Murray River

The Murray River, known as Millewa to the Ngarrindjeri people and Dhungala or Tongala to the Yorta Yorta, flows through southeastern Australia. Stretching 2,508 kilometers, it holds the title of the country’s longest river. Five of Australia’s next six longest rivers—the Murrumbidgee, Darling, Lachlan, Warrego, and Paroo—are its tributaries. Together with the Murray, their catchments make up the Murray–Darling basin, which spans roughly one-seventh of Australia’s land area. This basin is regarded as the nation’s most vital irrigated zone.

The river begins in the Australian Alps, draining the western slopes of the country’s highest peaks. From there, it meanders northwest across inland plains, forming the border between New South Wales and Victoria before entering South Australia. Near Morgan, it shifts from an east–west course to a southern one for its final 315 kilometers, reaching the eastern edge of Lake Alexandrina, a lake with fluctuating salinity. The water then passes through channels around Hindmarsh and Mundoo Islands, where it meets lagoon water from The Coorong to the southeast. Finally, it empties into Encounter Bay on the Southern Ocean through the Murray Mouth, about 10 kilometers east of Goolwa South. Although the river can discharge large volumes, especially before large-scale regulation, the waters at the mouth are almost always slow and shallow. As of 2010, the system received just 58 percent of its natural flow, though this figure varies.

The border between Victoria and New South Wales runs along the top of the river’s southern (left) bank, not the middle. This means that until the river enters South Australia, the entire water and riverbed belong to New South Wales. The combined Murray–Darling system stretches 3,750 kilometers, draining most of inland Victoria, New South Wales, and southern Queensland. Compared to rivers of similar length elsewhere, the Murray carries only a small fraction of water, with highly variable annual flows. Since official records began, it has dried up completely during three extreme droughts. More commonly, a sandbar forms at the mouth, stopping the flow.

A 1980 High Court ruling addressed the border ambiguity after a man died while fishing on the Victorian bank. Because the river’s course changes over time and banks have been modified, the boundary can be unclear. For 11 kilometers west of the 141°E line of longitude, the border between Victoria and South Australia lies in the middle of the river. This discrepancy arose from an east–west miscalculation of 3.72 kilometers during an 1840s survey, leading to a long-running dispute. West of this sector, the Murray lies entirely within South Australia.

The Murray agricultural region, centered on the river, includes nine local government areas: Albury, Balranald Shire, Berrigan Shire, Edward River Council, Federation Council, Greater Hume Shire, Murray River Council, Wentworth Shire, and Snowy Valleys Council. Major settlements along its course, from source to ocean, have populations recorded in the 2016 Australian census.

The river and its tributaries host a range of native life adapted to its fluctuations. Fish include the famous Murray cod, trout cod, golden perch, Macquarie perch, silver perch, eel-tailed catfish, Australian smelt, and western carp gudgeon. Other aquatic species include the Murray short-necked turtle, broad-clawed yabbies, and the large-clawed Macrobrachium shrimp. More widely distributed species like common long-necked turtles, common yabbies, the small clawless paratya shrimp, water rats, and platypus also live here. The endangered Murray crayfish has seen its numbers increase thanks to scientific efforts. River red gum forests and fringing corridors line the Murray.

Since European settlement, the river’s health has declined sharply, especially due to flow regulation. Extreme droughts from 2000 to 2007 stressed river red gum forests, raising concerns about their survival. Floods have also occurred, most notably in 1956, when waters inundated many lower-reach towns in South Australia for up to six months.

Between 2.5 and 0.5 million years ago, the river ended in a vast freshwater lake called Lake Bungunnia, formed by earth movements that blocked the river near Swan Reach. At its largest, the lake covered 33,000 square kilometers, extending near the Menindee Lakes to the north and Boundary Bend to the south. It drained about 600,000 years ago. Deep clays from the lake are visible in cliffs around Chowilla, South Australia. Keeping such a lake full would have required much higher rainfall; its draining likely marked the end of a wet period in the Murray–Darling Basin and the start of widespread arid conditions similar to today. A species of Neoceratodus lungfish once lived in Lake Bungunnia.