ST. LOUIS (AP) - The Army Corps of Engineers has cleared tons of rock from one section of the middle Mississippi River and is now moving work slightly upstream.

The drought has caused the river to be so low between St. Louis and Cairo, Ill., that barge traffic is endangered. To keep the channel open, the corps used dredging barges and explosives to remove rock pinnacles in the river near Thebes, Ill.

Now, the corps plans to do similar work about 31 miles north of Thebes near Grand Tower, Ill. The work will require midnight-to-noon closure of the channel for about 10 days.

Heavy rain fell in parts of the mid-Mississippi River valley on Tuesday, which could boost river levels.

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