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Standing Committee on Regional Australia
Certain matters relating to the proposed Murray-Darling Basin Plan

STUBBS, Mr Tim, Environmental Engineer, Wentworth Group of Concerned Scientists

WILLIAMS, Dr John, Member, Wentworth Group of Concerned Scientists


CHAIR: I welcome members of the Wentworth Group to today's hearing and thank them for coming. Although the committee does not require you to give evidence under oath, I should advise you that this hearing is a legal proceeding of the parliament and therefore has the some standing as proceedings of the respective houses. Would you like to make some opening statements? You are one of a few witnesses just wanting to essentially talk on the groundwater issue. There may be a few—

Mr Stubbs : We do not have an opening statement. We are happy to just take questions and go with it from there.

CHAIR: Okay. If I could start and I am sure that the others will have questions as well, but you heard the previously witness from Lachlan Valley talking about the different methodologies or use of the science to arrive at different numbers in terms of the guide and the draft and the relationship with the New South Wales water sharing plan. Would you like to comment on that? I know it is specific to one valley, but are there issues in other valleys that you have recognised as well?

Dr Williams : The lower Lachlan is one alluvial system that I have a little bit of a background in, because in my previous role in the commission we were asked to look at the New South Wales analysis and where this a 108 gigalitre level was established, so I am familiar with that. There are two matters which I think we need to put on the table. We had a 2008 process that was largely a New South Wales data set. We contracted consultants to analyse the system. The outcome of that analysis is available in a report, if you want it. It is up on the web. But it actually showed that the uncertainty on what the recharge numbers were for that system meant that they were very unreliable. The science and the measurements suggested a 70 per cent variability in what that would be. So the commission recommended to the minister that you should adopt a precautionary principle in doing that. He took a number towards a precautionary principle that would say a higher level of risk—we will take some risk. That is where the number arrived at of 108 gigalitres.

Then we had the report. That to me was a reasonable outcome in the circumstances, if we had monitoring and adjustment subsequently. Then, at the same time as that study was being done the CSIRO and the SKM in affiliation did actually look at the sustainable yields and used I think much better tools, and suggested that in fact that number probably needed revisiting. That was in the guide. The mystery that we have in Wentworth is then to see that in the subsequent revision on the first draft, we suddenly have the numbers change. We cannot understand that, when you had—under the CSIRO and SKM work, and the Murray-Darling work—a thorough analysis of the 108 and the bottom line is that it will at least stay there or maybe look for reduction. There certainly was not any grounds in the science that we are aware of that you would increase it. That is the first thing. The second thing that is really an important point with all these aquifers is that the groundwater and the surface water are connected. If you do not have flooding on the floodplain in the Lachlan, then you cannot recharge the damn thing. So if you do not allocate sufficient flooding in the surface water pattern, you cannot guarantee the actual recharge process that you are assuming in the actual calculation. That is the biggest problem that we have got. We are not ensuring the surface flooding and flow regimes are sufficient to do the recharge which is assumed in the recharging and the SDL that is allocated. As my dad would say, 'It's a great business if you can sell the dog twice.' You just can't, and that is what we tend to be doing. Those are the two concerns I have on that.

Tim has made a more thorough and recent analysis. But the bottom line is that there is a mystery in how we go from where CSIRO and SKM said, 'In most of the alluvium systems we should be capping or reducing them.' Suddenly, we get these numbers with no justification. I am a good hydrologist and I cannot see the rationale. It is not available publicly. It is a mystery.

CHAIR: Would you also like to comment?

Mr Stubbs : John summed it up there. Alluvium aquifers are the ones we do have models for and are the ones we probably know the most about. So that CSIRO-SKM stuff is probably the best groundwater stuff we know in the whole of the Murray-Darling Basin. There is a reasonable level of confidence in what is coming out of those models. I think there are 13 that there are good models for. It is concerning when those numbers go up from what the models and the science are saying we need scientifically to a number that is agreed from a program before those models were perhaps used to their full capacity.

