Wash. Rev. Code § 70.37.080
Proceeds from the sale of all bonds of a project issued under the provisions of this chapter received by the authority shall be deposited forthwith by the authority in qualified public depositaries in a special fund for the particular project for which the bonds were issued and sold, which money shall not be funds of the state of Washington. Such fund shall at all times be segregated and set apart from all other funds and in trust for the purposes of purchase, construction, acquisition, leasing, or use of a project or projects, and for other special needs of the project declared by the authority, including the manner of disposition of any money not finally needed in the construction, purchase, or other acquisition. Money other than bond sale proceeds received by the authority for these same purposes, such as contributions from a participant or a grant from the federal government may be deposited in the same project fund. Proceeds received from the sale of the bonds may also be used to defray the expenses of the authority in connection with and incidental to the issuance and sale of bonds for the project, as well as expenses for studies, surveys, estimates, inspections and examinations of or relating to the particular project, and other costs advanced therefor by the participant or by the authority. In lieu of itself receiving and handling these moneys in the manner here outlined the authority may appoint trustees, depositaries and paying agents to perform the functions outlined and to receive, hold, disburse, invest and reinvest such funds on its behalf and for the protection of the participants and of bondholders.
RCW 70.37.080