a levee gate and the process for the production thereof . the levee gate of the invention includes a rectangular sheet of thermoplastic material with a rectangular sleeve located on one edge of the thermoplastic material , the rectangular sleeve being a portion of the rectangular sheet fused to the rectangular sheet . the process for the production of the levee gate includes extruding a cylindrical tube of thermoplastic material , inflating the cylindrical tube as it is extruded to provide an inflated length of tube , flattening the inflated length of tube without fusing the opposed walls of the tube to each other , and continuously fusing a portion of the opposed walls together to form a seam .