On April 11, the U.S. Army Corps of Engineers announced the unofficial start of the Upper Mississippi River navigation season, the U.S. Department of Agriculture reported recently.

The start date is determined when the northernmost stretches of the Mississippi River are not closed due to ice accumulations and the first tow of barges arrives at Mississippi River Lock and Dam 2, near Hasting, Minn., the USDA said. This year marked the latest date for the opening of the Upper Miss, that was unrelated to flooding.

Historic flooding in 2001 delayed the arrival of the first tow until May 11 that year. According to the Corps, the earliest date for an upbound tow to reach Lock and Dam 2 was March 4. This occurred in 1983, 1984 and 2000. Last year, the first tow to reach Lock and Dam 2 was on March 9. The average start date of the navigation season is March 22.