The Regional Maritime Strategy notes that some cargo is transported on the Great Lakes during the winter, but this activity is restricted in areas due to winter ice cover and relies on icebreaking services from the U.S. and Canadian Coast Guards. Additionally, the Soo Locks, Welland Canal, and Montreal-Lake Ontario sections of the Seaway are closed for maintenance during the winter preventing any international trade and much of the domestic trades.

As a result of this seasonal shutdown, shippers have to use alternative modes of transportation, or stockpile inventories during the winter. This need to negotiate alternate shipping arrangements or stockpile goods increases the cost of using the Great Lakes-Seaway portion of the MTS. Given these seasonality considerations, shipping on the Great Lakes section of the MTS has traditionally focused on a narrow set of bulk commodities which can be stockpiled during the winter, while the remainder of the MTS (such as ports in Montreal and Quebec) supports more diverse trade. The Regional Maritime Strategy notes that this focus on select bulk goods inhibits the development of multi-modal logistics operations and economic clusters in the Great Lakes.

Potential investments to optimize the operating season of the Great Lakes portion of the MTS include:

  • Investments in navigational aids, such as all-season buoys.
  • Investments to increase the MTS’ icebreaking assets, which could help maintain passages for shipping later in the fall, and earlier in the spring.
  • Optimizing the operating season of the Seaway so that additional traffic can be accommodated at the beginning or end of the season.
  • Improved harmonization of lock closure dates between the Soo Locks and the St. Lawrence Seaway. Currently, the Welland Canal and Montreal-Lake Ontario section of the Seaway close before the Soo Locks, which reduces opportunities for traffic from Lake Superior to reach the Atlantic.

Currently, year-round operation of the St. Lawrence Seaway is unfeasible, as winter closures are needed to conduct critical maintenance and rehabilitation work. The feasibility of investments to optimize the length of the navigation season is not fully understood, and the Regional Maritime Strategy recommends that U.S. and Canadian agencies identify costs and benefits of season optimization.