By JIM SALTER and JIM SUHR
ST. LOUIS (AP) -- Barge operators along a key stretch of the Mississippi River braced Monday for months of restricted shipping as crews prepared to begin blasting large rock formations that are impeding navigation on the drought-plagued waterway.
The Army Corps of Engineers said contractors from Iowa and Ohio could begin demolition of the rock pinnacles on the bed of the Mississippi River south of St. Louis as early as Tuesday. They expect to remove enough rock to fill about 50 dump trucks, possibly more.
The demolition of the massive formations near Thebes, Ill., coincides with an unusual move by the agency to release water from a southern Illinois lake, adding a few inches of depth to a river that is getting lower by the day -- largely because of the lingering effects of the nation's worst drought in decades.
The corps said a six-mile stretch of the river will be closed to shipping starting Tuesday from 6 a.m. to 10 p.m. to allow for the safe use of the explosives. Barges seeking passage will have to line up and wait for an eight-hour window when that stretch will be open, with the Coast Guard essentially acting as a traffic officer letting barges through in one direction, then the other.
The project was initially to have begun in February but was expedited at the behest of U.S. lawmakers from Mississippi River states. Mike Petersen, a corps spokesman in St. Louis, said the agency was aiming to complete the project by the end of March.
"We're very confident we can do that," Peterson said Monday.
On Saturday, the corps began releasing water at Carlyle Lake, saying the additional water flowing into the Mississippi from the lake will provide 6 inches of depth by Christmas Eve, enabling barge traffic to safely pass the rock formations near Thebes. Gen. John Peabody, the corps' Mississippi Valley Division commander, said the "inches make a difference."
Months of drought have left water levels up to 20 feet below normal along a 180-mile stretch of the river from St. Louis to Cairo, Ill., fanning concerns among barge operators that river use soon may be dramatically restricted, if it is not completely shut down. The problem worsened last month when the corps cut the outflow from an upper Missouri River dam by two-thirds, meaning far less water from the Missouri River flows into the Mississippi.
Barges on the Mississippi already are carrying lighter and more frequent loads, and some operators say they'll halt shipping if they face more restrictions. Barge industry trade groups say a prolonged stoppage of shipping on the Mississippi could have an economic impact reaching into billions of dollars, with the movement of agricultural products, coal, petroleum and other goods reliant on the river for transit.
"The drought across much of the Midwest is making river navigation challenging," said Col. Chris Hall, commander of the Army Corps' district in St. Louis.
National Weather Service hydrologists forecast that the river at St. Louis, barring significant rainfall, could dip by the end of this month to about 9 feet deep -- the point at which the Coast Guard has said further restrictions on barge traffic are likely. The river depth in St. Louis as of Monday was about 10.5 feet.
A weather service hydrologist in St. Louis said there is a ray of hope: Snow, some of it heavy, is forecast in the upper Mississippi River area, perhaps up to a foot on Thursday in parts of Wisconsin and Michigan and lesser amounts in Iowa, Illinois and northern Missouri. Depending on how warm it then becomes, Mark Fuchs said Monday, some snowmelt could make its way downriver.
Then again, Fuchs said, ice "is the worst-case scenario" as the weather turns colder and freezes the river to the north, further reducing the amount of water flowing downstream and potentially lowering water levels even further.
The rock being removed typically would be beneath sand on the river bottom but has been exposed by the corps' dredging efforts to keep the channel open.
Copyright 2012 The Associated Press.