Another thing is we are really struggling to understand how these numbers have changed for the groundwater since the guide to the first draft. From our understanding, no new science has been undertaken. No-one has remapped aquifers or remeasured recharges or anything. No-one has been out and done anything. It appears that decisions have just been made based on conservatism or a less conservative approach. There is no new science. We are not saying we have new facts to make us change our mind; it just appears that people are changing their minds.

The even more concerning thing is that we go from the guide to the draft, which we were assured was based on the best available science and was done through rigorous analysis. Questions are raised about the quality of that science and those numbers in the draft and, in the revised draft released not so long ago, we see that those numbers are reduced significantly. There is no information to talk about how that happened and what science was behind it. We understand there was a one-day workshop. So it is a little bit concerning. It is actually a lot more than a little bit concerning that we are changing public policy, the future of the Murray-Darling Basin—massive amounts of groundwater and a program that is costing the taxpayer $8.9 billion—on the basis, from what we understand, of a one-day workshop. That cuts to it. If the numbers in the draft are right, as was ascertained—if they were achieved through a robust scientific process, how can they be changed in a one-day workshop? We do not understand that.

CHAIR: I am assuming that that might be a question that this committee—

Mr Stubbs : I think it would be a fantastic question.

Dr Williams : That should be investigated thoroughly. What is the science behind the sorts of numbers that were available from CSIRO and which were largely used in the first guide? That was not comprehensive. The CSIRO blokes did not analyse some aquifers. Basically, the thing that shocked me was when I saw in the first draft plan that there was such a change in groundwater. I could not see any justification for it on the new work, a thorough analysis—errors that were in the CSIRO work. You could ask the question: CSIRO must have got it wrong. They really made mistakes—our premium research organisation and you cannot trust the data. I think that is an important question to ask and we should investigate that. Then to go to the next stage, to go from the draft plan to the revised plan and suddenly find another load of numbers and, as Tim has just said, we cannot see the scientific rigour or the analysis. I do not mind what the answer is, as long as it is substantially confirmed by good science and robust analysis. We cannot find it. I encourage you to find out what the hell happened. It is a mystery.

Mr GIBBONS: When you say a one-day workshop, who conducted that?

Dr Williams : Tim, you may answer that.

Mr Stubbs : From memory, we were not at the workshop. We were not invited, so we do not know. At the time the revised draft came out, Craig Knowles, if my memory is correct, said something along the lines of, 'I pooled some groundwater boffins together in a room and we worked it out'—something to that effect. But my understanding—

Mr GIBBONS: You do not know who the boffins were?

Mr Stubbs : We were not invited to go so—

Mr GIBBONS: What I am saying is they may well have information that—

Dr Williams : There may well be documentation, but we just have not seen it. And it is not available publicly.

Mr Stubbs : What concerns us, though, is that those numbers can change so rapidly and also it is not presented with part of the revised document, to say, 'Well, here is how they changed,' particularly from the draft when we were again and again told that the groundwater numbers in the draft were robust, solid and then they changed.

Mr GIBBONS: That is fair enough.

Mr McCORMACK: When we talk of the CSIRO we talk about numbers. The CSIRO claimed 10 years ago that 1,500 gigalitres was needed to fix the Murray-Darling, yet now the figure seems to be, according to many, including you, at least 4,000 gigalitres. Can you tell us why there is an inconsistency and is it 1,500, 4,000 or maybe another number?

