Barge operators and those who ship on the Mississippi have warned that a shutdown would have disastrous economic consequences on those industries, with companies laying off workers if it lasts for any significant amount of time.
River shipping trade groups have even asked President Barack Obama to intervene.
"This is a pending economic emergency," said Ann McCulloch, director of public affairs for the American Waterways Operators.
A message left with the White House on Friday was not returned.
The weather forecast offers little hope with no big storms in sight.
While the drought has eased in the St. Louis area, it persists in the upper Mississippi and upper Missouri river basins, which feed water to the areas below, said Scott Truett, a meteorologist with the National Weather Service office in St. Louis.
"That means less runoff and hence low water levels," Truett said.
The corps has taken steps to keep the Mississippi open as long as possible, including increasing dredging. It also plans to remove two rock formations in the river in southern Illinois that jut up, potentially scraping the bottoms of barges when water levels are low.
But that work isn't expected until February, although 15 senators and 62 House members in separate letters asked for the rock removal to be expedited.
Corps officials in Omaha say the drought already has hurt recreation along the upper Missouri River areas. The low water has exposed Native American artifacts, leaving them prone to looting, and if it persists into spring, hydropower could be impacted.
Corps officials in Omaha say they are bound by the Missouri River Master Manual to act in the best interest of the Missouri River basin and what happens on the Mississippi is incidental.