Structures are seen partially submerged on Mud Island as floodwaters rise in Memphis, Tennessee May 9, 2011. The city of Memphis braced for the Mississippi River to peak within hours at a near record level, and downstream the U.S. government opened a spillway above New Orleans on Monday to relieve flooding pressure on the low-lying city. REUTERS/Eric Thayer (UNITED STATES - Tags: DISASTER ENVIRONMENT)