ORS § 780.050
The corporate authorities of the town wherein a wharf, dock, pier, moorage or similar structure is proposed to be constructed, or the commission of any port wherein the structure is proposed to be constructed if the proposed location of the structure is not within any town, may regulate the construction of the structure. Upon application of the person entitled to and desiring to construct the wharf, dock, pier, moorage or similar structure, the corporate authorities or port commission, as the case may be, may by ordinance or other like mode prescribe the mode and extent to which the structure may be constructed beyond the line of low-water mark so that the structure shall not be constructed any farther into the stream or other water beyond the low-water line than may be necessary and convenient for the use of the structure and so that it will not unnecessarily interfere with the navigation of the stream or other like water.
ORS 780.050