Some 25 years ago, when I first got involved with irrigation on the Darling River at Bourke I was struck by the massive variability of river flows, the apparent unawareness by the water authorities of the magnitude of the bigger flow events, how frequently (but irregularly) they occurred and the exaggerated view that water managers had of their level of control. I was also struck by what I have come to call the "blame factor" with downstream people on virtually every river attributing low flows to the upstream actions of other people rather than the impact of nature. In so many situations I have observed the dynamic nature of flows and the sensible controls imposed on extractors to protect downstream needs. These controls are either not understood or perhaps don't want to be understood. It is so much more satisfying to blame somebody than attribute low flows to the vagaries of nature.
On Tuesday the 6th. March, the Darling River peaked at Bourke at 13.78 metres. This is a daily flow of 240,000 megalitres. That is the equivalent of about one Sydney Harbour every two days. At these heights the river is well out of its huge banks and small height increases represent huge increases in the volume of water. The daily flow figure is about the same as the total "cap" on all irrigation extractions for twelve months along the Barwon /Darling from Mungindi to Menindee. One days flow, yet our critics claim that there are excessive extractions! In low flow times irrigators are not allowed to extract at all.
The turnaround in conditions following the record drought and now the big flood events of the last three years, is a classic reminder of how Dorothea Mackellar got is so right with her "droughts and flooding rains".
The conventional wisdom, particularly in our cities, is that our inland rivers are "unhealthy" and that this is due to excessive extractions. This view is judged by our politicians to be so widely held by voters that we have seen politicians of all persuasions, pressured by the green groups, proceed with legislation to further reduce extractions. The natural impact of drought has been painted as the consequence of the misguided actions of man. The turnaround in conditions, entirely due to natural events, goes unacknowledged.
I recently attended a high level NSW Government meeting to discuss the MDB Plan. The meeting was attended by three NSW Government Ministers (part time), MPs, current and former State Government water administrator's, representatives of irrigators, privatised water districts, cotton growers, NSW Farmers and green groups- the NSW Nature Conservation Council, the Australian Conservation Foundation and the Inland Rivers Network.
One thing, in particular struck me-the deep shared knowledge between all in the room except the green groups.They continued to spout their ideological mantra about the need to restore the Murray Darling Basin to good health by further restricting extractions. There was no acknowledgement of the turnaround and an assumption that all those awful drought induced problems could be prevented by limiting extactions. I heard statements about the need to return huge quantities of water (like7,600 gigalitres) to the rivers to "restore them to health". And even a comment that the Basin is on the point of eco-collapse. Apparently no recognition that nature, in its time honoured way, has already fixed the situation, which in any event was not caused by extractions. From my observations and from the many people I talk to who live in the Basin, it has probably never been in better condition.
The other point made by "the greens" was the need to take advantage of the $10bn. available from Government. "A once in a lifetime opportunity'.... If the Gillard Government are looking for every $ to achieve a surplus in 2012/13, these funds might be handy.
I remain greatly concerned that as a consequence of misguided action by Government, as proposed in the Plan, we will cause great socio-economic damage, unnecessarily limit future production, for negligible environmental gain. I often sight the Government purchase of Toorale Station at Bourke as a microcosm of the MDB Plan. If Toorale had continued to operate with all the socio-economic benefits to the Bourke community it would have reduced river flows in 2010/11 by 0.01%!
The Commonwealth Water Act and the Plan are deeply flawed. In particular the use of average flow statistics when there are such massive spreads around the averages, is really nonsensical. This leads to focus on single figures unrelated to actual flows. To ask CSIRO to calculate Sustainable Diversion Limits based on average flows is really a silly question asked by people who clearly have no understanding of the massively variable nature of all of our inland rivers. A set figure based on averages might be far too high in a dry year and absurdly low in a wet year. Limits need to be related to actual flows.
If we had more dams, in the big wet years, we could store very substantial additional amounts of water, yet they would represent only a tiny percentage of the big flows.