Persons signing said petition shall state following their respective names, in a place provided in said petition for that purpose, the legal description of the lands owned by them and the estimated irrigable acreage contained in the same: PROVIDED, That the petitioners shall be prima facie deemed to be the owners of lands susceptible of irrigation for the purposes of the petition in the absence of evidence to the contrary submitted prior to the day of the hearing hereinafter provided for on said petition.
RCW 89.30.028