The Murray-Darling Basin extends over 1 million km2 of south-eastern Australia, covering three-quarters of NSW, more than half of Victoria, significant portions of Queensland and South Australia, and all of the ACT.
While the average long-term annual inflow into the Basin has been calculated as 32,553GL, over the past 114 years inflows have ranged from a high of around 117,907 GL in 1956 to a low of around 6,740 GL in 2006.
On average, approximately 42% of annual surface-water run-off in the Basin is diverted for consumptive use.
In 2006, over 2 million people lived in the Basin. Agricultural production in the Basin accounts for 40% of Australia's agricultural production and is estimated to be worth $15 billion annually. The Basin is also environmentally significant, containing 16 Ramsar-listed wetlands covering 636,500 ha and one World Heritage site.