Wash. Rev. Code § 35.82.220
Notwithstanding any restrictions on investments contained in any laws of this state, the state and all public officers, municipal corporations, political subdivisions, and public bodies, all banks, bankers, trust companies, savings banks and institutions, building and loan associations, savings and loan associations, investment companies and other persons carrying on a banking business, all insurance companies, insurance associations and other persons carrying on an insurance business, and all executors, administrators, guardians, trustees and other fiduciaries may legally invest any sinking funds, moneys or other funds belonging to them or within their control in any bonds or other obligations issued by a housing authority pursuant to the housing authorities law of this state or issued by any public housing authority or agency in the United States, and such bonds and other obligations shall be authorized security for all public deposits; it being the purpose of this chapter to authorize any persons, firms, corporations, associations, political subdivisions, bodies and officers, public or private, to use any funds owned or controlled by them, including (but not limited to) sinking, insurance, investment, retirement, compensation, pension and trust funds, and funds held on deposit, for the purchase of any such bonds or other obligations: PROVIDED, HOWEVER, That nothing contained in this chapter shall be construed as relieving any person, firm or corporation from any duty of exercising reasonable care in selecting securities.
RCW 35.82.220