ABOUT $800 million in rural output and 800 jobs will be lost from the Murray Darling Basin if proposed cuts to irrigators' rights become reality.

But farm leaders say the impact will be far worse.

The MDBA’s guide to its proposed basin plan today confirmed cuts of between 27 and 37 per cent were proposed.

The cuts to Sustainable Diversion Limits would achieve another 3000 – 4000 gigalitres of water for environmental purposes.

The MDBA found the environment required between 3000 and 7600 GL more annually, but restricted its proposed cuts to between 3000 and 4000GL as it considered the economic and social impacts of the higher end of the range too great.

The cuts would result in a drop of 13 per cent of the gross value of irrigated agricultural production in the basin, the guide says.

However farm figures immediately poured scorn on the figures.

National Irrigators’ Council CEO Danny O'Brien called on Water Minister Tony Burke to intervene and reduce the cuts to irrigator’s entitlements and labelled the estimate of 800 job losses "beyond a joke"."

"Frankly, the social and economic numbers put forward by the MDBA … doesn’t pass the laugh test," Mr O'Brien said.

He said the range of cuts proposed went "too far" but refused to specify a range of cuts acceptable to the NIC.

National Farmers’ Federation president David Crombie also attacked the level of cuts proposed.

He said the NFF would "interrogate" the numbers and modelling used by the MDBA in drawing its conclusions.

A long term regional reduction in employment of 1.1 per cent is expected.

A reduction in current diversion limit of some 40-45 per cent is expected in Goulbourn-Broken, Loddon, Kiewa on the Murray, Ovens and Warrego regions.

The reduction expected in Victoria is between 27 and 36 per cent.

The Lachlan, Murrumbidgee, Barwon-Darling and Lower Darling are proposed to face a 40 per cent decrease in sustainable diversion limits for groundwater.

Regions expected to be suffer the greatest reduction in economic activity were Murrumbidgee and Goulburn-Broken.

Next on the list were Condamine – Balonne, Murray, Macquarie, Campaspe and Loddon.

Smaller towns are expected to be hardest hit by cuts to water entitlements as they tend to have less diverse economies, the guide said.

Industries which used high volumes of water – rice, cotton and broadacre cereals – will likely be hardest hit and could lose upwards of 30 per cent of the value of their production, according to the guide.

The guide noted money from buybacks would likely be used to reduce debt and so would not flow through local communities.

"Some regions and towns that are highly dependent on water diversions may experience significant impacts," the guide said.

"The Authority believes there is an urgent need to undertake a comprehensive assessment of social and economic impacts at a community and industry level."

The MDBA also recommended existing community assistance packages "help potentially create new opportunities and employment opportunities".

Making the cuts to entitlements is expected to open the mouth of the Murray River between 90 and 92 per cent of the time.

MDBA chair Mike Taylor said rivers systems needed to flow out to the sea.

"Systems need flow out of the mouth to expel nutrients, otherwise they die," he said.

Expelling salt from the river and into the ocean was also desperately required by the Murray, he said.

Total effects of the changes are not expected to be felt until 2019 when the plan is implemented.

Eleven out of 29 areas in the basin would be affected, losing between 26 and 35 per cent of their irrigation water entitlements, according to the long-awaited gide to the new basin plan.

Released today by the Murray Darling Basin Authority, the guide says the Murray Darling River system needs to have between an extra 3000 and 4000 gigalitres of water a year if it is to be revived.

The authority was critical of barriers to water trade, including Victoria's 4 per cent cap.