Atchafalaya Basin 1973. This water floods the Atchafalaya Basin between the levees along the western and eastern limits of the Morganza and Atchafalaya basin floodways. The control of the river's floods, along with those of the Mississippi River, has become a controversial issue in recent decades. The US Geological Survey (USGS) reports that Mississippi River delta salt marshes are wetlands degrading at a rate of 29 square miles per year. The Atchafalaya River Deltas are the only locations of land growth along the Louisiana Gulf Coast. During the early 20th century, the Atchafalaya River Basin was designated as a spillway for floods
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