If the water right records show two or more irrigation rights as primary on the same land, the right with the oldest priority date shall be considered the primary water right unless the applicant designates a right, other than the right with the oldest priority date, as the primary water right. All other water rights shall be diminished to supplemental water rights.
Or. Admin. Code § 690-380-5120
Stat. Auth.: ORS 536.025 & 536.027
Stats. Implemented: ORS 540.510 - 540.532