If any lands are excluded at the hearing by the board of supervisors on the ground that the lands may not be economically irrigated from the original proposed works, or some reasonable modification thereof or extension thereto, the district shall be obligated to pay to the person or persons owning the lands so excluded at the time of the exclusion thereof, all district taxes theretofore paid to the district treasury by any owner of the land, together with interest thereon at the rate of six per cent per annum.