(CNN) – May 10, 2011 - The U.S. Army Corps of Engineers on Monday opened the Bonnet Carré Spillway for the 10th time since 1932. This 7,000-foot structure of gates on the east bank of the Mississippi River, 30 miles above New Orleans, relieves pressure on levees protecting the city by shunting river water into nearby Lake Pontchartrain.

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