Lower Lakes Independent Science Review

The way the Lower Lakes in South Australia are managed is contested. There are differing opinions on their history, how they’re managed and whether anything needs to change.

The Murray-Darling Basin Authority initiated an independent review of the relevant science relating to the management of the Lower Lakes. In December last year, the MDBA asked ACSEES – the advisory committee to the MDBA – to manage the review. An independent panel – led by the CSIRO – has undertaken the review of the science.

Get involved

We understand there are many different perspectives, views and and we invite you to post your questions here for the experts.

The opportunity to post questions has now closed. All responses will be added to this site by Friday 22 May. Thank you to those who have taken an interest and posted questions (you will get an email to confirm when we answer your question).

Find out more

The Independent Review of Lower Lakes science informing water management considered hundreds of studies with input from almost 100 technical experts.

They addressed three key questions:

  1. What are the various scientific perspectives on the past and current hydrology and salinity of the Lower Lakes and how have the lakes come to be managed in the way they are?
  2. What would be the likely regional social, environmental and economic implications of removing the barrages, and would this result in significant water savings?
  3. What knowledge needs are required to plan for the main social, environmental and economic vulnerabilities of the Lower Lakes to climate change?


The way the Lower Lakes in South Australia are managed is contested. There are differing opinions on their history, how they’re managed and whether anything needs to change.

The Murray-Darling Basin Authority initiated an independent review of the relevant science relating to the management of the Lower Lakes. In December last year, the MDBA asked ACSEES – the advisory committee to the MDBA – to manage the review. An independent panel – led by the CSIRO – has undertaken the review of the science.

Get involved

We understand there are many different perspectives, views and and we invite you to post your questions here for the experts.

The opportunity to post questions has now closed. All responses will be added to this site by Friday 22 May. Thank you to those who have taken an interest and posted questions (you will get an email to confirm when we answer your question).

Find out more

The Independent Review of Lower Lakes science informing water management considered hundreds of studies with input from almost 100 technical experts.

They addressed three key questions:

  1. What are the various scientific perspectives on the past and current hydrology and salinity of the Lower Lakes and how have the lakes come to be managed in the way they are?
  2. What would be the likely regional social, environmental and economic implications of removing the barrages, and would this result in significant water savings?
  3. What knowledge needs are required to plan for the main social, environmental and economic vulnerabilities of the Lower Lakes to climate change?


This Q&A session has now closed. 

Ask your question here:

Didn't receive confirmation?
Seems like you are already registered, please provide the password. Forgot your password? Create a new one now.
  • I watched the presentation... I was actually a little disappointed because I it failed to answer the question that most critics of the current policy pose. If I can crudely summarise what I took from this morning’s presentation, it went something like this: • Pre-development the Lower Lakes were fresh most of the time (in itself this is an important piece of knowledge), and • the legislation says we need to keep them fresh (in my experience community members don’t take it well if you give the reason for doing something as – ‘the legislation says so’) • it takes less water to keep them fresh with the barrages in place, • therefore the science supports the current policy (but things are really going to go to pot as the climate changes). The argument that most critics of the current policy seem to be putting is: • keeping the Lower Lakes fresh takes an enormous amount of water, • the benefits of keeping the Lower Lakes fresh don’t justify the use of this much water. What I would like to know is details of how much water is required to keep the Lower Lakes fresh what would be the economic and ecological cost if there was a decision made to reduce the volume of water flowing into the Lower Lakes and therefore allow salinity to increase (I understand that there are a range of ways to manage that) what would be the upstream economic and environmental benefits of having access to water that previously was dedicated to maintaining the Lower Lakes. Essentially: what are the economic and ecological opportunity costs of the current policy?what does a cost benefit analysis of the current policy tell us? (I understand that the outcome of such an analysis will be greatly influenced by how ecological assets are valued). Personally I support the current policy, but underneath the misinformation and misplaced anger about the Lower Lakes are some valid questions which I would like to be able to answer.

    Tom M asked about 2 months ago

    Thank you for watching the presentation and for sharing your summary.  

    One of the key points to emerge from the review is that the Lower Lakes cannot be managed in isolation.  The Review found that the water that passes through to the Lakes has been used to achieve environmental outcomes upstream and subsequently achieves environmental outcomes in the Coorong and Murray Mouth.  

    The evidence is that flows during the drought have been inadequate to achieve the key Mouth Open target and this, along with other threats from Climate Change will need to be addressed through work the SA Government and MDBA are currently planning.  

    See more about the Lower Lakes Independent Science Review including the full report with all the detailed information on the findings.

  • What estimates, modelled or otherwise, has the Science Review provided on the ecological productivity opportunities and resultant huge public benefits of restoration ecology - returning the Lower Lakes to be once again, Australia’s biggest estuary?……and if not, when can I assist the MDBA in designing such an assessment [which of course i will contribute pro bono]

    Colin asked about 2 months ago

    The review examined all the relevant science relating to the management of the Lakes. The work being undertaken by the South Australian Government and the MDBA to identify adaptation strategies for the Coorong will explore opportunities for restoration and their potential social, economic and cultural benefits.  

