When said board of appraisers shall have made said determination of the ratio of benefits, as aforesaid, all the lands within the district shall be classified and properly designated and shall be described in terms of government sections, and fractions thereof in designated townships and ranges, on the base map, and the board of appraisers shall file said map with the secretary of the district: PROVIDED, That platted lands may be described in terms of the recorded plat thereof.
RCW 86.09.421