 Parts of the Riverina experienced substantial population growth in the late 1990s and early 2000s ; in the five @-@ year period between 1996 and 2001 , Griffith 's population increased by 10 @.@ 8 % . Until recently Wagga Wagga 's population was declining slowly and ageing with strong growth in age groups 40 and over . This has now changed and Wagga Wagga has become one of Australia 's leading examples of the " sponge " city phenomenon , attracting residents from smaller towns in the Riverina such as Urana . In the year ended 30 June 2006 , the population of Wagga Wagga grew by 1 @.@ 3 % , driven by its role as the regional centre for the Riverina and its hosting of a campus of Charles Sturt University and Australian Defence Force bases . 
