Murry-Darling water needs are not understood, CEDA finds. Photo: Nicolas Walker
More science is needed to understand the impact of returning water to the Murray-Darling Basin to bring it back to health, a new report says.
A Committee for Economic Development of Australia (CEDA) report on Wednesday says not enough is known about the ecosystem's water needs or how ecological targets will be met.
Farmers, on the other hand, are experienced in managing limited resources and know how much water they need to irrigate and produce the best crop yields, the report says.
By monitoring the impact of water delivery on the environment, authorities managing the basin could be more confident about using its limited resources more efficiently, says the report co-authored by CEDA, Harvard University and Uniwater.
"To achieve that, we need to understand the ecosystem's need for water - when, where, how much - a lot better than we do now," said Professor John Langford, joint editor of the report and director of Uniwater, a Melbourne water research centre.
"Farmers have got far more knowledge about the water needs of their crops ... than the environmental water holders."
The report also calls for a review of Australia's food supply chain.
Australia has been "very successful" at allocating water efficiently in the past, but talks on a draft basin plan are being overshadowed by single-issue disputes, it says.
Prof Langford said if environment flows were better understood, water could be delivered to achieve mutual benefits for farmers and environmentalists.
"If we treat the environment and irrigation water as two separate things, as we seem to be thinking at the moment, we'll get less value out of it for both parties," he told AAP.
"There's some reforms that, if we introduced them, would make this a less painful process."
For example, river managers - who adjust weirs and release dam valves - could deliver options to water holders instead of taking orders for particular amounts on a needs basis.
Through increased co-operation, and understanding the needs of farmers and environmental water holders, river operators like Goulburn Valley Water or the Murray-Darling Basin Authority could take advantage of opportunities for mutual benefit, Prof Langford said.
Without a rigorous evaluation system in place, the success or failures of environmental flows won't be known, leading to uncertainty and inflexibility when it comes to reviewing water allocations in the future.
Environment Minister Tony Burke has pledged to introduce a final Murray-Darling Basin Plan to parliament by the end of the year.