The opening and closing dates of the St. Lawrence Seaway vary from year to year due to weather conditions and the demands of commerce. The system’s locks have opened as early as March 20 and as late as March 31. The closing date has ranged from December 24 to December 31.
In an effort to enhance the reliability of the shipping system, attract new cargoes and foster employment in the maritime sector, the United States and Canada should harmonize the Seaway’s opening and closing dates with those of the Soo Locks in northern Michigan. Doing so would establish a fixed navigation season for the entire Great Lakes navigation system from March 25th – January 15th.
Just as climate change in the arctic has made new shipping patterns viable, warming temperatures may similarly benefit Great Lakes Seaway trade by enabling a longer navigation season. Each additional day of operations would allow for a more economical use of the capital investments that have been made in vessels, port infrastructure and private terminal facilities and equipment.
In 1970, Congress authorized a “Great Lakes-St. Lawrence Seaway Navigation Season Extension Program.” The program included a decade of studies to evaluate the viability of, and issues surrounding, year-round navigation on the Great Lakes and St. Lawrence Seaway system. At that time, the Corps determined that a year-round season could be achieved in the four upper Lakes (Superior, Huron, Michigan, and Erie) and that a 10 month season (from mid-March to mid-December) could be achieved for the St. Lawrence Seaway (Montreal to Lake Erie).
An extended season would require a number of challenges to be evaluated. These include the provision of sufficient ice-breaking services by the U.S. and Canadian Coast Guards, the deployment of all-season aids to navigation, the impact on hydro electric operations, the scheduling of winter lock maintenance, and possible environmental impacts.