LAKE CITY, Minn. – All eyes are on 22-mile long Lake Pepin in late winter because it’s key to the opening of the spring shipping season. The Army Corps of Engineers sends technicians out on the iced-over lake to sample the ice to calculate when barges can safely be navigated through the lake. The lake is the last barrier for vessels heading up the Corps’  navigation channel to St. Paul. It’s always the last part of the Mississippi River to break up because its’s wider and subsequently the current is slow.

Earlier: Sure sign of spring: The first barge array

February ice testing. Army Corps of Engineers survey technicians Dan DeVaney and Bill Chelmowski are out collecting ice samples for clues on when Lake Pepin ice will break up and clear the way for Upper Mississippi barge traffic. This survey trip was February 9. Image: Patrick Moes, U.S. Army Corps of Engineers

All clear in March. Lake Pepin navigation opened March 19. The commercial navigation industry estimates an annual average savings of $400 million by using inland waterways. On average, agricultural producers save $1 per bushel on corn and soybeans by using the river.