Large barges depart on the Upper Mississippi River before winter brings the shipping season to a closeView Source
The shipping season on the uppermost stretch of the Mississippi River has officially come to a close.
The last tow of the season, the Motor Vessel Thomas Erickson, departed Lock and Dam 10 near Guttenberg, Iowa on Sunday, the U.S. Army Corps of Engineers St. Paul District announced Tuesday. It was pushing 15 barges.
Barge traffic on the river's northern stretch halts each year until springtime because the river freezes over the winter.
This year, the season began March 12, when the Motor Vessel Philip M. Pfeffer broke through the ice of Lake Pepin to make it to St. Paul. Lake Pepin — the largest lake on the river — is regarded as the last major barrier for tows in spring because the river is wider there, causing the ice to take longer to break up, according to the Corps.
Sometimes called America's water superhighway, the Mississippi River plays a crucial role in transporting goods through and out of the U.S. It carries around 500 million short tons per year of goods, including corn, soy, fertilizer, road salt, coal and petroleum products. Sixty percent of all grain exported from the U.S., for example, is shipped on the river.
The infrastructure that makes navigation possible on the upper river is aging. A series of locks and dams that were installed between 1930 and 1940 guide tows from one section of river to the next. They have an estimated $1 billion backlog of maintenance costs, according to the Army Corps.
This winter, the Corps' St. Paul District will conduct maintenance on four of these structures: Lock and Dam 2, near Hastings, Minnesota, Lock and Dam 3, near Welch, Minnesota, Lock and Dam 4, near Alma, Wisconsin and Lock and Dam 7, near La Crescent, Minnesota.
That work is scheduled to be completed in March.
Shipping on the lower river continues year-round, but it's still affected by what's happening in the Midwest. A drought that fell across the region this summer could cause low river levels through the winter, restricting how much freight can be shipped, St. Louis Public Radio reported in October.
That could persist until the spring thaw, when snow and ice melts from up north and recharges the Mississippi.