Sepia aerial photograph of Morrisburg, Ontario before the Seaway, showing the old canal and Lock 23 along the St. Lawrence River waterfront

The St. Lawrence Seaway & Power Project · 1954–1959

When the River Rose

To open the St. Lawrence to ocean shipping and hydroelectric power, engineers dammed the river at Cornwall — and deliberately flooded the shoreline behind it. Ten Ontario communities, some older than Canada itself, went under the water of a new lake in the summer of 1958.

Morrisburg from the air before the flood: the old canal and Lock 23 in the foreground, the town behind. Much of the waterfront in this photograph now lies beneath Lake St. Lawrence. Photo via stlawrencepiks.com

6,500
people displaced on the Ontario shore — the largest relocation in Canadian history to that time
10
communities permanently submerged — nine villages and hamlets, plus the island of Sheek's Island
530
buildings picked up and moved to new lots; hundreds more were demolished
≈38,000
acres flooded on both shores — about 20,000 in Ontario and 18,000 in New York State
4 days
for Lake St. Lawrence to fill and cover every former townsite, July 1–5, 1958

1 · The Cause

Two megaprojects, one rising river

The flooding was not an accident — it was the plan. In the early 1950s, Canada and the United States agreed to build the St. Lawrence Seaway: a system of locks and deepened channels that would let ocean-going ships sail from the Atlantic all the way to ports on the Great Lakes, bypassing the rapids and shallow canals of the old river. At the same time, Ontario Hydro and the New York Power Authority would build a giant hydroelectric dam across the river between Cornwall, Ontario, and Massena, New York.

The dam — named the Moses–Saunders Power Dam for its two champions, Robert Moses and Robert H. Saunders — needed a reservoir. Its head pond, a new artificial lake, would back the river up for some 46 kilometres (28 miles) upstream to Iroquois, raising water levels along the whole reach. The engineers called it Lake St. Lawrence. The families who lived along that shore, on what locals called "the Old Front," called it something else: the end of their world.

Everything in the flood zone had to go. Before the water could rise, Ontario Hydro had to clear a future lakebed: more than 200 farms, some 1,000 cottages, 17 churches, 18 cemeteries, and over 100 kilometres of highway and railway were moved, demolished, or flattened — even the trees were cut, so nothing would snag the ships that would soon sail overhead.

Black and white photograph of the Moses-Saunders powerhouse under construction in April 1957, with cranes, turbine housings and workers
The Moses–Saunders powerhouse rising from the riverbed in April 1957, its row of turbine housings taking shape. The dam's reservoir — Lake St. Lawrence — is what flooded the villages upstream. Photo: Ron Beaupre collection, via stlawrencepiks.com

2 · Inundation Week

Raise the water yourself

Drag the slider through the first days of July 1958 and watch what the rising head pond did to a typical stretch of the Old Front — the village on its shore, Highway 2 running past the doorsteps, and the new town waiting on high ground.

New towns: Ingleside & Long Sault The Old Front villages Schematic — not to scale

3 · The Road to Inundation Day

Five years that erased 170

  1. 1784

    Loyalist settlement. United Empire Loyalists, displaced by the American Revolution, found the riverfront villages of the Old Front — farms, churches and graveyards that their descendants would still occupy in the 1950s.

  2. Aug 1954

    Construction begins. Work starts on the Seaway and the Moses–Saunders Power Dam. Along the shore, survey stakes mark the future high-water line — and everyone learns which side of it they live on.

  3. 1955–58

    The great relocation. Ontario Hydro buys up the flood zone. Houses are jacked onto trailers and trucked to the brand-new planned towns of Ingleside and Long Sault; Iroquois is rebuilt 1.5 km north; Morrisburg is shifted uphill. What cannot be moved is bulldozed and burned.

  4. Jul 1 1958

    Inundation Day. At 8:00 a.m., the cofferdam holding back the river above the new dam is demolished with explosives, and Lake St. Lawrence begins to fill.

  5. Jul 5 1958

    Under water. Four days after the blast, every former townsite is submerged. Roads, foundations and tree stumps vanish beneath the new lake.

  6. 1959

    The Seaway opens. The first ships transit in April; on June 26, Queen Elizabeth II and U.S. President Dwight D. Eisenhower officially open the Seaway, and the power dam is dedicated the next day.

  7. 1961

    Upper Canada Village opens near Morrisburg, where buildings rescued from the flooded villages have been reassembled into a living-history museum.

  8. 2008

    Apology and settlement. Fifty years on, Ontario Power Generation formally apologizes for the displacement, and reaches a settlement with the Mohawks of Akwesasne, whose lands and islands were flooded without consultation or compensation.

4 · The Lost Villages

Ten names on a memorial wall

East of Iroquois and west of Cornwall, along roughly 30 kilometres of the north shore, stood the communities now remembered as the Lost Villages. They were not boomtowns or camps — they were settled, rooted places with main streets, cheese factories, churches, schools, and cemeteries where generations of the same families lay side by side. All of them now lie under Lake St. Lawrence.

