Wash. Rev. Code § 33.24.090
An association may invest its funds in stock or notes, bonds, debentures, or other such obligations of any federal home loan bank, the Home Owners' Loan Corporation, any federal land bank, the Federal Savings and Loan Insurance Corporation, the Federal Housing Administration, the Federal National Mortgage Association, or any other instrumentality of the federal government, or any state or federal agency organized under the laws of the United States or of the state of Washington authorized to loan to or act as a fiscal agency for, or insurer of, a savings and loan association.
An association may become a member of and invest its funds in other savings and loan associations organized under either federal or state law, which have an authorized office in this state: PROVIDED, That the investment in any such other savings and loan association shall not exceed the amount which is insured by the Federal Savings and Loan Insurance Corporation.
RCW 33.24.090