LAKE PEPIN — If you see some folks drilling into the ice on Lake Pepin next Wednesday, don't be alarmed. The U.S. Army Corps of Engineers, St. Paul District, plans to conduct it's annual ice survey of the lake next week.
As part of its efforts to forecast the navigation outlook for the Upper Mississippi River, the Corps takes ice measurements on Lake Pepin, measuring the ice's thickness. The lake provides a good source for sampling the ice as it is the widest, naturally occurring part of the Mississippi River. Each year, the lake’s ice is the last major barrier for vessels reaching the head of the navigation channel in St. Paul.
Using an airboat, a global positioning system and ice augers to drill through the thick crust on the lake, a Corps survey crew collects the data that will help estimate when it’s safe to break through the ice and begin the 2020 navigation season.
Last year's navigation season was anything but normal, with flooding and high water on the Mississippi River hindering the navigation season. For example, Lock and Dam No. 4 — the last stop on the river before vessels would reach Red Wing — saw 1,371 commercial navigation lockages. That total was below the 10-year average of 1,442, according to the Corps.
The 2019 lockages supported 6,847,616 tons of commodities by the navigation industry. By comparison, the 2018 season saw 1,646 commercial lockages that moved 9,050,677 tons of commodities, the Corps reported.
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The first tow through Lake Pepin last year was the MV Aaron F. Barrett, which reached St. Paul on April 24. Historically, the average date for the first tow occurs during the third week of March.
Patrick Moes, a spokesman for the Corps, said ice conditions this winter have been anything but normal.
"The temperature roller coaster we had, obviously that created a lot of melt," Moes said. "Flows get into the river and break up that hard crust. That's why we have some of those ice jams we've had."
Whether that will impact the start of navigation season or not, he said, depends on how quickly the spring melt occurs and whether there will be significant flooding along the river in the spring.
Once the Corps starts measuring ice on the river, it typically takes weekly measurements until the first tow arrives. Ice measurements are posted on the St. Paul District website at www.mvp.usace.army.mil/Missions/Navigation/Ice-Measurements .
