Until about 1960 there was a clear policy that increasing production through irrigation was in the national interest, and should be supported by government. Subsidisation of agriculture was seen as justified to increase productivity and exports, which increased New Zealand’s foreign exchange earnings. Economic development took precedence over conservation or environmental interests.
Canterbury irrigation schemes
Irrigation schemes opened after the Second World War were:
- the Ashburton–Lyndhurst scheme, opened in 1945 and supplying 13,300 hectares
- the Mayfield–Hinds scheme, opened in 1948 and covering 35,400 hectares
- the Valetta–Tinwald scheme, opened in 1957 and covering 5,400 hectares.
By 1959 the total irrigated area within these schemes was about 62,500 hectares.
The name border dyke describes the channel that restricts the flow of irrigation water as it moves over farmland. A dyke is a bank that prevents water entering or leaving an area. Border dykes are no more than 20–30 centimetres high and built on slightly sloping ground. It can’t be steeper or water would erode the soil.
Research and advice
In 1946 the Department of Agriculture established the Winchmore Irrigation Research Station to investigate ways of improving the efficiency of irrigation. They looked at ways of making irrigation automatic, and evaluated the importance of irrigation in contrasting farm systems. By the mid-1960s almost all of the flood irrigation schemes in New Zealand used automatic systems. The Department of Agriculture employed irrigation advisory officers to provide information to farmers.
1960s to 1970s
From the 1960s there were rapid increases in irrigation development, largely supported by government subsidies. By 1970 the total area under government irrigation schemes was about 100,000 hectares.
Private developments also increased dramatically, mostly based on groundwater resources in Canterbury. These covered an additional 100,000 hectares. Irrigation was seen as a cost-efficient way of making farming more productive – especially dairying.
However, community concerns about negative impacts on the environment from farming began to emerge.
1980s to 2000
Since the mid-1980s farmers themselves, rather than the government, have led the demand for increased irrigation.
Concern about the environment, and the availability and quality of water, increased. The Resource Management Act 1991, which aims to promote the sustainable management of natural and physical resources, was introduced.