  • I thought the aim of the RAMSAR aggrement was to protect the Hyper saline environment, that is allowing the lakes to go saline would not jeopodise the RAMSAR agreement? (this is just a matter of fact, not an apeal against the findings that we should not attempt to keep the lower lakes somewhat fresh)

    anonymous asked about 2 months ago

    The Ramsar listing applies to the Coorong, Lower Lakes and Murray Mouth region not just to the Coorong.  More information on Ramsar sites in the Murray–Darling Basin.

  • What is the problem with the lakes being seasonally estaurine? the report equates a fresh water lakes system with a healthy CLLMM. But why wold an estaurine system be considered unnhealthy, when estaurine systems are also highlught ecologically productive. Why is a freshwa

    Claire M asked about 2 months ago

    Upstream development has reduced the river inflow by about half, resulting in more frequent incursion of seawater into the Lower Lakes, and the barrages were built in 1940 in response to these changes, isolating the Coorong and the sea from the Lower Lakes. Removing the barrages would have a significant ecological and socio-economic impact. The review found that in the past 1 to 2 thousand years the Lower Lakes were largely fresh, with moderate tidal influence of seawater during periods of low river inflows. Without the barrages, the freshwater values in the Lower Lakes could not be maintained and it would significantly change the ecological character of this internationally important wetland, which Australia has an obligation to look after.  

  • The report does not appear to fully explore the counteracting force of the Southern Ocean in depositing sand into the Murray Mouth, which means no amount of extra freshwater flow nt the lakes will achieve the Basin Plan objectives on keeping the muth open and salinity targets in the lakes.will . The Wentworth Group contends no amount of extra freshwater flows into the lakes will keep the mouth open

    Claire M asked about 2 months ago

    Over time, sea level rises will change the hydrodynamics of the Coorong and Murray Mouth, and increase seawater ingress into the Lower Lakes. There are two main challenges here. First, the barrier islands and the barrages will be overtopped more often. Second, the clogging of the Murray Mouth with sand transported by seawater, which is already happening, will be accelerated. However we need to appreciate that it will be some time before this happens, so we must start planning for this.  This may include engineering solutions. It may include identifying which ecosystems (and the services they provide) can be maintained, those that can transition to some new state, and those that cannot be sustained. It will be important to  know what is needed to help keep the system resilient to enable it to transition to a different future.

  • What consideration was given to the alterations with The South East Drainage system? Aquifer drainage?

    Daryl H asked about 2 months ago

    The panel did not discuss the south east drainage scheme in detail, except stating that the South East Flow Restoration project would deliver about 6-47 GL/yr to the South Coorong near Salt Creek. The contribution of the scheme to the CLLMM region as a whole is minimal. The South East Drainage scheme puts water into the South Lagoon of the Coorong which is downstream and isolated from the Lower Lakes. There is limited information available on historical flows out of the SE into the Coorong as human activity has been influencing them since the 1860s. 

    The projected volumes entering the South Lagoon have relatively minor influence on the Coorong and have been incorporated into the Basin Plan through the sustainable diversion limit adjustment mechanism process. The drainage scheme helps reduce the demand placed on Murray River inflows in achieving salinity targets. The volumes derived from the SE are, however, relatively minor inputs to the system when compared to Murray River inflows. The project was funded collaboratively by the SA and Commonwealth Governments as part of implementation of the Basin Plan as part of efficiently achieving environmental objectives.  More information on the SE flow restoration project.

  • Are you able to present, in table form any key findings that a) align with, and b) vary from (if any) the baseline assumptions upon which the Basin Plan was formed. Would be good to have these results as a learning resource ie: hand out) for the Basin Communities Leadership Program.

    Emma B asked about 2 months ago

    This question is out of scope for this review.  If you require further information please contact engagement@mdba.gov.au with specific requirements.

  • I was surprised to hear of the focus on the removal of the barrages. I hadnt heard of the debate about doing that and so my question is: what were the drivers for focussing the study on the barrages vis-a-vis other management strategy options that have been tossed around: Lock 0? Internal bunding of the lakes?

    Greg Co asked about 2 months ago

    The review considered what the impacts of removing the barrages would be because many people had questioned the need for the Lakes to be maintained as freshwater systems. The concept of a lock zero has been previously examined and found not to be feasible and therefore not considered in this review.  

  • The report also mentions average wet years define this?

    Tanya asked about 2 months ago

    This term was used generally to distinguish "wet" and/or "above average years" from "dry" and/or "below average years". The review did not specifically define what constitutes a "wet year".

