(CNN) -- Fears that portions of the drought-stricken Mississippi River could become impassable in coming days abated Monday as the Army Corps of Engineers announced a significant rise in water levels.
Recent rain in the region, along with the clearing of rock formations, has allowed the Coast Guard to lift all barge draft restrictions on the upper portion of the river, said Mike Petersen, a spokesman for the Corps of Engineers.
Water levels rose to as high as 13 feet in some areas thanks to the rainfall -- 4 feet above the minimum 9-foot mark needed for barge traffic to travel the river. And contractors have been working since December to remove rocks near the critical choke point of Thebes, Illinois, to maintain the channel for navigation. The effort along the six-mile stretch of river "deepened the navigation channel by 2 feet in just three weeks," said St. Louis District Commander Col. Christopher Hall.
Two trade groups had expressed concern that the portion of the river -- about 125 miles south of St. Louis -- would be impassable for many vessels as early as this month.
A historic drought and excessive heat reduced water levels and scorched wide sections of the Midwest last year.
Flooding in 2011 may have worsened the situation on the Mississippi by leaving deposits of silt and debris in areas that would normally be clear.
The Corps of Engineers is hopeful that it can get through the winter without any more problems as the river approaches its natural seasonal rise in water levels around mid- to late February, Petersen said.
Still, the region could see another year of drought, and the Corps of Engineers will be watching the Mississippi carefully, he said.