From the outback to the ocean
The waters of the Murray flow through several lakes that fluctuate in salinity (and were often fresh until recent decades) including Lake Alexandrina and the Coorong before emptying through the Murray Mouth into the Southern Ocean near Goolwa.
The Murray River forms part of the 3,750 kilometre long combined Murray-Darling river system which drains most of inland Victoria, New South Wales, and southern Queensland.
Overall the catchment area is one seventh of Australia's land mass hwoever it carries only a small fraction of the water of comparably-sized rivers in other parts of the world. In its natural state it has even been known to dry up completely in extreme drought.
The Murray River (and associated tributaries) support a variety of species. These include a variety of native fish such as the famous Murray cod, trout cod, golden perch, Macquarie perch, silver perch, eel-tailed catfish, Australian smelt and western carp gudgeon, and other aquatic species like the Murray short-necked turtle, Murray River crayfish, and broad-clawed yabbies.
The health of the Murray River has declined significantly since European settlement, particularly due to river regulation, and much of its aquatic life including native fish are now declining, rare or endangered. Recent extreme droughts (2000–2007) have put significant stress on river red gum forests, with mounting concern over their long term survival.
Introduced fish species such as carp, Gambusia, weather loach, redfin perch and brown trout and rainbow trout have also had serious negative effects on native fish, while carp have contributed to environmental degradation of the Murray River and tributaries by destroying aquatic plants and permanently raising turbidity. In some segments of the Murray, carp have been the only species found.
According to the Intergovernmental Panel on Climate Changes' 4th Assessment Report, the frequency of bird-breeding events in the Macquarie Marshes (Murray-Darling basin) is predicted to decrease with reduced streamflow, as breeding requires a certain minimum annual flow
Endangered birds: plains wanderer, red-tailed black-cockatoo (south-eastern), swift parrot, regent honeyeater, black-eared miner, western whipbird (eastern)
The Basin is Australia's most important agricultural region, accounting for 41 per cent of the nation's gross value of agricultural production.1