Northern Maine Independent System Administrator Northern Maine Independent System Administrator Home The NMISA a nonprofit entity responsible for the administration of the northern Maine transmission system and electric power markets in Aroostook and Washington counties with a load of approximately 130 MW. The NMISA is responsible for providing an independent objective and nondiscriminatory administration of all transmission access transmission information access and related functions and will monitor and operate the markets in Northern Maine for energy ancillary and other services. The NMISA administers the transmission systems of the investorowned and cooperativelyowned utilities in Northern Maine and its members also include all municipallyowned utilities generators suppliers of energy and large retail customers operating in the service area. .