  • I have read several papers about the science of the Lower Lakes and one in particular has raised some questions. Watching the tide roll away by Peter Gell set up a dispute between himself and Fluin et al. I am not a biologist (chemical engineer in fact) so I would appreciate some comment on this “dispute” because they seem at opposite end of the spectrum. David Thurley

    David T asked about 2 months ago

    We believe that the debate you are referring to is the Peter Gell paper last year that suggests that the seminal study of Fluin et al. in 2007 was misrepresented in a subsequent 2009 Fluin et al. report and in the broader literature, which present the Lower Lakes as predominantly fresh before European settlement. The Panel's assessment is that Fluin et al. in 2009 did not misrepresent the conclusions of the original paper. The original paper in 2007 specifically said “the Holocene diatom assemblages of Lake Alexandrina reflect relatively freshwater conditions with longstanding and major inputs from River Murray, particularly after 2,000 years before present” and “marine water indicators were never dominant in Lake Alexandrina”. 

    The review found that in the past 1 to 2 thousand years the Lower Lakes were largely fresh, with moderate tidal influence of seawater during periods of low river inflows. Scientific debates like these are common, particularly with the considerable uncertainty—in the palaeoecological data,  in identifying the diatoms, in relating the different diatoms to salinity, and in dating the sediments particularly when the geomorphology and the hydrodynamics of the system have also been changing over the past 10,000 years.

  • If Lock zero was installed at Wellington and the Barrages remain would this protect the Pumping Stations down stream of Lock 1 in drought or low flow situations.

    Anonymous asked about 2 months ago

    The review didn’t specifically look at the notion of a new weir at Wellington. However, by extension we can conclude that stopping the river at Wellington and letting the sea into the Lower Lakes would be contrary to the scientific evidence that the lakes are a naturally freshwater system. Building a lock at Wellington would not free-up more water for upstream communities. The current level of flows would still need to be released from the weir into the lakes to sustain the health of the river overall and the end of the system specifically.  

  • Thanks for the presentation. Did the panel consider the impact of the south east drainage on inflows into the lower lakes? What quantity now flows directly to the sea through these drains?

    Sharolyn asked about 2 months ago

    The panel did not discuss the south east drainage scheme in detail, except stating that the South East Flow Restoration project would deliver about 6-47 GL/yr to the South Coorong near Salt Creek. The contribution of the scheme to the CLLMM region as a whole is minimal. The SE Drainage scheme puts water into the South Lagoon of the Coorong which is downstream and isolated from the Lower Lakes. There is limited information available on historical flows out of the SE into the Coorong as human activity has been influencing them since the 1860s. 

    The projected volumes entering the South Lagoon have relatively minor influence on the Coorong and have been incorporated into the Basin Plan through the sustainable diversion limit adjustment mechanism process. The drainage scheme helps reduce the demand placed on Murray River inflows in achieving salinity targets. The volumes derived from the south east are, however, relatively minor inputs to the system when compared to Murray River inflows. The project was funded collaboratively by the South Australian and Commonwealth Governments as part of implementation of the Basin Plan as part of efficiently achieving environmental objectives.  More information on the SE flow restoration project.

  • Under the Ramsar agreement, it is my understanding that the Wise Use principle allows the community to help decide on the most appropriate and wise use of a wetland system. We know that there are plenty of potential options to consider. It seems that this study has applied a constraint that the lakes should retain the character consistent with the last few hundred years (ie. fresh). This seems to ignore the various changes in character over longer time frames in history, and projected future influences from climate variability going forward that may challenge our ability to deliver that outcome. Are there plans to build on this excellent study with an unconstrained investigation of the sustainability of alternative eco-hydrological systems, with and without further infrastructure intervention, rather than assuming that the current condition is optimum?

    Hugh asked about 2 months ago

    Over time, sea level rises will change the hydrodynamics of the Coorong and Murray Mouth, and increase seawater ingress into the Lower Lakes. There are two main challenges here. 

    First, the barrier islands and the barrages will be overtopped more often. 

    Second, the clogging of the Murray Mouth with sand transported by seawater, which is already happening, will be accelerated.

    It’s important  to appreciate that it will be some time before this happens, so we all must start planning for this.  

    This may include engineering solutions. It may include identifying which ecosystems (and the services they provide) can be maintained, those that can transition to some new state, and those that cannot be sustained. And then knowing what is needed to help keep the system resilient to enable it to transition to a different future is key.

  • Why wasn't there an economist on the panel who could have talked about the economic benefit to our state/nation with an extra 5/800 of water used to irrigate that wouldn't be required to meet evaporation loss?

    Mark asked about 2 months ago

    The terms of reference for this report were specifically about the science of the Lower Lakes and therefore this review did not consider socio-economic conditions in other regions of the Basin.  

    You may be interested in the Independent Assessment of Social and Economic Conditions in the Basin.

  • What is stopping the MDBA from building Lock Zero immediately.

    Graham J asked about 2 months ago

    The Review considered what the impacts of removing the barrages would be because many people had questioned the need for the Lakes to be maintained as freshwater systems. 

    The concept of a lock zero has been previously examined and found not to be feasible, it was not considered in this review.  

  • If we are to achieve the most productive ecosystem, one based on periods of fresh and ocean water and predominantly brackish we need to remove the barrages. Can we please have a supplementary study that based on an understanding of the system as it was of being brackish, we model the potential massive improvements in ecological productivity and commensurate social and economic benefits…..which indeed extend right along southern nearshore Australia

    Damien asked about 2 months ago

    Without the barrages, the freshwater values in the Lower Lakes cannot be maintained. This would significantly change the ecological character of the Ramsar-listed site, which is a wetland of international importance and which we have an obligation to maintain. 

