When a ferry mentioned in ORS § 384.105 is acquired, constructed, operated and maintained by the Department of Transportation alone, the entire cost and expense may be paid out of the State Highway Fund. If the ferry has been acquired, constructed and is being operated and maintained under a cooperative agreement between the state and a county, the proportion of the cost and expense to be borne by the state, as agreed upon, shall be paid out of the State Highway Fund and the proportion to be paid by the county shall be paid out of county road funds.