The winter deep freeze forecast by weather services is arriving in the heartland, and subzero conditions have begun affecting the western river basins. Ice formation could hamper river navigation and fleet operations in the upper Midwest.
In years past, ice season on the rivers meant keeping on the lookout for “ice gorges” or towering jumbles of ice blocks that could rise as high as a church steeple and whose sharp edges could slice through towboat hulls. In St. Louis, the Mississippi River froze solid at least 10 times between 1831 and 1938.
For old-time rivermen, ice gorges were a deadly danger that could crumple a towboat or barge like paper, so they observed them closely. Boat crews sometimes resorted to using dynamite to break them up. One 1930s mariner contrasted Missouri River ice with that of the Upper Mississippi River. The former, he said, was more crumbly and less dangerous, because it was mixed with sand and gravel, while the upper river ice, formed in still, clear water, had razor-sharp edges and lasted longer.
The danger of those ice gorges receded in the middle and Lower Mississippi River after completion of the Alton dam kept ice floes mostly in the upper river, and channel improvements made the current faster and the channel deeper. The Mississippi River still ices over at St. Louis after prolonged cold snaps, but no longer to the depths required for ice gorges.
Today, ice remains a concern in the upper rivers. The Corps of Engineers warns it is common for ice to build up beneath barges, causing subsequent grounding in shoal areas. Additionally, any build-up of ice between barges in a tow or on the sides of the barges will increase the tow’s overall width and could hamper its entrance or exit at the locks. Any noticeable build-up, either in or under the tow, should be checked to assure that the lockage can be accomplished without incident. If conditions warrant, vessel owners should consider adjusting their tow size to compensate for ice formation, the Corps said.
Winter brings the hardest work and the most dangerous conditions for towboat crews on the upper rivers. It’s good to remember they are the ones who are keeping our goods moving even in severe weather.