A call to use environmental water to help drought-affected farmers has been rekindled by Deputy Prime Minister Michael McCormack, but his own colleagues have ruled out the idea.

Key points: Deputy PM wants to discuss allowing famers to use environmental water

Deputy PM wants to discuss allowing famers to use environmental water Agriculture Minister and Environment Minister not happy to change allocations

Agriculture Minister and Environment Minister not happy to change allocations Environmental groups argue any change to allocations will undermine the basin plan

Sorry, this audio has expired Nationals cause confusion on water policy for drought-affected farmers

Mr McCormack said several times on Thursday the Federal Government "will certainly take a look at" changing legislation to allow water allocated for environmental flows under the Murray-Darling Basin Plan to be used by irrigators dealing with the drought.

"We're looking at what we can do in that regard," he said.

"We need to do whatever we can.

"This is an emergency situation and our farmers need help."

Only about 8 per cent of water in dams is environmental water. ( ABC News: Matthew Abbott )

Sorry, this audio has expired Mixed reaction from farmers over diverting Murray Darling flows

It follows earlier calls by Barnaby Joyce for the same measure.

However, both Agriculture Minister David Littleproud and the Environment Minister, Liberal MP Melissa Price, have ruled out changes to the water allocations in the basin plan.

Authority has been doing a good job

"We don't have any plans to change the legislation," a spokesman for Ms Price said.

Mr Littleproud, a Nationals colleague of Mr McCormack's, said the Commonwealth Environmental Water Holder, which determines water allocations under the Basin Plan, has been doing a good job.

"They're a statutory authority and they'll [continue to] do that in good conscience," he said.

"It's important to understand that only about 8 per cent of the total water in dams are environmental water, it's not a huge amount."

Sorry, this audio has expired Murray-Darling system would take 'decades to recover': David Papps

Environmental groups argue that any change to the agreed system of allocating water rights will undermine the hard-fought truce of the Basin Plan and create uncertainty for everyone.

James Trezise from the Australian Conservation Foundation warned that making an exception to help farmers in the short term would cause long-term trouble for everyone.

"The Murray-Darling Basin Plan is built to account for drought and it doesn't affect the entitlement of irrigators in drought," he said.

"They are subject to the same rules as environmental water in terms of entitlement.

"What is being proposed is changing the law, changing the basin plan, which has serious implications for stability."

It is a concern Mr Littleproud shares.

"It's important we provide certainty to the 2 million Australians that live up and down the Basin."

The conflicting messages risk offering false hope to drought-affected farmers that water allocations could be made immediately available when there is no sign of consensus on up-ending the basin plan.