in 1998 the new zealand government passed the electricity industry reform act 1998 which was intended to change the structure of the electricity industry to encourage competition. this act required the operational separation of lines and generation business activities by 1 july 1999 and separation of the ownership by 1 january 2004. as by now trustpower had built up a substantial generation portfolio it elected to be a generator/retailer and so sold its lines and its contracting business, powerlink limited. following a competitive sales process, trustpower sold its lines business to united networks limited (formerly power new zealand) for $485 million. trustpower also acquired the retail business from eight energy companies: waipa power, wairoa power, marlborough electric, buller electricity, westpower, electricity ashburton, central electric, and otago power.