Dr Williams : That was at a time when I was chief of land and water and the process we used was a thing called M-flat and that 1,500 was derived purely for the six sites on the Murray as part of Living Murray. As a first estimate the number was 3,500 on that, if you actually wanted a high level of certainty of success—1,500 was taken as a judgment as a fair go. And 750 was another number. That was just for the Living Murray sites. That is why it is at that number. If you actually go through the processes that are in the guide and in the mechanisms—simple methods that we worked up with the CRC for e-water and the best we could do—you are in the order of 4,000 gigalitres to give you a sense of confidence that you will flood the system and have returns from that flood to the river system so it will function as a functioning ecosystem. You cannot get that. You can do the sums very simply. Just take the area of wetland and put about 30 centimetres of water on it, which is the difference between rainfall and what a red gum requires to grow and you can work out the numbers of water you need. It is of the order of what we just said, the 4,000 gigalitres range.

Certainly, there is new science and better understanding of what CSIRO in that time. There are better models. But the numbers are shown and when you look at what others have done on looking at where you get to, it always comes up to that large amount of water. It is a major reform problem and therefore the attention of a government is: how do you bring that reform to be and manage the huge impact that it will have on people?

Mr Stubbs : I think we have to compare this. With the current draft and revised draft the number that is being thrown around is 2750. It is important to understand what that number actually achieves. It is clearly stated in the documentary it is not going to achieve the targets that the authorities said. Those targets were conservative in that they were just to maintain the assets that were left, so we are not going to get anything back that has been lost which is a large majority of a lot of the basin. It is to maintain those and try to improve those conditions. So they are very conservative targets. The 2750 falls well short of those targets and the CSIRO review undertaken on 2800 said it would achieve less than the majority of targets, so we are under 50 per cent. So that is where 2750 parks you. Their model is the best model at that moment. It is by far and away the best model. If they were to use that model and ask: how much water do we need to actually achieve the conservative targets that we set in the Murray-Darling Basin, I would imagine that number would be up around the 4,000 mark.

Mr McCORMACK: Tim, in your evidence just then you said, 'We have already lost a majority of the basin.' Can you just define what you mean by that.

Mr Stubbs : From my understanding and again this is not my area of speciality. I focus more on the water and the outcomes from the volumes to just get the targets we can achieve. My understanding from other people I have spoken to is that we have lost quite a lot of the assets of the basin already. Large areas of the basin have been lost as—

Mr McCORMACK: Because they are under water or because at the moment—

Mr Stubbs : No, no. Because we have changed the flooding regime so much. We put the dams in the basin and what we have very effectively done is caught the small to medium sized floods. The big events like we have seen in the last two years will always overtop the dams and we will still always see these big flood events. They are a part of the system, but the dams very effectively capture those small and medium sized floods. So what we see is flood plains that may have been watered every two to five years, which is the return cycle you need for healthy red gums and then maybe three to seven years for the black box up higher on the flood plain. So to have a functioning, healthy system to be flushing salts and water in the flood plain you need that return frequency. What we have done is effectively catch that. So now the flood plain is only getting watered every five, to 10, to 12 years. As you can imagine, the ecosystems are under stress constantly and failing at times under those sorts of arrangements. We now capture those smaller and medium sized floods and run down the channel to use as irrigation water.

The reform is about trying to get some water back so that on a opportunistic basis—and this is how the authority have modelled it with their models—you use that water to either increase flows to get it over the banks and get that wetting that you are after or maintain a tail on a flow, because the breeding event takes quite a bit of time. You need the area inundated for a number of months. You might use the environmental water to add a tail to a flow, to add a peak to a flow. You will use it strategically—maybe not in one year, maybe a lot in the next year to try to replicate that small and medium sized frequency.

Dr Williams : One of the core points Mr McCormack made was: what evidence is there that the rivers are not in a good condition? Just have a look at the sustainable river audit and the recent CSIRO work that reworked the data and took new data. That report is available on the web and it shows that the rivers are still in poor condition. I have just spent some time walking and working through some of the red gum stuff around Deniliquin, Balranald and up through that area. While we say there is a lot of water around, I am surprised how little of what I hoped would have been flooded has actually been flooded.