    All aspects of water management are regularly monitored and reviewed including: water use; the planning and delivery of water for the environment; water quality, including salinity; compliance with water laws impacts on Basin communities and industries; river operations; the design and development of projects to assist sustainable water use. 

    Read more about the Murray–Darling Basin Authority's monitoring and evaluation work. Please also see some of the other Q&As in this feed regarding the findings on the barrages and their important to the system.

  • Dilution flows and SA flows shouldn’t we relook? Evaporation rates – isn’t this water that could be better used upstream instead of evaporating in the lakes…

    Damien asked about 2 months ago

    It is important that the river reaches the sea to flush sediments and salt out of the system. Salinity can be a major issue for agriculture, communities and the environment—sending water through SA and out to sea contributes to whole-of- Basin health. Murray River inflows are needed to achieve Coorong, Lower Lakes and Murray Mouth outcomes. Read more about the importance of flows to South Australia.

    Evaporation rates are a focus for the whole Basin and will be a considered in climate change work.  Read more about climate change, science and evaluation.

  • We are now in the 21st century and barrage management has been inconsistent for best practice water management in the lower lakes for many years, which can be attributed to environmental damage in regards to soil erosion, increasing soil and water salinity in and around the lower lakes. Why was the pool level set at a nominal level of 0.75 m Australian Height Datum (AHD) when the barrages were constructed and not at 0.55 AHD / 0.60 AHD to help eliminate environmental damage?

    Bill Bagley asked about 2 months ago

    Water levels in Lake Alexandrina are maintained in accordance with the Barrage and Water level management Policy. This includes managing the lakes within a variable envelope above 0.5 and below 0.85 m AHD. These management actions seek to ensure that water levels in the Lakes and Coorong and barrage outflows are appropriate to maintain the ecological character of the region. Management also aims to ensure that lake levels are high enough to allow for delivery of water for critical human water needs and consumptive entitlement holders. From time to time there may be a departure from these levels, particularly when factors are beyond reasonable control, including periods of low water availability. When lake levels are predicted to dip below a critical threshold of 0.4m AHD a drought emergency framework is activated. More information on managing lake levels.

  • Where is the reference in the document to support the upstream development in the late 1800's to early 1900's to support upstream development reducing the river inflow by half? what data was used to support this?

    Tanya asked about 2 months ago

    On page 27 of the report there is reference to modelling of the last 118 years of discharge that shows, on average a reduction from 13,000 GL to 5,100GL.  The report is not saying that development in the late 1800s and early 1900s reduced inflows to the Lakes by half.  It is saying that if current levels of abstraction were in place over 114 years, then the long-term reduction would be more than half.  There is little doubt however, that diversions were taking place in the late 1800s and these had an impact on downstream flows.

  • Large freshwater surface flows into the Coorong from the South East of South Australia unconfined aquifer are well documented up to the late 1940s which flowed into Lake Alexandrina prior to the construction of the barrages in 1940 . Since this is contrary to the 1985 Ramsar Convention listing which do not need to be natural systems will the MDBA acknowledge this was the case ?

    Anonymous asked about 2 months ago

    The contribution of surface flows from the south-east to the CLLMM is relatively small. The review did not examine flows from the unconfined aquifer.

  • Two scientific studies as well as numerous anecdotal reports have shown substantial ocean water penetration into the lower lakes during floods when the barrages must be opened allowing the ocean water to then migrate around the lower lakes and not all expelled on the next low tide . Will the MDBA use the next floods to further validate such work ?

    Darren asked about 2 months ago

    Flooding is a natural process that can bring many benefits to the environment and agricultural production – renewing soils with nutrients and rehydrating groundwater stores.  Floods can also be damaging, presenting challenges for community and the environment. 

    The Murray-Darling Basin Authority aims to maximise learnings during times of flooding which vary greatly.  

  • Why won’t you publish all details including names to a water register.

    Graham J asked about 2 months ago

    Thanks for your question however it is out of scope for this review.

  • In addressing the future challenge of freshwater supplies to maintain the current characters of these lakes, did the Panel consider desalination in the mix of viable options as offering long-term solution?

    Isa asked about 2 months ago

    The Panel did not consider specific options for addressing climate change challenges as it was out of scope for this project.

  • Why have you completely ignored and or discounted and even attempted to discredit prior studies prior statistics prior fish varieties to name but a few issues when compiling your “report” and totally ignored the issue of fresh water flows into the Coorong NOT from the Murray but from the areas STILL being drained !!

    Robyn Wheeler asked about 2 months ago

    We hope the Review has synthesised and explained the science, where there’s clear consensus or knowledge and where there may be gaps. 

    Read more on the terms of reference and the detailed findings of the Lower Lakes independent Science Review.

