Like the Mississippians , Americans made massive changes in the floodplain ; their development has reduced its ability to absorb floods . The destruction of wetlands and paving over of areas along all the major rivers has increased the severity of flooding over the decades , despite attempted engineering solutions for flood control , which in turn have exacerbated flooding . During the Great Flood of 1993 , major portions of the southern Bottom were flooded ; 47,000 acres ( 190 km ² ) of land below Columbia , Illinois was inundated , destroying the town of Valmeyer . The waters came within five feet of overtopping the East St. Louis levee . If they had run over , they would have flooded 71,000 acres ( 290 km ² ) and destroyed this urban industrial area . More than nine feet of floodwater covered the town of Kaskaskia in 1993 after it overtopped the levee ; only the spire of the Catholic church and roof of a nearby shrine rose far above the waters
Great Flood of 1993
Great Flood of 1993
American Bottom