Mr McCORMACK: John, with respect to the figures that have been used in the latest revised draft, do you think they are consistent across all states, all stakeholders and all departments? I know you are concerned about the figures, but do you think they are consistent across all those areas?

Dr Williams : Do you mean across all the states?

Mr McCORMACK: Yes. States, stakeholders and departments.

Dr Williams : The point is that the analysis that the Murray-Darling Basin Authority has done has been by catchment by catchment and connecting it together. It has not had an analysis purely by state by state. It has been a basin analysis. I am not sure I understand what you mean. In that sense, it was said, with respect to the work that has been done, 'Have a look at how much you can water with this number, up to 2,800.' That is all that has been looked at. It does not answer the question that Tim put to us. I really want to answer your question, so help me a bit more. I do not think there has been an analysis done state by state. It has been catchment by catchment.

Mr McCORMACK: That is okay. That is good.

Mr TEHAN: I am interested in particularly point 2 of this inquiry, which you have addressed a little bit here in the evidence on the potential role that new environmental works and measure projects could play in partially offsetting SDL reductions under the basin plan. You were just talking before that basically the way we are set up at the moment, when there are big water events then you do get the flooding into the areas of the basin. What we are trying to address are the small and medium size flood events—if we can just capture that. You seem to be saying here that there is not much we can do with environmental works and measures to deal with that. If that is what you are saying—it might not be—why not? Also, how can we be sure that there is the monitoring there to know whether the measures that we take to try to address those small and medium sized floods are actually working?

Mr Stubbs : I will address the first part first. It comes back to how we have modelled the system. When the authority built its model for the Murray-Darling Basin to actually work out how much water needed to go back throughout the system, it analysed the basin and said there were 2,442 wetlands that were of importance. Obviously, they do not have the data or the information on all of those assets. It would take forever to build models that modelled them all. They identified 122 key sites, I think; of those, 18 were particularly big flood plain sites. The reasoning behind that was that if you sent a big enough flood down, or if you increased an existing flood with some environmental water on top to flood those larger flood plains, as that water travelled down the system it would move out onto the flood plain and back into the river all the way down, watering all those assets upstream of the big flood plain and all those assets downstream of the big flood plain.

Our main concern with environmental works and measures is: to some degree they have maybe lost sight of the function of the system and have focused simply on watering an asset. So we have become so focused on these key assets—because they were used to be proxies for watering the system upstream and down—we aim to water only them. So we then begin to look at putting up different structures in the river or throughout the wetland to get water out onto that wetland. The benefits for those wetlands are debatable; John can maybe talk a little bit more about that. But if we are using a much lower volume of water to water that wetland and not letting any of it get out onto the flood plain upstream or down—because we are just using these structures—then effectively we have taken the proxy and we are only looking after the proxy. It would be a little bit like your body, if you say the proxies for your health are your kidneys and your left knee and we had found a medical way to simply get blood to your kidneys and your left knee and said, 'You should be fine.' Clearly you will not be.

Mr TEHAN: Surely we can be smarter than that. I can understand what has happened in a way that the modelling is focused on a few key sites. I understand the point you are making, but can't we be smart enough to say, 'We've got to try to get balance as best we can.' We can focus on all the sites, and on these medium flood events and these smaller flood events, we do not focus just on one or two, on the knee or the kidney. We can say, 'Okay, let's focus on half of these when you have a medium event here and then the next half at the next medium event' so as best we can we ensure that we get balance right through the system.

Mr Stubbs : The modelling that the authority has done—the 4,000 number—is based on 119 years, I think, of data. That is cut up a thousand different ways and run through the model all different ways to work out: if we had all different combinations of those years of wet, dry and the climate that we have got, how much water would be the minimum—say four is the minimum—to just reach those targets so we achieve those targets and have a functioning river system. That is a number that says we achieve those targets. If the parliament decides that those targets are not the right targets anymore and wants to go for what whoever might call balanced—it is not up to me what balance is, but whoever does—then that is the parliament's decision and that is fine. We are just saying we need to be very clear and any works and measures need to be very clear that they are not just going to deliver benefits for a site but they need to be able to show that they are going to deliver benefits for the function and we are not just delivering benefits for a proxy.