  • Why do we have to accept your ‘evidence based science’ regarding the lower lakes when you continually deny the historical factual accounts from indigenous and local people living around the lakes and Coorong (before the barrages)?

    Marg Bray asked about 2 months ago

    Findings relating to the fresh water history of the Lower Lakes were informed by palaeoecological records, water balance estimates, hydrological and hydrodynamic modelling, and traditional knowledge of the Ngarrindjeri people and anecdotal evidence of early explorers and colonists. 

    The review discussed traditional knowledge and values of the Ngarrindjeri People in Sections 2.4.1 and 4.2.1 and pointed to the several references (in particular Hemming et al. 2019 and Ngarrindjeri Nation 2019).

  • How long did the 2016 flood keep the Murray mouth open for without the need for dredging? What were the peak flows of the 2016 flood at lock 10? Under the Murray Darling Basin Plan, the water targets for recovery are to meet objectives like keeping the Murray's mouth open 95% of years without the need for dredging. What volume of the recovery targets are needed to meet this objective?

    The Funny Farm asked about 2 months ago

    We’ve had to dredge the mouth since 2015. It’s important to remember, we haven’t seen the Basin Plan fully implemented yet and we are also in drought. We are yet to see for sure, how the system at the mouth will operate when those things are available to us. 

    See historical flow data for the River Murray at Lock 10

  • There has been much debate about how much fresh water historically passed through the Murray mouth. I would really appreciate the presentation of a graphic in the webinar that shows the outflows over time ie from before the introduction of the locks to now. The suggested graphic would be similar to the Annual Murray inflows graph that goes back to 1892. This graph provides a simple and clear picture on what has happened over time to inflows. (Combing the two sets of data on the same graph could be very interesting.)

    Rosalie asked about 2 months ago

    Unfortunately, we do not have historical information predating the installation of the locks showing what the actual flows out of the Murray Mouth were. 

    The graphs for the Murray that go back to 1892 are based on models and we have the same type of information that relates to flow out of the Murray Mouth under a range of modelled conditions such as modelled without development and modelled baseline diversions before the Basin Plan came into effect. 

    See more information on water resource modelling.

  • Explain who this report was funded and by whom?

    Tanya asked about 2 months ago

    The MDBA funded a panel of five independent experts led by CSIRO scientists to undertake a review and provide a report of findings. 

    The review was recommended by the Advisory Committee on Social, Economic and Environmental Sciences (ACSEES) who are an important source of independent, strategic advice to the Murray–Darling Basin Authority. 

    We will use the results to help make informed decisions and plan for the future.

  • I wonder whether we can develop 5k-60k GL of water that is losing to the ocean every year

    Anonymous asked about 2 months ago

    It is important that the river reaches the sea to flush sediments and salt out of the system. Salinity can be a major issue for agriculture, communities and the environment—sending water through SA and out to sea contributes to whole-of- Basin health. 

    Read more about the importance of flows to the lower Murray-Darling Basin.

  • Given the difficulty maintaining the CLLMM according to the Basin Plan targets and objectives, given increasing challenges posed by climate change and rising sea levels, at what point will the MDBA actually take account of the new science and knowledge to revisit the Basin Plan targets? Right now, you seem to be using this report to support recovery of more freshwater from irrigators, in a Quixotic attempt to sustain values that natural forces will inevitably override sooner than later?

    about 2 months ago

    We have a range of different targets in the Basin Plan and we are monitoring them as they go. The Basin plan isn’t fully implemented yet, but what’s important is the whole-of-system health for a river to run to the sea. The reality is that we have a river system that still needs efforts by governments to put it on a sustainable footing. There are two major evaluations hard-wired into the Basin Plan. The first one is 2020. We voluntarily did one in 2017. At this stage we are planning to launch the 2020 evaluation in October. It will looks at implementation, targets and how environment, communities and industries of the Basin are faring.

  • Have not seen it as yet but I’m curious about the authors’ consideration of extirpations and extinctions of small bodied fish. Have they recommended that these small native freshwater fish should be supported for reintroduction?

    Anonymous asked about 2 months ago

    Restocking options for restoring native fish populations was not in the scope of the review of science underpinning the current management of the CLLMM.  The populations of small native fish resident within the Lower Lakes were considered among the environmental values sustained by the Lakes in their freshwater state

  • Do we have annual average totals for silt carried in the river: (a) on entry from the channel into Lake Alexandrina, (b) out of the Mouth? ie equivalent to the figures used for salinity.

    Chris Bagley, Milang asked about 2 months ago

    Thanks for your question however it is out of scope for this review.

  • My question relates to the 2000GL on a 3 year rolling average that flows out to sea under the current MDBP. Why is this necessary? and where in the report is reference made to the effect of shoaling due to the barrages removing 90% of the tidal prism? Also explain why in the report no reference was made to the first explorers findings on the Lower Lakes eg Charles Sturt?

