AUSTRALIAN farmers claim their water efficiency levels match world's best practice, a view partially accepted by one of Australia's leading environmental scientists, CSIRO's Dr John Williams.
And they have a blunt message for environmental groups that might criticise the amount of water used for agriculture: farm practices are not what they were half a century ago.
NSW Irrigators Council chairman Col Thomson, a citrus grower at Wentworth on the northern side of the Murray, argues there has been a "very significant" increase in water-use efficiency over the past 20 years, with "hundreds of millions of dollars" spent on-farm to make the improvements.
Things such as laser levelling, whole farm planning, and complete reticulation systems on broadacre farms and the introduction of micro-irrigation by horticulturalists have driven the efficiency gains.
According to Mr Thomson, Australia's rice industry has improved its water efficiency by about 60pc in the past 10 years ‹ and another 10pc will be possible through a new variety with a shorter growing season, Quest, introduced in recent weeks.
Using a different measure of water-use efficiency, Mr Thomson says it's possible to feed more people from a given volume of water with rice than any other crop.
"There's been millions of dollars a year spent in research and development to get more efficiency and this will never stop ‹ and neither it should," Mr Thomson said.
"We must continue to have R and D to increase our water-use efficiency, not only for farm productivity, but also for environmental benefits."
It disappoints Mr Thomson ‹ who believes Australia's water efficiency levels are probably the equal of what can be found anywhere overseas ‹ that the wider community doesn't recognise the advances already made.
"It's been quite staggering ... (people) tend to believe that we're doing the same today as we did 50 years ago and I can assure you that is not the case," he said, adding the irrigation industry would accept it if the "whole community" decided more water should be put back into rivers at the expense of irrigated agriculture - provided there was compensation.
For its part, the Ricegrowers Association of Australia claims Australian growers use 50pc less water to grow a kilogram of rice than the world average and are recognised worldwide for being at the forefront of temperate rice growing.
CSIRO Land and Water chief Dr John Williams agrees "quite a significant part" of Australia's irrigation industry is on world's best water efficiency practice - for instance our horticulturalists - but the watering of pastures and grasses is not, despite improvements made through the increased use of sprinklers and sprays.
He says the horticultural industry does a good job at watering plants (something that usually has associated sub-surface drainage), but more broadly, there is a "lot of ground" for water to be used more efficiently and put back into rivers.
Dr Williams adds there is "quite a deal of scope" for improvement in relation to water "losses and leakages" that occur from Australian channels.
Water efficiency levels vary between different regions in Australia.
For instance the Sunraysia region on the NSW-Victorian border reaps far greater dollar returns per megalitre of water used than the Coleambally Irrigation Area (CIA) in NSW - differences Charles Sturt University Irrigation Professor Graeme Batten says largely reflect the crops grown.
The Sunraysia produces more high yielding crops such as grapes and citrus compared to the CIA, where rice is grown on 38pc of the area and there is a lack of highly-productive crops.
Professor Batten argues several key industries have shown "significant improvements in water-use efficiency" and is also happy to talk up the efforts of the rice industry.
He says it has set "maximum water allocations" for crop production and has spent "very significant research funds" improving returns on water used and reducing its environmental impact.
According to Professor Batten, tradition plays a significant role in where crops are produced - and hence what returns on water used are derived.
Some regions might consider themselves to be rice producers, while others could have traditionally grown vegetables.
"Some of them perhaps haven't really sat back and asked: `Why am I still growing a crop that returns $100/ML when maybe 100 kilometres up the road there are people earning $1000/ML of water?'"
However he accepts there are other factors other than tradition at play, such as differing soil types, infrastructure and the cost of change, especially for farmers in their fifties who might, at that stage in their lives, not want to make such a big investment.
Professor Batten believes it's important people recognise irrigators - whose profits have a flow-on effect that for ricegrowers is put at five times the farmgate value - produce food in response to demand, both from people living in cities, and abroad.
As such it's not unreasonable for them to expect cooperation from the wider community in terms of solving long-term sustainability issues.
He says people often ask why Australia doesn't use saline water and be as productive as irrigators over in Israel.
"But it's not as simple as taking some of their procedures where they use reasonably saline water and wastewaters to grow crops.
"If we did that in our environment we would very soon - in some cases in two or three years - build up such salt levels in our profiles that our crops would be non-productive."
He says due to Australia having heavier soils and production areas well away from the sea "where we could flush the salt", other ways have to be found to be highly productive.