Irrigation is a widespread practice required in many areas of Australia, the driest inhabited continent, to supplement low rainfall with water from other sources to assist in growing crops and pasture. Overuse or poor management of irrigation is held responsible by some for environmental problems such as soil salinity and loss of habitat for native flora and fauna. Irrigation differs from dryland farming (farming relying on rainfall) in Australia in its level of intensity and production. It is a far more economically productive land use than dryland farming. Common crops produced using irrigation include rice, cotton, canola, sugar, various fruits, and other tree crops, and pasture, hay, and grain for beef and dairy production. Surface irrigation is Australia's most common irrigation method, with drip and center pivots also utilised. All rights to use and control water are vested in the state, which issues conditional entitlements for water use. The first large-scale irrigation schemes in Australia were introduced during the 1880s, partially in response to drought. In 1915, the River Murray Waters Agreement was signed, setting out basic conditions for the river's water use which remain in force today. Towards the end of the 20th century, environmental problems in the basin became serious as diversions for irrigation approached or exceeded the capacity of natural flows. Following negotiations beginning in 1985, the Murray–Darling Basin Agreement was signed in 1987. The more comprehensive National Water Initiative was adopted in 2004.
Water sources
In general, water for irrigation comes from two main sources: river systems and underground aquifers. Major river systems used for irrigation in Australia include the Murray-Darling system, the Ord River in the Kimberley region of Western Australia, and many rivers along the east coast of Australia, including the Burdekin River Irrigation Area in North Queensland, where irrigation is used during the dry season for double-cropping. A major source of groundwater in Australia is the Great Artesian Basin. Although the Murray-Darling Basin receives only 6% of Australia's annual rainfall, over 70% of Australia's irrigation resources are concentrated there, which makes up around 90% of the resources in the basin. It contains 42% of the nation's farmland and produces 40% of its food.
History
The first schemes for irrigation commenced in the latter half of the nineteenth century. Goulburn Weir, constructed from 1887 to 1891, was the first major diversion structure built for irrigation development in Australia.
A major drought in Victoria from 1877 to 1884 prompted Alfred Deakin, then a minister in the State Government and chairman of a Royal Commission on water supply to visit the irrigation areas of California. There, he met the Canadian brothers George and William Chaffey, who had worked on irrigation schemes in California. In 1886, the Chaffey brothers came to Australia and selected a derelict sheep station covering 250,000 acres (1,000 km2) at Mildura as the site for their first irrigation settlement. They signed an agreement with the Victorian government to spend at least A£300,000 on permanent improvements at Mildura in the next twenty years. Also in 1886/87, the Chaffey brothers were invited by John Downer, the Premier of South Australia, to commence a settlement at Renmark, South Australia. The Dethridge wheel, used for measuring the flow of water delivered to individual farms was developed in 1910.
Irrigation in the Murrumbidgee valley began with the irrigation experiments of agricultural pioneer, Samuel McCaughey at North Yanco station in 1900. This private scheme involved the construction of around 320 kilometres of channels in irrigating about 162 square kilometres (63 sq mi) of land. McCaughey's success appeared to have encouraged the New South Wales government to commence large-scale irrigation. This process began with the Barren Jack and Murrumbidgee Canals Construction Act 1906 (Cth). Burrinjuck Dam on the Murrumbidgee River near Tumut was commenced in 1907, work commenced on the channels and the first farms were established soon after. In 1907, the Victorian government invited American Elwood Mead to become chairman of the newly formed State Rivers and Water Supply Commission of Victoria. The high hopes for government-controlled irrigation in Victoria owed much to Deakin's earlier efforts, who now as Prime Minister, expected Mead to advise at both national and state levels. Mead was not content with proposing only higher water rates in attempting to recover maintenance, management, and construction costs. He also insisted on the logical extension, which demanded higher-yielding uses of water and land. The Water Act 1909 was passed despite the fierce opposition of large landowners, and Mead's influence on rural development was greatly increased by his assumption of overriding control in the planning of closer settlement in Victoria's irrigation districts. Mead claimed much credit for the hierarchical arrangement of allotment sizes which characterized these designs, but his impact was rather in the very scale and complexity of the commission's operations, in Mead's salesmanship, and in the bureaucratic web in which the new settlers became enmeshed. Mead worked in Australia full-time for four years, but his involvement would continue until his resignation became effective in May 1915; this professional experience consolidated Mead's international reputation. In 1923, Mead's four-month Australia advisory tour was punctuated by disputes with Joseph Carruthers and leading irrigation authorities in New South Wales over the selection and use of land in the Murrumbidgee Irrigation Area. Mead rejected plans for further fruit planting, advocating larger dairy farms and improved co-ordination of grazing and irrigation enterprises, which would favour stock fattening and the intensive production of lucerne. In Western Australia, the state's first controlled irrigation scheme, the Harvey Irrigation Scheme, was officially started in 1916. It was further developed during the latter part of the 1930s depression to take unemployed workers to dig and build the extensive irrigation channels in the district.
Policy The management of irrigation, particularly with relation to the problems of the Murray-Darling Basin has long been a politically contentious issue in Australia.
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