Oregon Revised Statutes Water Resources: Irrigation, Drainage, Flood Control, Reclamation § 540.150

To bring about a more economical use of the available water supply, water users owning lands to which are attached water rights may rotate in the use of the supply to which they may be collectively entitled. Whenever two or more water users notify the watermaster that they desire to use the water by rotation, and present a written agreement as to the manner of rotation, the watermaster shall distribute the water in accordance with the written agreement.