Mississippi River floods among the largest and most damaging along the U.S. waterway in the past century, rivalling major floods in 1927 and 1993. In April 2011, two major storm systems dumped record rainfall on the Mississippi River watershed. Rising from springtime snowmelt, the river and many of its tributaries began to swell to record levels by the beginning of May. Areas along the Mississippi itself experiencing flooding include Illinois, Iowa, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana. U.S. President Barack Obama declared the western counties of Kentucky, Tennessee, and Mississippi federal disaster areas. For the second time in 38 years, the Morganza
Mississippi River Basin Model 1937, 1943, 1945 and 1952 were reproduced, as well as hypothetical floods at different periods of the year. Tests on individual problems were conducted until 1971 but high costs and growth of computer modelling meant that the facility was put on standby. The last use was in 1973, when a potentially catastrophic failure arose at the Old River Control Structure. The model was used to show that the untested Morganza Spillway could be opened effectively, without diverting polluted water through New Orleans and Baton Rouge, as well as identifying levees that required topping up. In 1993 the site was taken