Oregon Revised Statutes Water Resources: Irrigation, Drainage, Flood Control, Reclamation § 537.320

Any person may enter upon any land for the purpose of locating a point of diversion of the water intended to be appropriated, and upon any land lying between such point and the lower terminus of the proposed ditch, canal or flume of the person, for the purpose of examining the same and of locating and surveying the line of such ditch, canal or flume, together with the lines of necessary distributing ditches and feeders, and to locate and determine the site for reservoirs for storing water.