In this Aug. 22, 2012 photograph, a river navigation buoy floats in the Mississippi River near a sandbar north of Greenville, Miss. Navigation markers that mark channels require constant adjustment to... more 
In this Aug. 22, 2012 photograph, a river navigation buoy floats in the Mississippi River near a sandbar north of Greenville, Miss. Navigation markers that mark channels require constant adjustment to keep towboats and barges out of trouble zones. The buoys get displaced either by ships or the shifting river itself. The Dredge Jadwin, a U.S. Army Corps of Engineers vessel, is clearing out silt and leftover mud and debris from last year's record flood on the Mississippi River and cutting a deeper channel for barges and their towboats to navigate north. (AP Photo/Rogelio V. Solis) less 
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Associated Press | Photo By Rogelio V. Solis
Sat, Aug 25, 2012 1:36 PM EDT