Salinity Management in the Murray–Darling Basin, Australia

Abstract

The southern Murray–Darling Basin (MDB) is particularly vulnerable to salinity problems. Much of the Basin’s landscape and underlying groundwater is naturally saline with groundwater not being suitable for human or irrigation use. Since European settlement in the early 1800s, two actions—the clearance of deep-rooted native vegetation for dryland agriculture and the development of irrigation systems on the Riverine Plains and Mallee region—have resulted in more water now entering the groundwater systems, resulting in mobilization of the salt to the land surface and to rivers. While salinity has been a known issue since the 1960s, it was only in the mid-1980s that was recognized as one of the most significant environmental and economic challenges facing the MDB. Concerted and cooperative action since 1988 by the Commonwealth and Basin state governments under a salinity management approach implemented over the past 30 years has resulted in salinity now being largely under control, but still requiring on-going active management into the future. The approach has involved the development of three consecutive salinity strategies governing actions from 1988 to 2000, from 2001 to 2015, and the most recent from 2016 to 2030. The basis of the approach and all three strategies is an innovative, world-leading salinity management framework consisting of: An agreed salinity target; joint works and measures to reduce salt entering the rivers; and an agreed accountability and governance system consisting of a system of salinity credits to offset debits, a robust and agreed method to quantify the credits and debits, and a salinity register to keep track of credits and debits. This paper first provides background to the salinity issue in the MDB, then reviews the three salinity management strategies, the various actions that have been implemented through these strategies to control salinity, and the role of the recent Basin Plan in salinity management. We then discuss the future of salinity in the MDB given that climate change is forecast to lead to a hotter, drier and more variable climate (particularly more frequent droughts), and that increased salt loads to the River Murray are predicted to come from the lower reaches of the Mallee region. Finally, we identify the key success factors of the program.