The Western Catchment is the largest catchment in NSW, covering some 230,000 square kilometres. It includes the Barwon-Darling, Culgoa, Paroo, Warrego, Narran, Bokhara and Birrie River catchments. It takes in significant portions of the Bourke, Brewarrina, Central Darling, Cobar and Walgett Shires and the Unincorporated Area.

The Catchment is predominantly leasehold land, administered under the Western Lands Act 1901 by the Department of Infrastructure, Planning and Natural Resources. There are more than 630 pastoral and agricultural holdings. Excluding the City of Broken Hill, the population of the Western Catchment is approximately 18,000 people.

Predominant land uses in this semi-arid zone are grazing, dryland cropping, irrigated cotton production, mining, tourism and natural conservation. Bourke, Brewarrina, Cobar, Walgett, Lightning Ridge and Broken Hill are the major service centres.

The Western Catchment is not a ‘catchment’ in the traditional sense. A catchment is usually thought of as an area directly associated with a river basin or a river and its tributaries.

The Western Catchment is unique to other catchments in NSW because it not only encompasses a whole series of river systems, some of them seasonal, but it also includes the largest and most diverse areas of natural rangelands within NSW.