A new Lower Hunter dam could take years to fill, rendering it potentially useless in the midst of a severe drought, the minutes of a workshop to discuss new surface water storages show.
The numerous engineering, environmental and regulatory challenges associated with building dams were discussed in the workshop between Hunter Water engineering staff and consultants AECOM in February 2018.
The time taken between when a dam was completed and when it would become a viable water source was among the issues raised.
A staff member noted this period 'could be years depending on rainfall' while another suggested it could be as much as 20 years.
Communities opposed to the construction of new Lower Hunter dam have seized on the detail, revealed via a recent NSW Upper House Call for Papers order, to argue that dams do not represent a viable option for improving the region's water security.
Yet dams are among a series of options that Hunter Water is investigating as part of its review of the Lower Hunter Water Security Plan.
In particular it is examining options to build a so-called 'satellite dam' at either Limeburners Creek or Upper Chichester.
A Hunter Water spokeswoman said the latest modelling showed it could take about three-and-a-half years to fill a 230 gigalitre dam at Upper Chichester and about two years to fill a 160 gigalitre dam at Limeburners Creek.
These fill times could double in dry conditions.
"The merits of any specific proposal would need to be explored in detail, before arriving at a final view on the yield, lead-in times, potential benefits and impacts and potential cost," she said.
By comparison it was estimated it would have taken between eight and 15 years to fill the 450 gigalitre Tillegra Dam, which was abandoned in 2011.
Limeburners Creek Group spokesman Ken Edwards said he found the estimate to fill the Limeburners Creek Dam 'unbelievable'.
"Based on cost comparisons contained in the call for papers material, it would take at least eight years to fill," he said.
"It will take a lot more than two years unless they let Grahamstown Dam run dry, which I don't think they will do."
Hunter Water maintains no decisions have been made about what options will be included in the revised Lower Hunter Water Security Plan.
"There are benefits and trade-offs with all of the options and our role is to ensure we have a suitable balance to deliver a resilient and sustainable water system, both now and for future generations," the spokeswoman said.
Hunter Water highlighted the results of a 2019 community feedback forum that showed more than 60 per cent of the 153 participants felt that a new dam should be considered as an option to improve water security.
The participants displayed a stronger preference for the increased use of recycled water (94 per cent), stormwater harvesting (89 per cent), water conservation (88 per cent), water sharing (82 per cent).
Only 51 per cent said they preferred groundwater and 47 per cent opted for desalination.
Mr Edwards said he suspected Hunter Water was pursuing a predetermined agenda regarding dams.
"Community groups are gobsmacked at the arrogance of the water utility and demand that Hunter Water remove any new dams from their water demand/supply planning and adhere to the wishes of the community and many water experts, for more sustainable and environmentally friendly options," he said.
New dams were removed during the screening process for the 2014 Lower Hunter Water plan of over 70 water supply and demand options as not being able to secure the region's water supply.
"The 2014 plan was a 20 year plan, yet just three to four years into it, Hunter Water was organising a major review of the plan though there were no triggers to justify this under the terms of the original plan.
"Their prime focus seems to be the dams they have been covertly investigating for years."
The Hunter Water spokeswoman said the organisation was committed to ongoing community consultation about options to secure the region's supply.
"Information collected on all of the options under consideration in the Lower Hunter Water Security Plan has been shared with the community, and will form part of our upcoming community engagement, which is considering the benefits and trade-offs between portfolios of options," she said.
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