When the by-laws of a district are approved by the board of supervisors of the principal county, the board of directors shall adopt them by resolution entered in its minutes, unless prior to adoption by resolution by-laws are adopted and filed with the secretary by the written assent of the holders of title to a majoritiy in area of the land. The records of the United States Land Office for the district in which the land is situated, the records of the State Lands Commission, and the records in the office of the county recorder of each affected county are conclusive evidence of ownership for the purposes of this section.