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March 19, 2024

Independent assessment needed to determine use of Alstonville aquifers

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A typical geological cross section of the Casino, Lismore and Alstonville area.

The Save Alstonville Aquifer Group have raised concerns regarding the potential impact on the aquifer of making it part of the Rous County Council (RCC) IWCM (Integrated Water Cycle Management Plan). Chair of Rous County Council, Keith Williams has sought to address these while water expert Peter Coombes says care and independence is needed to get the process right.

The Save Alstonville Aquifer with Tamara Smith MP were fighting against industrial water extraction. Photo supplied.

‘Water NSW have recently agreed that the deepest aquifer accessed by the Rous test drilling program is no longer part of the Alstonville Plateau system at all and will be assessed as a new application into the much larger Clarence-Moreton sand aquifer below. This aquifer at more than 250m below the surface sits underneath the fractured basalt layers of the Plateau that make up the Alstonville system,’ said Mr Williams.

‘Proving up the deep bores in the Clarence-Moreton basin would be an excellent outcome for agriculture on the plateau, as it would enable the removal of existing shallow bores (40–80m) that do impact on rural users in dry times.

Cr Keith Williams. Photo David Lowe.

‘There are currently 1.2 Gigalitres (GL) of public water supply licences in the Alstonville aquifer. This compares to more than 8GL in private licences in the aquifer on which there is currently no metering,’ he said.

Mr Williams pointed out that ‘The NSW Chief Scientist highlighted this lack of metering as the primary source of uncertainty regarding the sustainability of the Alstonville aquifer in his 2018 report.’

Speaking to The Echo, Peter Coombes, Chair of Engineering at Southern Cross University said that ‘First the sustainability and resilience of the groundwater needs to be investigated.’

‘Alstonville aquifers are a complex system with multiple different layers that take different time periods to replenish,’ he highlighted.

‘If they (RCC) are seeking a license then the licensing process both at a State Government and Commonwealth Government level would require proper studies and processes to ensure there is an adequate re-charge rate. The recharge rate needs to be significantly higher than the rate of use.

‘The NSW chief scientist might be able to say that the particular amount being removed from the region in general will be okay, but the issue is that the ground water aquifers are highly variable across space, time and depth.’

Mr Coombes had previously pointed out that ‘There are shallow aquifers that respond immediately to rainfall and deeper aquifers in the soil that have much older water in them and take far longer to respond. When you use artesian basin water you may not be getting it back for a millennium or two’

Waterways can be impacted, particularly during drought, by bores. Photo Aslan Shand.

Local impacts

‘When you get to the small scale you need to find out if it is sustainable in its community – what the impacts are on the local aquifer,’ he said.

‘If you take extra supply it seems like a minute amount across the region but you have to look at the impacts downstream and locally, on communities, environments, farming etc.

‘You can have a situation where you are withdrawing say 100 Megalitres a year and across the region it seems like nothing; but on a local community level the impacts on nearby creeks, streams, local farmers – then you get to see those local impacts of the water extraction.’

Metering private bores

Currently there is no metering on private bores in the Alstonville aquifer with Water NSW proposing to introduce metering on private bores from 2023-24.

‘Given the level of public concern expressed about ground water extraction from the Alstonville aquifer in the recent community consultation conducted by Rous, I would invite the Save the Alstonville Aquifer group to join with me in calling for the State Government to bring forward it’s metering program and ensure the community can have confidence that the 8GL of privately held licences in the Alstonville aquifer are being properly observed,’ said Mr Williams.

But Mr Coombes highlighted the need to watch the impacts from the local bore field.

‘Colleagues have told me that there is not enough measuring and monitoring currently to determine what would happen if you begin to withdraw large amount of water from the system

‘More monitoring needs to be done on additional extraction from the local aquifers.

‘It is important that the process is transparent for the monitoring that takes place to ensure that they are clear as to the impacts on the local community’s water supply,’ he explained.

Channon Gorge area to be destroyed by proposed Dunoon/Channon Dam. Photo David Lowe.

Dunoon Dam ‘no solution’

Meanwhile, Mr Williams saidthat, ‘The calls for the Dunoon Dam are no solution to the need for an additional 1GL of permanent water supply to be added to the Rous system in 2024. There is no possibility a dam could be completed prior to 2029.’

