Me. Rev. Stat. tit. 20-A, § 3655

The courts of New Hampshire shall have the same jurisdiction over the district as though a New Hampshire member district were a party instead of the interstate district. The service necessary to institute suit in New Hampshire shall be made on the district by leaving a copy of the writ or other proceedings in hand or at the last and usual place of abode of one of the directors who resides in New Hampshire, and by mailing a like copy to the clerk and to one other director by certified mail with return receipt requested.