The McKenzie canal system in the central South Island was built in the 1970s and 1980s for the product of the hydro-electricity generation system, its also the perfect environment to grow colossal trout and salmon. Lakes Tekapo, Ohau, Pukaki and Ruataniwha are all connected by 58km of canals . The main purpose of the canals is to provide a regulated flow of water to the turbines in the hydro power stations