Wash. Rev. Code § 81.84.025
The commission, in granting a certificate to operate as a commercial ferry, shall require the operator to first obtain liability and property damage insurance from a company licensed to write liability insurance in the state or a surety bond of a company licensed to write surety bonds in the state, on each vessel or ferry to be used, in the amount of not less than one hundred thousand dollars for any recovery for personal injury by one person, and not less than one million dollars and in such additional amount as the commission shall determine, for all persons receiving personal injury and property damage by reason of one act of negligence, and not less than fifty thousand dollars for damage to property of any person other than the insured; or combined bodily injury and property damage liability insurance of not less than one million dollars, and to maintain such liability and property damage insurance or surety bond in force on each vessel or ferry while so used. Each policy for liability or property damage insurance or surety bond required by this section must be filed with the commission and kept in full force and effect, and failure to do so is cause for revocation of the operator's certificate.
RCW 81.84.025