SOUTH-EAST Australia's irrigators will have to wait until at least mid-May before knowing how much of Queensland's record flood reaches central NSW.
Much of the 403,000 gigalitres of rain that fell on Queensland and the Northern Territory will flow towards central Australia's Lake Eyre.
But irrigators' eyes are on the floodwater spread across Queensland's share of the Murray Darling Basin in the hope it reaches the Darling River.
A spokesman for NSW State Water said it would be a week or more before they knew what was happening at the NSW-Queensland border and even longer before the water reached Menindee Lakes.
NSW and Victorian irrigators have been disappointed before, when in 2008 Queensland irrigators harvested 1.014 million megalitres of that season's floods, leaving just a trickle for their southern counterparts.
But the latest flood is far larger than the 2008 event, with falls of 100mm to more than 200mm across an area the size of Victoria in Queensland and the Northern Territory.
The monsoonal low that delivered the rain hit southwest Queensland on February 28, but most of the rain fell on March 1-2.
In the 24 hours to 9am on March 1, Queensland's Bedourie Police Station recorded 188mm and Birdsville Airport's gauge hit 168mm.
"The big question is how much of the water spread out across the floodplain returns to the river channel and reaches the Darling River," the NSW State Water spokesman said.
The NSW Government is yet to decide whether it will divert the floodwater into the Menindee Lakes' third storage or allow it to flow down the Lower Darling to the Murray River.
A NSW Office of Water briefing paper, published last month, states that filling the third Menindee Lake would result in the loss of at least 100,000 megalitres in seepage and evaporation.
Victorian water bureaucrats are urging the NSW Government to fill the third lake rather than divert the water into the Murray River and downstream to South Australia's lower lakes.
But the NSW State Water spokesman said it was far too early to make any decision on the issue.
If NSW diverts the water down the Lower Darling to the Murray River, Victorian Murray irrigators should gain about 40,000 megalitres.
The water becomes available to Victorian irrigators as NSW pushes more water into its half-share of the Murray River storage, Lake Victoria, which then spills into Victoria's half.
