RCW 85.38.140 through 85.38.170 constitute a mutually exclusive alternative method by which diking, drainage, or sewerage improvement districts in existence as of July 28, 1985, may measure and impose special assessments and adopt budgets. RCW 85.38.150 through 85.38.170 constitute the exclusive method by which diking, drainage, or sewerage improvement districts created after July 28, 1985, may measure and impose special assessments and adopt budgets.