ORS § 539.190
Within six months from the date of the decree of the circuit court determining the rights upon any stream, or if appealed, within six months from the date of the decree of the circuit court on the decision of the Supreme Court, the Water Resources Director or any party interested may apply to the circuit court for a rehearing upon grounds to be stated in the application. If in the discretion of the court the application states good grounds for the rehearing, the circuit court or judge shall make an order fixing a time and place when the application shall be heard. The clerk of the circuit court shall, at the expense of the petitioner, forthwith mail written notice of the application to the director and to every party interested, and state in the notice the time and place when the application will be heard.
ORS 539.190