Large areas of the basin will suffer "permanent decline", with widespread loss of native fish, wetlands and coolibah woodlands, as well as increased salinity levels, according to an environmental risk study tabled by Friends of the Earth water policy spokesman Jonathan La Nauze.

The authority had "never published a simple summary of what the proposed plan means for the environment," Mr La Nauze told the Senate rural affairs inquiry.

"It took days of poring over some 20 Authority publications, but this is what it looks like - what lives and what dies under the plan," he said.

The study shows the plan will fail to meet 48 specific ecological targets needed to maintain river health across the basin, with a further 36 targets in doubt. The study estimates the plan will fail to meet four out of five targets for the Murrumbidgee wetlands, with loss of waterbird breeding sites, turtles, frog, native fish populations, wetlands and floodplain ecosystems.

Mr La Nauze said at least eight of the Basin's 16 internationally listed Ramsar wetlands would suffer "such a significant decline that it would amount to a change of ecological character." This would put Australia in breach of its duties under the Ramsar agreement, which protect wetlands of global significance.

Australian Conservation Foundation spokesman Paul Sinclair also told the inquiry the authority was "struggling to engage respectfully" with conservation groups.

"They see us as opponents to be held at bay," Dr Sinclair said.

The Senate inquiry is investigating the potential impacts of the authority's draft water management plan, which will introduce a new water management regime for Australia's major food production region. Federal environment minister has said he expects the plan to be finalised by the end of this year.