Service upon the state of Iowa shall be made by serving an original notice or summons, with a copy of the petition attached, upon any member of the Iowa state department of transportation in the manner provided for the service of original notices in actions brought in the district courts of the state of Iowa, or by serving summonses upon any member of the said department in the manner provided for service of summons in actions brought in United States district courts, except only that the state shall be required to appear within thirty days after the day such notice or summons is served upon a member of the said department.
Iowa Code § 613.13