    Tanya G asked about 2 months ago

    The environmental water requirements of the Coorong Lower Lakes Murray Mouth (CLLMM) region was determined in 2012 using the best available science. One of the many targets was that 2000 GL/year on a 3-year rolling average was needed to maintain the health of the CLLMM region. The specific considerations included habitat in terms of salinity ranges needed to support migratory birds, fish breeding and aquatic plants in the Coorong.  A second consideration was keeping the Murray mouth open which is critically dependent on freshwater flows.  Keeping the mouth open ensures that salt and nutrients can be exported rather than accumulating in the Coorong.  The connectivity between the Coorong and sea is also important for fish including lampreys and mulloway. The flow estimates were based on our understanding of environmental needs and modelling that identified flows required to keep the mouth open and maintain water quality parameters. The panel reviewed all relevant literature they were able to access.

  • Restoring the Estuary of the Lower Lakes is this possible? Can the Mundoo Barrage stop logs be removed allowing some sea water to enter the lakes?

    Dennis asked about 2 months ago

    The review examined all the relevant science relating to the management of the Lakes. The work being undertaken by the S.A. Government and the MDBA to identify adaptation strategies for the Coorong will explore opportunities for restoration and their potential social, economic and cultural benefits.  

  • At the risk of sounding somewhat impudent, I am inclined to respond “so what?” Surely it matters little whether the Lakes have been historically fresh water or, as an estuary, partly saline or partly fresh. Is it the case that approximately 1000 gigs evaporate off the lakes each year? Are there ways of reducing these losses without removing the barrage? (I was unaware that anyone had seriously made that suggestion) And finally, what sea level rises at the Murray mouth have been observed over the last 50 years?

    Stuart asked about 2 months ago

    People had argued that if the system had been saline prior to settlement, then the system should be returned to this state and that it would no longer be necessary to put freshwater into the Lower Lakes and the Coorong.  The report made two key points, firstly that the system had been predominantly fresh, acknowledging that during dry times sea water water intrudes.  Secondly, that letting the lakes become saline did not negate the need for freshwater flows to flush salt and nutrients out of the system, sustain the Coorong or keep the Murray Mouth open.  Given the risks associated with Climate Change, work will continue into how to make improvements to the management of the Lakes and other areas in the Basin that maximises outcomes and minimises evaporation. Sea level in the south-east coast of Australia has been rising by an average of about 3.2 mm/year.

  • How do we get the message across to the big corporates who are bankrolling misinformation across the basin

    Tracy H asked about 2 months ago

    Thank you for your comment.  It is noted however it is out of scope for this particular science review.  If you are looking for more factual information on a range of issues please visit www.mdba.gov.au

  • How is the flow volume into the lower lakes and through the mouth measured.

    asked about 2 months ago

    SA Water monitors the flow of water in the River Murray in South Australia. They have a network of flow gauges throughout the system. Water moving out of the mouth is not measured directly instead a computer model is used to estimate barrage flow volumes using observed flow volumes into the Lower Lakes (at Lock 1), observed lake levels, observed climatic information, and recorded diversion data. However, as these flow calculations are still subject to other uncertainties, including the impacts of seiching (tidal variations, in this instance, due to severe fluctuations in wind), Barrage flow volumes are generally presented as a multi-day or monthly averages. This approach reduces (not eliminates) the model uncertainty.

  • If sand build up due to sea level rise makes it unviable to keep the mouth open, how will that affect the management options? Do the current barrages become redundant? Will another structure be needed at the head of the lake to protect upstream water quality, as was considered during the millenium drought?

    Tony S asked about 2 months ago

    Dredges are currently used to remove sand and sediment from the Murray Mouth. The report identified the need for further investigations to determine the impact of climate change on the management of the CLLMM region and with the release of the report by Thom et al, this work will include consideration of changes in sediment deposition. The findings actually highlight the challenge that all governments face in managing and sharing this vital resource in the face of climate change. The MDBA will use the results of the review to further support current work in the area of climate change adaptation in this region and across the Basin. More information on the Basin Plan and climate change 

  • Where is the logic of the lake management, when no references were made to soil type, the effect of diffusion and osmosis in the lower lakes?

    Tanya asked about 2 months ago

    The review examined all the relevant science relating to the management of the Lakes in responding to the terms of reference. You can find more information on the SA Government's management of the Lower Lakes and their programs here.

  • What effect does the South East drainage scheme have on the operation of the Coorong and lower lakes? How many mega litres of fresh are intercepted diverted out to sea rather than the natural water movement?

    The Funny Farm asked about 2 months ago

    The panel did not discuss the SE drainage scheme in detail, except stating that the South East Flow Restoration project would deliver about 6-47 GL/yr to the South Coorong near Salt Creek. The contribution of the scheme to the CLLMM region as a whole is minimal. The SE Drainage scheme puts water into the South Lagoon of the Coorong which is downstream and isolated from the Lower Lakes. There is limited information available on historical flows out of the SE into the Coorong as human activity has been influencing them since the 1860s. 

