A few district employees from the channels and harbors section are getting the opportunity to take out the district airboat on the Mississippi River this month to complete ice measurements on Lake Pepin, near Red Wing, Minn.
The first measurements began Feb. 13, and they will continue on a weekly, or biweekly, basis until the navigation season begins.
The ice survey team is checking the ice depth by navigating between ice and open water along the river.
The team checks several spots for the current ice depth. The depths are used in a weekly report, and the measurements help the navigation industry determine when it might be possible to get tows upstream to St. Paul, Minn., said Nick Lorenz, operations.
Survey crews from the Corps’ Fountain City Service Base in Fountain City, Wis., use the airboat and a global positioning system to identify the exact measurement locations. Surveys for River Mile 770 during the past five years are:
Feb. 13, 2013, 19 inches;
Feb. 15, 2012, 15 inches;
Feb. 16, 2011, 22 inches;
Feb. 17, 2010, 26 inches; and
Feb. 18, 2009, 22 inches.
Lake Pepin, located on the Mississippi River between Red Wing and Wabasha, Minn., is used as the benchmark because the ice melts slower in this area due to the lake width and the slower current. Lorenz said, the lake is usually the last obstacle preventing northbound tows from arriving in St. Paul, Minn.
For many of the people who live in the Midwest, the first tow of the season is the unofficial start of spring. The first tow to break through Lake Pepin in 2012 was the Motor Vessel Deana Ann, a tow operated by Marquette Transportation Company, Inc., of Paducah, Ky., March 17. The average opening date of the navigation season in St. Paul for the last 10 years is March 20.
Lorenz said, the Corps does not anticipate any upbound tows in Lake Pepin until at least March 15 due to ongoing construction at Lock and Dam 6 until March 11. Data from the ice surveys is posted on the St. Paul District’s website. For figures on past and present Lake Pepin ice measurements, see: http://www.mvp.usace.army.mil/Missions/Navigation/IceMeasurements.aspx.