‘The upgrade of the Marom Creek Treatment Plant and its connection to newer, deeper bores is the result of secen years research and testing and the direct consequence of the decision by Rous to prioritise groundwater in 2014. It has the lowest cost and least environmental impacts of any of the options considered,’ he said.

‘As part of its decision last week, Rous Council also resolved that there would be no sale of the land at Dunoon until after the next review of the IWCM. The same decision the Council made in 2014. There remain significant issues with the Dunoon Dam site that need to be resolved before it can be progressed any further.’

‘In the meantime, Rous will re-double our efforts to make the best use of the water we have through water conservation, a pilot recycling scheme and ensuring our contingency arrangements for temporary groundwater and desalination can be brought on stream in the event of a serious drought.

‘The Alstonville aquifer is a precious resource. I am committed to Rous removing the public water supply bores from the aquifer and I will personally work to ensure that all private water extraction licences are metered and operating within their limits. It is only then that the community can have confidence that the Alstonville aquifer has been saved for future generations.’

Right questions need asking

Mr Coombes said it was essential that the right questions were asked as part of an independent analysis.

‘The studies required would have to be independent in the analysis process because water management can become a bit political,’ he told The Echo.

‘You will get different answers depending on the scale you use for the analysis and the parameters and basis of the analysis. You need a robust set of questions and answers to produce that level of report that is required.’


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3 COMMENTS

  1. No metering of bores: typical of a NATs approach, build a dam but we don’t want to know what getting extracted from the existing bores except the ones from Rous water. Seems to me we need clarity of what’s happening in the Alstonville aquifer so we can get a figure on water extraction.

  2. If an independent study is carried out to help Rous choose a new water supply source, an independent study should be carried out to help Rous understand how to best manage their existing water supply sources.

    Rous massively underused their smaller water sources (Wilsons River Source and Emigrant Creek Dam) in late 2019 and overused Rocky Creek Dam such that in six months the water level in the dam fell from 97% to 60% leading to water restrictions. Better management of their water sources (i.e. maximise the use of smaller water sources and leave as much water in RCD as possible for the very dry periods) will lead to a much greater system yield and reduce the need to panic and react by building 2nd choice water supply sources that cost rate payers hundreds of dollars extra a year, every year for the next 30-40 years, similar to what Rous did on 2003-2008. Rate payers are still paying for those mistakes.

    As for the new bore at Converys Lane (near Alstonville), a report prepared by consultant Jacobs for Rous states (p5) that “no bores have been constructed and pump tested as yet” meaning that the claimed yields from the aquifers are best estimates only. Jacobs adds yields “must be verified by thorough field testing of pilot production bores”. Rous needs to do much more work to prove the yield and water quality from the deeper Clarence-Moreton aquifer. The Federal Government report “Groundwater numerical modelling for the Clarence-Moreton bioregion” p34 states that yield from the Clarence-Moreton aquifer are less than 1L/s, way below Rous’s claimed 44L/s. If the Federal Government report is correct Rous will not get the required yield they need, most likely waste more millions and not have any additional water supply by 2024.

    Unless Rous gets help to better manage its water supply and to choose a new water source, rate payers can look forward to paying a lot more for their water, which may be welcomed by the Mayor of Lismore who is also a Rous delegate and others who think water is cheap, but ratepayers having to pay increasing bills for a less reliable service may not agree.

    The report “Groundwater numerical modelling for the Clarence-Moreton bioregion” is at https://www.bioregionalassessments.gov.au/sites/default/files/ba-clm-clm-262-gwmodelling-20170331.pdf

    Jacob’s report is available at Rous’s website https://rous.nsw.gov.au/page.asp?f=RES-TQK-65-50-21

  3. While this article is clearly focused on proving-up the Clarence-Moreton Basin, it’s disappointing that Mr. Coombes didn’t take the opportunity to address the failings of the rejected high-risk dam proposal, and to educate about the other water supply solutions that also promise security i.e water efficiency, water reuse , stormwater harvesting, and desalination. It’s not as if he lacks expertise in those areas, and putting the groundwater use into context as just part of a suite of supply options could assist in public understanding and depolarisation.
    Although its not his area of specialisation, given that SCU states ” Southern Cross University acknowledges and pays respect to the ancestors, Elders and descendants of the Lands upon which we meet and study. We are mindful that within and without the buildings, these Lands always were and always will be Aboriginal Land”, he might also have supported the Widjabul Wia-bal statements that have consistently rejected the dam option.

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