Wash. Rev. Code § 79.120.010
It is the duty of the department simultaneously with the establishment of harbor lines and the determination of harbor areas in front of any city or town, or as soon as practicable, to survey and plat all first-class tidelands and shorelands not previously platted, and in platting the tidelands and shorelands to lay out streets which shall be dedicated to public use, subject to the control of the cities or towns in which they are situated.
The department shall also establish one or more public waterways not less than fifty nor more than one thousand feet wide, beginning at the outer harbor line and extending inland across the tidelands belonging to the state. These waterways shall include within their boundaries, as nearly as practicable, all navigable streams running through the tidelands, and shall be located at other places as in the judgment of the department may be necessary for the present and future convenience of commerce and navigation. All waterways shall be reserved from sale or lease and remain as public highways for watercraft until vacated as provided for in this chapter.
The department shall appraise the value of platted tidelands and shorelands and enter the appraisals in its records.
RCW 79.120.010