Whoever wins the upcoming election will be at the helm when critical decisions must be made about the Murray-Darling Basin Plan in 2024, when it is due to wrap up. There is growing concern that if the MDBP's success is only judged by its water recovery targets, regional communities will suffer another round of water buybacks.

Retiring Nationals MP Damian Drum said once the plan ended in 2024, it was "time to put it to bed", regardless of the final amount of water recovered.

"We need to put a line in the sand and say enough is enough," Mr Drum said.

"In 2011 when finalising the plan, they had no idea what 2750 gigalitres was going to be able to achieve. What was agreed to was just a number. Now a decade down the track, we're still just looking at that number, not the pain and damage that comes with it."

Nationals Senator Perin Davey said the plan was based on models, predictions and assumptions made over a decade ago, all designed around achieving environmental outcomes through volumes of water.

But since then, she said, basin governments had learnt a great deal about how to effectively manage rivers.

"The biggest mistake we can make is worshipping numbers on a page - the intent was right, but it oversimplifies what is a complex issue," Senator Davey said.

"We really do need to sit down and look at the lessons we've learnt. We know now that there are other complimentary ways to achieve environmental outcomes besides volumes of water that were never considered.

"Fishways are a good example. You don't need more water for them, but without them you won't get environmental improvements."

IN OTHER NEWS:

Several reports have indicated the plan will not recover the remaining 605 gigalitres in time, and the NSW and Victorian government have both admitted it is unlikely they're water saving projects will not be completed in time.

Legislation states if the targets are not met by mid-2024, the federal government will be obliged to recover the remaining water through buybacks, a wildly unpopular policy in the regions. The Coalition has vowed not to enforce buybacks, but has not made the necessary changes to enshrine the promise in legislation.

Both Mr Drum and Senator Davey argue the focus of the plan and how its success was defined had to shift away from the "black and white" data of water recovery, towards a more nuanced look at what environmental outcomes have been achieved, regardless of the final targets.

It's a growing sentiment within the agricultural community. NSW Irrigators chief executive Claire Miller said with the basin plan likely to fall short and no plan about what to do when it does, there was "a train wreck racing at us".

"It has been well and truly established there is a very high risk the plan will not reach the 605 gigalitre target, so no one any side of politics can say they have not been warned," Ms Miller said

"We need to have a serious shift in dialogue away from recovering volumes of water and magically expecting to get environmental outcomes. Instead we need to look at what outcomes we're actually getting."

Ms Miller said a stock take of what environmental outcomes had been achieved - and what outcomes were actually possible - was a good place to start.

"One of the outcomes is that the Murray mouth be kept open at one metre 95 per cent of the time without dredging - the problem with that is it opens up to the sea, so it doesn't matter how much fresh water you push through, the tides will push sand back into the mouth," Ms Miller said.

Senator Davey said although the conversation about the plan's success had to move away from the recovery figures, that doesn't mean governments should stop their water saving projects.

"We're saying that we have to accept the numbers are purely that - just numbers on a page," she said.

"When we come to the deadline, we should not be black and white about it."