The Mallee is the most northwesterly district in the state of Victoria. Definitions vary, however all are based on the Victorian distribution of mallee eucalypts. These trees dominate the surviving vegetation through most of Mallee, except for swamps and areas along waterways, and the very rare stands of intact Casuarina.
The Australian Standard Geographic Classification region of Mallee covers Rural City of Mildura, Rural City of Swan Hill, the Shire of Gannawarra and the Shire of Buloke. This is the classification used by the Australian Bureau of Statistics.
The Government of the State of Victoria has historically had many departmental regions combining the Mallee with the greater Bendigo area, the current one being named the "Loddon Mallee". This region includes the Loddon River catchment and adjacent areas as well as the Mallee. This region is used by all state government departments, and often there is a central body for the region located in Bendigo. Some locals wish there to be a separate "Mallee" departmental region, as this would mean more services would be delivered there.
The Government of Victoria's Department of Innovation, Industry and Regional Development has a promotional region known as "Wimmera Mallee". This region is made up of the Wimmera and very small parts of the Mallee that are distant from the Murray River. A separate region known as "Mildura Swan Hill" covers the rural cities of Mildura and Swan Hill.
The Mallee has no surface drainage: the native vegetation has so high a rooting density that the rainfall of most years is easily absorbed and the porous sandy soils mean that any excess in an exceptionally wet year will recharge groundwater supplies which tend to be highly saline. Flow from the Wimmera River to the south supplies Lake Hindmarsh and, very occasionally (in 1918, 1956 and 1975), overflows to the north. The Murray River is, thus, the only source of fresh water for the region and is consequently overburdened by intensive irrigation.
The climate of the Mallee is the hottest and driest in Victoria owing to its inland location. Rainfall is usually only produced by the most vigorous frontal systems or by occasional penetration of tropical air in the summer. Average annual rainfall shows a well-defined north-south gradient: Mildura averages only 270 millimetres (under 11 inches) per year but Hopetoun in the south receives around 370 millimetres (just under 15 inches). Variability, however, is quite high: in 1973 the Mallee averaged as much as 650 millimetres (over 25 inches) but in 1982 only 115 millimetres (4.5 inches). Temperatures in summer are generally very hot: in January 1906 it is believed Mildura reached temperatures as high as 50.8°C (123.4°F) and the average maxima in January and February are around 32°C (90°). In the winter, maximum temperatures average a delightful 16°C (60°F), but minima average 4°C (39°F) and frosts are very common.
The Mallee is a primarily agricultural region: apart from possible mineral sands in the wheat and salt from certain ephemeral lakes there are no mineral deposits of value and industry is generally on a small scale and confined to food processing. Wheat and barley are widely grown on the less infertile soils in the southeast of the region, but fertilizers, especially superphosphate are essential for success and yields only a quarter of those in most of Europe or North America - in drought years, they can be as little as one twentieth of European wheat yields.
Fruit growing along the Murray River has in modern times overshadowed grain crops as the Mallee's major source of revenue. Oranges and grapes are particularly important and the region produces a large part of Victoria's wine though most of it is inexpensive cask wines. Dairying on irrigated pastures is important in the south of the region, but is threatened by its high water demand and the extreme scarcity of water in the Murray-Darling Basin.
Tourism is also significant industry. Mildura and Swan Hill contain a number of tourism focused businesses, including a number of specially built attractions and festivals. The Murray itself is also a major attraction, many people coming to the district for fishing and to stay on houseboats. The many Mallee national parks - Wyperfeld, Hattah-Kulkyne and Murray Sunset National Parks, wilderness parks, state forests, and other parks over the river are also major drawcards.