A lowering river allows the sand bars to emerge in the Mississippi River near Greenville, Miss.,Tuesday, Aug. 21, 2012. Officials with the U.S. Army Corps of Engineers say low water levels that are restricting shipping traffic, forcing harbor closures and causing towboats and barges to run aground on the Mississippi River are expected to continue into October. (AP Photo/Rogelio V. Solis)
A lowering river allows the sand bars to emerge in the Mississippi River near Greenville, Miss.,Tuesday, Aug. 21, 2012. Officials with the U.S. Army Corps of Engineers say low water levels that are restricting shipping traffic, forcing harbor closures and causing towboats and barges to run aground on the Mississippi River are expected to continue into October. (AP Photo/Rogelio V. Solis)
