ORS § 545.567
After bonds have been authorized under ORS 545.565 to 545.621 but before they are offered for sale, the board of directors shall make a preliminary determination of the area and description of irrigable land in each legal subdivision or other described tract if held in separate ownership within the district. The board shall also make a preliminary determination of the proportionate share or liability of each tract for assessment in payment of the total amount of the bonds issued. The determinations shall be for the purpose of fixing the irrigable area or, if the assessment is based on benefits, the total benefits accruing from the existing or proposed improvement to each ownership and tract, and of fixing the assessment in proportion to the benefits or irrigable area. The determination of benefits or irrigable area shall include a description of the land, name of the ownership, number or irrigable acres of each tract, proposed assessment against each tract, and such other data as may be necessary to identify the land and ownership.
ORS 545.567