Two tow boats pulling 12 barges between them — each barge loaded with some 1,500 to 1,600 tons of cement — broke through the frozen waters of Lake Pepin on Sunday, crossing from Wisconsin, on through Hastings and into St. Paul. In 17 frigid hours, they together delivered what in warm temperatures might take a single towboat three or four hours.

Their stop-and-go journey into the capital city marked the first official barge traffic of the season on the Upper Mississippi River, a home opener of sorts for river shipping.

“We’ve had no barges since the end of November,” said Lee Nelson, president of Upper River Services, the private company that serves as the harbor operator for the Twin Cities. “This marks the beginning of the season.”

The U.S. Army Corps of Engineers brought the Motor Vessel Phillip M. Pfeffer and Motor Vessel Neil N. Diehl on Sunday through Lock and Dam No. 2 in Hastings, the last major barrier for vessels reaching the head of the navigation channel in St. Paul.

Their arrival with cement loaded in Linwood, Iowa came a week earlier than the 30-year average opening date of the navigation season, which is around March 20. The earliest date for an up-bound tow to reach Lock and Dam 2 was March 4, in 1983, 1984 and 2000. The latest arrival in a non-flood year was April 4, 2008. Heavy flooding in 2001 delayed the first tow to May 11, according to the Army Corps.