Patterns of river modification since settler invasion of southern Australia are the product of a specific set of deep-seated and implicit cultural values concerning the purpose and function of waterways. Rivers have been dammed, diverted, dredged and straightened to meet a range of human needs and objectives. Such changes are routinely described as ‘improvements’ but there is a lack of critical engagement with what ‘improvement’ might mean. Interventions carried out initially on an ad hoc basis, and later more systematically with state support, collectively shed light on the persistent underlying drive to ‘Improve’ nature and society that has permeated Western thought since the Enlightenment. Here we use the example of one river system, the Loddon, to analyse ways in which Improvement intersected with settler engagement with Australian rivers. We argue that settler interventions have been informed by a consistent set of understandings about the purpose of rivers. The characteristics of water management infrastructure along the Loddon reveal how the river fell short of the settler-colonial ideal and why they thought it needed to be Improved at all.