Troubled wetlands including the Macquarie Marshes may get some relief after the Federal Government succeeded in buying back 35 billion litres of water for the environment from irrigators in the Murray-Darling Basin, its first big water buy-back under the plan to save the river system.

The Federal Climate Change Minister, Penny Wong, will give State Ministers details of the $50 million buy-back of permanent water licences from farmers at a meeting in Adelaide today.

Despite concerns that farmers would not sell and the buy-back would inflate the price of water, several irrigators appeared willing to sell their permanent water entitlements after one of the worst droughts in Australia's history.

The price is hard to assess because the Government bought valuable "high-security" entitlements often used by farmers with permanent plantings and general water entitlements.

"This first buy-back of entitlements is a down payment on the future of the Murray-Darling Basin as we tackle the effects of climate change, drought and over-allocation on its rivers and communities," Senator Wong said.

But she conceded that dams and water storage levels across the Murray-Darling are so low that "it may be some time before the water is able to be delivered".

"It's pretty much water on paper right now," Richard Kingsford, an adviser on the Government's water buy-back committee said.

Many dams in the Basin are only between 10pc and 20pc full.

Many holders of general entitlements have not been able to get water for several years.

But Professor Kingsford said he was very pleased with the first buy-back.

"It's water in the bank. When it does rain, you will have environmental flows ready to go," he said.

The water bought will eventually flow to critical wetlands that are home to bird breeding colonies in NSW and South Australia.

The Federal Government has allocated $3 billion to buy back water licences over the next 10 years and there are fears that this will eventually push up water prices for irrigators who want to remain on the land.

As well, water flows in the Murray-Darling are still extremely low.