If a majority of the votes cast at the election are against the merger, the irrigation district board shall enter an order refusing to assent to the merger. If a majority of the votes cast favor the merger, the board shall enter an order assenting to the proposed merger. A copy of the order certified by the president and secretary of the board shall be filed with the board of county commissioners or, in case the merger involves a joint drainage improvement district, with the boards of county commissioners of the counties in which the joint drainage improvement district is situated.