The catchment covers an area of some 29,150 km2 and encompasses four major urban centres. These include Toowoomba (pop 1999: 87,236) the second largest city in the Murray-Darling Basin), Warwick (pop 1999: 20,574), Dalby (pop 2001: 10,173) and Chinchilla (pop 2001: 5,850). Some 14 Local Government areas lie wholly or partly within the catchment (see Figure 2) and the total population is approximately 170,000 people.

Population change over the past ten years indicate a marked variance between the shires with population decline being experienced in Clifton and Millmerran Shire whilst Cambooya registered record growth (62%). Other shires experiencing moderate growth include, Toowoomba City, Rosalie and Jondaryn Shires.