The Commonwealth Environmental Water Office has vigorously defended its decision to flood forests along the Murray River during winter and spring.
The CEWO aimed to push 15,000 megalitres a day, downstream of Yarrawonga Weir, in its Southern Spring Flow, which began on August 1.
CEWO assistant secretary Hilton Taylor told a Southern Murray-Darling Basin seasonal outlook forum, in Shepparton, flooding replicated river conditions before dams were built.
"How do we decide when we water the forests?" Mr Taylor said.
"Without the dams, inflows would have meant water in those forests, every year, for the past 20 years, except 2006.
"With natural conditions, the river used to run low in the summer and high through the spring - now it runs flat chat through summer, it's quite a different shape, sending some very different signals."
The spring flows were intended to send the signals fish, shrimps and other aquatic life would have received, prior to dams being built.
"What we have done, through regulating these rivers, is completely change the natural signals, that all aquatic life would have been getting," Mr Taylor said.
"It has fundamentally changed, but you can't replace that, you are never going to replace that.
"To do that, you would have to take out Eildon, Dartmouth and Hume, which is crazy, la-la land stuff."
The dams took out small to medium floods, which went through the floodplains, the Barmah and Millewa forests, Koondrook and Perricoota.
Mr Taylor acknowledged the CEWO was getting "quite a bit of commentary and direct feedback" about running water into the forests.
"(People are saying) What on earth are you doing putting water in the forest in the middle of a drought?" Mr Taylor said.
But he said deciding on when to release environmental water was a highly integrated process.
"It's not that we wake up one morning and say 'here we are as environmental water holders, here's a wetland, we want to put some water in it'."
Priorities were determined, early in the watering year, as to what environmental outcomes were required.
Mr Taylor said the CEWO consulted closely with a range of stakeholders, including catchment management authorities, farmers and fisheries.
"We list those priorities, and then we start to look at the water available, and assign it against those priorities."
Mr Taylor said there was no intention of taking the system back to a pristine, pre-European type settlement.
"We can't do that, we can never do that, and it's not our intention to do that."
Low rainfall
Janice Green, Bureau of Meteorology acting general manager/water, told the forum the current drought was considered to have started in January 2017.
"While 2016 was quite wet, with good rainfall and streamflows, the last 33 months have seen below-average rainfalls predominantly, across the Murray-Darling Basin," Ms Green said.
"The only other time when Australia has experienced lower rainfall in 33 months was back in the Federation drought."
Ms Green said the weather was being influenced by a positive Indian Ocean Dipole, which meant for drier and warmer conditions.
"Maximum temperatures have been very much higher than average," she said.
"January to September, across Australia, has seen the highest average maximum temperature on record, with September being the fourth warmest," Ms Green said.
"We see this in tandem of not only low rainfall but also higher temperatures."
Minimum temperatures at night had also been high, so the earth had not been cooling.
"This is consistent with having high-pressure systems, with no cloud cover, which cools the earth," Ms Green said.
January to September saw the eighth highest period, on record, for minimum temperatures.
"Not unexpectedly, evaporation during winter has been very high, in the Basin.
"Very little rainfall, and very little soil moisture, high temperatures and high evaporation, is going to have an impact on our stream flows."
Claims challenged
NSW farmers Graeme Pyle and Southern Riverina Irrigators chairman Chris Brooks challenged Mr Taylor's comments.
Mr Pyle, Berrigan, said he refuted the claims.
"That is crazy stuff, it's a disgrace, it's just sad," Mr Pyle said.
There was little input into the Murray River, from the Darling.
"The Murray used to be supplied from the Darling; now it's less than 5 per cent," he said.
"I'd be curious if any water comes past Bourke (NSW) unless we have a Biblical flood - that's the thing where Noah get's the woodwork going."
Mr Brooks, Barooga, said the CEWO had flooded the Barmah forest for 141 days, sending hundreds of thousands of megalitres into the ocean.
He said 10 to 20 per cent of that water could have been released to irrigators, particularly in NSW, where farmers were on zero general security allocation.
"This is the best example I have seen of the environment having too much water and not knowing what to do with it," Mr Brooks said.
"What a great job they are doing, transferring water over bank.
"Call it what you like; it's just spilling and wasting water."
He had cut his canola crops, for silage, after they had failed and his wheat had died, even under centre pivots.
"There will be a fraction of a return, which will cover costs, instead of making a profit."
"We haven't had enough rain to water my lawn, let alone the Barmah Forest.
"But what you have effectively done is have them under water for six months of the year, for the last seven years, that's why they are dying.
"That's the problem.
"You are claiming it is an environmental benefit, but we all know you are making up a nice story, to justify shooting that water down the Murray, to get it to the almonds and South Australia
"We are not happy about it."
He said irrigators would never be convinced what the CEWO was doing was good for the environment.
"He was trying to convince us 152millimetres of rain, each year for the last two years, was enough to flood the Barmah forest, to the high levels they are running now."
No consideration had been given to releasing some of that water to productive irrigation, in the region.
"You are not replicating nature; it's the most destructive thing I have seen in my life."