- The race is 67 kilometres long
- Average width of 15 metres
- Average depth of 3 metres
- Average water speed of 0.8m/sec
The canal diverts water from the Rangitata River at Klondyke, across the Mid Canterbury Plains, to irrigate about 64, 000 hectares of farmland. A second intake is at the South Ashburton River. The race supplies water to the irrigation schemes of Mayfield Hinds, Valetta and Ashburton Lyndhurst and to the hydro electric power stations at Montalto and Highbank.
The RDR was built during the depression to give badly needed work for the unemployed. The RDR was the nation’s first major river diversion and opened in 1945. Construction began in 1937 initially by pick and shovel. Major control structures built along the race include the Rangitata intake and sandtrap, checkgates, spillways and siphons passing under rivers and streams which cross the race. The RDR’s design was completed in 1982 with the addition of Montalto.
The RDR’s affordable water shows the foresight of the people who built the scheme and the good fortune of today’s shareholders who benefit from paying for the water only.