Annual Corps of Engineers’ Lake Pepin Ice Measurements to Begin February 15

It’s a sign that spring is near, as the U.S. Army Corps of Engineers, St. Paul District, will start its annual Lake Pepin ice measurements Feb. 15.

Lake Pepin is a naturally occurring lake on the Mississippi River on the border between Minnesota and Wisconsin.

The Corps takes ice measurements on Lake Pepin annually to forecast the navigational outlook. Lake Pepin’s ice thickness is measured because it’s the widest naturally occurring part of the Mississippi River. The lake’s ice is the last major barrier for vessels reaching the head of the navigation channel in St. Paul, Minnesota.

A Corps survey crew uses an airboat and a global positioning system to collect the data. The information is used by the navigation industry to predict when it’s safe to break through the ice and begin the 2023 navigation season.


The Motor Vessel W. Red Harris was the first tow to pass through Lake Pepin last year and reach St. Paul, Minnesota, arriving March 21, 2022. Historically the average date in which navigation is open occurs during the third week of March.

Ice measurements are typically completed weekly until the first tow arrives. Ice measurement results are posted on the St. Paul District website at:

The St. Paul District navigation program provides a safe, reliable, cost-effective and environmentally sustainable waterborne transportation system on the Upper Mississippi River for the movement of commercial goods and for national security needs. To do this, the district maintains a 9-foot navigation channel and 13 locks and dams from Minneapolis to Guttenberg, Iowa. Keeping this system open is vital to the nation’s economy.

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