Senator: Rock removal on Mississippi to start soon

The river depth on Tuesday was at about 12 feet in St. Louis. The U.S. Coast Guard has said that if it dips to around 9 feet, further restrictions on barges may become necessary. The National Weather Service has forecast that the river will drop to the 9-foot level late this month, barring significant rainfall.

The Coast Guard has said it does not expect to close the river. But Tom Allegretti, president and CEO of American Waterways Operators, said any additional restrictions on barges will leave the river "as good as closed."

Barges, normally allowed 12-foot drafts, are already restricted to 9-foot drafts because of the low water level. That means lighter and more frequent loads. If the restriction goes to 8 feet, some operators say they'll halt shipping.

The trade groups say a prolonged stoppage of barge traffic could have an economic impact reaching into the billions of dollars. Agricultural products, coal, petroleum and other goods rely on river shipping.

"This is still very much a crisis situation," said Ann McCulloch of American Waterways Operators.