RCW 35A.14.010: Authority for annexation.

Any portion of a county not incorporated as part of a city or town but lying contiguous to a code city may become a part of the charter code city or noncharter code city by annexation. An area proposed to be annexed to a charter code city or noncharter code city shall be deemed contiguous thereto even though separated by water or tide or shore lands [tidelands or shorelands] and, upon annexation of such area, any such intervening water and/or tide or shore lands [tidelands or shorelands] shall become a part of such annexing city.