Whenever the Department of Transportation finds and determines that the operation of a ferry across any stream, river, bay, arm of the ocean or other body of water is necessary and convenient in connection with the use of any state highway, the department may acquire, construct, establish, maintain and operate the ferry. The department may operate the ferry under a contract, or with its own employees or under a license or permit granted by the department, the license or permit to contain such conditions, requirements, terms and provisions as to the department seem best. The maintenance or operation of any such ferry is subject, however, to the federal laws and requirements governing navigation.