Dr Williams : I think that is the key point. The thing is: you have got to return the functionality. That is, connect the river to the engine room and let that engine room flow back into the system and do that multiple times through the system. That is how it works. If your works and measure can actually replicate that function—but one of the big problems in your works and measures might be to get rid of some of the channellisation in the flood plain that you have put there to expedite the delivery of irrigation water. If you go through the Millewa Forest at the moment, it has got channels through it that are there to get the water through to the Wakool. That is not going to wet the flood plain. So what are you going to do? You are going to have to really have a look at re-engineering the basin, because we have put a lot of engineering in there to expedite the movement of water to the irrigation area. If you want to return the function of the river, you have got to connect that back to those flood plains that are sitting there, and they are largely disconnected because of the channellisation we have imposed. So there is certainly a place for engineering. The marshes are a very good example. Some of the channellisation is making it very hard for the water we have got to do its job.

CHAIR: We are going to have to draw this to a close.

Mr TEHAN: I have one last question, if that is all right. The re-engineering that really needs to take place is getting rid of the engineering which has occurred over the last 100-odd years.

Dr Williams : I think that is a big part of it.

Mr McCORMACK: All the channels?

Dr Williams : Not all the channels, but I think you have got to start to get rid of some of those channels and get the functionality back.

Dr STONE: I presume you are also talking about the engineering in the Lower Lakes and the analogy you used of having the mouth of the Murray open nine years in 10 as an indicator of total basin health.

Mr Stubbs : Nine years out of 10 tells us nothing about the basin health. It is a number. I do not understand what functionality that returns or what positive or negative outcomes that might mean for the health of the Lower Lakes, the Coorong or any of the river system. I think also it is a bit dangerous to focus simply on the mouth and the lakes. If you look at what environmental assets are driving the volumes and function that we need from the river system, it is actually the upstream ones, the larger floodplain assets, like Chowilla in South Australia. Again it comes back to this idea of proxies and whatnot. If you water those larger upstream assets, you will deal with the issues of the Lower Lakes and the Coorong and the mouth. The nine out of 10 on the mouth is a statistic that does not give me any indication of function or health of the river.

Dr STONE: Absolutely. We used to talk about total catchment management. That idea has been proved as the only sensible way to go for about three generations now, but, if we are just talking about the water, of course we have to work into this things like waterweed—the arrowweed and hyancinths—which mean that even if you do water them the wetlands are in a bad way, so I think there is a problem with the way we are addressing this whole thing. Does the Wentworth group have any thoughts about, in reconnecting the floodplains, whether we are talking about massive floods or new work plan measures? If we do not also look at the quality of the biodiversity that we are trying to water, we have a major issue there too.

Mr Stubbs : There are a lot of issues in the Murray-Darling that will need to be tackled over time, but, primarily, we are not going to have a healthy functioning system without the water. That needs to be in the system, but there definitely are other issues that will need to be addressed to make sure that gets the best possible outcomes and we get a healthy functioning system.

Dr Williams : You have got to use this whole-of-catchment and integrated catchment management to put all the pieces together. You have got to have water, but you have got to do all the other things too.

Dr STONE: Absolutely, that is my point.

CHAIR: We have to wrap it up there, otherwise we will get behind time. Thank you very much, gentlemen, for taking the time to come along. Answers to some of the questions are in your submission, and I thank you for that.

Dr Williams : We do appreciate you listening to us.

CHAIR: Thank you very much.

Mr McCORMACK: The meeting about the revised plan is next Wednesday, if you want to come, at 11.30 in Banna Avenue.

CHAIR: We might leave the politics alone today, Michael.

Mr McCORMACK: That is not politics; it is a community meeting.