Corps of Engineers set to resume ice measurements on Lake Pepin ahead of shipping season

A man uses an ice auger to measure ice thickness
Bill Chelmowski, a survey technician with the U.S. Army Corps of Engineers St. Paul District, uses an ice auger to measure the ice at Lake Pepin, near Red Wing, Minn., in February 2021.
Patrick N. Moes | U.S. Army Corps of Engineers file

An annual rite of approaching spring in the Upper Midwest gets underway this week, as the U.S. Army Corps of Engineers begins measuring the ice thickness on the Mississippi River at Lake Pepin.

Dan Cottrell with the St. Paul District of the Corps of Engineers said the towing season on the upper Mississippi typically begins in the third week of March. Ahead of that, the Corps has been providing the barge towing industry with ice thickness information on that specific part of the river in southeastern Minnesota since the late 1990s.

"The towing industry is already planning their first trips up at this time," he said. "They need to know what the Lake Pepin ice situation is like because it's the most slack water, or the widest area, on the upper river, so it actually thaws last."

The Corps of Engineers will repeatedly measure the ice thickness over the next few weeks. Lake Pepin ice measurements are posted online here.

"We could get colder temperatures between here and then when the towboats first come up," Cottrell said. So the river "could still make ice, it could get worse; a warm rain can sometimes take it out earlier. ... Our averages are usually in March sometime, when the first towboat comes up."

The first vessel to arrive in St. Paul last year arrived on March 19.

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