Negotiations on the Murray Darling Basin Plan may hinge on environmental modelling due to be released this month.
The Basin Authority is modelling the environmental outcomes using 3200GL of water, with some system constraints removed.
The figure is higher than the 2750GL to be recovered for the environment, proposed under the current plan, a figure Victoria and some irrigators say is too high and environment groups and South Australia say is too low.
Water Minister Tony Burke is is in talks with the states, with the aim of getting the plan into Parliament this year.
The Plan will become effective the day it is tabled in Parliament, despite there being 15 days in which any member of parliament can move a disallowance motion.
Environment Victoria Healthy Rivers campaigner Juliet Le Feuvre said there were signs the basin states were moving closer to a consensus by talking about environmental objectives instead of the amount of water to be recovered.
"It's bringing the states a bit closer together," Ms Le Feuvre said.
"We're expecting the result of the modelling of the 3200GL with constraints removed to be released fairly soon – then we'll see how close we get to meeting the objectives."
Ms Le Feuvre said the focus on outcomes instead of the figures was good "as long as it means those objectives are met".
"The MDBA has set some really good objectives and 2750GL only meets 55 per cent of them," she said.
"The 3200GL with constraints removed might meet more of these objectives."