ST. LOUIS, Mo. — Federal officials are close to finalizing plans to blow up sections of bedrock that may impede barge traffic along the drought-lowered Mississippi River south of St. Louis.

The project originally was planned to take place sometime in February 2013, but barge operators, the ag industry and several Midwest lawmakers pressed the White House to allow the U.S. Army Corps of Engineers to begin the work as soon as possible.

That same group also asked the Corps to change plans and allow more water to flow out of reservoirs along the Missouri River, which feeds into the Mississippi, to keep water levels high enough for barge traffic to continue unabated, but the Corps rejected that request.

Initial projects had the river south of St. Louis at a low enough level by Dec. 11 to shut down barge traffic completely, which would add millions of dollars to the cost of shipping coal, grain and other products. More than 100 million tons of cargo move annually through the stretch of the Mississippi, and the goods shipped in December-January alone are valued at about $7 billion, according to the American Waterways Operators.

Mike Peterson, a Corps spokesman based in St. Louis, said last week it was finalizing plans for the rock pinnacle removal near Thebes and Grand Tower in southern Illinois with the contractors hired to do the work.

“We hope to have something to announce as early as today (Dec. 14) or by next week,” Peterson said.

The Corps has hired Newt Marine Service of Dubuque, Iowa, and Kokosing Construction Co. of Fredericktown, Ohio, to do the work; Peterson said it is unclear how long the project will take and how long the section of river will need to be shut down while blasting and removal of the rock takes place.

Meanwhile, Democratic Sens. Dick Durbin of Illinois and Tom Harkin of Iowa, were told in a letter last week from Jo-Ellen Darcy, the assistant secretary of the Army for civil works, that the Corps does not believe it necessary to release more water from Missouri River reservoirs.

She cited revised National Weather Service forecasts for more rain, and that water levels along the Mississippi weren’t receding as originally thought earlier in the month. Depleting Missouri River reservoirs further, already down 20 percent than desired, would threaten access to water by communities for hydropower and for irrigation, Darcy wrote.

Reservoir releases would be “insufficient to maintain navigation on the middle Mississippi River without additional rainfall,” she added. Lowering the reservoirs now also would leave less water available for the 2013 shipping season on both rivers.

Given the Mississippi’s low level, tows along the river are down about 45 percent already and it has impacted the price of corn grown by farmers in the area, said Rodney Weinzierl, executive director of the Illinois Corn Growers Assoc.

“If you’re a farmer in the Saint Clair or Monroe County area, or in other areas of southwestern Illinois, your corn price is $1 less than if you’re over in Gallatin County or Richland County, where generally your corn is moving in the direction of the Ohio River,” he explained.