The Rangitata River, 75 miles in length, reaches the sea just north of Temuka and is formed by the confluence of two main tributaries, the Clyde and Have-lock Rivers, which with their tributaries drain the eastern side of the Southern Alps from the Lyell Glacier to the Godley Glacier. Other large tributaries are the Lawrence River, which drains the west side of the Arrowsmith Range, and Forest and Bush Streams, draining part of the Two Thumbs Range, and Potts River. These larger tributaries join the Rangitata in the large glacially excavated basin containing several sheep stations, including Mesopotamia Station, where Samuel Butler established himself in the early sixties.
Before it reaches the Canterbury Plain, the Rangitata runs through a gorge where, since 1945, part of the flow has been directed into a diversion channel and used for irrigation of a large area of the Canterbury Plains. The water in excess of that required for irrigation generates 25,200 kW. (maximum) of electricity at Highbank and is then discharged into the Rakaia River. This scheme could be extended if required, as only part of the flow is used at present. The name Rangitata (Rakitata) has been variously translated “close sky”, “day of lowering clouds”, and “the side of the sky”. It seems evident that the name has come down from very ancient times.
by Alan Copland Beck, M.SC., New Zealand Geological Survey, Christchurch.