Oregon Revised Statutes Water Resources: Irrigation, Drainage, Flood Control, Reclamation § 553.540

(1) All assessments shall be levied by an order of the board. The order shall state the description of the land assessed, the name of the owner of the land as such name appears on the records of the district, or the records of the county assessor, the type and kind of assessment, the amount of the assessment due, and the due date. It shall not be necessary to issue a separate order for each tract of land in a subdistrict, and any number of tracts in the same subdistrict and the same county may be included in one order. A copy of the order levying an assessment, certified and acknowledged by the secretary of the district, shall be filed with the county clerk of the county in which the land is located. Upon being filed, the assessment shall constitute a lien against the land assessed, prior in time to any other liens, rights or interests in the tracts of land described except liens for taxes levied by the state or county.

(2) Notice of all assessments levied by a district shall be given to the landowner by mail and shall be payable on the 30th day after such notice is mailed. All assessments paid after the due date shall be charged interest at the rate of not more than 12 percent per annum. All assessments shall be paid to the secretary-treasurer of the district and a receipt shall be issued therefor. From time to time the board shall order the satisfaction of the liens against lands on which assessments have been paid, and a copy of such order shall be filed with the county clerk of the county in which the lands are located.