Wash. Rev. Code § 24.06.115
The articles of incorporation or the bylaws may provide the number or percentage of votes which members or shareholders are entitled to cast in person, by mail, by electronic transmission, or by proxy, which shall constitute a quorum at meetings of shareholders or members. However, in no event shall a quorum be less than one-fourth, or in the case of consumer cooperatives, five percent, of the votes which members or shareholders are entitled to cast in person, by mail, by electronic transmission, or by proxy, at a meeting considering the adoption of a proposal which is required by the provisions of this chapter to be adopted by at least two-thirds of the votes which members or shareholders present at the meeting in person or by mail, by electronic transmission, or represented by proxy are entitled to cast. In all other matters and in the absence of any provision in the articles of incorporation or bylaws, a quorum shall consist of one-fourth, or in the case of consumer cooperatives, five percent, of the votes which members or shareholders are entitled to cast in person, by mail, by electronic transmission, or by proxy at the meeting. On any proposal on which a class of shareholders or members is entitled to vote as a class, a quorum of the class entitled to vote as such class must also be present in person, by mail, by electronic transmission, or represented by proxy.
RCW 24.06.115