Wash. Rev. Code § 35.22.140
On the petition of a number of registered voters of a city equal to twenty-five percent of the total votes cast at the last preceding city election, the city council of a charter city shall, or without such petition may, cause an election to be held for the purpose of electing a board of fifteen freeholders for the purpose of preparing a new charter for the city by altering, revising, adding to or repealing the existing charter including all amendments thereto. The members of the board of freeholders must be qualified electors and must have been residents in the city for a period of at least two years prior to their election. At such election the proposition of whether or not a board of freeholders shall be created at all shall be separately stated on the ballots and unless a majority of the votes cast upon that proposition favor it, no further steps shall be taken in the proceedings.
RCW 35.22.140
Amendment of charter: State Constitution Art. 11 s 10 (Amendment 40).