ORS § 551.020
One-half or more of the owners of lands which may be conveniently embraced in one diking district and which are subject to overflow by tidewaters or freshets, and who represent one-half or more of the area of the lands embraced within the proposed diking district, may present a petition to the county court of the county in which the lands are situated, reciting therein that it is desired to form a diking district for the purpose of improving by diking or damming the lands contained therein, which are subject to overflow by tidewater or by freshets, as the case may be, and further giving by legal subdivisions, or by metes and bounds, the description of such lands as are desired to be included in the district, and stating that the petitioners are the owners of one-half or more of the acreage to be embraced in the district. If, upon consideration of the petition, the county court finds the statements therein are substantially correct, the court shall require the petitioners to give a bond sufficient to cover the preliminary expenses of the proceedings.
ORS 551.020