Oregon Revised Statutes Public Health and Safety § 450.215

(1) If territory proposed to be annexed is within the limits of another sanitary district, the board of the district to which annexation is proposed and the board of such other district shall meet with each other prior to the hearing on the annexation petition to agree upon a division and disposal of the properties of the other district that lie within the territory proposed to be annexed. An agreement between the boards is effective only in the event the proposed annexation is approved by the electors.

(2) The plan of division of properties provided for in subsection (1) of this section shall be arrived at by giving consideration to the assessed valuation of the other district as a whole, the assessed valuation of the territory to be annexed, the types of properties and their location and intended use. If a plan of division of properties is agreed upon, the plan shall be reduced to writing and, if the proposed annexation is approved by the electors, shall be binding upon the districts party to the plan and upon all other interested persons.