Wash. Rev. Code § 35.23.091
The mayor and the members of the city council may be reimbursed for actual expenses incurred in the discharge of their official duties, upon presentation of a claim therefor, after allowance and approval thereof, by resolution of the city council; and each city councilmember may be paid for attending council meetings an amount which shall be fixed by ordinance and may be revised from time to time by ordinance, but any increase or reduction in the compensation attaching to an office shall not be applicable to the term then being served by the incumbent.
The city attorney, clerk and treasurer, if elective, shall severally receive at stated times a compensation to be fixed by ordinance by the city council.
The mayor and other officers shall receive such compensation as may be fixed by the city council at the time the estimates are made as provided by law.
Any city that provides a pension for any of its employees under a plan not administered by the state must notify the state auditor of the existence of the plan at the time of an audit of the city by the auditor. No city may establish a pension plan for its employees that is not administered by the state, except that any defined contribution plan in existence as of January 1, 1990, is deemed to have been authorized. No city that provides a defined contribution plan for its employees as authorized by this section may make any material changes in the terms or conditions of the plan after June 7, 1990.
RCW 35.23.091