Oregon Revised Statutes Water Resources: Irrigation, Drainage, Flood Control, Reclamation § 554.580

(1) As a condition to approval of an application, if the meeting is on an application to include lands, the members may require the applicant to agree to pay a pro rata share of all unpaid obligations incurred for improvements which the applicant would have been required to pay if the land of the applicant had been in the corporation from its formation or from the time the obligations were incurred.

(2) From the date of filing articles of amendment with the Secretary of State, providing for the inclusion of such lands they shall be liable for obligations incurred and assessments levied.