Wash. Rev. Code § 35.23.840
In a city initially classified as a second-class city prior to January 1, 1993, that retained its second-class city plan of government when the city reorganized as a noncharter code city, the mayor and twelve councilmembers shall constitute the city council. At the first council meeting in each calendar year, the city council shall elect one of their own body to serve as president of the council.
The mayor shall preside at all meetings at which the mayor is present. In the absence of the mayor, the president of the council shall preside. In the absence of both the mayor and the president of the council, the council may elect a president pro tempore from its own body. The president pro tempore shall have all the powers of the president of the council during the session of the council at which the president pro tempore is presiding.
RCW 35.23.840