Lachlan River - Course

Course

The river rises in the central highland of New South Wales, part of the Great Dividing Range, 13 km east of Gunning. Its major headwaters, the Carcoar River, the Belubula River and the Abercrombie River converge near the town of Cowra. Minor tributaries include the Morongla Creek. Other tributaries include the Boorowa River and Crookwell Rivers.

Wyangala Dam was built near Cowra to regulate the flow of the river. However, the Lachlan, unlike the Murrumbidgee River and the Murray River further south, does not have its source in the snowfields and does not enjoy the large and reliable spring flow from the melting snow from which those rivers benefit. Indeed, the annual flow of the Lachlan is too erratic for really reliable dams to be possible. Annual flows have ranged from less than 1,000 megalitres (810 acre feet (1,000,000 m3)) in 1944 to as much as 10,900 megalitres (8,800 acre feet (10,900,000 m3)) in 1950. In dry years, the Lachlan can have periods of zero flow of over a year (for example from April 1944 to April 1945), which is a complete contrast to the Murray and Murrumbidgee which have not been known to cease to flow since European settlement. The river has flooded every seven years since 1887 at Forbes.

The Lachlan River flows west and then south, terminating in the Great Cumbung swamp near Oxley (between Hay and Balranald). The 500 km² swamp, a floodplain for the Lachlan, joins the Murrumbidgee River to the south and becomes part of the Lowbidgee Floodplain. There is some irrigation in the middle reaches of the Lachlan.