Environmental scientists have welcomed plans to bring more water down the Murray but have concerns about pushing back the timeframe.
The federal government will put an extra 450 gigalitres into the system, taking the total to be returned under the Murray-Darling Basin Plan to 3200GL.
The trade-off is the deadline for the new plan will be extended from 2019 to 2024.
The extra water will be sourced from farms, where government funds will make water use more efficient, and more money will also be spent to remove constraints along the river, such as low bridges.
Director of Australian wetlands at the University of NSW, Richard Kingsford, described the move as an historic initiative, while human geographer from Flinders University Jonathan Sobels said the decision to remove constraints was obvious and sensible.
But they both expressed concern at the delay in finalising the plan.
'The downside is that it will be over a reasonably long period and if we have another dry cycle we may lose parts of the environment,' Professor Kingsford said.
Jennifer McKay, the director of water policy at the University of South Australia, said the extra water was good news for environmental protection.
'The key issue will be to ensure that it is used in ways that bring some consensus between stakeholder groups,' she said.
'The citizens of the Murray-Darling Basin have been at loggerheads over the production impact of water for the environment, and it is important that this water is used in ways to not make this worse.'
Prof McKay said it was important the extra water was used to preserve the health of the river and its aquifers for future generations.
'This concept of the future users of water is one that has created the most conflict in the past,' she said.
Agricultural economist at Charles Sturt University, Kevin Parton, said the extra water was the right move for the environment but questioned if subsidising infrastructure investment was the most cost-effective approach.
'Previous research shows that water buyback at fair market prices is the most cost-effective approach,' he said.