Located downstream from substantial irrigation extraction at the “end” of the Murray–Darling River system, South Australia (SA) struggles to maintain flows and the health of the rivers within its borders. Analysis of early twentieth century engineering reports reveals that this problem is not new, beginning in the 1880s with the growth of irrigation in Australia and the riparian demands of the eastern, upstream states. I use the theory of path dependency to analyse the history of the Murray–Darling Basin from a South Australian perspective to argue that the state’s current water issues stem from cultural, institutional, and technological lock-ins shaped by its geo-political position that made it vulnerable to upstream demands for water. As SA’s negotiations for a larger water allocation failed, it turned to construction of an enviro-technical network of weirs, locks and barrages designed to assist navigation, regulate the river’s flow, keep water fresh for landholders and towns, prevent the ingress of salty sea water, and mitigate the consequences of upstream irrigation. With construction of each component the state’s hydro-engineering scheme engineers warned that with increasing extraction these strategies would only buy time and bigger-scale structures would be essential in the future to alleviate accelerating problems. Within decades SA experienced the foretold problems of diminishing flows, increasing salinity, environmental degradation and declining water quality, problems that continue and with climate change are likely to grow worse. Only a fundamental shift in cultural, institutional, and technological lock-ins can change a future trajectory that could improve the health of the river.