Floodwaters inundate the eastern shores of the Mississippi River in Plaquemine Parish, La., Aug. 30, 2012. U.S. Coast Guard 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.