The Atchafalaya River is North America’s fifth-largest river by discharge, releasing an average of about 230,000 cubic feet of water every second, and as the major distributary of the Mississippi it carries about a third of the combined flow of the Red and Mississippi rivers at Old River; together, the Atchafalaya and Mississippi account for about 90 percent of the freshwater discharge into the Gulf of Mexico. Since the last ice age, the Mississippi has changed course several times, usually over about 100 years, when a distributary offers a shorter, steeper, and more hydraulically efficient route to the Gulf. Because the Atchafalaya is currently the quickest route, the Mississippi has been trying to switch to this channel since the late 1800s, with flow capture rising from a small and sometimes reversing amount to about 30 percent by 1960 through natural and man-made events. In 1963, the Old River Control Structure near Simmesport was built to keep more water from leaving the Mississippi channel for the Atchafalaya; without that intervention, the Mississippi would likely now occupy these banks. The river’s proximity has long made this area important for transportation and commerce: in the spring of 1863, a significant Civil War battle occurred at the former site of Fort Burton across from the boat landing on the eastern shore, and in Butte La Rose’s early settlement days residents traveled by skiffs and boats to nearby towns while a boat bus carried students to and from school. Today Butte La Rose is the only Atchafalaya Basin community still within the Basin levees, with access now provided by the Interstate 10 exit and local roads, yet residents remain closely tied to the river and surrounding swamps. Although the town stands on a high bank, it remains vulnerable to flooding during high water, with the Atchafalaya’s flood stage above Butte La Rose at 20 feet compared with 47 feet upriver at Simmesport, and the river stage there serves as an indicator of floodway water levels even though sedimentation in the old Atchafalaya River segment no longer accurately reflects stages in the isolated swamps to the south.