The right hereby granted shall not be exercised within the limits of any regularly organized port district, nor against the right-of-way of any railroad company within the yard limits thereof, nor unless and until the director of the department of agriculture after a full hearing shall have determined that existing facilities are inadequate and that a public necessity exists for the construction of additional facilities and shall specify what additional facilities are necessary and shall have further determined that the facilities contemplated to be established will be a public benefit. Such hearing shall be initiated and conducted in accordance with the statutes, rules and regulations relating to public hearings before the director.