A survey crew from the U-S Army Corps of Engineers begins measuring Lake Pepin's ice today to predict when the lake will be passable for the Upper Mississippi River navigation season.
Lake Pepin is the last part of the Mississippi River to break up, and the current is slower on the lake than it is on the rest of the river. That makes it the best location to do the measurements.
Lake Pepin is a widening of the Mississippi between Red Wing and Wabasha.
A surveying crew uses an airboat and a portable global positioning system every year to measure the thickness of Lake Pepin's ice. The crew also records the general condition of the ice. That enables the towing industry to predict whether towboats will be able to break through the ice and when it's safe to begin towing upriver to St. Paul.