Wash. Rev. Code § 43.180.340
Any bonds issued under this subchapter may be secured by a trust agreement between the commission and a corporate trustee, which may be any trust company or bank having the powers of a trust company within or without the state. The trust agreement may evidence a pledge or assignment of the financing documents and lease, sale, or loan revenues to be received from a lessee or purchaser of or borrower with respect to a nonprofit facility for the payment of principal of and interest and any premium on the bonds as the same shall become due and payable and may provide for creation and maintenance of reserves for these purposes. A trust agreement or resolution providing for the issuance of the revenue bonds may contain such provisions for protecting and enforcing the rights and remedies of the bondowners as may be reasonable and proper and not in violation of law, including covenants setting forth the duties in relation to the acquisition of property and the construction, improvement, maintenance, use, repair, operation, and insurance of the nonprofit facility for which the bonds are authorized, and the custody, safeguarding, and application of all money. Any bank or trust company incorporated under the laws of the state which may act as depository of the proceeds of revenue bonds or of revenues may furnish such indemnifying bonds or pledge such securities as may be required by the commission. A trust agreement may set forth the rights and remedies of the bondowners and of the trustee and may restrict the individual right of action by bondowners as is customary in trust agreements or trust indentures securing bonds and debentures of private corporations. In addition, a trust agreement may contain such provisions as the commission considers reasonable and proper for the security of the bondowners which are not in conflict with this subchapter.
RCW 43.180.340