The Welland Canal is a 43 km ship canal across Ontario's Niagara Peninsula. It connects Lake Ontario at Port Weller, near St. Catharines, with Lake Erie at Port Colborne, and lets ships bypass Niagara Falls. Its eight locks lift vessels about 99.5 m, the difference in level between the two lakes, and a full transit takes around 11 hours. The present canal, opened in 1932, is the fourth on the route. It is the part of the St. Lawrence Seaway that connects ocean shipping to Lake Erie and the upper Great Lakes.
Why Ships Can't Use the Niagara River
Lake Erie drains into Lake Ontario through the Niagara River, which drops about 100 m on the way. Most of that drop happens in one place. The river goes over the Niagara Escarpment at the falls and then runs through a gorge of rapids about 11 km long. No vessel can go up it, so for as long as people have traded on the Great Lakes, goods have been unloaded and carried overland around the falls. Before the canal, that portage ran along the river on the American and Canadian sides.
The Welland route avoids the river entirely. It cuts straight across the peninsula about 13 km west of the falls, climbing the same escarpment in a series of locks. More about the barrier itself is in our guide to the geography of Niagara Falls.
Four Canals on One Route
The first canal was a private venture promoted by William Hamilton Merritt, a St. Catharines mill owner who wanted a reliable water supply for his mills as well as a shipping route. The Welland Canal Company started digging in 1824. The hardest section was the Deep Cut, through the high ground near Allanburg, where banks collapsed repeatedly. The first boats made the crossing in November 1829, using 40 wooden locks, and the canal was later extended south to Port Colborne on Lake Erie.
Each rebuild followed an increase in ship size. The private company never made a profit, and the government of the Province of Canada bought out its shareholders in 1841. The second canal, completed in 1845 after that takeover, had 27 stone locks. The third, opened in 1887, cut the number to 26 larger locks on a partly new line. The fourth, the present canal, was begun in 1913, slowed by the First World War and opened in 1932. When the St. Lawrence Seaway opened downstream in 1959, the Welland became the final link in a deep-water route from the Atlantic to the head of Lake Superior.
Climbing the Escarpment at Thorold
Almost the whole lift happens in the northern third of the canal. Locks 1 to 3 in St. Catharines raise ships from Lake Ontario towards the base of the escarpment. Locks 4, 5 and 6 at Thorold are the Flight Locks, three chambers stacked one above the other up the face of the escarpment. They are built as twin flights side by side, so upbound and downbound ships can pass. Lock 7 completes the climb. South of Thorold the canal crosses almost level ground for more than 20 km to Lock 8 at Port Colborne. That is a guard lock, which adjusts for small changes in Lake Erie's level and makes the smallest lift on the canal.
Each lift lock raises a ship about 14 m. Water flows in by gravity through culverts in the lock walls, without pumping, and a lock fills or empties in roughly 10 to 15 minutes.
What Fits: The Seaway-Max Ship
The lock chambers are about 233 m long and 24.4 m wide. Those dimensions set the Seaway-max standard: vessels up to 225.5 m long, 23.8 m wide and with a draft of about 8 m. Great Lakes freighters called "lakers" are built to that box exactly, long and narrow with the wheelhouse at one end, so they carry as much as the locks allow, typically 25,000 tonnes or more of bulk cargo on a single trip. Ocean ships that come up from the Atlantic, known on the lakes as "salties", are usually smaller. The largest lakers, the 305 m "thousand-footers", are too long for the Welland and trade only on the lakes above it.
Bridges, Tunnels and the Welland Bypass
A canal that cuts across a populated peninsula creates a problem for everyone who wants to cross it. The Welland is crossed by a series of vertical lift bridges, which rise to let ships pass and back up road traffic when they do. The city of Welland, which grew up on both banks of the third and fourth canals, had to deal with this every day. The Welland Bypass, opened in 1973, moved the canal to a new channel east of the city centre. Road and rail now pass under the new channel in two tunnels, the Townline and Main Street tunnels, and the old channel through town became a recreational waterway.
The lift bridges have a safety record that is mostly good but not perfect. In August 2001 the lake freighter Windoc was struck by a bridge span that was lowered onto it near Allanburg, which destroyed its wheelhouse and funnel and started a fire. The crew survived, but the canal was blocked for two days.
Water, Power and the Winter Shutdown
The canal carries more than ships. It draws water from Lake Erie at Port Colborne and delivers a steady flow north, and part of that supply feeds Lake Gibson, a reservoir above the escarpment. Water from there drops to the DeCew Falls generating stations near St. Catharines, where hydro power has been produced since 1898. The canal also supplies water to industry and to farms along its route, a use that William Hamilton Merritt had in mind for his mills in the 1820s.
When the shipping season ends in late December, the Seaway uses the closure to repair the locks. Chambers are drained so that crews can work on gates, valves and concrete walls that are under water for the rest of the year. The dry, empty locks are a striking sight, some of them more than 20 m deep, and the work has to be finished before the canal refills and reopens in late March.
What Moves Through It
The canal usually opens in late March and closes around the end of December, when ice and maintenance shut it for the winter. In a season, roughly 3,000 transits carry about 30 to 40 million tonnes of cargo. The main loads are grain from the Prairies and the American Midwest heading for export, iron ore and coal for steel mills, salt, stone and cement. That is much less than the peak years of the 1970s, when steel production on the lakes was higher, but a single laker carries a cargo that would otherwise need hundreds of trucks. The canal's place in the wider system is covered in our guide to the St. Lawrence Seaway.
Why the Lakes Sit 99 Metres Apart
The drop the canal climbs was made by the Niagara Escarpment, a long ridge of hard dolostone over softer shale that curves from New York through Ontario into Wisconsin. Lake Erie sits on top of it, at about 174 m above sea level, and Lake Ontario sits below it, at about 74 m. When the ice sheet retreated around 12,500 years ago, the Niagara River began flowing over the edge of the escarpment near present-day Queenston and Lewiston. Since then, erosion undercutting the soft rock beneath the hard cap has moved the falls about 11 km upstream, carving the gorge that makes the river impassable. The canal climbs the same ridge in one lock flight instead of one waterfall.
The Old Canals You Can Still See
Parts of the first three canals survive next to the present one. Port Dalhousie, now part of St. Catharines, was the Lake Ontario entrance for the first three canals before Port Weller replaced it, and its harbour, stone locks and lighthouses remain. Stone locks from the second and third canals can be found along the Merritt Trail between St. Catharines and Thorold, and the old channel through Welland is now used for rowing and paddling. The Welland is not the only canal to have carried shipping around a barrier into the Great Lakes. New York's Erie Canal, completed in 1825, linked Lake Erie with the Hudson River four years before the first Welland crossing.
Watching the Ships
The Welland is one of the few places where you can stand a few metres from a working ocean freighter. The St. Catharines Museum at Lock 3 has a raised viewing platform and posts expected ship times. The Lock 7 viewing complex in Thorold looks up and down the Flight Locks, where ships rise through the three stacked chambers in the twin flights, with about 30 cm to spare on each side of a Seaway-max hull. For comparison with a canal built to join oceans rather than lakes, see how the Panama Canal's locks lift ships 26 m to Gatun Lake.