The jurisdiction of the Mississippi River Commission, established by section 641
of this title, is extended to include
(1) all of the area between the eastern side of the Bayou Lafourche Ridge from Donaldsonville, Louisiana, to the Gulf of Mexico and the west guide levee of the Mississippi River from Donaldsonville, Louisiana, to the Gulf of Mexico;
(2) Alexander County, Illinois; and
(3) the area in the State of Illinois from the confluence of the Mississippi and Ohio Rivers northward to the vicinity of Mississippi River mile 39.5, including the Len Small Drainage and Levee District, insofar as such area is affected by the flood waters of the Mississippi River.