A petition for the construction of a dam or a system of dams, including gates and other proper and necessary structures incidental thereto, may be made in writing to the board of flood irrigation. Such petition shall be signed by at least six freeholders of the district to be affected by the flood irrigation project and shall set forth and particularly describe the boundaries of the district which will be affected. The petitioners must accompany the petition with a map of such    proposed district. Such map shall show the approximate location of the proposed dam or dams and other necessary works by means of which it is intended to control the waters of a river or stream. Said petition also shall describe in a general way the benefits expected to be derived from the establishment of such improvement.