Wash. Rev. Code § 19.16.300
The board shall meet as soon as practicable after the governor has appointed the initial members of the board. The board shall meet at least once a year and at such other times as may be necessary for the transaction of its business.
The time and place of the initial meeting of the board and the annual meetings shall be at a time and place fixed by the director. Other meetings of the board shall be held upon written request of the director at a time and place designated by him or her, or upon the written request of any two members of the board at a time and place designated by them.
A majority of the board shall constitute a quorum.
A vacancy in the board membership shall not impair the right of the remaining members of the board to exercise any power or to perform any duty of the board, so long as the power is exercised or the duty performed by a quorum of the board.
RCW 19.16.300