Wash. Rev. Code § 35A.40.030
The legislative body of a code city, at the end of each fiscal year, or at such other times as the legislative body may direct, shall designate one or more financial institutions which are qualified public depositaries as set forth by the public deposit protection commission as depositary or depositaries of the moneys required to be kept by the code city treasurer or other officer performing the duties commonly performed by the treasurer of a code city: PROVIDED, That where any bank has been designated as a depositary hereunder such designation shall continue in force until revoked by a majority vote of the legislative body of such code city. The provisions relating to depositaries, contained in chapter 39.58 RCW, as now or hereafter amended, are hereby recognized as applicable to code cities and to the depositaries designated by them.
RCW 35A.40.030