Debris lines levees along the east bank of the Mississippi River in Plaquemine Parish, La., Aug. 30, 2012. U.S. Coast Guardsmen assigned to Coast Guard Air Station New Orleans in helicopters from New Orleans, Houston and Mobile, Ala., flew the greater New Orleans area searching for signs of distress and giving assistance as needed. Isaac developed as a tropical storm over the Western Atlantic Ocean Aug. 21, 2012, affecting Puerto Rico, the Dominican Republic, Haiti and Cuba before making landfall as a hurricane on the Gulf Coast of the United States.