The Murrumbidgee River rises in the Snowy Mountains at 1600 metres elevation. While still in the mountains the river
becomes involved in the Snowy Mountains Hydro-Electric Scheme then flows into Burrinjuck Dam on the western edge of the
mountains. After Burrinjuck the Murrumbidgee leaves the uplands north-east of Gundagai (elevation 250 metres)
emerging into a broad river valley through the rolling hills of the western slopes and foothills of the Great Dividing
Range. This terrain, extending past Wagga Wagga, has been extensively cleared of eucalypt woodlands for cropping and
grazing with introduced pastures. There are some remnants of eucalypt woodland, eucalypt open forests, grasslands and
Past Wagga Wagga the river leaves the western slopes and around Berembed Weir east of Narrandera enters the broad plains of the lowlands continuing in a gentle descent to join the Murray River west of Balranald at about 60 metres elevation and 1470 kilometres from the source. Shortly before the Murrumbidgee reaches the Murray River, the Lachlan River joins from the north. Between Narrandera (elevation less than 140 metres) and Balranald the river flows through the Riverina bioregion characterised by treeless plains covered with saltbush, bluebush and native grasses. River red gum communities grow along rivers and creeks where the watertable is high enough to saturate the root zone. Watercourses with less water available are lined with Black Box communities. These plains have traditionally been used for grazing sheep, and are particularly well-known for merino studs, but activity has expanded to include cattle grazing and broadacre crops such as wheat and sorghum. When irrigation water is available, major horticultural projects grow grapes, vegetables and citrus.
Climate along the Murrumbidgee varies from cool high country around the headwaters to hot plains in the west. Rainfall varies from more than 1500 mm annually in the highlands to less than 400 mm on the western plains (310 mm at Balranald). Low rainfall and high evaporation in the western plains (1800 mm in an average year) are important factors contributing to low runoff into the lower Murrumbidgee. 24% of rainfall received under average climate conditions upstream of Wagga Wagga becomes runoff into the river; on the flat lowlands below Wagga Wagga only 2% of rainfall becomes runoff.
Burrinjuck Dam is a major storage on the Murrumbidgee River built primarily for irrigation. Blowering Dam on the Tumut River, joining the Murrumbidgee upstream of Gundagai, is part of the Snowy Mountains Scheme and receives the outflow from Tumut power stations. Some water flowing down the Tumut River from the Snowy Scheme originated in the upper reaches of the Murrumbidgee River and has been diverted through Tantangara Reservoir and Lake Eucumbene before entering the Tumut as power station outflow.
Murrumbidgee River water is extensively used for irrigation with over 10,000 kilometres of irrigation channels served by weirs at Berembed, Yanco, Gogeldrie, Hay, Maude and Redbank. Berembed Weir diverts water into the Main Channel delivering water to the Murrumbidgee Irrigation Area around Griffith and Leeton; Gogeldrie Weir supplies water to Coleambally Irrigation Area. The irrigated area is used to grow mainly rice, grapes, citrus, fruit and vegetables. The MIA is Australia's largest wine producer and nearly all of Australia's rice output comes from the Riverina region (including the Murrumbidgee and Murray Irrigation areas north of the Murray River).
More than 500,000 people live in the Murrumbidgee catchment (including the Australian Capital Territory where the Molonglo River is a tributary of the Murrumbidgee) with several population centres along the river. Downstream from the ACT the river passes through or near Gundagai, Wagga Wagga, Narrandera, Darlington Point, Hay and Balranald.
In the nineteenth century paddle-steamers used the Murrumbidgee River to serve sheep stations and settlements along the river. In good years, when the river held a lot of water, vessels could reach as far upstream as Gundagai but Wagga Wagga was initially accepted as the practical limit of navigation; with time, the navigation limit was revised downstream to Narrandera then to Darlington Point. The 1902 plan to make the Murray, Darling and Murrumbidgee Rivers navigable envisaged eight locks along the Murrumbidgee from its junction with the Murray; the furthest upstream lock would have been at Hay confirming the Darlington Point area (depending on how far water backed up behind Hay weir) as the normal upper limit of navigation.
But, by the time the plan for a series of locks was prepared, the expanding railway system was taking business from the paddle-steamers and river trade had entered terminal decline. Locks were built in the Murray below Mildura and at a few other places but none on the Murrumbidgee River. Within a few years most of the paddle-steamers had been scrapped or abandoned to become derelict. When weirs were built it was for irrigation and those weirs do not have locks so navigation by larger vessels is now impractical. As well, there is trend towards facilitating native fish breeding by encouraging fallen trees and snags to remain in the river making navigation difficult. While the Murrumbidgee was once considered primarily as a transport corridor that role is no longer relevant and the river's irrigation role is dominant.
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¶ Lower Murrumbidgee Catchment documentation for UNESCO Hydrology, Environment, Life and Policy project at CSIRO Land and Water website updated 2003. Downloaded 4 April 2008
¶ Australian Natural Resources Atlas - Natural Resources Topics, Biodiversity and Vegetation - NSW. Downloaded 6 April 2008
¶ Australian Natural Resources Atlas - Rangelands Overview. Downloaded 6 April 2008