Wash. Rev. Code § 51.44.080
The department shall notify the state treasurer from time to time, of such transfers as a whole from the state fund to the reserve fund and the interest or other earnings of the reserve fund shall become a part of the reserve fund itself. As soon as possible after June 30th of each year the department shall expert the reserve fund to ascertain its standing as of June 30th of that year and the relation of its outstanding annuities at their then value to the cash on hand or at interest belonging to the fund. The department shall promptly report the result of the examination to the state treasurer in writing not later than September 30th following. If the report shows that there was on said June 30th, in the reserve fund in cash or at interest, a greater sum than the then annuity value of the outstanding pension obligations, the surplus shall be forthwith turned over to the state fund but, if the report shows the contrary condition of the reserve fund, the deficiency shall be forthwith made good out of the state fund.
RCW 51.44.080