ORS § 539.220
Whenever the rights to the waters of any stream have been determined as provided in this chapter and it appears by the records of such determination that it had not been at one and the same proceeding, then the Water Resources Director may open to public inspection all proofs or evidence of rights to the water, and the findings of the director in relation thereto, in the manner provided in ORS 539.090. Any person who then desires to contest the claims or rights of other persons, as set forth in the proofs or established by the director, shall proceed in the manner provided for in ORS 539.100 and 539.110; provided, that contests may not be entered into and shall not be maintained except between claimants who were not parties to the same adjudication proceedings in the original hearings.
ORS 539.220