About three-quarters of the water needed for the Murray-Darling Basin Plan is now in government hands.

The MDBA’s 2013-14 annual report on the plan shows the progress of water reform in the region, as authorities fight to recover supplies in Australia's largest river system.

The report shows that $2.3 billion has been spent on water buybacks since 2007-2008, while just under $2.3 billion was spent on infrastructure upgrades.

It is the first time the figure for buyback has been so close to the amount spent on infrastructure.

The MDBA says the shift shows a change in government policy in regard to the ways that water is amasses for environmental use in the Murray-Darling.

Recent reforms have led to caps on the amount of water achieved through buybacks and the promotion of infrastructure investment as the way to get more water.

In just the last 12 months, nearly $500 million worth of infrastructure work helped close the gap between buybacks and upgrades.

The policies have allowed seventy per cent of the initial 2,750 gigalitres of water required under the Basin Plan to reach government hands.

But the remaining 30 per cent of water will be harder to attain.

The MDBA says it will work out how to find that last 30 per cent after its review of Sustainable Diversion Limits in mid-2016.

That review could see the amount of water taken for the Murray-Darling Basin changed, if it can be proven that water can be managed more efficiently.