Marine transportation on the system involves two general trade communities: traffic moved on the Seaway, much of which is overseas import/export trade, and interlake domestic trades contained within the Great Lakes.

The Seaway trades have lately been in the range of 50 million metric tonnes a year. Seaway cargoes are borne both by Canadian-flag vessels and foreign-flag ocean vessels. The U.S.-flag laker fleet is almost exclusively employed in the interlake trades. Prevalent Seaway trade patterns include:

• Upbound (westward) movements of general cargo, including semi-finished steel in the form of slabs, coils, beams and other products from overseas producers.
• Upbound movements of iron ore from mines in eastern Canada.
• Downbound (eastern) shipments of export grain by Canadian bulkers to transshipment points on the St. Lawrence River, and by ocean vessels for direct export overseas.
• The Seaway also handles project cargoes, forest products, petroleum products, containers, chemicals, edible oils, coal, salt, cement, fertilizers, ores, nonferrous metals and other bulk commodities.

The interlake trades, approaching some 200 million tonnes a year, are dominated by the dry bulk commodities of iron ore, coal, stone and grain. Also moved within the Lakes are salt, cement, potash and liquid bulk cargoes such as petroleum products, asphalt and industrial chemicals. This commerce is handled by U.S. and Canadian-flag fleets in the Great Lakes. Some of the larger movements within the Lakes are:

• Iron ore, in the form of taconite pellets, moving from the Minnesota Iron Range and Michigan’s Upper Peninsula to steel mills around Lakes Michigan and Erie.
• Low-sulphur coal mined in the western U.S., railed to Great Lakes loading ports and moved on water to electrical generating stations on the Great Lakes, and coal mined in the eastern U.S. moved to steel mills, generating stations and other industries.
• Stone moved from quarries to steel mills and taconite plants for flux, and to all major markets for construction.

Seaway and Great Lakes Lock Systems

For the purposes of the GLSLS Study, the evaluation of the existing marine transportation infrastructure will be principally focused on the lock systems of the Seaway and the Great Lakes, which include the locks in the Montreal/Lake Ontario section of the Seaway from Montreal, Quebec (beginning with the St. Lambert Lock), the locks in the Welland Canal between Lake Ontario and the top of the Niagara escarpment, and the Soo locks at Sault Ste. Marie, Michigan.

Seaway Locks

The St. Lawrence Seaway proper extends from Montreal to Lake Erie. The Seaway locks (fifteen in total) overcome the differences in elevation in the system. The Montreal/Lake Ontario section encompasses a series of seven locks over roughly 300 kilometres (187 miles) – five Canadian and two American – from Montreal, Quebec to Iroquois, Ontario enabling ships to navigate between the St. Lawrence River and Lake Ontario. The Welland Canal links Lake Ontario and Lake Erie with a series of eight locks over approximately 42 kilometres (27 miles) – all Canadian. The Welland Canal provides more than half the lift needed between tidewater and the lakehead.

All of the seven locks of the Montreal/Lake Ontario section of the Seaway (St. Lambert, Côte Ste. Catherine, Lower and Upper Beauharnois, Bertrand H. Snell, Dwight D. Eisenhower and Iroquois) as well as those of the Welland Canal, are 233.5 metres long (766 feet), 24.4 metres wide (80 feet) and 9.1 metres deep (30 feet) over the sill.

Responsibility for the operations and maintenance of the navigational aspects of the Canadian portion of the Seaway (thirteen locks) resides with the St. Lawrence Seaway Management Corporation, a not-for-profit corporation, under a long-term management agreement with the Government of Canada pursuant to the Canada Marine Act. The Government of Canada continues to own all fixed assets of the Canadian Seaway.

The two United States locks in the Seaway are operated and maintained by the Saint Lawrence Seaway Development Corporation, a wholly owned government corporation within the U.S. Department of Transportation.

Soo Locks

Further to the northwest are the Soo locks at Sault Ste. Marie, Michigan, which provide a vital connection between the upper Great Lakes and Lake Superior. Access to Lake Superior and the Canadian lakehead at Thunder Bay, Ontario and the U.S. lakehead at Duluth, Minnesota is gained via the locks on the St. Mary’s canal, which are administered by the U.S. Army Corps of Engineers.

The two locks currently operational for commercial navigation purposes are the Poe and the MacArthur. The Poe lock is 1200 feet long (366 metres), 110 feet wide (33.5 metres) and 32 feet deep (9.8 metres). The MacArthur lock is 800 feet long (244 metres), 80 feet wide (24.4 metres) and 31 feet deep (9.4 metres).