Wash. Rev. Code § 70.37.060
The bonds of the authority shall be subject to such terms, conditions and covenants and protective provisions as shall be found necessary or desirable by the authority, which may include but shall not be limited to provisions for the establishment and maintenance by the participant of rates for health services of the project, fees and other charges of every kind and nature sufficient in amount and adequate, over and above costs of operation and maintenance and all other costs other than costs and expenses of capital, associated with the project, to pay the principal of and interest on the bonds payable out of the special fund or funds of the project, to set aside and maintain reserves as determined by the authority to secure the payment of such principal and interest, to set aside and maintain reserves for repairs and replacement, to maintain coverage which may be agreed upon over and above the requirements of payment of principal and interest, and for other needs found by the authority to be required for the security of the bonds. When issuing bonds the authority may provide for the future issuance of additional bonds on a parity with outstanding bonds, and the terms and conditions of their issuance.
All bonds issued under the authority of this chapter shall constitute legal investments for trustees and other fiduciaries and for savings and loan associations, banks, and insurance companies doing business in this state. All such bonds and all coupons appertaining thereto shall be negotiable instruments within the meaning of and for all purposes of the negotiable instruments law of this state.
RCW 70.37.060