on Thomas Young’s 1841 map. Landfill from the 1800s onward, including the Esplanade completed in 1865, pushed the water’s edge south.
Was the Gardiner Expressway removed?
Not as a whole. The City says Council adopted the Hybrid option for the eastern section in June 2015 and approved a realignment design in April 2016. The City describes the expressway as in a major rehabilitation.
Related reading
- The Toronto Islands: history and rules
- Pearson and Billy Bishop airports
- Toronto’s economy, port and housing
- Buried creeks and the rivers that stayed open
- An overview of Toronto’s history
Last verified: October 2026
Sources
- Toronto Port Authority (PortsToronto): history timeline
- Waterfront Toronto: About us; Port Lands history
- City of Toronto: news release of July 18, 2025 on Biidaasige Park; About the Gardiner Expressway
- Government of Ontario: Don Mouth Naturalization and Port Lands Flood Protection Project
- The Canadian Encyclopedia: Toronto Feature, Ward’s Island
- Spacing: Heritage Toronto lost-shoreline project (August 6, 2025)
Cite this page
APA: History of Toronto. (2026, October 23). Toronto Harbour and Waterfront: How the Shore Was Rebuilt. https://historyoftoronto.ca/blog/toronto-harbour-and-waterfront-history
MLA: “Toronto Harbour and Waterfront: How the Shore Was Rebuilt.” History of Toronto, 23 Oct. 2026, https://historyoftoronto.ca/blog/toronto-harbour-and-waterfront-history. Accessed .
Chicago: History of Toronto. “Toronto Harbour and Waterfront: How the Shore Was Rebuilt.” Last modified October 23, 2026. https://historyoftoronto.ca/blog/toronto-harbour-and-waterfront-history.
The pages have no named author, so the site is given as the author. Add the date you read the page if your style asks for it.