At any time after the completion of such reservoir or reservoirs, which shall be constructed and completed within two years after filing such declaratory statement, such person, company, or corporation shall have the same accurately surveyed, as hereinafter provided, and shall file in the United States land office in the district in which such reservoir is located a map or plat showing the location of such reservoir, which map or plat shall be transmitted by the officer, as the Secretary of the Interior may designate, of said United States land office to the Secretary of the Interior and approved by him, and thereafter such land shall be reserved from sale by the Secretary of the Interior so long as such reservoir is kept in repair and water kept therein.