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.
‘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.
‘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’
‘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.
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.’