Wash. Rev. Code § 47.56.200
Notwithstanding anything contained in this chapter, the proceeds received from the sale of bonds and the tolls or other revenues received from the operation of any toll bridge or toll bridges may be used to defray any expenses incurred by the department in connection with and incidental to the issuance and sale of bonds for the construction of the toll bridge or toll bridges including expenses for the preparation of surveys and estimates and making inspections and examinations required by the purchasers of the bonds. In addition, the proceedings authorizing the issuance of the bonds may contain appropriate provisions governing the use and application of the bond proceeds and toll or other revenues for the purposes herein specified.
RCW 47.56.200