Wash. Rev. Code § 47.56.060
The department, the officials thereof, and all other state officials are empowered to act and make agreements consistent with law as may be necessary or desirable in connection with the duties and powers conferred upon them respectively by law regarding the construction, maintenance, operation, and insurance of toll bridges or the safeguarding of the funds and revenues required for such construction and the payment of the indebtedness incurred therefor. The department shall keep full, complete, and separate accounts of each toll bridge, and annually shall prepare balance sheet and income and profit and loss statements showing the financial condition of each such toll bridge, which statement shall be open at all reasonable times to the inspection of holders of bonds issued by the department.
RCW 47.56.060