in addition, the 1998 reforms forced the separation between lines (transmission and distribution) and supply (generation and retailing). on 1 april 1999, mercury energy, then the major lines and supply company for auckland, new zealand's largest city, was split between lines and supply. mighty river power inherited mercury energy's retail base and its share in the southdown power station (in conjunction with the natural gas corporation). mercury energy then became the name of mighty river's retail business, and the sub-transmission and distribution business of mercury energy was renamed vector.