Western New South Wales towns are struggling to adapt to having less water since the introduction of the Murray Darling Basin Plan, farmers have warned.

It has been three years since the Commonwealth bought millions of litres of water from irrigators in NSW, Victoria and South Australia for environmental purposes.

More than 400,000 megalitres have been recovered from the Macquarie, Lachlan and Gwydir rivers.

But Jock Coupland, who farms on the Lachlan near Condobolin, said the Federal Government's buybacks were not working.

"It's a failure," Mr Coupland said.

"We're just losing more and more and more water under these reforms without any evidence of improving the environment.

"I'm not sure when it's going to stop but it's clearly, it's got to."

Mary Ewing from the irrigators group Lachlan Valley Water said little was offered to help farming communities adjust.

"There was relatively little funding for irrigation efficiency, so I think it's been very difficult for people to improve their operations as a result of so much water being purchased," she said.

The Macquarie River relinquished the highest volume of water with 170,000 megalitres flowing back to the environment.

The Warren Shire, west of Dubbo, was among the hardest hit.

A harvest on the Moree Plains in NSW. ( ABC: Joanna Woodburn )

The Warren Shire Council has applied for federal and state government assistance to help it adjust to having less water.

"The Murray Darling Basin Authority's own socio-economic experts said that Warren was one of the communities that would end up on a knife edge," said the Warren Shire Council's general manager Ashley Weilinga.

"That basically means that we've gone from a productive community probably to a community that's going to rely on government services and transfer payments."

Water users on the Gwydir River in the state's north sold 100,000 megalitres.

Mark Winter, who farms north-west of Moree, said the balance had shifted.

"It's tipped too far to the other side now, there's too much water for the environment," Mr Winter said.

"It's just cut production too much and cut the jobs in the town and that's just not going to revive."

River systems showing signs of recovery, scientist says

But a leading environmentalist scientist disagrees.

Professor Richard Kingsford from the University of NSW said there was clear evidence that the river systems were starting to recover.

"What we're seeing is actually a bit of a bounce back but we can't ever go back to before rivers were developed obviously," he said.

"We've seen trees respond. We've seen invertebrates. We've seen the whole food web come back."

The environmental scientist said the Basin Plan was integral to restore the rivers.

"I think it's been fundamentally important," Professor Kingswood said.

"I think the worst it can have done is slow the very accelerated rate of degradation that was going on."

He said one option being flagged by irrigators to sell back water in wetter times was not viable.

"If you're going to trade your water in a wet time it essentially means that you could be dampening the amount of boom that you could be getting for your water, so my argument would be you'd have to be careful about that," he said.