The Macquarie River, in central NSW, is one of the major inland rivers systems in the state. It forms near Bathurst by the joining of the Fish and Campbell Rivers before travelling some 960 km, generally northwest, through the towns of Bathurst, Wellington, Dubbo and Warren to the Macquarie Marshes. Following major flood events, water can flow past the Macquarie Marshes and into the Barwon-Darling river system upstream of Brewarrina.
The major tributaries in the Macquarie system are the Turon, Cudgegong, Bell, Little and Talbragar Rivers. There are also a number of important effluent streams downstream of Warren including the Gunningbar, Duck, Crooked, Monkeygar, Marra, Bulgeragar and Gumcowl creeks.
The regulated section of the Macquarie system incorporates the Cudgegong River, from Windemere Dam, downstream to the junctions of where the Macquarie River and its effluent creeks meet with the Barwon River.
The Lower Macquarie Groundwater Sources covers an area of approximately 4,050 square kilometres generally to the west of Narromine in central NSW. The area is located south of the Macquarie River commencing 12 kilometres east of Narromine and running to Warren. The other boundaries are the Warren-Nevertire-Bogan road to the west and the Bogan River to the south.
The Lower Macquarie Groundwater Sources is made up of alluvial and sandstone aquifers. The alluvial aquifers are higher yielding (approximately 150 litres/sec) than the sandstone (approximately 5 to 10 litres/sec).
The Lower Macquarie Groundwater Sources is divided into six zones. Zones 1, 2 and 6 are predominately alluvial and zones 3, 4 and 5 are predominantly sandstone.