    The projected volumes entering the South Lagoon have relatively minor influence on the Coorong and have been incorporated into the Basin Plan through the SDLAM process. The Drainage scheme helps reduce the demand placed on Murray River inflows in achieving salinity targets. The volumes derived from the SE are, however, relatively minor inputs to the system when compared to Murray River inflows. The project was funded collaboratively by the SA and Commonwealth Governments as part of implementation of the Basin Plan as part of efficiently achieving environmental objectives.  More Information on the SE flow restoration project 

  • Why have you released your report and given NO REASONABLE TIME to anyone to digest it ? Why are you denying procedural fairness ?

    Robyn Wheeler asked about 2 months ago

    Thank you for your question.  The report was released on 12 May and was made publicly available. As mentioned in the presentation there was an opportunity to ask a question on the MDBA Get Involved webpage until 15 May.  If you have further questions on the report we are happy to answer them -  please send them to engagement@mdba.gov.au  

  • * Why is the current plan which is wasting precious water still being pursued, when surely it is obvious that it’s not working? The Murray mouth still has to be dredged 24/7, the lower lakes are full of carp, the Barmah Choke is being ruined trying to push too much water through, the banks along the Murray are being eroded due to unnaturally high rivers and our irrigation communities have to sit back and watch this water flow past and eventually out to sea without getting any allocation. The proposed solution of pushing a further 450g along a river that cannot possible manage that is surely ridiculous.

    Marg Bray asked about 2 months ago

    Thanks for your comments. It’s important for whole of system health for a river to run to the sea – it benefits the entire river community. Additionally,  the implementation of the Basin Plan isn’t over yet, we are still in a severe drought (and many years of implementation have been severe drought years). We have some way to go to restore system health across the Basin.

  • Captain Charles Stuart was the first white man to view the Lower Lakes, he found brackish water with NO connection to the Southern ocean, way before irrigators were there to blame. How come now we are supposed to believe that the LL were always fresh.

    Mark asked about 2 months ago

    It is important to note that the review found that the Lakes were not always fresh, rather they were predominantly fresh (occasional intrusions of sea water) and in the time leading up to settlement were more frequently fresh due to inflows and falling sea levels.  The Panel reviewed several lines of evidence, including historical accounts, Aboriginal people's oral histories, water quality records and hydrodynamic models of the system. These lines of evidence all confirmed that the Lakes were predominantly fresh and that it was this that attracted farmers to the region.

  • There is a major element missing form this report relating to Indigenous occupation of the area. There is import archaeological evidence such as Dr Chris Wilson's discovery of Murray Cod in shell middens that needs to be documented. Including evidence of occupation that sustained thousands of generations of people would help connect science and community. Can the panel reflect on how to include this important knowledge and science?

    David Crew asked about 2 months ago

    The review discussed traditional knowledge and values of the Ngarrindjeri People in Sections 2.4.1 and 4.2.1 and pointed to the several references (in particular Hemming et al. 2019 and Ngarrindjeri Nation 2019). You are correct that Chris Wilson's work is not cited in the report, but we thank you for bringing it to our attention.

  • In regards to seawater incursion into the lower lakes, can you please give an indication as to what the low river inflows were, and how that compares in relation to the average inflow now?

    Anonymous asked about 2 months ago

    The modelling with 114 years of data indicates that the average annual Murray River inflow without development (water abstraction) is 13,127 GL/yr. With current development, the average annual inflow is about half (5,966 GL/yr under pre-Basin Plan and 7,443 GL/yr under Basin Plan). With less inflow (and therefore longer and more severe periods of low flows), seawater incursion would occur more frequently and the Lower Lakes would spend significantly more time under high salinity.

  • Does the MDBA acknowledge that this being the case alternative strategies could be used to keep the Murray Mouth open at substantially reduced costs with greatly improved environmental outcomes ?

    Anonymous asked about 2 months ago

    Freshwater flows are currently important to keeping the Murray Mouth open and in the future if in flows decline, then other options may need to be explored.  However, keeping the mouth physically open is only one of the roles that freshwater flows play and at this point there are no alternatives to these functions that include flushing salt and nutrients out of the system and maintaining estuarine habitats.

  • Averages seems to be a problematic way of measuring flows per year as the 50's 70's and 90's were way above average flows. and to balance out would need periods of no flow out the barrages, like the last few years of extreme drought for example. Could I have more detail on how the average flows per year are calculated. Are the extreme years removed?

    Peter asked about 2 months ago

    Flows are measured daily. Average flow per year is calculated by summing all the daily values and dividing by how many years the specific flow record extends. No years are removed.  The Murray-Darling Basin is such a variable system it is rare for the flow in any given year to be the average flow. Long-term averages are a useful measure of river behaviour, but it is important to examine the flow during extreme years (i.e. floods and droughts) to understand the characteristics of each river.  This is particularly important in a highly variable system such as the Murray–Darling Basin.  

  • Define best available science and good science?

    Tanya asked about 2 months ago

    Best available science is complex to define, but includes consideration of its relevance, the strength of evidence used to produce it, the quality assurance processes applied to it and the extent to which uncertainty is transparent.  If you are interested in a discussion of these many considerations, please see ‘Defining and Using ‘Best Available Science:’ A Policy Conundrum for the Management of Aquatic Ecosystems’

    Best science is very similar in terms of the criteria, but focussed on the ability to repeat the research, falsify the hypotheses, the strength of evidence and the quality assurance processes applied to the work

  • Can your expert panel put a $ value on the ecological outcomes under the current management regime?

