Wash. Rev. Code § 24.36.130
Each association shall within thirty days after its incorporation, adopt for its government and management, a code of bylaws, not inconsistent with this chapter. A majority vote of the members or shares of stock issued and outstanding and entitled to vote, or the written assent of a majority of the members or of stockholders representing a majority of all the shares of stock issued and outstanding and entitled to vote, is necessary to adopt such bylaws and is effectual to repeal or amend any bylaws or to adopt additional bylaws. The power to repeal and amend the bylaws, and adopt new bylaws, may, by a similar vote, or similar written assent, be delegated to the board of directors, which authority may, by a similar vote, or similar written assent, be revoked.
RCW 24.36.130