Oregon Revised Statutes Public Health and Safety § 451.585

(1) Whenever the entire area of a district is incorporated in or annexed to a city in accordance with law, the district shall be extinguished and the city shall upon the effective date of such annexation succeed to all the assets and become charged with all the liabilities, obligations and functions of the district. The district officers shall forthwith deliver to the city officers the district assets and records. Uncollected taxes theretofore levied by such district shall become the property of the city and be delivered to it by the county treasurer upon collection.

(2) Notwithstanding subsection (1) of this section, a district, the entire area of which becomes incorporated in a city, may continue to provide services if the continuation is proposed by petitioners in a petition for incorporation that is subsequently approved by voters in an incorporation election. At any time after incorporation, a city may cause a district to be extinguished and succeed to all the assets and become charged with all the liabilities, obligations and functions of the district if:

(3) For the public hearing required in subsection (2)(a) of this section, the governing body shall fix a date, time and place for the hearing and cause notice of the date, time, place and purpose of the hearing to be published once each week for two successive weeks prior to the date of the hearing in a newspaper of general circulation in the city, and shall cause notices of the hearing to be posted in four public places in the city for a like period.

(4) Whenever a part less than the whole of a district becomes incorporated in or annexed to a city in accordance with law, the city may at any time after such incorporation or annexation cause that part to be withdrawn from such district in the manner set forth in ORS 222.524, and the provisions of ORS 222.510 to 222.580 shall be applicable to such withdrawal except that in case the district and the city cannot agree upon a division of assets or obligations and liabilities, then and in such case, either the district or the city may petition the circuit court for the county in which the city has its legal situs to determine such division.