Mo. Rev. Stat. § 242.680
Where proceedings have been begun under the provisions of the sections repealed by the act of April 8, 1905, they may be proceeded with and completed under the provisions of sections 242.010 to 242.690; provided, that all liens, remedies and processes for the collection of taxes provided for in said sections, shall, so far as applicable, be available for the collection of taxes levied and bonds issued under the sections thereby repealed; provided further, that in all cases where drainage districts have been incorporated under the said sections repealed and the work of drainage has been commenced or completed, in whole or in part, no rights or obligations incurred by district or individual shall be nullified, invalidated or for naught held.
§ 242.680, RSMo