Map of the flooded reach of the St. Lawrence River showing the original river, the new Lake St. Lawrence in pale blue, and the positions of the Lost Villages along the Ontario shore
The flooded reach: the original river ran in a narrow channel (dark blue); the new lake (pale blue) spread across the villages, farms and Highway 2. Map via North Country Public Radio
Black and white photograph of Highway 2 passing through Aultsville in the 1950s, lined with shade trees and houses
Highway 2 through Aultsville, the largest of the Lost Villages, in its last years. This street — Ontario's main east–west road — is now a lakebed, and divers still follow its pavement. Photo via ontariohistory.org

5 · Moved, Not Lost

Morrisburg and Iroquois climbed the hill

Two larger towns stood at the edge of the flood zone and survived — barely, and transformed. Iroquois was picked up entire: its houses, churches and stores were moved about 1.5 kilometres (a mile) north to a new townsite, one of the largest community relocations ever attempted. Morrisburg, at the western end of the head pond, lost its original main street and business district to the water and rebuilt its commercial heart on higher ground within the same townsite. The Morrisburg of the pre-Seaway photographs — its canal-side waterfront, its old Lock 23, its tree-lined main street — exists now only in pictures and in the memories of those who walked it.

1950s photograph of Morrisburg's main street with brick storefronts, an Esso sign, and period cars, before the Seaway flooding
Morrisburg's main street in the 1950s, in its final years before the town's business district was demolished or moved uphill ahead of the water. Photo: Claire Delage, via stlawrencepiks.com

The new communities built for the displaced — Ingleside and Long Sault, laid out from scratch by Ontario Hydro west of Cornwall — received most of the village families. Hydro built the streets, sewers, schools and shopping plazas; movers delivered the houses, sometimes with the furniture still inside and, in stories still told locally, the cat still asleep on the porch.

6 · The Human Cost

"Market value" for a world

Residents were paid market value for their homes and farms — but many argued the price was rigged from the start: word of the Seaway had hung over the valley for years, depressing property values long before the buyouts began. Some families held out and were expropriated; a few had to be removed by force. Compensation could replace a house. It could not replace the view from the kitchen window, the orchard a grandfather planted, or the neighbours of forty years — now scattered between two new towns and a dozen other places.

The dead had to move too. Eighteen cemeteries stood in the flood zone, some dating to the first Loyalist burials of the 1780s. Ontario Hydro re-interred more than 2,000 bodies — but only where surviving family asked for it. Headstones from the drowned graveyards were gathered into a Pioneer Memorial at the Lost Villages Museum in Long Sault, where they stand mounted in rows today.

For the Mohawks of Akwesasne, downstream at Cornwall, there were no negotiations at all: more than 1,200 acres of reserve land and some 15,000 acres of traditional territory — including ten islands — were flooded for the head pond without consultation or compensation. That grievance took fifty years to address, ending in a settlement and a formal apology from Ontario Power Generation in 2008.

"After the massive explosion propelled debris sky-high from the blown cofferdam, the expected great wall of water was instead just a trickle."
— Legion Magazine, recalling eyewitness Jim Brownell, who watched Inundation Day as a boy on the shore

That quiet anticlimax was, in its way, the cruelest part. There was no single dramatic moment to mourn — just water rising steadily for four days, lapping over fields, then doorsteps, then rooftops, while former residents watched from the new shore until there was nothing left to watch.

7 · What Remains

The villages are still down there

Lake St. Lawrence never quite let the Old Front disappear. Along the shore, sidewalks and stretches of old Highway 2 still run down the bank and into the water. When the lake level drops, foundations, roadbeds and bridge abutments emerge in the shallows. The hilltops of the flooded farms became the islands of the Long Sault Parkway, a scenic drive strung along the drowned landscape.

Underwater, the Lost Villages have become one of Canada's most storied freshwater dive sites: divers swim the submerged streets of Aultsville, explore the old Lock 23 near Morrisburg, and follow sidewalks past the foundations of houses whose families they can still name. On shore, the story is kept by the Lost Villages Museum at Ault Park in Long Sault — a cluster of buildings rescued from the villages — and by Upper Canada Village, the living-history museum built from salvaged homes, churches and mills.

Aerial view of Upper Canada Village with its white church, historic houses, millpond and canal near Morrisburg
Upper Canada Village from the air. Dozens of its buildings were hauled here from the flood zone in the late 1950s — the villages' architecture, saved one structure at a time. Photo via Cornwall Tourism

For the families of the Old Front, "before the flood" remains a dividing line in local memory — grandparents still give directions by landmarks that have been underwater for more than six decades. The Seaway is now simply a fact of the continent's geography, and ships pass over the villages every day of the shipping season. But on a still evening at Long Sault, when the lake drops and the old roadbeds show, the river gives a little of it back.