    Frank D asked about 2 months ago

    The panel reviewed the science relating to the management of the CLLMM region, they did not do an economic assessment of environmental outcomes.  This is an active area of interest and research is being undertaken that will inform this type of analysis in the future.

  • Why is the climate change agenda being pushed when clearly SA has been on the take of upstream water ever since federation?

    Tanya asked about 2 months ago

    The findings actually highlight the challenge that all governments face in sharing this vital resource in the face of climate change. The MDBA will use the results of the review to further support our current work in the area of climate change adaptation in this region and across the Basin. For more information see www.mdba.gov.au/basin-plan-roll-out/climate-change

  • No reference in the report was made to the SE drains, why is this the case, and if this report is of good science why wasn't this considered

    Tanya asked about 2 months ago

    The panel did not discuss the SE drainage scheme in detail, except stating that the South East Flow Restoration project would deliver about 6-47 GL/yr to the South Coorong near Salt Creek. The contribution of the scheme to the CLLMM region as a whole is minimal. The SE Drainage scheme puts water into the South Lagoon of the Coorong which is downstream and isolated from the Lower Lakes. There is limited information available on historical flows out of the SE into the Coorong as human activity has been influencing them since the 1860s. The projected volumes entering the South Lagoon have relatively minor influence on the Coorong and have been incorporated into the Basin Plan through the SDLAM process. The Drainage scheme helps reduce the demand placed on Murray River inflows in achieving salinity targets. The volumes derived from the SE are, however, relatively minor inputs to the system when compared to Murray River inflows. The project was funded collaboratively by the SA and Commonwealth Governments as part of implementation of the Basin Plan as part of efficiently achieving environmental objectives.   Information on the SE flow restoration project is at www.naturalresources.sa.gov.au/southeast/projects/se-flows

  • I think that if the barrages are removed and less water flows, the mouth would just silt up and stop sea water entering. Hence why there is dredging currently.

    Tracy H asked about 2 months ago

    Without the barrages, the freshwater values in the Lower Lakes cannot be maintained.  Secondly, the clogging of the Murray Mouth with sand transported by seawater, which is already happening, will be accelerated. We’ve had to dredge the mouth since 2015. It’s important to remember, we haven’t seen the Basin Plan fully implemented and that we are also in drought. We are yet to see for sure, how the system at the mouth will operate when the system is operating as planned. 

  • does this show the importance of money spent upgrading and aotomating the barrages.

    Daryl H asked about 2 months ago

    The report provided information about the importance of maintaining the barrages in place particularly in respect to water quality and sea level management, however the operation and maintenance of the infrastructure was out of scope for this project.

  • Do the presenters believe this review, or any other, can ever be authoriative enough to settle the question about the history and ideal state of the Lower Lakes once and for all?

    Perri asked about 2 months ago

    We hope this review which has been the most comprehensive to date has synthesised and explained the science.  It considered a lot of reports and shows where there’s clear consensus or knowledge and where there may be gaps.  Debates on management and on choices can then be better informed by the science, knowledge and data.

  • I will look at the report details but it appears from the webinar it was prepared with an ideological cloak………. Were the lakes fresh durring the federation drought…???.when there was no inflow…..The absolutist nature of conclusions presented in this webinar makes me suspicious as to the validity of the output. A conditional report would not have been as useful politically than a measured report noting the episodic nature of traditional freshwater inflows.

    Anonymous asked about 2 months ago

    Thank you for your comment on the report.  The MDBA welcomed the report from an independent panel which confirms water management of the Lower Lakes in South Australia is informed by evidence-based science.  The review addresses the specific terms of reference for the review.

  • Under climate change,where is the extra water going to come from if extra capacity is not put into the murray/darling system by Australian govts?

    Frank D asked about 2 months ago

    The findings actually highlight the challenge all governments face in sharing this vital resource in the face of climate change. The MDBA will use the results of the review to further support our current work in the area of climate change adaptation. For more information see www.mdba.gov.au/basin-plan-roll-out/climate-change  

  • Why is phillip Glyde requesting we leave behind this historial debate, when clearly we have the right to question the science and peer reviews? What is he protecting and who are the beneficiaries of this report?

    Tanya asked about 2 months ago

    We hope this review by an independent scientific panel looking at all historic science has synthesised and explained the science, where there’s clear consensus or knowledge and where there may be gaps. Debates on management and on choices can then be better informed by the science, knowledge and data. This comprehensive review of the science confirms it is time to put history to bed and focus on the future.

  • What plans are in place to extensively communicate the positive outcomes which have been achieved through the flows recovered to date?

    Amy W asked about 2 months ago
    Communicating on the effectiveness of Basin Plan outcomes is a high priority for all governments and communities. More information can be found at www.mdba.gov.au/managing-water/water-for-environment