Except as specified, amendments to this chapter do not affect the validity of any valid outstanding warrants, bonds, or other obligations of drainage districts, and all sinking funds created for the payment of these obligations continue in force until the liquidation of the obligations. All valid rules adopted by any board of county commissioners or board of drainage commissioners remain in full force and effect until altered or repealed by the board.
N.D.C.C. § 61-16.1-59.2