Agriculture Minister David Littleproud has branded Labor's plan to reform the Murray-Darling Basin Plan a "hoax" aimed at grabbing South Australian votes.
In December all basin state governments and the Commonwealth agreed water recovered must have neutral or positive socio-economic impacts.
But Labor wants to revert to the original definition of "socio-economic impacts", a move criticised by irrigators who fear the bipartisan agreement across different levels of governments will be destroyed.
"Labor knows full well the neutrality test can't be changed without the agreement of the states - this is a hoax," Mr Littleproud said.
"It took years of negotiation to finally deliver this agreement on our nation's biggest ever environmental project and nobody should be playing politics with it."
Labor's water spokesman Tony Burke said the environment and surrounding communities were suffering as a result of the government's inaction.
"Labor will act urgently to restore the basin to health," he said.
National Irrigators' Council chief executive Steve Whan said Labor's pledge to reverse the neutrality test could put the plan at risk.
"That's a concern because what that does is take away that agreement that's actually needed to progress the basin plan," he told the ABC.
Labor has already promised to lift the 1500GL on water buybacks, which has been dismissed by Mr Littleproud.
"The 1500GL buyback cap has not been reached so removing it is a stunt aimed at South Australian votes - but it rips certainty away from basin communities," the minister said.
SA Liberal MP Tony Pasin launched a counterattack on his coalition colleague Barnaby Joyce, after the former Nationals leader said his party needed to focus on water for farms over "Adelaide".
Mr Pasin said that glossed over the Nationals issues, which stemmed from Mr Joyce damaging the party's brand by having an affair with a staffer.
"I thought Barnaby's comments were ill-advised," the rural Liberal MP told Sky News.
"The National Party brand and the damage done to it has more to do with the 'values proposition' than in particular discussions around the Murray Darling Basin."
He said focusing on water policy misunderstood why western NSW voters abandoned the Nationals at last week's state election.
"Unless the National Party is honest with themselves about what is driving that vote, they won't address it," Mr Pasin said.
