(CNN) -- As politicians and barge companies express fear of a shutdown or significant disruption, the U.S. Army Corps of Engineers is tackling one of two significant problems presented in the drought-stricken Mississippi River.
The Corps, aware that barge traffic could be disrupted as early as next week because of sharply lower water levels, can't do anything about ice forming in northern portions of the river, impeding adequate water flow.
But it is using contractors to remove rock formations in the river near Thebes, Illinois, to help maintain a 9-foot-deep channel for navigation, said St. Louis District spokesman Mike Petersen. Blasting, one of the removal measures, began December 21.
The removal of 890 cubic yards of limestone will continue until the end of January, Petersen told CNN on Thursday. Dredging has been ongoing since early July.
A historic drought and excessive heat reduced water levels and scorched wide sections of the Midwest. Flooding last year may have worsened the situation on the Mississippi by leaving deposits of silt and debris in areas that would normally be clear.
Two trade groups expressed concern Thursday that the portion of the river near Thebes -- about 125 miles south of St. Louis -- may be impassable for many vessels around January 3 or 4. They urged the administration to release water from Missouri River reservoirs.
"This potential supply-chain disruption could amount to a staggering loss for the U.S. economy, affecting nearly 20,000 jobs," said the statement from the American Waterways Operators and the Waterways Council, Inc.
Sen. Claire McCaskill, D-Missouri, and Senate colleagues from the Midwest and South late last month called on President Barack Obama to ensure commercial navigation of the river. The letter mentioned the need for sufficient water flow into the Mississippi River from the Missouri River.
"Significant curtailment of navigation...will threaten manufacturing industries and power generation, and risk thousands of related jobs in the Midwest," the letter read. It cited in particular the stretch of the river between St. Louis and Cairo, Illinois.
Corps officials recently met with Illinois leaders to discuss its operations, among them the release of additional water from Carlyle Lake, 50 miles east of St. Louis in south-central Illinois.
Mark Fuchs, an hydrologist with the National Weather Service in St. Louis, said bitterly cold air expected in Minnesota and Iowa was expected to freeze much of the flow from the Upper Mississippi late this week.
"However, that may not have much impact on levels this far south unless the ice makes significant progress southward, roughly past Iowa," Fuchs said on Friday.